Add logging levels

[jkutner]

@sclevine @ekcasey @ameyer-pivotal @jromero before i go any further, can you confirm that this is the along the lines of what we discussed?

[sclevine]

Looking great to me 😄

[jromero]

Is the intent that pack would move to start using this implementation by having lifecycle as a dependency so that there is no duplication (and maintenance overhead)?

[jkutner]

idk. maybe we split the logging stuff out as its only lib?

[jromero]

@ekcasey what are your thoughts here?

[ameyer-pivotal]

I considered the same thing way back when we began talking about a similar logger in lifecycle as we were using in pack. I think a separate repo might have some overhead with maintenance, but not sure if I like pack having to continue to depend on lifecycle...

[jromero]

I think we could consider this issue resolved. It seems like we are aligned on what the future would look like but not part of this issue.

[jkutner]

@sclevine @ekcasey Can you help figure out what I need to do to move this forward?

• Should I break from the pattern pack uses for NewLogWithWriters?
• Do we need to split out a logging lib, or wait?
• Do we need to add log levels to all binaries, or can we merge just these first? (I don't actually think /lifecycle/builder will work the same way because we might want to preserve stdout/stderr from the buildpack, so I'd like to wait).

[ameyer-pivotal]

Nice work!

[jkutner]

This is what it looks like in practice:

$ pack build myimage --builder heroku/buildpacks:18 --no-pull
Selected run image heroku/pack:18
Executing lifecycle version 0.0.0
Using build cache volume pack-cache-67f7abf58243.build
===> DETECTING
[detector] Success! (1)
===> RESTORING
[restorer] Restoring cached layer 'heroku/java:jdk'
[restorer] Restoring cached layer 'heroku/java:maven_m2'
===> ANALYZING
[analyzer] Analyzing image '3f066b64904aecb1541ad7468cf13efe913e068af7a1373a72bd4c352e926782'
[analyzer] Using cached layer 'heroku/java:jdk'
[analyzer] Using cached layer 'heroku/java:maven_m2'
[analyzer] Writing metadata for uncached layer 'heroku/java:jre'
===> BUILDING
[builder]
...
[builder]
===> EXPORTING
[exporter] Reusing layers from image with id '3f066b64904aecb1541ad7468cf13efe913e068af7a1373a72bd4c352e926782'
[exporter] *** Images:
[exporter]       index.docker.io/library/myimage:latest - succeeded
[exporter]
[exporter] *** Image ID: e6c614dd4f6d9da837391533c647fc562fbeffe2c29f8ae5800fd84f804dcec6
===> CACHING
[cacher] Reusing layer 'heroku/java:jdk'
[cacher] Caching layer 'heroku/java:maven_m2'
Successfully built image myimage