Add textfile collector for subordinate info metric #109
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Abuelodelanada
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Abuelodelanada
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LGTM!
Some minor comments added!
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| def _write_node_exporter_textfile(self) -> None: | ||
| """Write a per-unit metrics file for node-exporter's textfile collector. | ||
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| The file will contain one or more `subordinate_charm_info` metrics with | ||
| labels identifying the subordinate (this unit) and the principal unit, | ||
| plus juju topology labels. | ||
| """ | ||
| topology = JujuTopology.from_charm(self) | ||
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| # Gather principal units from cos-agent and juju-info relations | ||
| principals = set() | ||
| for rel_name in ("cos-agent", "juju-info"): | ||
| for rel in self.model.relations.get(rel_name, []): | ||
| for unit in rel.units: | ||
| principals.add(unit.name) | ||
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| # Build metric lines | ||
| lines = [] | ||
| for principal in sorted(principals): | ||
| labels = { | ||
| "subordinate_unit": self.unit.name, | ||
| "principal_unit": principal, | ||
| "juju_model": topology.model, | ||
| "juju_model_uuid": topology.model_uuid, | ||
| } | ||
| # Format labels as key="value" | ||
| label_str = ",".join(f'{k}="{v}"' for k, v in labels.items()) | ||
| lines.append(f"subordinate_charm_info{{{label_str}}} 1") | ||
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| LocalPath(NODE_EXPORTER_TEXTFILE_DIR).mkdir(parents=True, exist_ok=True) | ||
| # Filename must match the glob `*.prom` used by node-exporter's textfile collector | ||
| # Ref: https://github.com/prometheus/node_exporter/tree/master?tab=readme-ov-file#textfile-collector | ||
| LocalPath(os.path.join(NODE_EXPORTER_TEXTFILE_DIR, f'{self.unit.name.replace("/", "_")}.prom')).write_text("\n".join(lines) + ("\n" if lines else "")) | ||
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Contributor
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Some separations of concerns:
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The topology object is already created in line 151, I would remove this responsibility from the method.
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I would extract the responsibility of generating the set of principal's unit names to another method.
Suggested change
| def _write_node_exporter_textfile(self) -> None: | |
| """Write a per-unit metrics file for node-exporter's textfile collector. | |
| The file will contain one or more `subordinate_charm_info` metrics with | |
| labels identifying the subordinate (this unit) and the principal unit, | |
| plus juju topology labels. | |
| """ | |
| topology = JujuTopology.from_charm(self) | |
| # Gather principal units from cos-agent and juju-info relations | |
| principals = set() | |
| for rel_name in ("cos-agent", "juju-info"): | |
| for rel in self.model.relations.get(rel_name, []): | |
| for unit in rel.units: | |
| principals.add(unit.name) | |
| # Build metric lines | |
| lines = [] | |
| for principal in sorted(principals): | |
| labels = { | |
| "subordinate_unit": self.unit.name, | |
| "principal_unit": principal, | |
| "juju_model": topology.model, | |
| "juju_model_uuid": topology.model_uuid, | |
| } | |
| # Format labels as key="value" | |
| label_str = ",".join(f'{k}="{v}"' for k, v in labels.items()) | |
| lines.append(f"subordinate_charm_info{{{label_str}}} 1") | |
| LocalPath(NODE_EXPORTER_TEXTFILE_DIR).mkdir(parents=True, exist_ok=True) | |
| # Filename must match the glob `*.prom` used by node-exporter's textfile collector | |
| # Ref: https://github.com/prometheus/node_exporter/tree/master?tab=readme-ov-file#textfile-collector | |
| LocalPath(os.path.join(NODE_EXPORTER_TEXTFILE_DIR, f'{self.unit.name.replace("/", "_")}.prom')).write_text("\n".join(lines) + ("\n" if lines else "")) | |
| def _get_principal_units(self) -> set: | |
| # Gather principal units from cos-agent and juju-info relations | |
| principals = set() | |
| for rel_name in ("cos-agent", "juju-info"): | |
| for rel in self.model.relations.get(rel_name, []): | |
| for unit in rel.units: | |
| principals.add(unit.name) | |
| return sorted(principals) | |
| def _write_node_exporter_textfile(self, topology: JujuTopology) -> None: | |
| """Write a per-unit metrics file for node-exporter's textfile collector. | |
| The file will contain one or more `subordinate_charm_info` metrics with | |
| labels identifying the subordinate (this unit) and the principal unit, | |
| plus juju topology labels. | |
| """ | |
| # Gather principal units from cos-agent and juju-info relations | |
| principals = self._get_principal_units() | |
| # Build metric lines | |
| lines = [] | |
| for principal in principals: | |
| labels = { | |
| "subordinate_unit": self.unit.name, | |
| "principal_unit": principal, | |
| "juju_model": topology.model, | |
| "juju_model_uuid": topology.model_uuid, | |
| } | |
| # Format labels as key="value" | |
| label_str = ",".join(f'{k}="{v}"' for k, v in labels.items()) | |
| lines.append(f"subordinate_charm_info{{{label_str}}} 1") | |
| LocalPath(NODE_EXPORTER_TEXTFILE_DIR).mkdir(parents=True, exist_ok=True) | |
| # Filename must match the glob `*.prom` used by node-exporter's textfile collector | |
| # Ref: https://github.com/prometheus/node_exporter/tree/master?tab=readme-ov-file#textfile-collector | |
| LocalPath(os.path.join(NODE_EXPORTER_TEXTFILE_DIR, f'{self.unit.name.replace("/", "_")}.prom')).write_text("\n".join(lines) + ("\n" if lines else "")) | |
| return | ||
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| # Update node-exporter textfile collector with info about subordinate relations | ||
| self._write_node_exporter_textfile() |
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Suggested change
| self._write_node_exporter_textfile() | |
| self._write_node_exporter_textfile(topology) |
Contributor
Author
|
Need to demo for @marcusboden with alerts for principal charm that include the charm name (not app). |
Updated the node exporter textfile collector directory to use $SNAP_COMMON. Signed-off-by: Leon <[email protected]>
Signed-off-by: Leon <[email protected]>
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This PR is a PoC for #108.
Fixes #98.
Fixes #108.
In tandem with:Add read access to /etc/node-exporter node-exporter-snap#19Testing
Deploy the bundle:
Context
Since node-exporter is not necessarily installed when
constants.pyis parsed, the value for $SNAP_COMMON is hard-coded rather than obtained dynamically.