Adapt (semi-)standard OAuth to Docker's token system.

Needs custom registry build because distribution/distribution#2875 (See ghcr.io/beryju/distribution:jwt)

• TOKEN_URL: URL to send POST Token request to
• CLIENT_ID: OAuth Client ID
• SCOPE: Special scope to append to requests
• LOG_LEVEL: Log level, defaults to info, can be set to trace which will print out credentials for debugging

Optional variables

• ANON_USERNAME: Credentials to be used when the client doesn't send any (optional)
• ANON_PASSWORD: Credentials to be used when the client doesn't send any (optional)
• ANON_KUBE_JWT: (Requires kubernetes) If set, will use the current pod's service account as anonymous credentials
• PASS_JWT_USERNAME: Username clients can use to pass a JWT directly as password (optional)
• SESSION_KEY: Secret key used for sessions (only used when registry is used in a browser, for example https://github.com/Joxit/docker-registry-ui)

Scope mapping with this code to allow everything:

scopes = request.http_request.POST.get("scope", "").split()
access = []
for scope in scopes:
    if scope.count(":") < 2:
        continue
    type, name, actions = scope.split(":")
    access.append({
        "type": type,
        "name": name,
        "actions": actions.split(","),
    })
return {
    "access": access,
}

Create with unique scope name, add scope to provider and configure env correctly