It’s been 5 years since a version of NBuilder was released. As happens to many of us, the original author got busy with life and was unable to spend the time brining it up to date. I volunteered to shepherd the project along, but I was also waylaid by life. However, I was recently able to spend some focused time fixing the final bugs and getting together an automated build with AppVeyor.
Given that it’s been 5 years, it’s impossible to know fully what has been changed. I did put together release notes for the things I know were changed.
My next task will be to port NBuilder to .NET Core
Release Notes for NBuilder 4.0.0
Breaking changes
1. Obsolete methods have been removed.
Any method previously marked with the Obsolete attribute has now been removed.
2. Silverlight No Longer Supported
As Silverlight is effective a dead technology, we have officially ended support for it. This will allow us to better focus on
a forthcoming release with .NET Core support.
New Features
1. Builder has a non-static implementation.
This will allow you to create customized BuilderSettings for different testing scenarios.
Old Code
<br />var results = Builder<MyObject>.CreateListOfSize(10).Build();
New Code
<br />var settings = new BuilderSettings()
var results = new Builder(settings).CreateListOfSize<MyObject>(10).Build();
2. With and Do action now supports a signature that receives an index.
Example
<br />var builderSettings = new BuilderSettings();
var list = new Builder(builderSettings)
.CreateListOfSize<MyClassWithConstructor>(10)
.All()
.Do((row, index) => row.Int = index*2)
.WithConstructor(() => new MyClassWithConstructor(1, 2f))
.Build();
Bug Fixes
- The decimal separator was wrong for some cultures.
- Random number generation of decimals was sometimes incorrect.
- Sequences were not created in the correct order.
- Random strings were not always generated between the expected lengths.
1. DevOps is hard
It might not seem like it, but DevOps is hard. A few years ago I thought to myself that it can’t be that difficult since installing an individual application isn’t that difficult. I was wrong in part because…
2. Security is hard
Production is scary. I’d rather not have access when possible. On the other hand the tools that we use will definitely need access to production since it’s kind of the reason they exist. This means we have to have very tight control over who has access to the credentials that the tools run under. We work to limit our own day-to-day accounts so that their access is limited as well.
As a developer I didn’t think much about Security. I pretty much just stuffed an AD Group in a config file somewhere when I was told to and I was done. As a DevOps engineer I have had (and will continue) to learn a lot more about security and its organization even though I don’t manage security for my organization. Security impacts deployments at every level so you will have to learn about security infrastructure in order to make safe and practical recommendations to your security administration group.
3. You are not Netflix (unless you are)
Our organization got excited about DevOps tools after seeing some compelling presentations by Netflix at QCon San Francisco. Netflix has the need for highly scaled web servers which fully embrace the “cattle vs. pets” philosophy because they have millions of concurrent users of a publicly facing service.
We are not Netflix. We have 50+ internal applications with usage rates measured in the 10’s. They’re important to us–they run our business–but our problems are not the same ones Netflix faces. The tools that Netflix uses are designed to solve problems Netflix has. That doesn’t necessarily make them a good fit for our needs. We lost a lot of time and effort trying to make Netflix solutions fit our problems.
4. Windows vs. Linux matters when choosing your tools.
There are basically 5 possibilities when it comes to your server topology:
- Windows Only
- Linux Only
- Windows Dominant
- Linux Dominant
- Hetergeneous
If you are managing a homogeneous ecosystem then it’s imperative that you use tools that natively support that system. Don’t try to use Linux tools to manage Windows and vice versa. If you do, you’re gonna have a bad time. If you are primarily deploying to Windows you should look at tools like Octopus Deploy or Build Master. If you’re managing a Linux ecosystem look into Chef, Puppet, or even Docker.
If you’re managing a mixed ecosystem where one OS was dominant, you should still use tools designed to support the dominant system. It may be worth the effort to see if your existing tools can also manage the subdominant system. In our case it’s not worth the effort so we have instead moved toward an “appliance” model for our Linux servers. What this means is instead of managing a bunch of code to deploy RabbitMQ to Linux, we’re instead creating VM Images for the Rabbit installation which we can hydrate at will. We have far fewer resources who know how to administer Linux so this model works better for us.
5. DevOps tools are in their infancy
DevOps tools are optimized for the problems their creators were facing. There are many more problems in the DevOps space than any of the dominant tools are capable of managing on their own.
For example, Chef wants to deploy a machine. It’s not primarily concerned about applications. The Chef model is to declare the state of the machine and then let Chef decide how to bring the machine to that state. This approach optimizes for horizontally scaling hundreds or thousands of identical nodes with very few commands. Awesome!
In our organization we see the world in terms of Applications–not machines. Our whole way of thinking about deployment is different than the way Chef looks at it. This isn’t a deficiency in Chef or in the way we look at the world, but when we started using Chef we weren’t aware of how fundamental that difference in perspective would actually be.
Because Chef looks at the world in terms of nodes, it has no built-in (or even recommended) solution for artifact and version management. We had to build that. We had to build solutions for managing cookbook versions, publishing artifact and cookbook versions into targeted environments, and forwarding changes to production to antecedent environments.
