Conditionally execute a TeamCity build step

Question

I am working on defining a general-purpose build template for all our projects -- which I have placed at the "root project" level (thanks to this new feature of TeamCity 8). Some of our projects create an installer, which needs to be generated by a separate "build step" that runs a powershell script. However, some of our projects do not create this installer, and hence do not need this additional build step.

Is there a way to conditionally execute a build step, based on a build parameter? I thought that perhaps the "disable build step" feature could be leveraged here, but I don't see a way to define the enabled/disabled status of a step via a parameter.

Of course I could bake this conditional into the build step that performs the installer generation, but it would be cleaner if this could be handled from within teamcity itself.

Answer 1

I've had need for conditional build steps on numerous occasions but alas, the feature does not exist at the moment. http://youtrack.jetbrains.com/issue/TW-17939

There's no reason you can't have a template used by many build configurations and then simply disable the build step in the build configs/projects that do not need to create the installer. Disabling the step in an individual build config does not affect the parent template it is based on.

Not as tidy as having a runtime/dynamic method built in to TC but I use it on occasion. I've done iwo has suggested as well.

Answer 2

It seems TC does not support conditional runner step execution at their level except the execution policy (only if build status is successful, if all previous steps finished successfully, even if some prev steps failed, always) but that is not what you want.

So it seems you need to provide a custom system build param for your installer generator powershell build step like system.Generate which should be a bool (you can make it hidden, prompt, get its value based a on a config param, etc), and then in your powershell runner, add this:

param([int]$Generate)
if ($Generate) {
  Write-Host "generating installer..."
   # call your func()
} else {
   Write-Host "skip installer"
}

In your runner config, add -Generate %system.Generate% as a script argument (careful, not additional command argument!). %system.Generate% should expand to 1 or 0 based on its runtime value.

Answer 3

I've been researching this use case as I have a very similar problem to solve. The best solution I've found so far is the one stated in fwise's answer - to include all possible steps you might need within your template, but then on a case-by-case basis disable the unrequired steps for each project.

So in your case you would include your 'installer' build step at the root level, but disable it for any projects which inherit this template and don't have an installer.

For a single optional step this feels like a good approach but admittedly it wouldn't scale very well to large complex templates with many optional steps.

I picked this up from the TeamCity documentation here:

• You can reorder build steps as needed. Note, that if you have a build configuration inherited from a template, you cannot reorder inherited build steps. However, you can insert custom build steps (not inherited) at any place and in any order, even before or between inherited build steps. Inherited build steps can be reordered in the original template only.
• You can disable a build step temporarily or permanently, even if it is inherited from a build configuration template.