We do support build reuse between components as long as we can determine there are no differences in the spec that would affect the build phase.

For example, you can modify the run_command between two different components and it will share the build, but if the build_command or commit_hash was different, then we would have to issue a new build for each component.

Procfile is also supported and you can create a file similar to the following in order to specify a default run_command for your component:

web: bin/sample-golang

In your case, it sounds like something is causing us to detect a difference in the build key for reusing builds between your components. Is it possible for you to provide a sanitized version of your app spec for us to view? Alternatively, you can reach out to support with more detailed information and we can take a look at your specific application.

In general though, you should be able to achieve your approach by just changing the run_command for each of your components and leaving the rest of the configuration between the components the same.