Battleship Travis-CI

The What:

There are a lot of CI/CD systems out there. If you’re in .NET land, Azure DevOps has some pretty excellent tooling out there. Jenkins is another that has some extremely robust capabilities. There are oodles more I’ve never even brushed up against, including rolling your own on a virtual machine somewhere in the cloud (or even on your own machine).

But wait. What the heck is a CI/CD pipeline? Why do you need one? If you’re asking either of those questions, please take a look at this recent post of mine.

The Why:

This post is about Travis-CI, because

• It’s free (for our use case, anyway)
• It integrates beautifully with GitHub (which is my repo of choice)
• It’s platform agnostic (works equally well for a variety of tech stacks)

The How:

Step One is to get yourself a Travis account. This is absurdly, almost suspiciously easy: you sign up with your GitHub account.

This means you may need to allow Travis as an authorized connection or app in your GitHub account, because Travis will be accessing your repo in order to detect changes and to clone the repo so it can build the application.

You’ll end up at your dashboard, which eventually will display your most recent build and a quick link to your repositories–for now, you shouldn’t see anything.

Step Two is to link a repository, which means you need to access your profile settings. Click your avatar in the top right of the screen, then the “Settings” link.

Step Three is to find and switch on your repository so Travis knows to check it for builds. Your public repos are all listed under the “Repositories” tab, which should be the default view (private repos required a paid subscription with travis-ci.com, currently).

It can take several minutes for your repositories to show up in Travis the first time. You may have to click the “sync account” button. It also may take refreshing the browser window itself–I once waited almost ten minutes to see a repo list and as soon as I refreshed the browser it all showed up.

Find the one you want to activate, and toggle it on.

Now Travis is going to be scanning that repo through GitHub APIs and looking for a .travis.yml file to get build instructions. Which means…

Step Four is to create a .travis.yml file in the root of your repository. The dot-travis file is, as you might guess from the dot starting the name, a configuration file used by the Travis-CI build system to know what language you’re using, what build environment to use, what commands to run, and any deployment steps. It’s sort of a big deal, and if there’s no .travis.yml file found in the code pushed to GitHub, Travis simply won’t do anything.

Again, you want to create an empty file in the root of your repository–not necessarily the root of your code base. Find the .git folder, and save your yml file there. I do this step typically in VS Code or Notepad++, depending what OS I’m on.

Step Five is to define the build configuration. This will vary significantly depending on which language you’re developing in and what flavor of that tech stack you prefer, and the folks at Travis do a really great job documenting what goes in the .travis file.

The .travis.yml file I will use for this project including some helpful (to me, anyway) comments about what each line means…

language: csharp
# Mono is used to build .NET on Linux--we don't need it with Core.
mono: none
# Needed to run commands in the Xenial CLI
sudo: required
# The version of Ubuntu to run the Travis virtual machine -- needed for .NET Core
dist: xenial
# Your SDK version, not your run-time version
dotnet: 2.2
script: # These commands are executed in the Travis VM just like you would on your local machine
# Use a "cd" command to move the Travis command line prompt into your solution directory
# - cd /home/travis/build/<yourTravisAccount>/<yourRepoRootDirectory>/.../<yourSolutionDirectory>/
  - cd ./BattleshipTDD/
# Use these to build the project without tests
# - dotnet restore
# - dotnet build
# if your project has tests, you can skip "restore" and "build" and just use "test" command -- "test" will run the other two automatically
  - dotnet test

Step Six is to commit the new file and push it up to your repo, where Travis should catch the change and trigger a build.

Step Seven is to review the build in Travis. Even before I was done prepping the terminal photo above for the post, I got an e-mail from Travis saying my build passed–hooray!

When we look at the dashboard we get some key items right away. The repository name and a build badge are at the top, and then the specific build info–what branch was built, the commit message, commit ID, the build number, how long it ran for are all front and center.

If we keep scrolling down, you can see the actual build logs, starting with info on the build environment–handy for debugging problems, like when your build is fine locally, but fails when Travis tries it.

For instance, if one tries to run a .NET Core app in the default Travis Linux OS, it won’t work–hence needing to specify Xenial to make sure we were running on Ubuntu. Being able to compare the build environment with the suggestion on a help document was key to figuring this out.

Scrolling down further we get to the actual build process. Each command you specify in the .travis.yml is listed out separately–you can see on line 246, even the “cd ./BattleshipTDD/” got it’s own result output (and yes, I have seen this fail, especially on complicated solution structures where I was missing a directory level in the path).

The test output is particularly helpful–my one test passes here, but should it fail it outputs the exception message just like any other test runner, letting you know what failed and why.

At the very bottom, the build status gets reported–if any of the commands exited with anything except a 0 code, the entire build is marked as a failure.

Some examples of unhappy build logs…

Failing tests give you the output of your testing framework–no guessing what happened

Wrapping It All Up:

What we’ve done here is linked your GitHub to Travis-CI, which will build the project and run tests against it whenever changes are pushed to master. This by itself may not provide a lot of value (I mean, if you’re not running your tests before pushing code, we need to talk) but it does lay an important foundation.

From here, we’re able to automate deployment, headless browser testing, dockerizing, packaging, updating a badge on your repo to tell the world your code is sound, and more. And it happens without having to remember it–push the code, and Travis checks it. It’s one heck of a safety net, if nothing else. It lets you focus more on the code than on the boring devopsy* stuff.

*I mean, I don’t exactly think devops is boring stuff, but no shame if you do–most programmers get into code to write code, not manage deployments and QA etc etc etc.