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Operating Aeron cluster

Cluster Tool

Cluster Tool allows you to operate a running cluster, including describing the cluster, changing membership, taking snapshots and clean shutdowns.

Obtaining Cluster Tool

Cluster Tool is found in the aeron-all jar, which can be downloaded from Maven Central. The tool is run pointing at the cluster folder, unlike AeronStat which needs to point at the Aeron directory.

Describing the Cluster

During operational incident investigations, one of the first things one needs to do is understand the state of the cluster. The describe option does this.

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . describe
INFO: Mark file exists: ./cluster-mark.dat
Type: CONSENSUS_MODULE 19:36:24 (start: 2020-05-28 19:18:26, activity: 2020-05-28 19:18:34)
[MarkFileHeader](sbeTemplateId=200|sbeSchemaId=110|sbeSchemaVersion=0|sbeBlockLength=128):version=512|componentType=CONSENSUS_MODULE|activityTimestamp=1590707914066|startTimestamp=1590707906036|pid=68862|candidateTermId=-1|archiveStreamId=11|serviceStreamId=104|consensusModuleStreamId=105|ingressStreamId=101|memberId=0|serviceId=-1|headerLength=8192|errorBufferLength=1048576|clusterId=0|aeronDirectory='/var/folders/np/9nn7kn7d15qfc7qcnt9rbsgm0000gn/T/aeron-u001'|controlChannel='aeron:ipc?term-length=64k|mtu=8k'|ingressChannel='aeron:udp?endpoint=localhost:9010'|serviceName=''|authenticator='class io.aeron.security.DefaultAuthenticatorSupplier'
INFO: Mark file exists: ./cluster-mark-service-0.dat
Type: CONTAINER 19:36:24 (start: 2020-05-28 19:18:26, activity: 2020-05-28 19:18:33)
[MarkFileHeader](sbeTemplateId=200|sbeSchemaId=110|sbeSchemaVersion=0|sbeBlockLength=128):version=512|componentType=CONTAINER|activityTimestamp=1590707913147|startTimestamp=1590707906122|pid=68862|candidateTermId=-1|archiveStreamId=11|serviceStreamId=104|consensusModuleStreamId=105|ingressStreamId=-1|memberId=0|serviceId=0|headerLength=8192|errorBufferLength=1048576|clusterId=0|aeronDirectory='/var/folders/np/9nn7kn7d15qfc7qcnt9rbsgm0000gn/T/aeron-u001'|controlChannel='aeron:ipc?term-length=64k|mtu=8k'|ingressChannel=''|serviceName='clustered-service'|authenticator=''

Listing members

Cluster tool can also list the members of the cluster:

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . list-members
INFO: Mark file exists: ./cluster-mark.dat
currentTimeNs=1591054805865000000, leaderMemberId=0, memberId=0, activeMembers=[ClusterMember{id=0, isBallotSent=false, isLeader=false, hasRequestedJoin=false, leadershipTermId=4, logPosition=20224, candidateTermId=-1, catchupReplaySessionId=-1, correlationId=-1, removalPosition=-1, timeOfLastAppendPositionNs=1591054805865000000, ingressEndpoint='localhost:9003', consensusEndpoint='localhost:9004', logEndpoint='localhost:9005', catchupEndpoint='localhost:9006', archiveEndpoint='localhost:9001', endpoints='localhost:9003,localhost:9004,localhost:9005,localhost:9006,localhost:9001', publication=null, vote=null}], passiveMembers=[]

Inspecting the recording log

The recording log can be inspected. This shows the recording.

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . recording-log
RecordingLog{entries=[Entry{recordingId=0, leadershipTermId=0, termBaseLogPosition=0, logPosition=96, timestamp=1590707882622, serviceId=-1, type=0, isValid=true, entryIndex=0}, Entry{recordingId=0, leadershipTermId=1, termBaseLogPosition=96, logPosition=-1, timestamp=1590707906982, serviceId=-1, type=0, isValid=true, entryIndex=1}], cacheIndex={1=1, 0=0}}

Taking a snapshot

Cluster tool can be used to take a snapshot, although this requires that the running cluster has the appropriate code to write and read snapshots.

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . snapshot
INFO: Mark file exists: ./cluster-mark.dat
Member [0]: SNAPSHOT applied successfully

Listing errors

Errors raised and captured by Aeron Cluster & Aeron are provided:

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . errors
INFO: Mark file exists: ./cluster-mark.dat
Type: CONSENSUS_MODULE 19:41:41 (start: 2020-05-28 19:18:26, activity: 2020-05-28 19:18:34)
Cluster component error log:

Aeron driver error log (directory: /var/folders/np/9nn7kn7d15qfc7qcnt9rbsgm0000gn/T/aeron-u001):
INFO: Mark file exists: ./cluster-mark-service-0.dat
Type: CONTAINER 19:41:41 (start: 2020-05-28 19:18:26, activity: 2020-05-28 19:18:33)
Cluster component error log:

For common errors, see Cluster Errors

Obtaining the PID for the Cluster process

Cluster tool can obtain the operating system PID for the cluster pointing at this folder:

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . pid
68862

Shutting down the cluster

Cluster tool can shutdown the cluster:

➜ java -cp /Users/u001/src/aeron-all-*.jar io.aeron.cluster.ClusterTool . shutdown
INFO: Mark file exists: ./cluster-mark.dat
Member [0]: SHUTDOWN applied successfully
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