docker_registry_client.py: Add generic registry support

Add support of a generic container registry, so a user can provide
access to an arbitrary registry for the container CI job. The secret
value must be defined as "<user-name>:token|password|secret>", so the CI
will do `docker login <url> -u <user-name> -p <token|password|secret>`.

Signed-off-by: Mike Sul <mike.sul@foundries.io>

Author: mike-sul

apps/docker_registry_client.py

@@ -209,5 +209,14 @@ def login(self):
                     subprocess.run(cmd, check=True)
                 except subprocess.CalledProcessError as e:
                     sys.exit(e.returncode)
+            elif reg["type"] == "generic":
+                secrets_file = Path("/secrets") / reg["generic_secret_name"]
+                creds = secrets_file.read_text().strip()
+                user, token = creds.split(":")
+                try:
+                    cmd = [self._client, "login", "--password-stdin", "-u", user, reg["url"]]
+                    subprocess.run(cmd, check=True, input=token.encode())
+                except subprocess.CalledProcessError as e:
+                    sys.exit(e.returncode)
             else:
                 sys.exit("Unsupported registry type")