Sealed segment without IndexStart #31
Description
[INFO] raft: initial configuration: index=7 servers="[{Suffrage:Voter ID:00000001-0001-0001-0001-000000000001 Address:192.168.121.27:4419} {Suffrage:Voter ID:00000003-0003-0003-0003-000000000003 Address:192.168.121.217:4419} {Suffrage:Voter ID:00000002-0002-0002-0002-000000000002 Address:192.168.121.112:4419}]"
[INFO] raft: entering follower state: follower="Node at 00000001-0001-0001-0001-000000000001 [Follower]" leader-address= leader-id=
[WARN] raft: heartbeat timeout reached, not part of a stable configuration or a non-voter or not allowed to candidate, not triggering a leader election
[DEBUG] raft: lost leadership because received a requestVote with a newer term
[WARN] raft: rejecting vote request since our last index is greater: candidate=00000003-0003-0003-0003-000000000003 last-index=424 last-candidate-index=423
[WARN] raft: clearing log suffix: from=424 to=424
# Process is restarted
[ERROR] raft: failed to get log: index=1 error="sealed segment has no index block"
panic: sealed segment has no index block
goroutine 1 [running]:
github.com/hashicorp/raft.NewRaft(0xc0003423c0, {0x32b3ec0?, 0xc000355f50}, {0x32b7b90?, 0xc000342460}, {0x32b5b48?, 0xc000342460}, {0x32b3470?, 0xc000355ec0}, {0x32bb698, ...})
[...]
In this trace, raft is clearing the last index from the WAL (424). It calls (w *WAL) DeleteRange() which calls (w *WAL) truncateTailLocked().
truncateTailLocked() seals the segment but does not set the IndexStart, which is wrong from my understanding. So at the next start, the segment is sealed without any IndexStart set, which triggers the panic from (r *Reader) findFrameOffset.