Support development on air-gapped environments

[jsoriano]

Users may be developing on restricted environments, where they have to access external resources through mirrors or proxies. Support this use case by allowing to configure the access to these resources. This will translate to allow the configuration of any currently hard-coded external URL.

For convenience with these use cases, the configuration to access these resources should be supported at the profile level. elastic-package should allow the configuration of any hard-coded external URL.

Some identified resources at the moment:

• Package Registry managed by elastic-package uses EPR_PROXY_TO to connect to https://epr.elastic.co.
• ECS schemas are retrieved from the hard-coded ecsSchemaURL.
• elastic-package status:
  • It looks for packages published in https://epr.elastic.co, this could be parameterizable to use a custom registry.
  • It looks for serverless config in github, this should be probably optional.

[nimarezainia]

@jsoriano do we have a full list of these hard-coded settings? (trying to gauge the extent of this effort)

[jsoriano]

@jsoriano do we have a full list of these hard-coded settings? (trying to gauge the extent of this effort)

The ones in the description are the only ones we have identified, I have added another reference to epr.elastic.co that is probably not so blocker.

There are some other hard-coded URLs used in the serverless stack provider, but we can probably ignore them as it doesn't make sense to use serverless in air-gapped environments.