If you’re using Octopus (we’re migrating from Chef to Octopus) and looking at the world in terms of applications, you will have problems when you need to spin up new environments and whole machines with many applications pre-installed. Either way, you will have to build other tools to glue the off-the-shelf tools together.
(Aside: Though I am not personally a fan of Chef, I have heard of people using Chef to deploy their infrastructure and using Octopus to deploy applications.)
6. DevOps “best practices” are in their infancy
Chef likes to advertise “use Chef however you want! We’re flexible!” Great…. except Chef is complicated and I would like some guidance on how to use it! This isn’t so much a problem with Chef though–DevOps in general is a very young field so we don’t have the wealth of shared experience from which to draw generalized lessons. To the extent that there is guidance it’s basically cribbed from Software Engineering best practices and doesn’t always apply well.
Here are some of mine:
- Have a canary environment that rebuilds all machines and redeploys all software on a regularly scheduled basis. Use this environment to detect problems in your deployment tool chain early.
- Every developer should have an individual environment of their own to test deployments.
- Every team should have at least one environment for testing and/or UAT.
- Avoid “Standard Failures.” These are errors that occur often and either do not have a known solution or have a manual workaround. Identify the root cause of errors and address them. Incorporate manual workaround solutions into your automated solutions.
- Where possible, embed some sort of “health check” into your applications that you can invoke to have the application check it own configuration.
- Identify rollback strategies for your applications.
7. Developers will have to learn infrastructure
If you come from a development background you will have to learn about security, networking, hardware, virtual hardware, etc. This is the domain you are working in now. I’m still at the beginning of this process myself but I’m starting to see the size of how much I still have to learn. For example, if you’re deploying to the cloud you’ll have to learn the inner workings of your chosen cloud infrastructure.
8. Ops will have to learn development patterns and practices.
If you come from an Ops background you will have to learn Software Engineering patterns and practices. You are graduating from someone who writes the occasional script to someone who manages code. Writing some code that only has to be run once is easy. Writing code that has to work again and again and again as well as tolerate change is much, much harder. As the number of people, environments, and machines grow software engineering skills will become more and more important.
9. Don’t automate a bad process.
Consider this: Chef doesn’t provide a built-in way to define which artifacts should be deployed to which environments. To that end we built an “application versions” cookbook which contains a list of all applications, their version, and their artifact location. In order to start work a team must:
- Take a branch of the application versions cookbook.
- Edit the versions/artifact information.
- Upload the cookbook to Chef
- commit and push the changes back to github
- clone the chef-repo
- edit the affected environment to use the new version of the application versions cookbook.
- commit/push chef-repo
- upload the edited environment to Chef.
Does that sound like a good idea to you? It doesn’t to me–but it’s necessary if you’re going to use a Chef Cookbook as a source for environment application versions. Before you go and wrap some automation around this to make it “easier,” let’s challenge the basic assumption: should we maybe just store application versions by environment elsewhere? A json file on a network share would be easier than this.
When you automate a process (even to make it “easier”) you’re pouring a certain amount of lime over it. Be careful.
10. “Infrastructure as Code!” is not always a good idea.
Code != Artifacts != Configuration. The daily work of DevOps breaks down into basically three disciplines: Code, Configuration, and Artifact management. A change to one of these should not necessitate a change to the other. That means that Code, Configuration, and Artifacts should not live together in github.
Use a Package Manager for your artifacts. If you don’t know where to look check out Artifactory. It’s a versatile artifact repository that supports many different kinds of package managers. It’s API even understands version numbers and will let you identify and retrieve the “latest” version of your artifact. Let your CI server publish artifacts to your package manager and make it the canonical source for artifact retrieval.
Configuration should not be managed like code. Configuration data is any data required by applications to run. Examples are things like dns addresses, email addresses for notifications, database connection strings, api endpoints, etc.. Configuration data is just data about environments. Unlike code it does not need to be branched. It should be stored in some central repository and accessed directly by the deployment code.
The code that you use to execute your deployments is most emphatically and in every possible way code. This means it should be tested, stored in source control, subject to your company’s chosen branching strategies, built by a CI server, etc..
The “infrastructure as code” idea is a really great idea, but it applies only to the procedure of deploying hardware and software. It does not fit well with the metadata that describes which hardware and software should be deployed. Don’t use “infrastructure as code” as an execute to push square pegs into round holes.
As part of our Octopus Deploy migration effort we are writing a powershell module that we use to automatically bootstrap the Tentacle installation into Octopus. This involves maintaining metadata about machines and environments outside of Octopus. The reason we need this capability is to adhere to the “cattle vs. pets” approach to hardware. We want to be able to destroy and recreate our machines at will and have them show up again in Octopus ready to receive deployments.
