IBM DB2 Add support to use go_ibm_db library in metricbeat

[muthu-mps]

Using go_ibm_db driver library needs run time environment variables to be set. This dependency blocks generating metricbeat binary.
The use-case already executed and the details are captured here
After discussing with the observability robots team, Issue has been raised on the same.
Checking with the possibilities to see, Whether we could set those variables in the build script.

[muthu-mps]

Working on exploring the approaches used in Packet-beat for libpcap to see if we could leverage the same capabilities for DB2 as well.

[muthu-mps]

IBM DB2 requires new library needs to be included in golang-crossbuild. Discussions around this here

[muthu-mps]

After discussing with Lalit and Agi - Started looking into the below options.

• Can we release a separate Metricbeat binary only for DB2?
• Where do we put the additional setting, as part of the build flow?
  Installing the CLI driver
  Setting the env variables
• Can we handle the script error at Jenkins CI.
• Can we download the clidriver and add it as a part of the source code and set the environment variables ?
• Is it possible to have an optional flag to build just for IBM DB2.

[botelastic]

Hi! We just realized that we haven't looked into this issue in a while. We're sorry! We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1. Thank you for your contribution!