Unstable leadership when running server is demoted/removed without its participation #524

szechuen · 2022-09-06T18:46:26Z

Hi 👋

We have discovered an issue with the library that results in unstable leadership when running server is demoted/removed without its participation, which we have managed to reasonably reproduce in Consul OSS/Enterprise >= v1.13.0 and Vault Enterprise >= v1.11.0. We believe the livelock behavior was uncovered by the logically correct check introduced in #477 and released as part of Raft v1.3.7.

Reproduction: https://github.com/szechuen/raft-524

Precondition

A running server is demoted or removed from the cluster without its participation. Realistically, this is likely to occur when a server is temporarily disconnected from the rest of the cluster and automatically demoted/removed by the remaining servers via a process like raft-autopilot which both Consul and Vault utilizes before being reconnected.

Consul

As of Consul v1.13.x, the behavior is tied to the CleanupDeadServers option (default: true) offered by raft-autopilot which when invoked removes all failed servers subject to the configured MinQuorum (default: 0). This is triggered once LastContactThreshold (default: 200ms) is exceeded and the server is considered unhealthy.

Vault

As of Vault v1.11.x, the cleanup_dead_servers option is false by default and even when enabled defaults to the much higher dead_server_last_contact_threshold of 24h, hence less likely to occur with reasonable configuration.

However, the Automated Upgrades Autopilot feature was introduced in the Enterprise variant which is enabled by default (disable_upgrade_migration, default: false) and automatically demotes any server with an UpgradeVersionTag not matching the majority of the servers to a non-voter. There must be a leadership transfer during the loss of connectivity for the last known information to be reset and thus triggering the behavior. This is ensured when the server cut off is the existing leader.

Behavior

All log samples reference the Consul and Vault issue reproduction linked above with a 3-node (node0, node1, node2) cluster setup where node0 is the initial node bootstrapped (hence existing leader) and disconnected from the remaining nodes for a period of 30s after the cluster has been formed.

First, ensure that the cluster has stabilized and the remaining nodes have been promoted to voters if the ServerStabilizationTime Autopilot config is set (default: 10s for both Consul and Vault).

# Consul

consul-node0-1  | 2022-09-06T17:02:28.227Z [INFO]  agent.server.autopilot: Promoting server: id=6d5eb694-fa44-1622-2b81-8e8f5a162251 address=172.20.0.2:8300 name=node2
consul-node0-1  | 2022-09-06T17:02:28.230Z [INFO]  agent.server.raft: updating configuration: command=AddVoter server-id=6d5eb694-fa44-1622-2b81-8e8f5a162251 server-addr=172.20.0.2:8300 servers="[{Suffrage:Voter ID:2332eb10-d58f-1820-d7fc-153abfaa7111 Address:172.20.0.3:8300} {Suffrage:Voter ID:6d5eb694-fa44-1622-2b81-8e8f5a162251 Address:172.20.0.2:8300} {Suffrage:Nonvoter ID:11e503a2-f8e5-a39c-d1c0-834b15ae01a6 Address:172.20.0.4:8300}]"
consul-node0-1  | 2022-09-06T17:02:28.231Z [INFO]  agent.server.autopilot: Promoting server: id=11e503a2-f8e5-a39c-d1c0-834b15ae01a6 address=172.20.0.4:8300 name=node1
consul-node0-1  | 2022-09-06T17:02:28.231Z [INFO]  agent.server.raft: updating configuration: command=AddVoter server-id=11e503a2-f8e5-a39c-d1c0-834b15ae01a6 server-addr=172.20.0.4:8300 servers="[{Suffrage:Voter ID:2332eb10-d58f-1820-d7fc-153abfaa7111 Address:172.20.0.3:8300} {Suffrage:Voter ID:6d5eb694-fa44-1622-2b81-8e8f5a162251 Address:172.20.0.2:8300} {Suffrage:Voter ID:11e503a2-f8e5-a39c-d1c0-834b15ae01a6 Address:172.20.0.4:8300}]"

