Add config option for log_level (#217)

* Add config option for log_level
* Migrate to ops.testing (Scenario v7)
* Merge the test_machine_charm dir with scenario dir root
* Set BlockedStatus on invalid config
* Add status.config_error

charmcraft.yaml

@@ -210,6 +210,13 @@ config:
         Ref: https://grafana.com/docs/agent/latest/static/configuration/flags/#report-information-usage
       type: boolean
       default: true
+    log_level:
+      description: |
+        Grafana Agent server log level (only log messages with the given severity
+        or above). Must be one of: [debug, info, warn, error].
+        If not set, the Grafana Agent default (info) will be used.
+      type: string
+      default: info
     path_exclude:
       description: >
         Glob for a set of log files present in `/var/log` that should be ignored by Grafana Agent.

src/grafana_agent.py

@@ -12,7 +12,7 @@
 import socket
 from collections import namedtuple
 from dataclasses import dataclass
-from typing import Any, Callable, Dict, List, Optional, Set, Union
+from typing import Any, Callable, Dict, List, Optional, Set, Union, cast
 
 import yaml
 from charms.certificate_transfer_interface.v0.certificate_transfer import (
@@ -72,6 +72,7 @@ class CompoundStatus:
     # None = good; do not use ActiveStatus here.
     update_config: Optional[Union[BlockedStatus, WaitingStatus]] = None
     validation_error: Optional[BlockedStatus] = None
+    config_error: Optional[BlockedStatus] = None
 
 
 class GrafanaAgentCharm(CharmBase):
@@ -150,6 +151,7 @@ def __init__(self, *args):
 
         for rules in [self.loki_rules_paths, self.dashboard_paths]:
             if not os.path.isdir(rules.dest):
+                rules.src.mkdir(parents=True, exist_ok=True)
                 shutil.copytree(rules.src, rules.dest, dirs_exist_ok=True)
 
         self._remote_write = PrometheusRemoteWriteConsumer(
@@ -518,6 +520,10 @@ def _update_status(self, *_):
             self.unit.status = self.status.validation_error
             return
 
+        if self.status.config_error:
+            self.unit.status = self.status.config_error
+            return
+
         # Put charm in blocked status if all incoming relations are missing
         active_relations = {k for k, v in self.model.relations.items() if v}
         if not set(self.mandatory_relation_pairs.keys()).intersection(active_relations):
@@ -750,7 +756,7 @@ def _server_config(self) -> dict:
         Returns:
             The dict representing the config
         """
-        server_config: Dict[str, Any] = {"log_level": "info"}
+        server_config: Dict[str, Any] = {"log_level": self.log_level}
         if self.cert.enabled:
             server_config["http_tls_config"] = self.tls_config
             server_config["grpc_tls_config"] = self.tls_config
@@ -1066,6 +1072,21 @@ def _instance_name(self) -> str:
 
         return socket.getfqdn()
 
+    @property
+    def log_level(self) -> str:
+        """The log level configured for the charm."""
+        # Valid upstream log levels in server_config
+        # https://grafana.com/docs/agent/latest/static/configuration/server-config/#server_config
+        allowed_log_levels = ["debug", "info", "warn", "error"]
+        log_level = cast(str, self.config.get("log_level")).lower()
+
+        if log_level not in allowed_log_levels:
+            message = "log_level must be one of {}".format(allowed_log_levels)
+            self.status.config_error = BlockedStatus(message)
+            logging.warning(message)
+            log_level = "info"
+        return log_level
+
     def _reload_config(self, attempts: int = 10) -> None:
         """Reload the config file.
 

tests/scenario/conftest.py

@@ -1,19 +1,48 @@
-import shutil
-from pathlib import Path, PosixPath
+# Copyright 2022 Canonical Ltd.
+# See LICENSE file for licensing details.
+from unittest.mock import PropertyMock, patch
 
 import pytest
+from charms.tempo_coordinator_k8s.v0.charm_tracing import charm_tracing_disabled
 
-from tests.scenario.helpers import CHARM_ROOT
 
+@pytest.fixture
+def placeholder_cfg_path(tmp_path):
+    return tmp_path / "foo.yaml"
 
-class Vroot(PosixPath):
-    def clean(self) -> None:
-        shutil.rmtree(self)
-        shutil.copytree(CHARM_ROOT / "src", self / "src")
 
+@pytest.fixture()
+def mock_config_path(placeholder_cfg_path):
+    with patch("grafana_agent.CONFIG_PATH", placeholder_cfg_path):
+        yield
 
-@pytest.fixture
-def vroot(tmp_path) -> Path:
-    vroot = Vroot(str(tmp_path.absolute()))
-    vroot.clean()
-    return vroot
+
+@pytest.fixture(autouse=True)
+def mock_snap():
+    """Mock the charm's snap property so we don't access the host."""
+    with patch("charm.GrafanaAgentMachineCharm.snap", new_callable=PropertyMock):
+        yield
+
+
+@pytest.fixture(autouse=True)
+def mock_refresh():
+    """Mock the refresh call so we don't access the host."""
+    with patch("snap_management._install_snap", new_callable=PropertyMock):
+        yield
+
+
+CONFIG_MATRIX = [
+    {"classic_snap": True},
+    {"classic_snap": False},
+]
+
+
+@pytest.fixture(params=CONFIG_MATRIX)
+def charm_config(request):
+    return request.param
+
+
+@pytest.fixture(autouse=True)
+def mock_charm_tracing():
+    with charm_tracing_disabled():
+        yield

