Description

When you run a composition, testground output the logs with a prefix in your CLI,
for example:

Jul 26 13:11:31.064168	INFO	1.6502s      ERROR << v0.19[000] (182365) >> exec /testplan: no such file or directory
Jul 26 13:11:31.064568	INFO	1.6507s INCOMPLETE << v0.19[000] (182365) >>
Jul 26 13:11:31.072007	INFO	1.6543s    MESSAGE << v0.17[000] (127910) >> registering default http handler at: http://[::]:6060/ (pprof: http://[::]:6060/debug/pprof/)
Jul 26 13:11:31.088385	INFO	1.6745s      ERROR << master[000] (c13d8b) >> exec /testplan: no such file or directory

Note the v0.19[000] prefix, which means "instance id=0 in group id=v0.19"

When you build a composition, testground "just" dump the docker build logs on stdout without prefix. Logs are intertwined and it's hard to tell which build is passing/failing.

What defines this endeavor to be complete?

• Add a prefix to docker build logs,
• Check that all the logs are sent back to the user (I suspect some parts of the build logs are skipped).