discovery/rds: skip DB clusters whose ARN is unset - #19501
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DBClusterArn is optional in the DescribeDBClusters response. The explicit-cluster path (config: clusters) stores the returned cluster keyed by the configured ARN without checking the ARN came back, so a cluster response missing it panicked the refresh goroutine at the describeDBInstances call. Skip the cluster like describeAllDBClusters already does for the same field, and say so in the log. Signed-off-by: Rohit Behera <126186063+r0h1tb@users.noreply.github.com>
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In what situation would you have a cluster without an ARN??? Or is this just to be more defensive, in which case I'm all for it. |
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Fixes a panic in the RDS service discovery refresh; no tracking issue, found by code reading in the same class as #19324/#19396.
Problem
refresh()dereferences*cluster.DBClusterArnto look up the cluster's instances (rds.go:540 on main).DBClusterArnis optional in theDescribeDBClustersresponse — the SDK marks no member ofDBClusteras required — so a cluster response missing it panics the refresh goroutine and takes the whole process down.The explicit-cluster path (
clusters:config) reaches this most easily:describeDBClustersstores whatever the API returns keyed by the configured ARN without checking the ARN came back.describeAllDBClustersalready skips ARN-less clusters (rds.go:421), which is why the all-clusters path never trips this.Fix
Skip the cluster with a warning, mirroring the existing
describeAllDBClustersbehaviour and the "Skipping invalid ElastiCache ARN" precedent in elasticache.go.Tests
TestRDSRefreshSkipsClusterWithoutArndrives the realrefresh()— the existing table test rebuilds the target list inline and never calls it, which is how this survived review. Against unfixed code:With the fix the ARN-less cluster is skipped, the healthy cluster in the same config still produces its target, and the package suite is green (
ok github.com/prometheus/prometheus/discovery/aws, matching main).