Please let the Debian package depend on headless JDK

[jmillikin-stripe]

The official Bazel packages for Debian/Ubuntu depend on java8-sdk, which usually resolves to openjdk-8-jdk. This is the full JDK including graphical toolkits, and it's fairly bulky when working within a Docker container:

$ apt-get install --no-install-recommends openjdk-8-jdk
[...]
Need to get 72.8 MB of archives.
After this operation, 384 MB of additional disk space will be used.

Since Bazel doesn't have a graphical component, it would be nice if it depended on java8-sdk-headless, which is less than half as big:

$ apt-get install --no-install-recommends openjdk-8-jdk-headless
[...]
Need to get 39.8 MB of archives.
After this operation, 155 MB of additional disk space will be used.

[laszlocsomor]

Sounds like a good idea! @philwo , @aehlig : WDYT?

[philwo]

@jmillikin-stripe Considering that java8-jdk-headless doesn't exist, should we then change the dependency list from:

google-jdk | java8-jdk | java8-sdk | oracle-java8-installer

into:

google-jdk | java8-sdk-headless | oracle-java8-installer

?

The java8-sdk-headless package seems to exist and do the job for Debian and Ubuntu:
https://packages.debian.org/sid/java8-sdk-headless
https://packages.ubuntu.com/zesty/java8-sdk-headless

Not sure why we even had the java8-jdk one in there.

[jmillikin-stripe]

java8-jdk exists in Debian: https://packages.debian.org/sid/java8-jdk

I'm slightly nervous about changing/removing virtual packages, because they can be mapped to different things on different systems. I think a safe, minimally-intrusive change would be to change the dep to:

google-jdk | java8-sdk-headless | java8-jdk | java8-sdk | oracle-java8-installer

That should prioritize the headless version if available, without breaking any existing dependency resolution on Dpkg-based non-Debian systems.

[jmillikin-stripe]

Gentle ping.

I could send a PR for this if you want, but someone in the Bazel side would still need to handle updating the Debian packages and such.

[jmillikin-stripe]

Note for future readers: the Debian package deps are duplicated, and need to be updated in both debian/control and debian/BUILD. See #4686.