# Vault

vault-node0-1  | 2022-09-06T17:04:24.259Z [INFO]  storage.raft.autopilot: Promoting server: id=node1 address=node1:8201 name=node1
vault-node0-1  | 2022-09-06T17:04:24.259Z [INFO]  storage.raft: updating configuration: command=AddVoter server-id=node1 server-addr=node1:8201 servers="[{Suffrage:Voter ID:node0 Address:node0:8201} {Suffrage:Voter ID:node1 Address:node1:8201} {Suffrage:Nonvoter ID:node2 Address:node2:8201}]"
vault-node0-1  | 2022-09-06T17:04:24.261Z [INFO]  storage.raft.autopilot: Promoting server: id=node2 address=node2:8201 name=node2
vault-node0-1  | 2022-09-06T17:04:24.261Z [INFO]  storage.raft: updating configuration: command=AddVoter server-id=node2 server-addr=node2:8201 servers="[{Suffrage:Voter ID:node0 Address:node0:8201} {Suffrage:Voter ID:node1 Address:node1:8201} {Suffrage:Voter ID:node2 Address:node2:8201}]"

Next, node0 is disconnected from the cluster for 30s during which it would be either demoted to a non-voter (Vault) or removed as a server entirely (Consul). Since node0 can't learn about the configuration change and hear from the leader, it would continuously attempt to start an election and request for votes as a candidate with progressively higher terms.

# Consul

consul-node0-1  | Disconnecting node...
consul-node0-1  | 2022-09-06T17:02:40.621Z [WARN]  agent.server.raft: failed to contact quorum of nodes, stepping down
consul-node0-1  | 2022-09-06T17:02:40.621Z [INFO]  agent.server.raft: entering follower state: follower="Node at 172.20.0.3:8300 [Follower]" leader-address= leader-id=
consul-node0-1  | 2022-09-06T17:02:45.924Z [WARN]  agent.server.raft: heartbeat timeout reached, starting election: last-leader-addr= last-leader-id=
consul-node0-1  | 2022-09-06T17:02:45.924Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.3:8300 [Candidate]" term=3
consul-node0-1  | 2022-09-06T17:02:51.257Z [WARN]  agent.server.raft: Election timeout reached, restarting election
consul-node0-1  | 2022-09-06T17:02:51.257Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.3:8300 [Candidate]" term=4

consul-node2-1  | 2022-09-06T17:02:52.733Z [INFO]  agent.server.raft: election won: tally=2
consul-node2-1  | 2022-09-06T17:02:52.733Z [INFO]  agent.server.raft: entering leader state: leader="Node at 172.20.0.2:8300 [Leader]"
consul-node2-1  | 2022-09-06T17:02:58.170Z [INFO]  agent.server.autopilot: Attempting removal of failed server node: id=2332eb10-d58f-1820-d7fc-153abfaa7111 name=node0 address=172.20.0.3:8300
consul-node2-1  | 2022-09-06T17:02:58.172Z [INFO]  agent.server.raft: updating configuration: command=RemoveServer server-id=2332eb10-d58f-1820-d7fc-153abfaa7111 server-addr= servers="[{Suffrage:Voter ID:6d5eb694-fa44-1622-2b81-8e8f5a162251 Address:172.20.0.2:8300} {Suffrage:Voter ID:11e503a2-f8e5-a39c-d1c0-834b15ae01a6 Address:172.20.0.4:8300}]"
consul-node2-1  | 2022-09-06T17:02:58.175Z [INFO]  agent.server.autopilot: removed server: id=2332eb10-d58f-1820-d7fc-153abfaa7111

# Vault

vault-node0-1  | Disconnecting node...
vault-node0-1  | 2022-09-06T17:04:42.574Z [WARN]  storage.raft: failed to contact quorum of nodes, stepping down
vault-node0-1  | 2022-09-06T17:04:42.574Z [INFO]  storage.raft: entering follower state: follower="Node at node0:8201 [Follower]" leader-address= leader-id=
vault-node0-1  | 2022-09-06T17:04:50.062Z [WARN]  storage.raft: heartbeat timeout reached, starting election: last-leader-addr= last-leader-id=
vault-node0-1  | 2022-09-06T17:04:50.062Z [INFO]  storage.raft: entering candidate state: node="Node at node0:8201 [Candidate]" term=4
vault-node0-1  | 2022-09-06T17:04:58.072Z [WARN]  storage.raft: Election timeout reached, restarting election
vault-node0-1  | 2022-09-06T17:04:58.072Z [INFO]  storage.raft: entering candidate state: node="Node at node0:8201 [Candidate]" term=5

