[installer] Make the server mount the Github App secret

[andrew-farries]

Description

One of the Webapp team's epics for Q2 is to use the Gitpod installer to deploy to Gitpod SaaS. In order to do that we will need to add additional configuration to the installer to make the output suitable for a SaaS deployment as opposed to a self-hosted deployment.

This PR adds an an extra volume and volume mount to the server component to allow it to mount the github app secret, when a github app is specified in the installer config. The ability to add github app config was added in #9297.

Related Issue(s)

Part of #9097

How to test

Create an installer config file containing this experimental section:

experimental:
  webapp:
      githubApp:
        appId: 123
        authProviderId: 'someAuthProviderId'
        baseUrl: 'someBaseUrl'
        certPath: 'someCertpath'
        enabled: true
        logLevel: 'someLogLevel'
        marketplaceName: 'someMarketPlacename'
        webhookSecret: 'somewebhookSecret'
        certSecretName: 'certSecretName'

Get a versions.yaml for use with the installer:

docker run -it --rm "eu.gcr.io/gitpod-core-dev/build/versions:${version}" cat versions.yaml > versions.yaml

Then invoke the installer as:

go run . render --debug-version-file versions.yaml --config /path/to/config --use-experimental-config

The server component will have an extra volume and volume mount

Release Notes

Make sure the server mounts the github app secret when an app is specified in the installer

Documentation

None.

[geropl]

Awesome - looks like this might be the last PR! 🎉 😍