Limit the amount of parallel jobs running in a stage

[Jurn van Mieghem]

Due to an integration with BrowserStack I can (currently) only run 2 browser tests at the same time. However I'd like to run all browsers in parallel jobs instead of sequential tasks. Is it possible to limit the amount of jobs that can run simultaneously within a stage using YAML specs.

I have seen something about a concurrent-build-plugin but cannot find any documentation on the YAML specs for that. 

[Steffen Opel _Utoolity_]

You can configure the default number of concurrent builds for a plan in the Bamboo administration. The default can then be overridden on the Miscellaneous tab of a plan's configuration (called Other tab in recent Bamboo versions, the docs are outdated).

With Bamboo Specs (Java), this can be programmatically handled as documented in the Miscellaneous plugins (Java) section:

ConcurrentBuilds concurrentBuilds = new ConcurrentBuilds()
    .maximumNumberOfConcurrentBuilds(7);

Plan plan = new Plan(project, "My Plan One", "PLAN1")
    .description("This is an example of a plan")
    .enabled(true)
    .stages(stage1)
    .pluginConfigurations(concurrentBuilds, configurationForPlan);

I haven't tried whether this is also available for Bamboo Specs (YAML), but correlating the Java approach and the resp. Miscellaneous plugins (YAML) section seems to suggest that such settings might be surfaced via the "other" key in YAML:

version: 2

Build binaries:
  ...
  other:
    clean-working-dir: true

Unfortunately this doesn't seem to be covered by the export plan feature yet (not even the Java version), so as mentioned in the docs,  I'm afraid spelunking in the source code or some trial and error is required to identify the key, if any:

In case a plugin doesn’t have a dedicated builder, you can use AllOtherPluginsConfiguration to provide configuration for such plugins as a workaround. Refer to plugin documentation to obtain a list of valid keys. Note that keys imported with AllOtherPluginsConfiguration are not validated.

Good luck!

[Jurn van Mieghem]

Thanks, Steffen for this extended answer and it learned me a thing or two. Unfortunately it does not answer my direct question as I want to limit the number of parallel jobs from my YAML file.