chore: refactor provider config reconciliation

charms/garm-configurator/charmcraft.yaml

@@ -108,6 +108,10 @@ config:
         A Python dict-like string containing key-value pairs of script name
         to bash script to be run prior to runner installation.
 
+provides:
+  garm-configurator:
+    interface: garm_configurator_v0
+
 requires:
   image:
     interface: github_runner_image_v0

charms/garm-configurator/src/charm.py

@@ -4,6 +4,7 @@
 
 """Charm entrypoint for the GARM configurator charm."""
 
+import json
 import typing
 
 import ops
@@ -15,6 +16,8 @@
     CharmState,
 )
 
+GARM_CONFIGURATOR_RELATION_NAME = "garm-configurator"
+
 
 class GarmConfiguratorCharm(ops.CharmBase):
     """GARM configurator charm."""
@@ -29,6 +32,7 @@ def __init__(self, *args: typing.Any) -> None:
         for event in [
             self.on.config_changed,
             self.on.secret_changed,
+            self.on[GARM_CONFIGURATOR_RELATION_NAME].relation_changed,
             self.on[IMAGE_RELATION_NAME].relation_joined,
             self.on[IMAGE_RELATION_NAME].relation_changed,
             self.on[IMAGE_RELATION_NAME].relation_broken,
@@ -65,6 +69,33 @@ def _reconcile(self, event: ops.EventBase) -> None:
                 }
             )
 
+        pre_install = state.scaleset_config.pre_install_scripts
+        relation_data = {
+            "name": state.scaleset_config.name,
+            "provider_name": state.provider_name,
+            "credentials_name": state.credentials_name,
+            "image_id": str(state.image_id),
+            "flavor": state.scaleset_config.flavor,
+            "os_arch": state.scaleset_config.os_arch,
+            "min_idle_runner": str(state.scaleset_config.min_idle_runner),
+            "max_runner": str(state.scaleset_config.max_runner),
+            "labels": (
+                state.scaleset_config.labels
+                if isinstance(state.scaleset_config.labels, str)
+                else ",".join(state.scaleset_config.labels)
+            ),
+            "runner_group": state.scaleset_config.runner_group,
+            "pre_install_scripts": json.dumps({"pre_install.sh": pre_install})
+            if pre_install
+            else "",
+        }
+        if state.scaleset_config.org:
+            relation_data["org"] = state.scaleset_config.org
+        if state.scaleset_config.repo:
+            relation_data["repo"] = state.scaleset_config.repo
+        for garm_relation in self.model.relations[GARM_CONFIGURATOR_RELATION_NAME]:
+            garm_relation.data[self.unit].update(relation_data)
+
         if relation is None:
             self.unit.status = ops.WaitingStatus("Waiting for image builder relation")
             return

charms/garm-configurator/src/charm_state.py

@@ -348,6 +348,16 @@ def from_charm(cls, charm: ops.CharmBase) -> "CharmState":
             image_id=image_id,
         )
 
+    @property
+    def provider_name(self) -> str:
+        """Derived GARM provider name for scalesets."""
+        return f"openstack-{self.provider_config.project_name}"
+
+    @property
+    def credentials_name(self) -> str:
+        """Derived GARM credentials name for scalesets."""
+        return f"github-app-{self.github_app_config.client_id}"
+
 
 def _get_image_id_from_relation(charm: ops.CharmBase) -> str | None:
     """Return the OpenStack image UUID from the image builder relation, if available.

charms/garm-configurator/tests/unit/test_charm.py

@@ -18,6 +18,10 @@ def _make_private_key_secret():
     return Secret(tracked_content={"value": "random-secret"})
 
 
+def _make_garm_configurator_relation():
+    return Relation(endpoint="garm-configurator")
+
+
 def _valid_config(secret: Secret, private_key_secret: Secret) -> dict:
     return {
         "openstack-auth-url": "https://keystone.example.com:5000/v3",
@@ -432,13 +436,117 @@ def test_status_waiting_on_relation_broken():
     assert out.unit_status == ops.WaitingStatus("Waiting for image builder relation")
 