vault-node2-1  | 2022-09-06T17:04:52.566Z [INFO]  storage.raft: election won: tally=2
vault-node2-1  | 2022-09-06T17:04:52.566Z [INFO]  storage.raft: entering leader state: leader="Node at node2:8201 [Leader]"
vault-node2-1  | 2022-09-06T17:05:02.612Z [ERROR] storage.raft.autopilot: UpgradeVersionTag not found in server metadata: id=node0 name=node0 address=node0:8201 upgrade_version_tag=upgrade_version
vault-node2-1  | 2022-09-06T17:05:02.612Z [INFO]  storage.raft.autopilot: Demoting server: id=node0 address=node0:8201 name=node0
vault-node2-1  | 2022-09-06T17:05:02.612Z [INFO]  storage.raft: updating configuration: command=DemoteVoter server-id=node0 server-addr= servers="[{Suffrage:Nonvoter ID:node0 Address:node0:8201} {Suffrage:Voter ID:node1 Address:node1:8201} {Suffrage:Voter ID:node2 Address:node2:8201}]"

Once node0 is reconnected, we see that it continues to attempt starting an election and request for votes as a candidate since it does not learn about the configuration change. The check introduced in #477 makes the remaining nodes ignore the vote request but because node0 has a higher term, they abandon their quorum and step down to followers before restarting elections. However, the terms on node1/node2 are not updated to the highest term seen (from node0) and the next round of elections continues to be made with a lower term than that of node0 causing the process to repeat all over again.

Note that prior to #477, node1/node2 would have accepted the vote request from node0 despite not being a voter and elected it as the new leader which while incorrect would have allowed the cluster to make forward progress.

# Consul

consul-node0-1  | Reconnecting node...

consul-node2-1  | 2022-09-06T17:03:08.443Z [INFO]  agent.server.raft: updating configuration: command=AddNonvoter server-id=2332eb10-d58f-1820-d7fc-153abfaa7111 server-addr=172.20.0.3:8300 servers="[{Suffrage:Voter ID:6d5eb694-fa44-1622-2b81-8e8f5a162251 Address:172.20.0.2:8300} {Suffrage:Voter ID:11e503a2-f8e5-a39c-d1c0-834b15ae01a6 Address:172.20.0.4:8300} {Suffrage:Nonvoter ID:2332eb10-d58f-1820-d7fc-153abfaa7111 Address:172.20.0.3:8300}]"
consul-node2-1  | 2022-09-06T17:03:08.448Z [ERROR] agent.server.raft: peer has newer term, stopping replication: peer="{Nonvoter 2332eb10-d58f-1820-d7fc-153abfaa7111 172.20.0.3:8300}"
consul-node2-1  | 2022-09-06T17:03:08.448Z [INFO]  agent.server.raft: entering follower state: follower="Node at 172.20.0.2:8300 [Follower]" leader-address= leader-id=
consul-node2-1  | 2022-09-06T17:03:08.448Z [ERROR] agent.server.autopilot: failed to add raft non-voting peer: id=2332eb10-d58f-1820-d7fc-153abfaa7111 address=172.20.0.3:8300 error="leadership lost while committing log"

consul-node0-1  | 2022-09-06T17:03:12.909Z [WARN]  agent.server.raft: Election timeout reached, restarting election
consul-node0-1  | 2022-09-06T17:03:12.909Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.3:8300 [Candidate]" term=7
consul-node1-1  | 2022-09-06T17:03:12.916Z [WARN]  agent.server.raft: rejecting vote request since node is not a voter: from=172.20.0.3:8300
consul-node2-1  | 2022-09-06T17:03:12.916Z [WARN]  agent.server.raft: rejecting vote request since node is not a voter: from=172.20.0.3:8300

consul-node2-1  | 2022-09-06T17:03:17.405Z [WARN]  agent.server.raft: heartbeat timeout reached, starting election: last-leader-addr= last-leader-id=
consul-node2-1  | 2022-09-06T17:03:17.405Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.2:8300 [Candidate]" term=5
consul-node2-1  | 2022-09-06T17:03:17.413Z [INFO]  agent.server.raft: election won: tally=2
consul-node2-1  | 2022-09-06T17:03:17.414Z [INFO]  agent.server.raft: entering leader state: leader="Node at 172.20.0.2:8300 [Leader]"