Our initial implementation cycled through one machine at a time, installing Tentacle, registering it with Octopus (with the same security certificate so that Octopus recognizes it as the same machine), then moving on to the next machine. This is fine for small environments with few machines, but not awesome for larger environments with many machines. If it takes 2m to install Tentacle and I have 30 machines, I’m waiting an hour to be able to use the environment. With this problem in mind I decided to figure out how we could parallelize the boostrapping of machines in our Powershell module.
Start-Job
Start-Job is one of a family of Powershell functions created to support asynchrony. Other related functions are Get-Job, Wait-Job, Receive-Job, and Remove-Job. In it’s most basic form, Start-Job accepts a script block as a parameter and executes it on a background thread.
# executes "dir" on a background thread.
$job = Start-Job -ScriptBlock { dir }
The job object returned by Start-Job gives you useful information such as the job id, name, and current state. You can run Get-Job to get a list of running jobs, Wait-Job to wait on one or more jobs to complete, Receive-Job to get the output of each job, and Remove-Job to delist jobs in the current Powershell session.
Complexity
If that’s all there was to it, I wouldn’t be writing this blog post. I’d just tweet the link to the Start-Jobs msdn page and call it done. My scenario is that I need to bootstrap machines using code defined in my Powershell module, but run those commands in a background process. I also need to collate and log the output of those processes as well as report on the succes/failure of each job.
When you call Start-Job in Powershell it creates a new session in which currently loaded modules are not automatically loaded. If you have your powershell module in the $PsModulePath you’re probably okay. However, there is a difference between the version of the module I’m currently working on and testing vs. the one I have on my machine for normal use.
Start-Job has an additional parameter for a script block used to initialize the new Powershell session prior to executing your background process. The difficulty is that while you can pass arguments to the background process script block, you cannot pass arguments to the initialization script. Here’s how you make it all work.
Setup Code
<br /># Store the working module path in an environment variable so that the new powershell session can locate the correct version of the module.
# The environment variable will not persist beyond the current powershell session so we don't have to worry about poluting our machine state.
$env:OctobootModulePath = (get-module Octoboot).Path
$init = {
# When initializing the new session, use the -Force parameter in case a different version of the module is already loaded by a profile.
import-module $env:OctobootModulePath -Force
}
# create a parameterized script block
$scriptBlock = {
Param(
$computerName,
$environment,
$roles,
$userName,
$password,
$apiKey,
)
Install-Tentacle -computer $computerName `
-environment $environment `
-roles $roles `
-userName $userName -password $password `
-apiKey $apiKey
}
# I like to use an -Async switch on the controlling function. Debugging issues is easier in a synchronous context than in an async context. Making the async functionality optional is a win.
if ($async) {
$job = Start-Job `
-ScriptBlock $scriptBlock `
-InitializationScript $init `
-Name "Install Tentacle on $($computerName)" `
-ArgumentList @(
$computerName, $environment, $roles
$userName, $password,
$apiKey) -Debug:$debug
} else {
Install-Tentacle -computer $computerName `
-environment $environment `
-roles $roles `
-userName $userName -password $password `
-apiKey $apiKey
}
The above code is in a loop in the controlling powershell function. After I’ve kicked off all of the jobs I’m going to execute, I just need to wait on them to finish and collect their results.
Finalization Code
<br />if ($async) {
$jobs = get-job
$jobs | Wait-Job | Receive-Job
$jobs | foreach {
$job = $_
write-host "$($job.Id) - $($job.Name) - $($job.State)"
}
$jobs | remove-job
}
Since each individual job is now running in parallel, bootstrapping large environments doesn’t take much longer than bootstrapping smaller ones. The end result is that hour is now reduced to a few minutes.
Why We’re Migrating From Chef to Octopus
A couple of months ago I started leading a team that was using Chef to manage our deployment infrastructure. We are now migrating from Chef to Octopus Deploy. I thought it might be interesting to explain why. What follows is my opinion and my best understanding of the facts. As always, do your own thinking. 🙂
Chef
Chef takes the DevOps mantra “infrastructure as code” to heart. Everything created for consumption by Chef is code. This is a strength in many ways, but sometimes a weakness.
Architecture
Chef consists of a server which contains metadata about your infrastructure, “cookbooks” which contain instructions for configuring machines and applications, and a client application which does the work of truing up a machine to its representation in the Chef Server.
In Chef, the target of work is a node. When chef_client runs it’s goal is to make the node it’s running on look like Chef Server expects it to. It has little awareness of applications except insofar as you layer that into your cookbook design. chef_client pulls the data it needs from the chef server in order to do its work. This means that in order to update a machine you have to have access to that machine as well as rights to run chef_client. This also means that it takes a bit more effort to be able to redeploy a single application to the node in the event something goes wrong. If you are running single-purpose nodes that’s probably not an issue for you.
It bears mentioning that Chef was designed for Linux first. Windows is an afterthought and it shows. There was no built-in support for common Windows constructs such as IIS and Windows Services at the time of our implementation. (My understanding from a coworker is that Chef now has built-in support for windows services.)