 
+def test_garm_configurator_relation_data_written_on_reconcile():
+    """
+    arrange: Valid config and an active garm-configurator relation.
+    act: Run config-changed.
+    assert: The charm writes all expected scaleset fields to local unit relation data.
+    """
+    ctx = Context(GarmConfiguratorCharm)
+    secret = _make_secret()
+    pk_secret = _make_private_key_secret()
+    config = _valid_config(secret, pk_secret)
+    config["labels"] = "self-hosted,linux"
+    config["pre-install-scripts"] = "echo hello"
+    garm_relation = _make_garm_configurator_relation()
+    state = State(
+        config=config,
+        secrets=[secret, pk_secret],
+        relations=[garm_relation],
+    )
+
+    out = ctx.run(ctx.on.config_changed(), state)
+
+    rel_out = out.get_relation(garm_relation.id)
+    expected_relation_data = {
+        "name": "my-scaleset",
+        "provider_name": "openstack-myproject",
+        "credentials_name": "github-app-12345",
+        "image_id": "None",
+        "flavor": "m1.large",
+        "os_arch": "amd64",
+        "min_idle_runner": "0",
+        "max_runner": "5",
+        "labels": "self-hosted,linux",
+        "runner_group": "default",
+        "pre_install_scripts": '{"pre_install.sh": "echo hello"}',
+        "repo": "myorg/myrepo",
+    }
+    for key, value in expected_relation_data.items():
+        assert rel_out.local_unit_data[key] == value
+
+
+def test_garm_configurator_relation_data_reflects_charm_state():
+    """
+    arrange: Valid config with project and client identifiers plus a garm-configurator relation.
+    act: Run config-changed.
+    assert: Derived provider and credentials names are written from CharmState.
+    """
+    ctx = Context(GarmConfiguratorCharm)
+    secret = _make_secret()
+    pk_secret = _make_private_key_secret()
+    config = _valid_config(secret, pk_secret)
+    config["openstack-project-name"] = "demo-project"
+    config["github-app-client-id"] = "abc123"
+    garm_relation = _make_garm_configurator_relation()
+    state = State(
+        config=config,
+        secrets=[secret, pk_secret],
+        relations=[garm_relation],
+    )
+
+    out = ctx.run(ctx.on.config_changed(), state)
+
+    rel_out = out.get_relation(garm_relation.id)
+    assert rel_out.local_unit_data["provider_name"] == "openstack-demo-project"
+    assert rel_out.local_unit_data["credentials_name"] == "github-app-abc123"
+
+
+def test_garm_configurator_no_error_when_no_relation():
+    """
+    arrange: Valid config with no garm-configurator relation.
+    act: Run config-changed.
+    assert: Reconcile completes and preserves the existing waiting status behavior.
+    """
+    ctx = Context(GarmConfiguratorCharm)
+    secret = _make_secret()
+    pk_secret = _make_private_key_secret()
+    state = State(config=_valid_config(secret, pk_secret), secrets=[secret, pk_secret])
+
+    out = ctx.run(ctx.on.config_changed(), state)
+
+    assert out.unit_status == ops.WaitingStatus("Waiting for image builder relation")
+
+
+def test_garm_configurator_relation_changed_triggers_reconcile():
+    """
+    arrange: Valid config and a garm-configurator relation with no existing local unit data.
+    act: Run garm-configurator relation-changed.
+    assert: Reconcile writes relation data for the local unit.
+    """
+    ctx = Context(GarmConfiguratorCharm)
+    secret = _make_secret()
+    pk_secret = _make_private_key_secret()
+    garm_relation = _make_garm_configurator_relation()
+    state = State(
+        config=_valid_config(secret, pk_secret),
+        secrets=[secret, pk_secret],
+        relations=[garm_relation],
+    )
+
+    out = ctx.run(ctx.on.relation_changed(garm_relation), state)
+
+    rel_out = out.get_relation(garm_relation.id)
+    assert rel_out.local_unit_data["name"] == "my-scaleset"
+
+
 def test_reconcile_writes_full_config_to_garm_relation():
     """
     arrange: All configs valid, image relation has a UUID, garm relation is joined.
     act: config-changed fires (holistic reconcile).
     assert: The full config payload (provider, github, scaleset, image_id) is written
         to the garm-configurator relation's local unit data.
-    """
+        """
     ctx = Context(GarmConfiguratorCharm)
     secret = _make_secret()
     pk_secret = _make_private_key_secret()

charms/garm-configurator/tests/unit/test_charm_state.py

@@ -0,0 +1,72 @@
+# Copyright 2026 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""Unit tests for charm_state."""
+
+from charm_state import CharmState, GithubAppConfig, ProviderConfig, ScalesetConfig
+
+
+def test_provider_name_derived_from_project_name():
+    """CharmState.provider_name is openstack-{project_name}."""
+    project_name = "myproject"
+    state = CharmState(
+        provider_config=ProviderConfig(
+            auth_url="https://keystone.example.com:5000/v3",
+            username="admin",
+            password="s3cr3t",
+            project_name=project_name,
+            user_domain_name="Default",
+            project_domain_name="Default",
+            region_name="RegionOne",
+            network="external-net",
+        ),
+        github_app_config=GithubAppConfig(
+            client_id="12345",
+            installation_id="67890",
+            private_key="private-key",
+        ),
+        scaleset_config=ScalesetConfig(
+            name="my-scaleset",
+            flavor="m1.large",
+            os_arch="amd64",
+            min_idle_runner=0,
+            max_runner=5,
+            repo="myorg/myrepo",
+        ),
+        image_id=None,
+    )
+
+    assert state.provider_name == f"openstack-{project_name}"
+
+
+def test_credentials_name_derived_from_client_id():
+    """CharmState.credentials_name is github-app-{client_id}."""
+    client_id = "12345"
+    state = CharmState(
+        provider_config=ProviderConfig(
+            auth_url="https://keystone.example.com:5000/v3",
+            username="admin",
+            password="s3cr3t",
+            project_name="myproject",
+            user_domain_name="Default",
+            project_domain_name="Default",
+            region_name="RegionOne",
+            network="external-net",
+        ),
+        github_app_config=GithubAppConfig(
+            client_id=client_id,
+            installation_id="67890",
+            private_key="private-key",
+        ),
+        scaleset_config=ScalesetConfig(
+            name="my-scaleset",
+            flavor="m1.large",
+            os_arch="amd64",
+            min_idle_runner=0,
+            max_runner=5,
+            repo="myorg/myrepo",
+        ),
+        image_id=None,
+    )
+
+    assert state.credentials_name == f"github-app-{client_id}"

charms/garm/charmcraft.yaml

@@ -31,4 +31,3 @@ requires:
   garm-configurator:
     interface: garm_configurator_v0
     limit: 1
-