consul-node2-1  | 2022-09-06T17:03:17.414Z [INFO]  agent.server.raft: added peer, starting replication: peer=11e503a2-f8e5-a39c-d1c0-834b15ae01a6
consul-node2-1  | 2022-09-06T17:03:17.414Z [INFO]  agent.server.raft: pipelining replication: peer="{Voter 11e503a2-f8e5-a39c-d1c0-834b15ae01a6 172.20.0.4:8300}"
consul-node2-1  | 2022-09-06T17:03:17.415Z [ERROR] agent.server.raft: peer has newer term, stopping replication: peer="{Nonvoter 2332eb10-d58f-1820-d7fc-153abfaa7111 172.20.0.3:8300}"
consul-node2-1  | 2022-09-06T17:03:17.416Z [INFO]  agent.server.raft: entering follower state: follower="Node at 172.20.0.2:8300 [Follower]" leader-address= leader-id=

# Vault

vault-node0-1  | Reconnecting node...

vault-node0-1  | 2022-09-06T17:05:12.453Z [WARN]  storage.raft: Election timeout reached, restarting election
vault-node0-1  | 2022-09-06T17:05:12.453Z [INFO]  storage.raft: entering candidate state: node="Node at node0:8201 [Candidate]" term=7
vault-node1-1  | 2022-09-06T17:05:12.477Z [WARN]  storage.raft: rejecting vote request since node is not a voter: from=node0:8201
vault-node2-1  | 2022-09-06T17:05:12.484Z [WARN]  storage.raft: rejecting vote request since node is not a voter: from=node0:8201

vault-node2-1  | 2022-09-06T17:05:12.558Z [ERROR] storage.raft: failed to appendEntries to: peer="{Voter node0 node0:8201}" error="dial tcp 172.19.0.3:8201: i/o timeout"
vault-node2-1  | 2022-09-06T17:05:12.570Z [ERROR] storage.raft: peer has newer term, stopping replication: peer="{Voter node0 node0:8201}"
vault-node2-1  | 2022-09-06T17:05:12.570Z [INFO]  storage.raft: entering follower state: follower="Node at node2:8201 [Follower]" leader-address= leader-id=

vault-node0-1  | 2022-09-06T17:05:17.671Z [WARN]  storage.raft: Election timeout reached, restarting election
vault-node0-1  | 2022-09-06T17:05:17.671Z [INFO]  storage.raft: entering candidate state: node="Node at node0:8201 [Candidate]" term=8
vault-node2-1  | 2022-09-06T17:05:17.675Z [WARN]  storage.raft: rejecting vote request since node is not a voter: from=node0:8201
vault-node1-1  | 2022-09-06T17:05:17.675Z [WARN]  storage.raft: rejecting vote request since node is not a voter: from=node0:8201

vault-node2-1  | 2022-09-06T17:05:21.425Z [INFO]  storage.raft: entering candidate state: node="Node at node2:8201 [Candidate]" term=6
vault-node2-1  | 2022-09-06T17:05:21.432Z [INFO]  storage.raft: election won: tally=2
vault-node2-1  | 2022-09-06T17:05:21.432Z [INFO]  storage.raft: entering leader state: leader="Node at node2:8201 [Leader]"

vault-node2-1  | 2022-09-06T17:05:21.432Z [INFO]  storage.raft: added peer, starting replication: peer=node0
vault-node2-1  | 2022-09-06T17:05:21.432Z [ERROR] storage.raft: peer has newer term, stopping replication: peer="{Nonvoter node0 node0:8201}"
vault-node2-1  | 2022-09-06T17:05:21.434Z [INFO]  storage.raft: entering follower state: follower="Node at node2:8201 [Follower]" leader-address= leader-id=

The result of which is a cluster that is henceforth trapped in a livelock and never able to regain stable leadership until node0 is reset.

The text was updated successfully, but these errors were encountered:

dhiaayachi · 2022-09-06T20:16:36Z

Thank you for reporting this and for the detailed reproduction @szechuen !