Chef has an api, but it’s nearly impossible to access using standard tools due to a convoluted authentication model. Chef as a CLI called knife which wraps up most api behavior. It should be stated that you cannot initiate activities through the api–that is all done by running chef_client on the target machines. knife can query the api for the machines you want and initiate chef_client runs for you however.
Developer Experience
The developer experience with Chef is all about editing cookbooks. A “cookbook” is a collection of “recipes” that can be executed by chef_client on the target node. Cookbook development involves using a ruby dsl that transpiles to raw ruby on the target node during a process called “convergence.” You edit the cookbook, push the modified cookbook to the chef server, then run chef_client on the node. On the surface this seems simple. It’s not.
If you are staying “in the rails” (rimshots for the ruby joke 🙂 ) with chef and using their built in functions (called “resources”) to do your work, you will mostly be okay. If you are interested in testing your work you will start to feel pain. Chef provides the ability to do “local” testing–by which they mean spinning up VM’s using Vagrant over VirtualBox. “Local” in this context doesn’t mean you get to see the transpiled ruby before it executes, or step into a debugger. It just means that the VM you’re testing on happens to be running on your developer machine.
There are tools or automated testing with Chef cookbooks. We haven’t really learned to use them very well so I can’t personally comment on their quality. My coworker had this to say:
There is a commonly used unit testing framework for Chef, called ChefSpec (which is built upon RSpec). I have issues with ChefSpec, so most of my Chef unit tests are done in pure RSpec. However, ChefSpec is not officially supported by Chef.
There is chef-zero, which allows you to spin up an in memory mock Chef Server, which will allow you to start/pause/stop a mock node convergence, and will allow you to examine attributes at different steps of resolution. Test-Kitchen is the integration testing framework, which spins up actual VMs and uses Vagrant as a driver (it may use Docker now? Not sure), then fully converges that VM as a node. So the Chef ecosystem has the ability to do lots of testing at various levels. I feel it is inaccurate to state that testing is poor in Chef. What is accurate to state is that Chef is Linux first, Windows afterthought. So all the testing goodness in the Chef ecosystem was either unavailable to us as a Windows shop, or it was extremely difficult to use. … we knew that lack of testing was a weakness in our Chef code. We really tried to make it happen, but the hurdles were insurmountable with the resources available.
You can customize chef behavior by writing “resources” and “providers.” This process is not straightforward or easy to understand and frankly I still find it confusing. When writing new code for chef you can use straight ruby, but consuming standard ruby gems is problematic because of the convergence process. It’s not clear when the ruby code will run. Sometimes it runs during convergence. Sometimes it runs at when a recipe is called. Keeping it all straight and making it work as expected requires some mental and technical gymnastics. We had numerous errors caused by ruby code not executing when we thought it would.
Guidance
There is very little guidance about the correct way to use Chef. In fact, Opscode seems to pride itself on this fact. They exclaim on twitter and at conferences “You can use Chef anyway you want!” Great–but how should I use Chef? This is not a trivial question as there are at least 3 kinds of cookbooks in Chef development. There are cookbooks that define data, define utilities or “resources”, and deploy applications. There are 6 levels of overrides for variables. Which data should you put in application cookbooks vs. environment cookbooks? When should you use overrides and how?
Community
Chef has elected to rely on the community to provide cookbooks for most things. Some vendors have created officially supported cookbooks for their products, but most have not. Who can blame them? There’s no clear winner in the DevOps space yet, so why spend the time and money to support a tool that may fizz out? This means that most community cookbooks are of dubious quality. They are generally designed to solve the particular problem the author was facing when they were trying to install something. They may or may not set things up in a recommended fashion. They make assumptions about the OS, version, security, and logging strategies that are by no means universal. This left us in the position of having to read and fully understand the cookbook before deciding whether or not to use it. More often, we just ended up writing our own customized version of the same cookbook.
Conclusion
It’s clear to us that Chef is not a good fit for our organization. We deploy 50+ applications to 40+ environments. Because chef provisions a node and not an application if there’s a problem in any one application the entire deployment is considered a failure. We were never able to get above 80% successful deployments across our environments. Many of the reasons for this failure were non-technical and have nothing to do with the tool, but the complexity of the tool did not help us. Finding expert-level help with Chef on Windows was equally problematic. Even at the conferences we attended, the Windows Chef implementors were like the un-cool kids sitting at a table by themselves in the corner not quite excited by the “ra ra ra” of the pep rally.
If I were going to use Chef I would use it in an ecosystem that had fewer applications and more servers. Let’s say I had a web service that I needed to horizontally scale across 1000 Linux nodes. Chef would be a great fit for this scenario.
My co-worker says:
Chef would be a good choice if
a. You use Linux
b. You have a simple deployment topology, which can be supported by Systems Engineers who can do a little scripting (i.e., use only the built in resources).
c. Or you have a large DevOps engineering team that has enough throughput to dissect the bowels of Chef.Chef is designed for a setup where there are thousands of nodes, each node is responsible for doing 1 thing, and it is cheap to kill and provision nodes. Because we use Windows, we have hundreds of nodes [and] each node is responsible for many things. It is expensive to kill and provision nodes. Windows is moving towards the cattle not pets paradigm, but it’s not there yet. Chef is designed to work with setups that are already at the cattle stage.
