SourceGraph does not work in an air-gapped environment

Summary

We set up sourcegraph and "connected" it to an air-gapped instance but it requires importing the sourcegraph/server docker image into the offline registry, then using keyboard/monitor on the airgap machine to configuring things like externalURL and corsOrigin inside the Sourcegraph web UI, and it would require to require DNS config and self-signed certificates to actually work in an airgap/offline environment. Sourcegraph also runs its own db and webserver, both of which should use HTTPS to encrypt traffic.

Steps to reproduce

Turn on SourceGraph integration in an air-gapped network (one without internet connection)

Example Project

@greg has a project where he tried this, but it is air-gapped and not available on GitLab.com

What is the current bug behavior?

SourceGraph does not work

What is the expected correct behavior?

SourceGraph should work if we have access to the sourcegraph docker image on the air-gapped network -- this may be only a documentation issue similar to #11520 (closed)

Relevant logs and/or screenshots

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Output of checks

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Results of GitLab environment info

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Results of GitLab application Check

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Possible fixes

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