Going though those logs, I see this log line:

consul-node2-1  | 2022-09-06T17:03:08.443Z [INFO]  agent.server.raft: updating configuration: command=AddNonvoter server-id=2332eb10-d58f-1820-d7fc-153abfaa7111 server-addr=172.20.0.3:8300 servers="[{Suffrage:Voter ID:6d5eb694-fa44-1622-2b81-8e8f5a162251 Address:172.20.0.2:8300} {Suffrage:Voter ID:11e503a2-f8e5-a39c-d1c0-834b15ae01a6 Address:172.20.0.4:8300} {Suffrage:Nonvoter ID:2332eb10-d58f-1820-d7fc-153abfaa7111 Address:172.20.0.3:8300}]"

which I presume is autopilot adding the server back to the cluster as a non voter and the cluster became unstable when we try to replicate to it which happen over and over again and lead to the cluster staying unstable.

I'm wondering if it would be sufficient to add a check similar to the one we added in #477 when checking for term in the replication routine here.That would prevent the election from happening as it does not make sense to start an election when a non voter is encountered with a higher term, that non voter can't participate in the election anyway.

szechuen · 2022-09-06T20:32:09Z

Would node0 be reset to the lower term held by node1/node2 in that case? If it retains the higher term, the issue would still be present once autopilot promotes it to a voter.

Update: Also node0 would not accept the appendEntries RPC in the first place since the request's term is lower than the node's term

raft/raft.go

Lines 1378 to 1381 in 1075246

    
           // Ignore an older term 
        
           if a.Term < r.getCurrentTerm() { 
        
           	return 
        
           }

szechuen · 2022-09-06T22:31:15Z

Confirmed that Nomad OSS/Enterprise >= v1.3.3 is also affected and updated https://github.com/szechuen/raft-524 to reproduce the issue. Its preconditions are similar to Consul's https://www.nomadproject.io/docs/configuration/autopilot

raskchanky · 2022-09-06T23:24:12Z

@szechuen Hi 👋

After reading your description of how Vault behaves, I believe hashicorp/vault#17019 might mitigate this somewhat, at least from the perspective that UpgradeVersionTag will no longer disappear when the connectivity intermittently drops.

szechuen · 2022-09-06T23:28:27Z

Yep hashicorp/vault#17019 mitigates the issue for Vault, or you could toggle disable_upgrade_migration to true as well (which we have done). But the root issue is with the Raft library.

ncabatoff · 2022-09-07T14:06:47Z

We have an open issue in the private raft-autopilot-enterprise repo (https://github.com/hashicorp/raft-autopilot-enterprise/issues/5) that relates to this. I intend to tackle it later, once I've got the quick fix for Vault merged. I don't claim to have fully digested everything in this here issue, so I'm not saying it covers all the concerns raised, just wanted to add this detail for now.

dhiaayachi · 2022-09-08T19:16:14Z

Would node0 be reset to the lower term held by node1/node2 in that case? If it retains the higher term, the issue would still be present once autopilot promotes it to a voter.

Update: Also node0 would not accept the appendEntries RPC in the first place since the request's term is lower than the node's term

raft/raft.go

Lines 1378 to 1381 in 1075246

// Ignore an older term

if a.Term < r.getCurrentTerm() {

return

}

Yes the term should be reset, I think. The idea is that NonVoters d should accept the term that the cluster agree upon as they don't have a voting right they should not be able to destabilize the cluster as non voters won't be able to win an election.

I've put a PR up that have a test that reproduce the same behaviour and propose a fix (#525)

szechuen · 2022-09-23T16:35:12Z

Verified that #526 resolves the behavior in Consul and Nomad (can't test Vault since the primary behavior is only present on Enterprise).

Consul

consul-node0-1  | Reconnecting node...

consul-node0-1  | 2022-09-23T16:03:14.368Z [WARN]  agent.server.raft: Election timeout reached, restarting election
consul-node0-1  | 2022-09-23T16:03:14.368Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.4:8300 [Candidate]" term=10
consul-node1-1  | 2022-09-23T16:03:14.374Z [WARN]  agent.server.raft: rejecting vote request since node is not in configuration: from=172.20.0.4:8300
consul-node2-1  | 2022-09-23T16:03:14.375Z [WARN]  agent.server.raft: rejecting vote request since node is not in configuration: from=172.20.0.4:8300
consul-node0-1  | 2022-09-23T16:03:23.648Z [WARN]  agent.server.raft: Election timeout reached, restarting election
consul-node0-1  | 2022-09-23T16:03:23.648Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.4:8300 [Candidate]" term=11
consul-node2-1  | 2022-09-23T16:03:23.654Z [WARN]  agent.server.raft: rejecting vote request since node is not in configuration: from=172.20.0.4:8300
consul-node1-1  | 2022-09-23T16:03:23.654Z [WARN]  agent.server.raft: rejecting vote request since node is not in configuration: from=172.20.0.4:8300