Octopus
Octopus kind of ignores the “infrastructure as code” idea and tries to give you a button-click experience for deployments.
Architecture
Octopus Deploy is composed of a web server and a windows service. The web server stores metadata about your hardware and software ecosystem. The windows service (called Tentacle) is installed on each machine that Octopus will manage and performs the work locally. Octopus was developed api-first which means that all of the functionality you invoke through the Web UI is available through the api. The api is secured using standard models which means it is easy to consume using your favorite tools.
Instructions are packaged up by the server and pushed to the Tentacle agents where they are executed. As long as the Tentacle service account has the requisite permissions, anyone with permission to deploy through Octopus Server can deploy to the target machines even if they don’t otherwise have access to those machines.
Whereas Chef is node-centric, Octopus is application-centric. This is a strength in that it’s easy to deploy or redeploy a single application to a node that may have many applications on it. This is a weakness in that it’s harder to deploy all of the applications required for a particular machine (more button clicks). This weakness will be mitigated by the elastic environment features of the soon-to-be-released 3.4 version.
Octopus separates artifact management from release process management. You can modify your release process without ever editing your deployment artifacts, and vice versa. Deployment artifacts are a first class citizen in Octopus. You will have to layer in your own artifact management into Chef.
Developer Experience
Octopus is written in C# and runs on Windows. The advantage over Chef here is that we get native Active Directory integration for security purposes. In the Octopus world developers publish their applications as NuGet packages which are already understood by most .NET developers. The nuget package defintion lives with the application source code so no external mapping of deployment code to the application is required. Further, it’s obvious which bits go in the NuGet package and which bits will live on the Octopus Server.
Octopus uses one of several variable substitution techniques to manage the config files. Since Octopus was written with Windows deployments in mind, it contains built in processes for deploying IIS applications and Windows Services. If further customization is needed, developers can write custom scripts in Powershell as either a Step Template or a script included in the nuget package.
Unlike Chef, you can test the scripts you write locally with the caveat that you will have to provide any variables they require to execute. Since it’s just Powershell you can use any of the existing tools and debuggers written for Powershell. The lack of a transpilation step means that the code you wrote is the code that will run.
Guidance
Like Chef, Octopus has not “won” the DevOps space. My impression from the community is that the percentage of shops working in the DevOps space at all is fairly low so this isn’t a mark against either tool. However, low adoption means that there are fewer people sharing their lessons learned with the world. If you go looking for Octopus best practices, you won’t find much more than my blog series. Most “best practice” articles and videos about DevOps consist of little more than advice to automate all the things.
On the other hand, the way Octopus itself is structured steers you toward some best practices. Some of these ideas could be layered onto a Chef implementation just as easily, but Octopus is opinionated in such a way that it steers you in the right direction. It’s nice to have Octopus tell us “this is the blessed path to accomplish your goal.”
Octopus distinguishes variables from processes. A Release Process is a set of logic that results in the successful deployment of an application to a machine in an environment. It is informed by variables, which can be scoped to environments and roles (and channels as of version 3.3). Variables can be managed at a project level or in shared libraries called Variable Sets.
Custom logical steps can be defined in powershell, stored and versioned in Octopus, and used as part of the Release Process. These are called Step Templates. Step Templates are usually a lighter weight maintenance effort than a cookbook since they’re just powershell and often targeted at very small units of functionality that can be chained together without much overhead.
In Octopus, a Release is created which binds a deployment artifact to a set of variables and instructions. This release is then promoted through a series of environments defined in a lifecycle. There is no binding of artifacts to cookbooks in Chef unless you write that yourself.
Community
My impression is that the Octopus community is smaller than the Chef community. There is only one sanctioned mechanism for the community to share code–a github repo which Octopus itself reviews before accepting pull requests. The fact that Octopus reviews contributions gives me the impression that the quality of the community code is better than what we found in Chef. Having gone through the review process with them for a new step template we created we know that they are actually looking at the code. On the other hand, since Octopus targets the Windows ecosystem and has built-in support for most things Windows the need for community help isn’t as great.
Conclusion
When we were first learning Octopus, our first deploy from time to install was about 30 minutes. With Chef there were days of training and hours spent tweaking cookbooks until we got our first deployment. Octopus is simply easier for us to understand. We have a small team of 3 dedicated developers to manage 40+ environments that must be deployed with 50+ applications on demand. In addition this team manages Artifactory, TeamCity, and glue-code that ties these systems together. Our goal is to bring our successful deployment rate up to 95+% and not need babysit deployments to production.
For our needs Octopus is the clear winner. We are a .NET shop deploying C# applications to the Windows ecosystem. Octopus is a C# application that runs on Windows. Octopus’ understanding of our problem space is far superior to Chef. The tools they provide are high quality, easy to use, and work with very little configuration. There are gaps to fill, but the fact that Octopus is written API-first gives me confidence that we can easily fill them.
