A broker starts with no settings at all, and most installations change very few. These are the ones that matter most. Some are read only once, when a node creates its data directory, so choose them before the first start. The pages of this section explain each one where it is used, and Configuration lists every setting.
Read only at the first start
| Setting | Default | What it does |
|---|---|---|
QUEEN_QLOG_SHARDS |
0 | 0: each queue has its own log files. K: all queues share K logs, so a write syncs at most K files. For thousands of queues. |
QUEEN_RAFT_PEERS |
unset | The nodes of a cluster (see Run a cluster with Docker). After the first start, members change only through the membership API. |
QUEEN_RAFT_DIR |
/var/lib/queen/raft | The data directory, one per node. |
How fast old data leaves
| Setting | Default | What it does |
|---|---|---|
PARTITION_CLEANUP_SECONDS |
30 days | An empty partition is deleted after this long without a write. At least 60. |
QUEEN_RAFT_TXN_WINDOW_MIN_S |
900 | The least time a message’s dedup record is kept. Nothing is deleted sooner, partitions included. |
QUEEN_RAFT_RETENTION_SCAN_PER_S |
50000 | Partitions the retention scan visits a second. On 2.6.0, set 40000 when partitions come and go fast (see Many short-lived partitions). |
QUEEN_RAFT_TRACE_RETENTION_S |
7 days | How long message traces are kept. |
Limits
| Setting | Default | What it does |
|---|---|---|
QUEEN_RAFT_DISK_HIGH_PCT |
85 | Above this share of the disk, writes that would grow it answer 507. |
QUEEN_EPHEMERAL_MAX_BYTES |
256 MiB | The memory for ephemeral queues. Above it, their pushes answer 503. |
Security
| Setting | Default | What it does |
|---|---|---|
QUEEN_RAFT_TOKEN |
unset | The secret the nodes of a cluster share. |
JWT_ENABLED |
false | Check a token on every request. |
QUEEN_ENCRYPTION_KEY |
unset | The key of encrypted queues: 64 hex characters, the same on every node. |
Upgrades and logs
| Setting | Default | What it does |
|---|---|---|
QUEEN_RAFT_CLUSTER_VERSION_MS |
1000 | 0 keeps the way back to the previous release open. |
LOG_LEVEL, QUEEN_LOG_JSON |
info, false | How much the node logs, and whether each line is a JSON object for a log collector. |
Why
most settings have a default that is right for most installations. The few above decide the shape of a cluster, how fast old data leaves, and who may talk to it, so they are worth a decision before the first start.
On these pages
| Page | What it covers |
|---|---|
| Cluster with Docker | Three nodes with Docker Compose, and what happens when one stops. |
| Kubernetes | A StatefulSet with Helm or the operator, probes, and rolling updates. |
| Configuration by need | The settings for each need, from trying QueenMQ to surviving a site. |
| Upgrades and monitoring | One node at a time, the way back, and what to watch. |
| Recovery | What to do when a node, a disk or a majority is gone. |
| Backups, Standby cluster | Copies of the data, and a second cluster to fail over to. |
| Security, Tenants and API keys | Who may talk to the cluster, and many tenants on one. |
| Kubernetes operator, Terraform | Clusters and queues declared as resources. |