feat: limit num units deployment to 1 (#50)

Co-authored-by: arturo-seijas <[email protected]>

src-docs/charm.py.md

@@ -12,7 +12,7 @@ Charm Jenkins.
 ## <kbd>class</kbd> `JenkinsK8sOperatorCharm`
 Charm Jenkins. 
 
-<a href="../src/charm.py#L30"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/charm.py#L35"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>function</kbd> `__init__`
 

src-docs/state.py.md

@@ -29,7 +29,7 @@ Metadata for registering Jenkins Agent.
 
 ---
 
-<a href="../src/state.py#L103"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/state.py#L119"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_agent_relation`
 
@@ -54,7 +54,7 @@ Instantiate AgentMeta from charm relation databag.
 
 ---
 
-<a href="../src/state.py#L84"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/state.py#L100"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_deprecated_agent_relation`
 
@@ -79,7 +79,7 @@ Instantiate AgentMeta from charm relation databag.
 
 ---
 
-<a href="../src/state.py#L71"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/state.py#L87"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `numeric_executors`
 
@@ -132,6 +132,37 @@ Initialize a new instance of the CharmConfigInvalidError exception.
 
 
 
+---
+
+## <kbd>class</kbd> `CharmIllegalNumUnitsError`
+Represents an error with invalid number of units deployed. 
+
+
+
+**Attributes:**
+
+ - <b>`msg`</b>:  Explanation of the error. 
+
+<a href="../src/state.py#L65"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+
+### <kbd>function</kbd> `__init__`
+
+```python
+__init__(msg: str)
+```
+
+Initialize a new instance of the CharmIllegalNumUnitsError exception. 
+
+
+
+**Args:**
+
+ - <b>`msg`</b>:  Explanation of the error. 
+
+
+
+
+
 ---
 
 ## <kbd>class</kbd> `CharmRelationDataInvalidError`
@@ -190,7 +221,7 @@ Configuration for accessing Jenkins through proxy.
 
 ---
 
-<a href="../src/state.py#L183"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/state.py#L199"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_env`
 
@@ -227,7 +258,7 @@ The Jenkins k8s operator charm state.
 
 ---
 
-<a href="../src/state.py#L224"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/state.py#L240"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ### <kbd>classmethod</kbd> `from_charm`
 
@@ -254,5 +285,6 @@ Initialize the state from charm.
 
  - <b>`CharmConfigInvalidError`</b>:  if invalid state values were encountered. 
  - <b>`CharmRelationDataInvalidError`</b>:  if invalid relation data was received. 
+ - <b>`CharmIllegalNumUnitsError`</b>:  if more than 1 unit of Jenkins charm is deployed. 
 
 

src/charm.py

@@ -15,7 +15,12 @@
 import ingress
 import jenkins
 import timerange
-from state import CharmConfigInvalidError, CharmRelationDataInvalidError, State
+from state import (
+    CharmConfigInvalidError,
+    CharmIllegalNumUnitsError,
+    CharmRelationDataInvalidError,
+    State,
+)
 
 if typing.TYPE_CHECKING:
     from ops.pebble import LayerDict  # pragma: no cover
@@ -39,7 +44,7 @@ def __init__(self, *args: typing.Any):
         super().__init__(*args)
         try:
             self.state = State.from_charm(self)
-        except CharmConfigInvalidError as exc:
+        except (CharmConfigInvalidError, CharmIllegalNumUnitsError) as exc:
             self.unit.status = ops.BlockedStatus(exc.msg)
             return
         except CharmRelationDataInvalidError as exc:

src/state.py

@@ -55,6 +55,22 @@ def __init__(self, msg: str):
         self.msg = msg
 
 
+class CharmIllegalNumUnitsError(CharmStateBaseError):
+    """Represents an error with invalid number of units deployed.
+
+    Attributes:
+        msg: Explanation of the error.
+    """
+
+    def __init__(self, msg: str):
+        """Initialize a new instance of the CharmIllegalNumUnitsError exception.
+
+        Args:
+            msg: Explanation of the error.
+        """
+        self.msg = msg
+
+
 class AgentMeta(BaseModel):
     """Metadata for registering Jenkins Agent.
 