consul-node2-1  | 2022-09-23T16:03:29.204Z [INFO]  agent.server: Adding LAN server: server="node0 (Addr: tcp/172.20.0.4:8300) (DC: dc1)"
consul-node2-1  | 2022-09-23T16:03:29.204Z [INFO]  agent.server.raft: updating configuration: command=AddNonvoter server-id=4eb54902-3d04-7dbc-7668-19c31807eead server-addr=172.20.0.4:8300 servers="[{Suffrage:Voter ID:033dc655-af7b-4538-14ef-3cf701bc7bd3 Address:172.20.0.2:8300} {Suffrage:Voter ID:501ca8a4-2eb3-3752-728c-07686c7a639e Address:172.20.0.3:8300} {Suffrage:Nonvoter ID:4eb54902-3d04-7dbc-7668-19c31807eead Address:172.20.0.4:8300}]"
consul-node2-1  | 2022-09-23T16:03:29.206Z [INFO]  agent.server.raft: added peer, starting replication: peer=4eb54902-3d04-7dbc-7668-19c31807eead
consul-node2-1  | 2022-09-23T16:03:29.207Z [ERROR] agent.server.raft: peer has newer term, stopping replication: peer="{Nonvoter 4eb54902-3d04-7dbc-7668-19c31807eead 172.20.0.4:8300}"
consul-node2-1  | 2022-09-23T16:03:29.207Z [INFO]  agent.server.raft: entering follower state: follower="Node at 172.20.0.3:8300 [Follower]" leader-address= leader-id=

consul-node0-1  | 2022-09-23T16:03:33.372Z [WARN]  agent.server.raft: Election timeout reached, restarting election
consul-node0-1  | 2022-09-23T16:03:33.372Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.4:8300 [Candidate]" term=12
consul-node1-1  | 2022-09-23T16:03:33.376Z [WARN]  agent.server.raft: rejecting vote request since we have a leader: from=172.20.0.4:8300 leader=172.20.0.3:8300 leader-id=501ca8a4-2eb3-3752-728c-07686c7a639e
consul-node2-1  | 2022-09-23T16:03:33.377Z [WARN]  agent.server.raft: rejecting vote request since node is not a voter: from=172.20.0.4:8300
consul-node2-1  | 2022-09-23T16:03:37.065Z [WARN]  agent.server.raft: heartbeat timeout reached, starting election: last-leader-addr= last-leader-id=
consul-node2-1  | 2022-09-23T16:03:37.065Z [INFO]  agent.server.raft: entering candidate state: node="Node at 172.20.0.3:8300 [Candidate]" term=13
consul-node2-1  | 2022-09-23T16:03:37.072Z [INFO]  agent.server.raft: election won: term=13 tally=2
consul-node2-1  | 2022-09-23T16:03:37.072Z [INFO]  agent.server.raft: entering leader state: leader="Node at 172.20.0.3:8300 [Leader]"

consul-node2-1  | 2022-09-23T16:03:49.022Z [INFO]  agent.server.autopilot: Promoting server: id=4eb54902-3d04-7dbc-7668-19c31807eead address=172.20.0.4:8300 name=node0
consul-node2-1  | 2022-09-23T16:03:49.022Z [INFO]  agent.server.raft: updating configuration: command=AddVoter server-id=4eb54902-3d04-7dbc-7668-19c31807eead server-addr=172.20.0.4:8300 servers="[{Suffrage:Voter ID:033dc655-af7b-4538-14ef-3cf701bc7bd3 Address:172.20.0.2:8300} {Suffrage:Voter ID:501ca8a4-2eb3-3752-728c-07686c7a639e Address:172.20.0.3:8300} {Suffrage:Voter ID:4eb54902-3d04-7dbc-7668-19c31807eead Address:172.20.0.4:8300}]"