DevOps is a relatively new space in the software engineering world. There are a smattering of tools to aid in the automation of application deployments, but precious little guidance with respect to patterns and practices for using the new tools. As a guy who loves leaning on principles this lack of attention to best practices leaves me feeling a bit uncomfortable. Since I’m leading a migration to Octopus Deploy, I thought I would share some of the decisions we’ve made.
This series of posts is an attempt to start a conversation about best practices. I want to be clear: We have not been applying these ideas long enough to know what all of the ramifications are. Your mileage may vary.
Posts in this series
1. Environments
2. Roles
3. Variables & Variable Sets
Variables & Variable Sets
Octopus Deploy allows you to modify your application’s configuration through the use of variables. You can define variables at the project level, or share variable values between projects through variable sets. If you have relatively little sharing of variables between projects you will likely prefer to create variables at the project level. My team manages over 50 different applications. Many of them are web services designed to support SOA. The net impact is that we have a lot of shared variables and for this reason we define variables exclusively through variable sets. This saves us time hunting for where a given variable is defined.
We use 2 kinds of variable sets
1. Global
2. Role based
Global variable sets define values that might be required across the company irrespective of any particular application, or that are more easily managed together. For example, we wish to capture metadata about environments. Octopus itself does not have a facility for tagging environments with arbitrary metadata. To satisfy this goal we created a variable set called “environment” in which we create variables to indicate values such as “owner” and “abbr”. We use these values to compose the values of other variables such as dns addresses or email addresses.
We also have some environments for which we do not create dns addresses for the sites. In these environments we need to install web applications with alternate ports. We keep a variable sets to define the port number we use for web applications in these environments since they must be unique across the web server.
The number of global variable sets should be as small as possible.
Role based variable sets are variables defined for the specific roles they target. If we have a role called heroes-iis we will also have a variable set called heroes-iis. Since we create roles on a per-deployed-application basis, this helps us keep roles, projects, and variable sets linked. If heroes-iis as web service end points, this variable set may be included in some other project that depends on those end points.
Naming Conventions
It is important to have naming conventions for your variables. I highly recommend prefixing all variables in a variable set with the name of the variable set to avoid potential naming collisions. For example, If I have a variable set called heroes-iis it will have variables with names like:
- heroes-iis.application-pool.name
- heroes-iis.application-pool.password
Define a Standard Structure for Similar Variable Sets
Once you get the rhythm of installing applications with Octopus, you will discover that similar kinds of applications have similar variable definition needs. You can save yourself a lot of time and Chrome tabs by establishing a variable set template that you use when creating a variable set for each kind of application you deploy. Here is our variable set template for web applications being deployed to iis:
| Variable Set Name | Segment | Field | Variable Name | Notes |
|---|---|---|---|---|
| name-iis | application-pool | name | name-iis.application-pool.name | The name of the application pool |
| username | name-iis.application-pool.username | the username the application pool runs under | ||
| password | name-iis.application-pool.password | the password the application pool runs under | ||
| host | name.host | This corresponds to the site name as registered in IIS. It does not include the protocol (http://, https://). It should be blank if the site is being deployed into an environment without a dns entry. | ||
| site-name | name.site-name | This will be just the name of the web application in environments that do not have a dns entry. If the environment has a dns entry, it should resolve the host property. | ||
| site-root | name.site-root | This is the url root for the site. It should include the protocol (http://, https://) as well as the port, and any additional routing information. | ||
| endpoints | endpoint-name | name.endpoints.endpoint-name | A web service may expose one or more endpoints. These should have unique names. Their values should be defined with reference to the host and port variables. | connection-strings | cs-name | name.connection-strings.cs-name | The name of the connection string in the config file. |
Scope
Octopus Deploy allows you to scope variables by environment, role, or channel (as of 3.3). The scoping rules are as follows:
(environment1 OR environment2 OR ...) AND (role1 OR role2 OR ...) AND (channel1 OR channel2 OR ...)
I recommend that you scope variable values as broadly as possible. Use composed variable values where you can to minimize the number of variable values you have to maintain. For example:
<br />heroes-iis.connection-strings.heroes-db => "Server=#{environment.sql-server.url}; Database=#{heroes-db.database-name};"
heroes-db.database-name => #{HEROES_}#{environment.name}
environment.sql-server.url => http://sql-server.#{environment.name}.com
By using a composed variable value I don’t need to scope the connection string variable itself. Instead, I can confine scoping to environment.name and satisfy the resolution of all of the descendant variables. This minimizes the number of variables I have to actively maintain as new environments are created.
DevOps is a relatively new space in the software engineering world. There are a smattering of tools to aid in the automation of application deployments, but precious little guidance with respect to patterns and practices for using the new tools. As a guy who loves leaning on principles this lack of attention to best practices leaves me feeling a bit uncomfortable. Since I’m leading a migration to Octopus Deploy, I thought I would share some of the decisions we’ve made.
