nixos/prometheus-snmp-exporter: add config check

This is introduced and enabled by default because the config syntax for
the exporter changed with release 0.23.0.

This should make the breaking config change obvious before services are
deployed with an incompatible old config.

The check is based on the check present in the blackbox-exporter module.

1 files changed, 4 insertions, 0 deletions

diff --git a/nixos/doc/manual/release-notes/rl-2405.section.md b/nixos/doc/manual/release-notes/rl-2405.section.md
index c075149a0e5d..724307c0940a 100644
--- a/nixos/doc/manual/release-notes/rl-2405.section.md
+++ b/nixos/doc/manual/release-notes/rl-2405.section.md
@@ -124,6 +124,10 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 - `security.pam.enableSSHAgentAuth` now requires `services.openssh.authorizedKeysFiles` to be non-empty,
   which is the case when `services.openssh.enable` is true. Previously, `pam_ssh_agent_auth` silently failed to work.
 
+- The configuration format for `services.prometheus.exporters.snmp` changed with release 0.23.0.
+  The module now includes an optional config check, that is enabled by default, to make the change obvious before any deployment.
+  More information about the configuration syntax change is available in the [upstream repository](https://github.com/prometheus/snmp_exporter/blob/b75fc6b839ee3f3ccbee68bee55f1ae99555084a/auth-split-migration.md).
+
 ## Other Notable Changes {#sec-release-24.05-notable-changes}
 
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