Nomad

nomad-node0-1  | Reconnecting node...

nomad-node0-1  |     2022-09-23T16:19:00.143Z [WARN]  nomad.raft: Election timeout reached, restarting election
nomad-node0-1  |     2022-09-23T16:19:00.143Z [INFO]  nomad.raft: entering candidate state: node="Node at 172.26.0.4:4647 [Candidate]" term=41
nomad-node2-1  |     2022-09-23T16:19:00.601Z [WARN]  nomad.raft: rejecting vote request since node is not in configuration: from=172.26.0.4:4647
nomad-node1-1  |     2022-09-23T16:19:01.175Z [WARN]  nomad.raft: rejecting vote request since node is not in configuration: from=172.26.0.4:4647

nomad-node1-1  |     2022-09-23T16:19:01.352Z [INFO]  nomad: adding server: server="node0.global (Addr: 172.26.0.4:4647) (DC: dc1)"
nomad-node1-1  |     2022-09-23T16:19:01.352Z [INFO]  nomad.raft: updating configuration: command=AddNonvoter server-id=39cc4e8a-de6b-a8e2-da12-8c1495d86b70 server-addr=172.26.0.4:4647 servers="[{Suffrage:Voter ID:916e4c98-7ddb-a9c0-16c1-48032b3295d0 Address:172.26.0.3:4647} {Suffrage:Voter ID:029a4697-b02c-1ee8-1d7b-11e4b0a22824 Address:172.26.0.2:4647} {Suffrage:Nonvoter ID:39cc4e8a-de6b-a8e2-da12-8c1495d86b70 Address:172.26.0.4:4647}]"
nomad-node1-1  |     2022-09-23T16:19:01.354Z [INFO]  nomad.raft: added peer, starting replication: peer=39cc4e8a-de6b-a8e2-da12-8c1495d86b70
nomad-node1-1  |     2022-09-23T16:19:01.355Z [ERROR] nomad.raft: peer has newer term, stopping replication: peer="{Nonvoter 39cc4e8a-de6b-a8e2-da12-8c1495d86b70 172.26.0.4:4647}"
nomad-node1-1  |     2022-09-23T16:19:01.355Z [INFO]  nomad.raft: entering follower state: follower="Node at 172.26.0.3:4647 [Follower]" leader-address= leader-id=

nomad-node0-1  |     2022-09-23T16:19:01.497Z [WARN]  nomad.raft: Election timeout reached, restarting election
nomad-node0-1  |     2022-09-23T16:19:01.497Z [INFO]  nomad.raft: entering candidate state: node="Node at 172.26.0.4:4647 [Candidate]" term=42
nomad-node2-1  |     2022-09-23T16:19:01.501Z [WARN]  nomad.raft: rejecting vote request since we have a leader: from=172.26.0.4:4647 leader=172.26.0.3:4647 leader-id=916e4c98-7ddb-a9c0-16c1-48032b3295d0
nomad-node1-1  |     2022-09-23T16:19:01.502Z [WARN]  nomad.raft: rejecting vote request since node is not a voter: from=172.26.0.4:4647
nomad-node0-1  |     2022-09-23T16:19:03.104Z [WARN]  nomad.raft: Election timeout reached, restarting election
nomad-node0-1  |     2022-09-23T16:19:03.104Z [INFO]  nomad.raft: entering candidate state: node="Node at 172.26.0.4:4647 [Candidate]" term=43
nomad-node2-1  |     2022-09-23T16:19:03.109Z [WARN]  nomad.raft: rejecting vote request since we have a leader: from=172.26.0.4:4647 leader=172.26.0.3:4647 leader-id=916e4c98-7ddb-a9c0-16c1-48032b3295d0
nomad-node1-1  |     2022-09-23T16:19:03.110Z [WARN]  nomad.raft: rejecting vote request since node is not a voter: from=172.26.0.4:4647
nomad-node1-1  |     2022-09-23T16:19:03.209Z [WARN]  nomad.raft: heartbeat timeout reached, starting election: last-leader-addr= last-leader-id=
nomad-node1-1  |     2022-09-23T16:19:03.209Z [INFO]  nomad.raft: entering candidate state: node="Node at 172.26.0.3:4647 [Candidate]" term=44
nomad-node1-1  |     2022-09-23T16:19:03.219Z [INFO]  nomad.raft: election won: term=44 tally=2
nomad-node1-1  |     2022-09-23T16:19:03.219Z [INFO]  nomad.raft: entering leader state: leader="Node at 172.26.0.3:4647 [Leader]"