This series of posts is an attempt to start a conversation about best practices. I want to be clear: We have not been applying these ideas long enough to know what all of the ramifications are. Your mileage may vary.
Posts in this series
1. Environments
2. Roles
3. Variables & Variable Sets
Roles
When you add machines into Octopus, you must specify environments and roles for that machine. For our purposes, environments were pretty easy to define. Roles however took some work. Here are the kinds of roles we defined.
Operating Systems
Example: windows, linux
This is pretty easy. We started with Linux and Windows for this type of role. I can see a day when we may need to additionally specify ubuntu-14 or 2k8-r2. In the meantime, YAGNI.
Environment Types
Example: dev, uat, integration, staging, prod, support
Our environment naming convention for developer environments is dev-{first initial}{last name}. For uat environments it’s uat-{team}. There is only one of each integration, staging, production, and support environments. There are certain variables that are defined consistently across all dev environments but may differ in uat environments. For this reason we are applying the environment type as a role across all machines in the relevant environments.
Commands
Example: hero-db.migrator
This is a standalone role. There will only be one machine in each environment that will have this role. It’s purpose is to execute commands on some resource in the enviornment that should not be run multiple times or concurrently. A good example of this is an Entity Framework database migration. We choose one machine in an environment that database migrations can be run from.
Applications
Example: webapp-iis, topshelf-service
Each deployable application has its own role. Not every application gets installed on every machine in an environment. We use the -iis affix for applications installed into IIS regardless of whether they’re sites or web services. We use the -service affix for Windows Services. We do this because we sometimes have a family of applications that have the same name but target a different kind of application.
DevOps is a relatively new space in the software engineering world. There are a smattering of tools to aid in the automation of application deployments, but precious little guidance with respect to patterns and practices for using the new tools. As a guy who loves leaning on principles this lack of attention to best practices leaves me feeling a bit uncomfortable. Since I’m leading a migration to Octopus Deploy, I thought I would share some of the decisions we’ve made.
This series of posts is an attempt to start a conversation about best practices. I want to be clear: We have not been applying these ideas long enough to know what all of the ramifications are. Your mileage may vary.
Posts in this series
1. Environments
2. Roles
3. Variables & Variable Sets
Our Default Lifecycle
Before I begin, I should give you some background on our development ecosystem. Our Octopus Lifecycle looks like this:
dev => uat => integration => staging => prod => support
The Environments
| Name | Convention | Purpose | Notes |
|---|---|---|---|
| dev | dev-{first initial}{last name} | The primary purpose of these environments is to test the deployment tooling itself. | We have 15 or so individual developer environments. Each developer gets their own environment with 2 servers (1 Linux, 1 Windows) and all of our 60 or so proprietary applications installed to it. |
| uat | uat-{team} | These environments are used by teams to test their work. | We have 10 or so User Acceptance Testing environments. These are a little bit more fleshed out in terms of hardware. There are multiple web servers behind load balancers. The machines are beefier. These enviornments are usually owned by a single team, though they may sometimes be shared. |
| integration | N/A | Dress rehearsal by Development for releases | The integration environment is much closer to production. When multiple teams are releasing their software during the same release window, integration gives us a rehearsal environment to make sure all of the work done by the various teams will work well together. |
| staging | N/A | Dress rehearsal by Support for releases | Staging is exactly like integration except that it is not owned by the Development department. We have a team of people who are responsible for executing releases. This is their environment to verify that the steps development gave them will work. |
| prod | N/A | Business Use | Prod is not managed by the deployment engineering team. We build the button that pushes to prod, but we do not push it. |
| support | N/A | Rehearsal environment for support solutions | Support is a post-production environment that mirrors production. It allows support personnel to test and verify support tasks in a non-prod environment prior to running them in production. |
When I started following @OctopusDeploy on twitter in preparation for adopting it for Redacted Financial Services Inc., I saw that they were sending representatives to the Kansas City Developer’s Conference (@kc_dc, #kcdc16). I looked up the conference and saw that @jeffreypalermo was going to be there as well. Excited, I reached out to @darrencauthon to see if he would be there too. When I got the confirmation, I’d made up my mind to go.
Living in the Northwest, I’d never heard of this conference. I’m super glad I came. There 1600 people at the conference. The topics’ focus are a little .NET centric but range toward the philosophical as well as the technical. In addition to .NET, there are presentations on R, Ruby, Javascript, leadership, etc.. The keynote encouraged attendees to learn more deeply about something they’re already doing and also learn something completely new.
This is exactly what I was wishing for in a conference. I’ve enjoyed the opportunity to talk with the gentlemen at @OctopusDeploy. I was impressed by the quality of Jeffrey Palermo’s talk about Continuous Delivery. I greatly enjoyed hearing about new technologies such as Semantic UI. I was fascinated by the differences between Angular, Ember, Knockout, and ReactJS. I’m now very interesting in trying out React.
The highlight was meeting Darren Cauthon in person after 5 years of being twitter friends. Darren & I are kindred spirits in that we both believe in TDD and strive for quality, well-crafted code. We both have backgrounds in .NET and experience with Ruby (though his experience with Ruby is far superior to mine).
