From: Guillem Jover Date: Tue, 19 Jan 2021 00:34:59 +0100 Subject: Send the readiness notification when we are ready to accept connections On a replica we do accept connections, even though commands accessing the database will operate in read-only mode. But the server is still already operational and processing commands. Not sending the readiness notification means that on a HA setup where the nodes all start as replicas (with replicaof in the config) with a replica that cannot connect to the master server and which might not come back in a predictable amount of time or at all, the service supervisor will end up timing out the service and terminating it, with no option to promote it to be the main instance. This seems counter to what the readiness notification is supposed to be signaling. Instead send the readiness notification when we start accepting commands, and then send the various server status changes as that. Fixes: commit 641c64ada10404356fc76c0b56a69b32c76f253c Fixes: commit dfb598cf3304818e608ceb6b5d9529a293345c4a Ref: Debian:#981226 Ref: --- src/replication.c | 6 ++---- src/server.c | 4 ++-- 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/src/replication.c b/src/replication.c index a691f75..be85454 100644 --- a/src/replication.c +++ b/src/replication.c @@ -1806,8 +1806,7 @@ void readSyncBulkPayload(connection *conn) { serverLog(LL_NOTICE, "MASTER <-> REPLICA sync: Finished with success"); if (server.supervised_mode == SUPERVISED_SYSTEMD) { - redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Finished with success. Ready to accept connections.\n"); - redisCommunicateSystemd("READY=1\n"); + redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Finished with success. Ready to accept connections in read-write mode.\n"); } /* Restart the AOF subsystem now that we finished the sync. This @@ -2314,8 +2313,7 @@ void syncWithMaster(connection *conn) { if (psync_result == PSYNC_CONTINUE) { serverLog(LL_NOTICE, "MASTER <-> REPLICA sync: Master accepted a Partial Resynchronization."); if (server.supervised_mode == SUPERVISED_SYSTEMD) { - redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Partial Resynchronization accepted. Ready to accept connections.\n"); - redisCommunicateSystemd("READY=1\n"); + redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Partial Resynchronization accepted. Ready to accept connections in read-write mode.\n"); } return; } diff --git a/src/server.c b/src/server.c index 93148f8..8b4e341 100644 --- a/src/server.c +++ b/src/server.c @@ -5513,10 +5513,10 @@ int main(int argc, char **argv) { if (server.supervised_mode == SUPERVISED_SYSTEMD) { if (!server.masterhost) { redisCommunicateSystemd("STATUS=Ready to accept connections\n"); - redisCommunicateSystemd("READY=1\n"); } else { - redisCommunicateSystemd("STATUS=Waiting for MASTER <-> REPLICA sync\n"); + redisCommunicateSystemd("STATUS=Ready to accept connections in read-only mode. Waiting for MASTER <-> REPLICA sync\n"); } + redisCommunicateSystemd("READY=1\n"); } } else { InitServerLast();