nomad-node1-1  |     2022-09-23T16:19:23.202Z [INFO]  nomad.autopilot: Promoting server to voter: server="Server (ID: \"39cc4e8a-de6b-a8e2-da12-8c1495d86b70\" Address: \"172.26.0.4:4647\")"
nomad-node1-1  |     2022-09-23T16:19:23.202Z [INFO]  nomad.raft: updating configuration: command=AddVoter server-id=39cc4e8a-de6b-a8e2-da12-8c1495d86b70 server-addr=172.26.0.4:4647 servers="[{Suffrage:Voter ID:916e4c98-7ddb-a9c0-16c1-48032b3295d0 Address:172.26.0.3:4647} {Suffrage:Voter ID:029a4697-b02c-1ee8-1d7b-11e4b0a22824 Address:172.26.0.2:4647} {Suffrage:Voter ID:39cc4e8a-de6b-a8e2-da12-8c1495d86b70 Address:172.26.0.4:4647}]"

szechuen · 2022-10-07T22:14:58Z

@dhiaayachi Do you think we should keep the ticket open until pre-vote is done, or track that separately?

#525 (comment)

Includes part of the fix for hashicorp/raft#524

* deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

(manual cherry pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

(manual cherry-pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

(manual cherry-pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry Co-authored-by: Seth Hoenig <[email protected]>

(manual cherry pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry Co-authored-by: Seth Hoenig <[email protected]>

dhiaayachi · 2023-06-07T16:32:26Z

Closing this as we have a workaround in place. Pre vote could be tracked in the relevant open PR #530

dhiaayachi mentioned this issue Sep 8, 2022

Non voter with higher term should not cause cluster instability #525

Closed

dhiaayachi mentioned this issue Sep 14, 2022

check if server is in configuration when receiving a voteRequest #526

Merged

shoenig mentioned this issue Oct 24, 2022

deps: update hashicorp/raft to v1.3.11 hashicorp/nomad#15021

Merged

shoenig added a commit to hashicorp/nomad that referenced this issue Oct 24, 2022

deps: update hashicorp/raft to v1.3.11

7ca57d5

Includes part of the fix for hashicorp/raft#524

shoenig added a commit to hashicorp/nomad that referenced this issue Oct 24, 2022

deps: update hashicorp/raft to v1.3.11 (#15021)

a0071f4

* deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

shoenig added a commit to hashicorp/nomad that referenced this issue Oct 24, 2022

deps: update hashicorp/raft to v1.3.11 (#15021)

ae6a9fd

(manual cherry pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

shoenig added a commit to hashicorp/nomad that referenced this issue Oct 24, 2022

deps: update hashicorp/raft to v1.3.11 (#15021)

dad0c3e

(manual cherry-pick of a0071f4) * deps: update hashicorp/raft to v1.3.11 Includes part of the fix for hashicorp/raft#524 * cl: add changelog entry

TheDevOps mentioned this issue Nov 2, 2022

Leader Election taking between 3 to 15 minutes in openshift deployment when any single node - even non leader - is evicted starting from version 1.13.x hashicorp/consul#15231

Closed

dpericaxon mentioned this issue Nov 17, 2022

Proposal: Release v1.13.4 hashicorp/consul#15427

Closed

erikschul mentioned this issue Mar 24, 2023

Cluster unable to elect a leader after restarting a follower and stopping the leader while the follower is down hashicorp/consul#15940

Closed

dhiaayachi closed this as completed Jun 7, 2023

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Unstable leadership when running server is demoted/removed without its participation #524

Unstable leadership when running server is demoted/removed without its participation #524

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dhiaayachi commented Jun 7, 2023

Unstable leadership when running server is demoted/removed without its participation #524

Unstable leadership when running server is demoted/removed without its participation #524

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szechuen commented Sep 6, 2022 • edited Loading

Precondition

Consul

Vault

Behavior

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szechuen commented Sep 23, 2022

Consul

Nomad

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