I’ll come to this conference again–perhaps as a speaker next time.
I’m in the midst of setting Redacted Financial Services Inc. up to use Octopus Deploy. An issue we’ve had with automated deployments in the past is that the tooling reports that everything is okay, but later we find out the software is misconfigured for the environment it’s installed in. To resolve this problem we’ve started including a service health api into our deployed web services & sites. At the end of any deployment we can issue a GET to the api and have the site tell us whether or not it is at least configured in such a way that it can access its dependent databases and services. Anything other than a 200 and we fail the deployment. We are also handing this api call off to Nagios for monitoring.
The code sample below demonstrates the implementation of this api. We deliver as a code-based add-in using our internal nuget feed. It includes health checks for Sql Server, Couchbase, Rabbit MQ, and standard REST services. This code is longish and we’ll probably open source it after we’ve had a chance to bake it. If you try it out let me know how it works for you.
In the time since I first wrote about my software engineering internship program I’ve gotten a bit more organized and had some new observations and insights. The philosophy behind the program is the same, but I can now better discuss the practical implementation, side-effects, and ROI. If you are interested in starting your own program, you should definitely read my first post on the topic as it covers the strategic elements in greater detail.
Return on Investment
Running the internship has costs. They are:
- ~15% of the mentor’s salary
- ~5% of the coach’s salary
- The intern’s salary
- The cost of equipment
- The cost of a Pluralsight License
- The cost of Clean Code and The Pragmatic Programmer
How do we justify this to the business? How is the program cost-effective?
After the bootcamp phase of the program the interns can usually write test-driven code with a level of quality approaching that of any other software engineer. We give them projects to work on that would not otherwise be approved. They “fill in the gaps” solving problems for our development organization.
Here are some of the projects they’ve worked on:
- GitBack – a console application used to backup all of your git repos to disk
- It’s open source. Feel free to use it and/or enhance it.
- A web application portal to host prototypes of tools and reports needed by the business that don’t neatly fit into any existing application.
- A web application to report on our hardware eco-system–which machines are used for what in which environments?
- A web application to scrub and provision sql server databases into non-production environments for testing purposes
The other major way we benefit as a department is that we get the opportunity to work with people while they’re starting out. We train them to build software our way. We get to know their warts, and they ours. When we have open positions, we prefer to offer them to people we know. We have had 2 direct hires of college students out of our internship program. When they come to work for us, they already know they like our environment. That may not sound like a lot but it can add up fast when you consider recruiter fees.
But wait! There’s more!
Alternative Career Path
After I’d been running the program for a year or so, something interesting happened: We had a member of another department request to go through our internship program. He wanted to effect a career-change into Software Engineering. Since we already had the program in place, we were able to accomodate him. Before he had even finished the program, we had another member of our organization request the same thing. We are able to provide an alternative career path to our organization and the development department benefits.
As of this moment we have hired:
- 2 interns out of college
- 2 career changes out of our internal organization
- 1 career change from outside our organization
That’s roughly 20% of our development organization.
Further, we have made the program available to people in other departments whose jobs require that they write code even though they’re not software engineers. It is my hope that this will result in higher quality code across the rest of our organization as well, though that remains to be seen.
Curriculum
The curriculum of the program has remained largely unchanged since I first wrote about it. However, I’ve found that I can make it largely self-serve for the first 4-6 weeks by organizing it as a sequence. This reduces the amount of time I need to spend mentoring the intern. Of course, once they get started on their real project my investment will be greater.
Here is the updated curriculum:
- Clean Code
- Read chapters 1-9 before the refactoring your homework exercise.
- Setup your dev machine (we have powershell scripts for this).
- Learn about Github & Branching
- Refactor your own school homework exercises to improve the readability of your code
- you are practicing what you have learned in Clean Code
- Movies Tutorial – build an ASP .NET MVC web application
- watch ASP .NET MVC 4 Fundamentals
- Sections 1 & 2
- The purpose here is to learn in detail what you did in the Movies Tutorial
- watch MVC5 Fundamentals
- Identity & Security
- Bootstrap
- Web Api 2
- Entity Framework 6
- Music Store Tutorial – build another ASP .NET MVC web application
- You should see that you are much faster this time around.
- You should understand the “why” in the steps of the tutorial.
- Nerd Dinner Tutorial – here’s another version updated for EF4
- These tutorials are out of date. To complete the project you will likely have to switch between them.
- Use EF Code first instead of what’s in the tutorial for data access.
- Stop when the tutorial tells you to import MicrosoftAjax.js.
- Chris will give you his speech on why this file is historically important and why we’re not going to use it.
- You’ll use jquery instead.
- Pair on the Bowling Game Kata
- Implement Fizz Buzz on your own using TDD.
- Learn about Dependency Injection
- Introduce Fakes, Stubs, and Mocks using this PluralSight video on Rhino Mocks
- Practice using Mocks and Stubs using this exercise
- Get started on your first real project!
