Elasticsearch debian packaging: Pre-Depends: java8-runtime-headless missing, apt-get install fails

[minfrin]

Elasticsearch version (bin/elasticsearch --version): 6.8.5

Plugins installed: [elasticsearch-analysis-icu]

JVM version (java -version): openjdk version "11.0.4" 2019-07-16

OS version (uname -a if on a Unix-like system): Linux x-jm-unstable-black-els01 4.15.0-1056-aws #58-Ubuntu SMP Tue Nov 26 15:14:34 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Description of the problem including expected versus actual behavior:

The elasticsearch Debian packaging does not following the Debian packaging guidelines at

https://www.debian.org/doc/debian-policy/ch-relationships.html#binary-dependencies-depends-recommends-suggests-enhances-pre-depends

nor the Java packaging guideline at

https://wiki.debian.org/Java#Java_and_Debian

Most specifically:

"Pre-Depends are also required if the preinst script depends on the named package. It is best to avoid this situation if possible."

and

"There are several virtual packages used in Debian for Java. These cover runtime compatibility and come in two flavours; headless (omits graphical interfaces) and normal. A dependency on javaX-runtime means that the package can work with any runtime which implements version X."

To fix this, the elasticsearch package must add a Pre-Depends with the virtual package for Java as follows:

Pre-Depends: java8-runtime-headless

Any JDK that follows the Debian packaging guidelines will then work.

Steps to reproduce:

1. Deploy elasticsearch debian package to any apt repository.

2. Attempt to install elasticsearch using apt.

3. apt fails as follows, and apt is broken from this point on until elasticsearch is manually removed:

   Errors were encountered while processing:
   /tmp/apt-dpkg-install-EqsMZQ/21-elasticsearch_6.8.5_all.deb
   E: Sub-process /usr/bin/dpkg returned an error code (1)

Provide logs (if relevant):

[elasticmachine]

Pinging @elastic/es-core-infra (:Core/Infra/Packaging)

[rjernst]

Please see #31845. This was a long known issue, which we have now solved since 7.0 by bundling java in Elasticsearch. As we have no plans to backport that change to 6.8 (it was quite invasive on our packaging build structure, and changes the packages themselves to be platform dependent), I hope you don't mind that I close this issue.