hyperhive/nix/module-eval/agent-otel.nix
müde dc418a5223 nix: split module-eval into per-subsystem checks
The single module-eval derivation forced ~62 full nixosSystem
fixtures live at once to compute its cases list: 10.6GB peak RSS /
5m25s to evaluate, by far the dominant cost in nix flake check.
Splits it into 21 independent checks.module-eval-* derivations
(1-7 fixtures each) sharing builders/helpers via module-eval/lib.nix,
so no single derivation needs more than a handful of fixtures live
at once. A few cases spanning two clusters carry a small duplicated
fixture rather than threading shared state through lib.nix.
2026-09-20 04:25:54 +02:00

95 lines
3.3 KiB
Nix

# `checks.module-eval-agent-otel` — see ./lib.nix for the shared
# rationale (why this suite exists, naming convention, "evaluates
# not executes").
{
pkgs,
lib,
self,
nixosSystem,
}:
let
inherit
(import ./lib.nix {
inherit
pkgs
lib
self
nixosSystem
;
})
agent
runGroup
;
# The log path's three hops, one fixture each. Nothing carries a journal
# record end to end at eval time, so what these defend is the part no tier
# can check for itself: each hop's output is the next hop's input, and
# every mismatch between them is silent — a push accepted and routed
# nowhere, a receiver pointed at an empty directory, a pipeline that does
# not exist.
agentBridge = "http://10.42.0.1:4318";
agentOtel = agent {
otel.enable = true;
otel.endpoint = agentBridge;
};
# The same agent over the other wire protocol. An exporter's NAME is what
# selects it, so this is where a defined exporter and the pipeline's
# reference to it can drift apart.
agentOtelGrpc = agent {
otel.enable = true;
otel.endpoint = agentBridge;
otel.protocol = "grpc";
};
agentNoOtel = agent { };
agentSettings = machine: machine.services.opentelemetry-collector.settings;
cases = [
{
# The journald receiver's own default directory is the RUNTIME
# journal, and a container that stores persistently leaves that
# empty. At the default the forwarder validates, starts, reports
# healthy and ships nothing, so this one literal is the difference
# between the path working and silently not.
name = "the agent forwarder reads the persistent journal, not the runtime one";
ok = ((agentSettings agentOtel).receivers.journald.directory or null) == "/var/log/journal";
}
{
# The hop's two ends: what it reads, and where what it reads goes.
# The endpoint is compared against the value the fixture handed the
# option rather than a literal spelled here, so an exporter that
# stopped reading the option fails instead of matching a constant
# that travelled beside it.
name = "the agent forwarder ships the journal to the endpoint its hive gave it";
ok =
let
s = agentSettings agentOtel;
p = s.service.pipelines.logs;
in
p.receivers == [ "journald" ]
&& p.exporters != [ ]
&& lib.all (e: (s.exporters ? ${e}) && s.exporters.${e}.endpoint == agentBridge) p.exporters;
}
{
# Presence control for the two cases above: with the switch off there
# is no collector in the container at all, so their passing is about
# the wiring rather than about a unit that renders regardless.
name = "an agent that has not opted into telemetry runs no collector";
ok = !agentNoOtel.services.opentelemetry-collector.enable;
}
{
# `otlp` and `otlphttp` are different components and the protocol
# option picks which one is defined. A pipeline left naming the other
# is a startup failure; an exporter no pipeline names is silence.
name = "the agent forwarder's exporter and its pipeline agree on the protocol";
ok =
let
s = agentSettings agentOtelGrpc;
in
(s.exporters ? otlp) && s.service.pipelines.logs.exporters == [ "otlp" ];
}
];
in
runGroup "agent-otel" cases