alertmanager: return error on invalid SMTP smarthost format#8586
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simonpasquier merged 1 commit intoMay 26, 2026
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net.SplitHostPort error is silently discarded when converting email receiver configuration. If validation is bypassed or incomplete, the host and port fields are set to empty strings, producing a broken SMTP configuration that fails silently at send time. The original pattern predates validation added in prometheus-operator#8270. Signed-off-by: Sebastien Tardif <[email protected]>
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The field is already validated when the controller selects AlertmanagerConfig resources but it doesn't hurt to do it twice.
simonpasquier
merged commit May 26, 2026
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…r to v0.92.1 (#1765) ##### [\`v0.92.1\`](https://github.com/prometheus-operator/prometheus-operator/releases/tag/v0.92.1) - \[BUGFIX] Fix "namespace not found" errors when the operator watches monitoring and workload resources in different resources. [#8658](prometheus-operator/prometheus-operator#8658) --- ##### [\`v0.92.0\`](https://github.com/prometheus-operator/prometheus-operator/releases/tag/v0.92.0) > \[!NOTE] > The `PrometheusTopologySharding` and `PrometheusShardRetentionPolicy` feature gates have been promoted to **Beta** in this release and are now enabled by default. See the [sharding documentation](https://prometheus-operator.dev/docs/platform/sharding/) for details. - \[CHANGE] Add URL validation for the `tokenUrl` field in OAuth2 configuration across all CRDs. [#8579](prometheus-operator/prometheus-operator#8579) - \[CHANGE] Add URL validation for the `url` field in `RemoteReadSpec` in `Prometheus` CRD. [#8596](prometheus-operator/prometheus-operator#8596) - \[FEATURE] Migrate retention options from CLI flags to the config file for `Prometheus` CRD (Prometheus >= v3 uses the config file; older versions continue to use CLI flags). [#8547](prometheus-operator/prometheus-operator#8547) - \[FEATURE] Add `staleSeriesCompactionThreshold` field to `TSDBSpec` in `Prometheus` and `PrometheusAgent` CRDs. [#8563](prometheus-operator/prometheus-operator#8563) - \[FEATURE] Add `labelNameUnderscoreSanitization` and `labelNamePreserveMultipleUnderscores` fields to `OTLPConfig` in `Prometheus` and `PrometheusAgent` CRDs. [#8562](prometheus-operator/prometheus-operator#8562) - \[FEATURE] Add `payload` field to Webhook receiver in `AlertmanagerConfig` CRD. [#8507](prometheus-operator/prometheus-operator#8507) - \[ENHANCEMENT] Use pod topology labels for zone sharding on Kubernetes >= 1.35 when the `PrometheusTopologySharding` feature gate is enabled (removes the need for `attachMetadata.node=true`). [#8564](prometheus-operator/prometheus-operator#8564) - \[ENHANCEMENT] Add validation for the Slack `update_message` field in Alertmanager configuration Secret. [#8556](prometheus-operator/prometheus-operator#8556) - \[BUGFIX] Validate target labels in `Probe` static configuration to prevent invalid Prometheus scrape configs. [#7901](prometheus-operator/prometheus-operator#7901) - \[BUGFIX] Fix goroutine leak and data race in `pollBasedListerWatcher`. [#8593](prometheus-operator/prometheus-operator#8593) - \[BUGFIX] Validate `ProxyConfig` in OAuth2 configuration. [#8610](prometheus-operator/prometheus-operator#8610) - \[BUGFIX] Fix SMTP smarthost format error handling in Alertmanager configuration. [#8586](prometheus-operator/prometheus-operator#8586) - \[BUGFIX] Fix missing `return` in admission webhook after marshal failure. [#8582](prometheus-operator/prometheus-operator#8582) - \[BUGFIX] Fix `FindOwner` to return `nil` on `meta.Accessor` error. [#8585](prometheus-operator/prometheus-operator#8585) - \[BUGFIX] Fix dropped gzip `Close` errors in `GzipConfig` and `GunzipConfig`. [#8573](prometheus-operator/prometheus-operator#8573) - \[BUGFIX] Fix panic on malformed key=value flag input (e.g. `--labels "key"`). [#8560](prometheus-operator/prometheus-operator#8560) Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
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The
net.SplitHostPorterror in the email receiver config conversion is silently discarded with_. On failure,HostandPortare set to empty strings, producing an SMTP configuration that fails silently at email send time.Failure scenario
If the smarthost value reaches the conversion layer without passing through validation (e.g., a new API version or an alternative code path that skips the v1alpha1/v1beta1 validators), a malformed smarthost like
no-port-heresilently produces empty Host and Port fields. The resulting Alertmanager config connects to an empty host, and email notifications fail with no indication of what went wrong.Context
Validation in
pkg/alertmanager/validation/checksSplitHostPortand rejects invalid values. However, the conversion layer inamcfg.goshould independently handle errors as a defense-in-depth measure. The_assignment predates the validation code added in #8270.