Wrapper layout compressing the output of a delegate (LOG4J2-3023)

[der-eismann]

As it was explained in #2495 (comment), all JSON-based layouts are deprecated in favor of JSON Template Layout. However the GELF layout has a compressionType option, which is missing from the JTL.
Would be really nice to have, as it can save a nice amount of traffic costs.

[vy]

Instead adding compression support to <your-layout-of-preference>, we better create a wrapper layout that compresses the output of another layout. This issue has already been discussed in LOG4J2-3023.

@der-eismann, would you be interested in submitting a PR? If so, I would be more than happy to assist you.

[der-eismann]

I'm kinda interested, but my Java knowledge is very basic and I'm not sure if my help is really useful here 🙈

[ppkarwasz]

I think we should introduce an OutputStream abstraction:

public interface OutputStreamWrapper {

    OutputStream wrap(OutputStream stream);
}

Such an abstraction could solve several issues:

• it would allow users to introduce their own compression/decompression algorithms (Zstd compression support #1508),
• it would allow us to remove the dependency on commons-compress from Log4j Core,
• it would allow users to implement some sort of end-to-end encryption (cf. LOG4J2-1000 and LOG4J2-2930).

[ppkarwasz]

I marked LOG4J2-3023 as duplicate of this issue, so we don't need to use JIRA any more.