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https://github.com/kevinveenbirkenbach/computer-playbook.git
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evangelostsak
e300d3a0dc
The lookup filtered on group_names, so each fragment had to re-check whether its app was actually scraped. Deployed and scraped are different conditions: metrics can be off on a deployed role, and a rule on a series nothing scrapes alerts on absent() forever. Intersecting with native_metrics_apps moves that check to one place, and every fragment from here on is plain rules with no guard.
62 lines
2.1 KiB
Python
62 lines
2.1 KiB
Python
from __future__ import annotations
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from typing import Any
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from ansible.plugins.loader import lookup_loader
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from ansible.plugins.lookup import LookupBase
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from utils.cache import ROLES_DIR
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ALERT_RULES_TEMPLATE = ("templates", "prometheus", "alert_rules.yml.j2")
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class LookupModule(LookupBase):
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"""
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Return a sorted list of role IDs whose Prometheus alert rules belong in
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this deploy: every role that ships a template at
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``roles/<role_id>/templates/prometheus/alert_rules.yml.j2`` and is actually
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scraped, i.e. appears in ``native_metrics_apps``.
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Keeps alert rules at the role that owns the metric instead of collecting
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them in web-app-prometheus: a role declares what "unhealthy" means for
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itself, and the Prometheus role only concatenates what the play enabled.
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Filtering on activation here rather than inside each fragment is what keeps
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the fragments free of boilerplate. A rule that fires on a series nothing
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scrapes is worse than no rule: it alerts on ``absent()`` forever.
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Usage in a template:
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{% for role_id in lookup('alert_rule_roles') %}
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{% include 'roles/' + role_id + '/templates/prometheus/alert_rules.yml.j2' %}
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{% endfor %}
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The rendered fragment MUST start at the ``groups:`` item level (two-space
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indented ``- name: <group>`` entries), because it is concatenated into the
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single ``groups:`` list of the Prometheus rule file.
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"""
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def run(
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self,
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terms: list[Any],
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variables: dict[str, Any] | None = None,
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**kwargs: Any,
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) -> list[list[str]]:
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if terms:
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raise ValueError("alert_rule_roles lookup takes no positional terms")
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vars_ = variables or getattr(self._templar, "available_variables", {}) or {}
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scraped: list[str] = lookup_loader.get(
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"native_metrics_apps",
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loader=self._loader,
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templar=getattr(self, "_templar", None),
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).run([], variables=vars_)[0]
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result = [
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role_id
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for role_id in sorted(set(scraped))
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if (ROLES_DIR / role_id).joinpath(*ALERT_RULES_TEMPLATE).exists()
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]
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return [result]
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