tests/scenario/helpers.py

@@ -1,12 +1,15 @@
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
-from pathlib import Path
-
-import yaml
-
-CHARM_ROOT = Path(__file__).parent.parent.parent
-
-
-def get_charm_meta(charm_type) -> dict:
-    raw_meta = (CHARM_ROOT / "charmcraft").with_suffix(".yaml").read_text()
-    return yaml.safe_load(raw_meta)
+from unittest.mock import MagicMock
+
+
+def set_run_out(mock_run, returncode: int = 0, stdout: str = "", stderr: str = ""):
+    mock_stdout = MagicMock()
+    mock_stdout.configure_mock(
+        **{
+            "returncode": returncode,
+            "stdout.decode.return_value": stdout,
+            "stderr.decode.return_value": stderr,
+        }
+    )
+    mock_run.return_value = mock_stdout

tests/scenario/test_machine_charm/test_alert_labels.py → tests/scenario/test_alert_labels.py

@@ -4,7 +4,7 @@
 import json
 
 import pytest
-from scenario import Context, PeerRelation, Relation, State, SubordinateRelation
+from ops.testing import Context, PeerRelation, Relation, State, SubordinateRelation
 
 import charm
 
@@ -15,7 +15,7 @@ def use_mock_config_path(mock_config_path):
     yield
 
 
-def test_metrics_alert_rule_labels(vroot, charm_config):
+def test_metrics_alert_rule_labels(charm_config):
     """Check that metrics alert rules are labeled with principal topology."""
     cos_agent_primary_data = {
         "config": json.dumps(
@@ -97,9 +97,8 @@ def test_metrics_alert_rule_labels(vroot, charm_config):
     )
     remote_write_relation = Relation("send-remote-write", remote_app_name="prometheus")
 
-    context = Context(
+    ctx = Context(
         charm_type=charm.GrafanaAgentMachineCharm,
-        charm_root=vroot,
     )
     state = State(
         leader=True,
@@ -112,11 +111,13 @@ def test_metrics_alert_rule_labels(vroot, charm_config):
         config=charm_config,
     )
 
-    state_0 = context.run(event=cos_agent_primary_relation.changed_event, state=state)
-    state_1 = context.run(event=cos_agent_subordinate_relation.changed_event, state=state_0)
-    state_2 = context.run(event=remote_write_relation.joined_event, state=state_1)
+    state_0 = ctx.run(ctx.on.relation_changed(relation=cos_agent_primary_relation), state)
+    state_1 = ctx.run(ctx.on.relation_changed(relation=cos_agent_subordinate_relation), state_0)
+    state_2 = ctx.run(ctx.on.relation_joined(relation=remote_write_relation), state_1)
 
-    alert_rules = json.loads(state_2.relations[2].local_app_data["alert_rules"])
+    alert_rules = json.loads(
+        state_2.get_relation(remote_write_relation.id).local_app_data["alert_rules"]
+    )
     for group in alert_rules["groups"]:
         for rule in group["rules"]:
             if "grafana-agent_alertgroup_alerts" in group["name"]:

tests/scenario/test_config.py

@@ -0,0 +1,50 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+from unittest.mock import patch
+
+import pytest
+import yaml
+from ops import BlockedStatus
+from ops.testing import Context, State
+
+import charm
+
+
+@pytest.fixture(autouse=True)
+def patch_all(placeholder_cfg_path):
+    with patch("grafana_agent.CONFIG_PATH", placeholder_cfg_path):
+        yield
+
+
+@pytest.mark.parametrize("log_level", ("debug", "info", "warn", "error"))
+def test_valid_config_log_level(placeholder_cfg_path, log_level):
+    """Asserts that all valid log_levels set the correct config."""
+    # GIVEN a GrafanaAgentMachineCharm
+    with patch("charm.GrafanaAgentMachineCharm.is_ready", True):
+        ctx = Context(charm_type=charm.GrafanaAgentMachineCharm)
+        # WHEN the config option for log_level is set to a VALID option
+        ctx.run(ctx.on.start(), State(config={"log_level": log_level}))
+
+    # THEN the config file has the correct server:log_level field
+    yaml_cfg = yaml.safe_load(placeholder_cfg_path.read_text())
+    assert yaml_cfg["server"]["log_level"] == log_level
+
+
+@patch("charm.GrafanaAgentMachineCharm.is_ready", True)
+def test_invalid_config_log_level(placeholder_cfg_path):
+    """Asserts that an invalid log_level sets Blocked status."""
+    # GIVEN a GrafanaAgentMachineCharm
+    ctx = Context(charm_type=charm.GrafanaAgentMachineCharm)
+    with ctx(ctx.on.start(), State(config={"log_level": "foo"})) as mgr:
+        # WHEN the config option for log_level is set to an invalid option
+        mgr.run()
+        # THEN a warning Juju debug-log is created
+        assert any(
+            log.level == "WARNING" and "log_level must be one of" in log.message
+            for log in ctx.juju_log
+        )
+        # AND the charm goes into blocked status
+        assert isinstance(mgr.charm.unit.status, BlockedStatus)
+    # AND the config file defaults the server:log_level field to "info"
+    yaml_cfg = yaml.safe_load(placeholder_cfg_path.read_text())
+    assert yaml_cfg["server"]["log_level"] == "info"