feat(client): expose ClusterID via Client interface - #3694
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shashank-reddy-nr wants to merge 1 commit into
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feat(client): expose ClusterID via Client interface#3694shashank-reddy-nr wants to merge 1 commit into
shashank-reddy-nr wants to merge 1 commit into
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Add ClusterID() string to the Client interface, backed by the ClusterID field already present in MetadataResponse (protocol version >= 2, Kafka >= 0.10.1). The value is stored on each successful metadata refresh under the existing client.lock RWMutex, consistent with how controllerID is handled. Returns an empty string for brokers that predate Kafka 0.10.1 or before the first metadata response is received. Also add SetClusterID to MockMetadataResponse so tests can configure the mock to return a cluster ID, and add stubLeaderClient.ClusterID() to satisfy the updated interface in async_producer_test.go. Assisted-by: Claude Sonnet 4.6
puellanivis
reviewed
Jul 28, 2026
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| // ClusterID returns the cluster ID reported by the broker in the most recent | ||
| // metadata response. It returns an empty string if the broker has not yet | ||
| // responded or if the Kafka version predates 0.10.1 (MetadataResponse v2). | ||
| ClusterID() string |
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This is expanding an exported interface, and thus a breaking change.
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| if data.ClusterID != nil && *data.ClusterID != "" { | ||
| client.clusterID = *data.ClusterID | ||
| } |
Collaborator
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The test against *data.ClusterID != "" is unnecessary. We can simply assign a zero value as a no-op.
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Summary
Adds
ClusterID() stringto theClientinterface, surfacing the cluster ID that brokers already return inMetadataResponse(protocol version ≥ 2, Kafka ≥ 0.10.1.0) but that was never stored or accessible to callers.Changes
client.go— addsclusterID stringfield to theclientstruct; stores the value inupdateMetadata()under the existingclient.lockRWMutex (same pattern ascontrollerID); addsClusterID() stringto theClientinterface; implements(*client).ClusterID()withRLock.mockresponses.go— addsclusterIDfield andSetClusterID()builder toMockMetadataResponseso tests can configure the mock; populatesMetadataResponse.ClusterIDinFor().client_test.go— addsTestClientClusterIDwith two subtests: one atV0_10_1_0that asserts the value round-trips correctly, and one atV0_10_0_0that asserts an empty string is returned when the broker does not include a cluster ID.async_producer_test.go— adds theClusterID() stringstub tostubLeaderClientto satisfy the updated interface.Design notes
string(not(string, error)): the cluster ID is either present or not; returning empty string for pre-0.10.1 brokers is consistent with howcontrollerIDbehaves before any metadata has been received.nopCloserClientrequires no changes — it embeds theClientinterface by value and inherits the new method automatically.MetadataResponse.ClusterIDis*string; the store path checks!= nil && != ""before overwriting, so a nil pointer from an old-version response never clears a previously cached value.