Add support to upload packages directly to Kibana/Fleet

[ruflin]

In elastic/kibana#70582 the Fleet team is working on adding an API to support uploading packages directly to Kibana. elastic-package should have a command available that allows to use this API. The initial idea I had was:

elastic-package upload --kibana=http://localhost:5601

In case this is run inside a package, the package is built and then uploaded to Kibana. Alternatively if a package zip file already exists, the following could be used:

elastic-package upload --path=/foo/bar/package.zip --kibana=http://localhost:5601

In this scenario, elastic-package assumes the package inside the zip file is already validated.

[jsoriano]

We have the elastic-package install command to install packages, should we update this subcommand instead of adding a new one? Having two for the same thing may be confusing.

[ruflin]

No strong opinion on my end around naming, the above is not necessarily a proposal on how we should name things and structure the params, much more to explain it.

For everyone curious on what the install command does:

The command uses Kibana API to install the package in Kibana. The package must be exposed via the Package Registry.

[amitkanfer]

@juliaElastic is this related to elastic/kibana#148599 ?

[juliaElastic]

@amitkanfer Yes, this is a planned improvement in elastic-package to support the upload command. It is for convenience to call the Fleet API.

[jsoriano]

Once we have this, #1157 can be a low hanging fruit. #1157 will help with development experience and reliability.

[mrodm]

This issue could be done in different steps:

• Add a new --zip parameter into the install command that just installs the given zip file
  • Add parameter --zip into install command #1160
• Update install command to build and use that zip to install (just if Elastic stack >= 8.7.0)
  • Update install command to use new Kibana API to install packages by default #1163

[jlind23]

@mrodm If you have could you please think about recording a demo for this? 😄