@@ -234,6 +250,7 @@ def from_charm(cls, charm: ops.CharmBase) -> "State":
         Raises:
             CharmConfigInvalidError: if invalid state values were encountered.
             CharmRelationDataInvalidError: if invalid relation data was received.
+            CharmIllegalNumUnitsError: if more than 1 unit of Jenkins charm is deployed.
         """
         time_range_str = charm.config.get("restart-time-range")
         if time_range_str:
@@ -251,24 +268,11 @@ def from_charm(cls, charm: ops.CharmBase) -> "State":
             agent_relation_meta_map = _get_agent_meta_map_from_relation(
                 charm.model.relations[AGENT_RELATION], charm.app.name
             )
-        except ValidationError as exc:
-            logger.error(
-                "Invalid agent relation data received from %s relation, %s", AGENT_RELATION, exc
-            )
-            raise CharmRelationDataInvalidError(
-                f"Invalid {AGENT_RELATION} relation data."
-            ) from exc
-
-        try:
             deprecated_agent_meta_map = _get_agent_meta_map_from_relation(
                 charm.model.relations[DEPRECATED_AGENT_RELATION], charm.app.name
             )
         except ValidationError as exc:
-            logger.error(
-                "Invalid agent relation data received from %s relation, %s",
-                DEPRECATED_AGENT_RELATION,
-                exc,
-            )
+            logger.error("Invalid agent relation data received, %s", exc)
             raise CharmRelationDataInvalidError(
                 f"Invalid {DEPRECATED_AGENT_RELATION} relation data."
             ) from exc
@@ -282,6 +286,11 @@ def from_charm(cls, charm: ops.CharmBase) -> "State":
         plugins_str = charm.config.get("allowed-plugins")
         plugins = (plugin.strip() for plugin in plugins_str.split(",")) if plugins_str else None
 
+        if charm.app.planned_units() > 1:
+            raise CharmIllegalNumUnitsError(
+                "The Jenkins charm supports only 1 unit of deployment."
+            )
+
         return cls(
             restart_time_range=restart_time_range,
             agent_relation_meta=agent_relation_meta_map,

tests/unit/conftest.py

@@ -13,6 +13,7 @@
 import pytest
 import requests
 import yaml
+from ops.charm import CharmBase
 from ops.model import Container
 from ops.pebble import ExecError
 from ops.testing import Harness
@@ -432,3 +433,11 @@ def plugin_groovy_script_result_fixture():
         dep-b-b (v0.0.4) => []
         """
     )
+
+
+@pytest.fixture(scope="module", name="mock_charm")
+def mock_charm_fixture():
+    """A valid mock charm."""
+    mock_charm = unittest.mock.MagicMock(spec=CharmBase)
+    mock_charm.app.planned_units.return_value = 1
+    return mock_charm

tests/unit/test_state.py

@@ -30,13 +30,12 @@ def test_state_invalid_time_config():
         pytest.param("", id="empty string"),
     ],
 )
-def test_no_time_range_config(time_range: str):
+def test_no_time_range_config(time_range: str, mock_charm: unittest.mock.MagicMock):
     """
     arrange: given an empty time range config value.
     act: when state is instantiated.
     assert: state without time range is returned.
     """
-    mock_charm = unittest.mock.MagicMock(spec=ops.CharmBase)
     mock_charm.config = {"restart-time-range": time_range}
 
     returned_state = state.State.from_charm(mock_charm)
@@ -108,7 +107,9 @@ def test_proxyconfig_none(monkeypatch: pytest.MonkeyPatch):
 
 
 def test_proxyconfig_from_charm_env(
-    monkeypatch: pytest.MonkeyPatch, proxy_config: state.ProxyConfig
+    monkeypatch: pytest.MonkeyPatch,
+    proxy_config: state.ProxyConfig,
+    mock_charm: unittest.mock.MagicMock,
 ):
     """
     arrange: given a monkeypatched os.environ with proxy configurations.
@@ -124,7 +125,6 @@ def test_proxyconfig_from_charm_env(
             "JUJU_CHARM_NO_PROXY": str(proxy_config.no_proxy),
         },
     )
-    mock_charm = unittest.mock.MagicMock(spec=ops.CharmBase)
     mock_charm.config = {}
 
     config = state.State.from_charm(mock_charm).proxy_config
@@ -134,28 +134,38 @@ def test_proxyconfig_from_charm_env(
     assert config.no_proxy == proxy_config.no_proxy
 
 
-def test_plugins_config_none():
+def test_plugins_config_none(mock_charm: unittest.mock.MagicMock):
     """
     arrange: given a charm with no plugins config.
     act: when state is initialized from charm.
     assert: plugin state is None.
     """
-    mock_charm = unittest.mock.MagicMock(spec=ops.CharmBase)
     mock_charm.config = {}
 
     config = state.State.from_charm(mock_charm)
     assert config.plugins is None
 
 
-def test_plugins_config():
+def test_plugins_config(mock_charm: unittest.mock.MagicMock):
     """
     arrange: given a charm with comma separated plugins.
     act: when state is initialized from charm.
     assert: plugin state contains an iterable of plugins.
     """
-    mock_charm = unittest.mock.MagicMock(spec=ops.CharmBase)
     mock_charm.config = {"allowed-plugins": "hello, world"}
 
     config = state.State.from_charm(mock_charm)
     assert config.plugins is not None
     assert tuple(config.plugins) == ("hello", "world")
+
+
+def test_invalid_num_units(mock_charm: unittest.mock.MagicMock):
+    """
+    arrange: given a mock charm with more than 1 unit of deployment.
+    act: when state is initialized from charm.
+    assert: CharmIllegalNumUnitsError is raised.
+    """
+    mock_charm.app.planned_units.return_value = 2
+
+    with pytest.raises(state.CharmIllegalNumUnitsError):
+        state.State.from_charm(mock_charm)