feat: option to start a local docker registry

[superewald]

Adds the --registry option to gitlab-ci-local to run a local docker registry. This is useful if jobs build and push docker images using the CI_REGISTRY variable.

implementation

{gclRegistryPrefix} refers to Utils.gclRegistryPrefixand is set toregistry.gcl.local` currently.

1. starts a local docker registry prior to executing pipelines using registry:2 image if --registry was specified
   1. creates self-signed ssl certificate using alpine/openssl and cache them in {gclRegistryPrefix}.certs volume
   2. runs detached docker registry container configured to use the self-signed ssl certificate within their own network
2. configure gitlab-ci-local containers to use the local docker registry (as described in "container context")
3. after pipeline completed, stops and removes the local registry container (but not the network and volumes to avoid recreating the certificate and caching built images)

container context

Using the --registry flag will apply the following modifications to gitlab-ci-local job containers:

• mount volume with self-signed certificates ({gclRegistryPrefix}.certs, mounted 2 times to support oci and docker cert paths)
• change $CI_REGISTRY env var to {gclRegistryPrefix} before expanding variables
• add $CI_REGISTRY_USER={gclRegistryPrefix}.user and $CI_REGISTRY_PASSWORD={gclRegistryPrefix}.pass env variables
• attach the {gclRegistryPrefix}.net network for communicating with the local registry

Implements #1600

[firecow]

@superewald Without a wait-for-port you risk jobs start pushing to the registry before it is ready.