refactor(garm): move workload config to entrypoint

[yanksyoon]

Summary

• Move GARM config and provider-file rendering into the container entrypoint.
• Pass workload configuration through environment variables and use the paas-charm application environment handling.
• Preserve normalized HTTP, HTTPS, and no-proxy environment propagation.
• Add entrypoint unit coverage and update the GARM rock layout.

Test plan

• tox -c tox.toml -e static — passed.
• tox -c tox.toml -e fmt — passed.
• ruff check and ruff format --check on changed production files — passed.
• tests/unit/test_garm_entrypoint.py — 7 passed.

Note: the full unit environment is currently blocked during collection because tests/unit/test_garm_toml.py still imports config-rendering helpers removed by this refactor (_build_provider_list, _proxy_environment, and render_garm_toml).

[Copilot]

Pull request overview

This PR refactors the garm charm/workload boundary so that GARM’s file-based configuration (config.toml + provider files) is rendered inside the container entrypoint from environment variables, aligning the workload more closely with the paas-charm 12-factor model.

Changes:

• Added a Python-based GARM entrypoint (garm_entrypoint.py) plus dedicated unit tests for config rendering and execution behavior.
• Updated the garm charm to pass workload configuration via environment variables and to point the Pebble service at the entrypoint via a custom App wrapper.
• Updated the GARM rockcraft definition to include Python dependencies and install the entrypoint script, and adjusted related unit tests and ignore rules.

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
garm-rockcraft.yaml	Adds Python dependencies + installs the entrypoint script; modifies the base Pebble layer command/startup behavior.
charms/garm/uv.lock	Updates the lockfile’s declared requires-python constraint.
charms/garm/tests/unit/test_garm_entrypoint.py	New unit tests covering entrypoint config rendering, path safety, and exec behavior.
charms/garm/tests/unit/test_charm.py	Updates Scenario-based tests to validate env-driven configuration and the new service naming/command behavior.
charms/garm/src/garm_entrypoint.py	New entrypoint implementation: reads env, renders TOML/YAML files, and execs the GARM binary.
charms/garm/src/charm.py	Refactors charm-side config handling to env-only, introduces GarmApp, and updates restart/config logic.
.gitignore	Ignores virtualenv and additional charm/terraform generated directories.

Suppressed comments (2)

charms/garm/src/charm.py:193

• GarmApp.restart() accepts rerun_migrations but discards it by calling super().restart() without passing the flag. This can prevent the charm’s rerun_migrations path from working as intended.

class GarmCharm(paas_charm.go.Charm):
    """GARM charm — manages the GARM service via Pebble."""

    def __init__(self, *args: typing.Any) -> None:
        """Initialize the charm.

charms/garm/src/charm.py:334

• The _compute_state docstring still claims it returns provider configuration files to push, but the refactor now passes provider config via GARM_PROVIDERS_JSON and the entrypoint owns file rendering. This makes the docstring misleading.

        Returns a ``ComputeState`` containing the environment variables the
        GARM entrypoint needs and the provider configuration files to push.
        When paas-charm gains native ``_compute_state`` support, this data
        gathering can be returned directly and the ``GarmApp`` wrapper

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Suppressed comments (2)

charms/garm/src/garm_entrypoint.py:127

• GARM_PROVIDERS_JSON is decoded with json.loads(...) without handling JSONDecodeError or validating the decoded type. If the env var is set but malformed (or not a JSON list), the entrypoint will crash with a traceback or behave unexpectedly.

    providers_json = env.get("GARM_PROVIDERS_JSON", "")
    providers = json.loads(providers_json) if providers_json else []

charms/garm/src/garm_entrypoint.py:83

• POSTGRESQL_DB_PORT is parsed with int(...) without validation; a malformed value will raise ValueError and crash the entrypoint with a traceback. It’s better to raise a clear ValueError that main() can log and exit on.

This issue also appears on line 126 of the same file.

    db_port = int(env.get("POSTGRESQL_DB_PORT", DEFAULT_DB_PORT))
    db_name = env.get("POSTGRESQL_DB_NAME", DEFAULT_DB_NAME)

[yhaliaw]

Major changes needed

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