Configuration
Liftbridge provides limited configuration through command-line flags and full configuration using a configuration file. Flags will always take precedent over settings in the configuration file.
The configuration file is passed in using the --config flag:
$ liftbridge --config liftbridge.conf
To get a full list of the CLI flags, use the --help flag:
$ liftbridge --help
NAME:
liftbridge - Lightweight, fault-tolerant message streams
USAGE:
liftbridge [global options] command [command options] [arguments...]
VERSION:
0.0.1
COMMANDS:
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--config FILE, -c FILE load configuration from FILE
--server-id value, --id value ID of the server in the cluster if there is no stored ID (default: random ID)
--namespace value, --ns value cluster namespace (default: "liftbridge-default")
--nats-servers ADDR[,ADDR], -n ADDR[,ADDR] connect to NATS cluster at ADDR[,ADDR] (default: "nats://localhost:4222")
--data-dir DIR, -d DIR store data in DIR (default: "/tmp/liftbridge/<namespace>")
--port value, -p value port to bind to (default: 9292)
--tls-cert value server certificate file
--tls-key value private key for server certificate
--tls-client-auth value enforce client authentication
--tls-client-auth-ca value CA certificate to use when authenticating clients
--level value, -l value logging level [debug|info|warn|error] (default: "info")
--raft-bootstrap-seed bootstrap the Raft cluster by electing self as leader if there is no existing state
--raft-bootstrap-peers value bootstrap the Raft cluster with the provided list of peer IDs if there is no existing state
--help, -h show help
--version, -v print the version
Configuration File Format
The configuration file format borrows from the NATS configuration format. It is a flexible format that combines the best of traditional configuration formats and newer styles such as JSON and YAML.
The config file format supports the following syntax:
- Mixed Arrays:
[...] - Nested Maps:
{...} - Multiple comment types:
#and// - Key value assigments using:
- Equals sign (
foo = 2) - Colon (
foo: 2) - Whitespace (
foo 2)
- Equals sign (
- Maps can be assigned with no key separator
- Semicolons as value terminators in key/value assignments are optional
Example Configuration File
An example configuration file is shown below.
listen: localhost:9293
data.dir: /tmp/liftbridge/server-2
log.level: debug
# Define NATS cluster to connect to.
nats {
servers: ["nats://localhost:4300", "nats://localhost:4301"]
}
# Specify message log settings.
log {
retention.max.age: "24h"
}
# Specify cluster settings.
clustering {
server.id: server-2
raft.logging: true
raft.bootstrap.seed: true
replica.max.lag.time: "20s"
}
Configuration Settings
Below is the list of Liftbridge configuration settings, including the name of the setting in the configuration file and the CLI flag if it exists.
| Name | Flag | Description | Type | Default | Valid Values |
|---|---|---|---|---|---|
| listen | The server listen host/port. This is the host and port the server will bind to. If this is not specified but host and port are specified, these values will be used. If neither listen nor host/port are specified, the default listen address will be used. | string | 0:0:0:0:9292 | ||
| host | The server host that is advertised to clients, i.e. the address clients will attempt to connect to based on metadata API responses. If not set, listen will be returned to clients. This value may differ from listen in situations where the external address differs from the internal address, e.g. when running in a container. If listen is not specified, the server will also bind to this host. | string | localhost | ||
| port | port | The server port that is advertised to clients. See host for more information on how this behaves. | int | 9292 | |
| tls.key | tls-key | The private key file for server certificate. This must be set in combination with tls.cert to enable TLS. | string | ||
| tls.cert | tls-cert | The server certificate file. This must be set in combination with tls.key to enable TLS. | string | ||
| tls.client.auth | tls-client-auth | Enforce client-side authentication via certificate. | bool | false | |
| tls.client.auth.ca | tls-client-auth-ca | The CA certificate file to use when authenticating clients. | string | ||
| log.level | level | The logging level. | string | info | [debug, info, warn, error] |
| log.recovery | Log messages resulting from the replay of the Raft log on server recovery. | bool | false | ||
| data.dir | data-dir | The directory to store data in. | string | /tmp/liftbridge/namespace | |
| batch.max.messages | The maximum number of messages to batch when writing to disk. | int | 1024 | ||
| batch.wait.time | The time to wait to batch more messages when writing to disk. | duration | 0 | ||
| metadata.cache.max.age | The maximum age of cached broker metadata. | duration | 2m | ||
| nats | NATS configuration. | map | See below | ||
| log | Stream write-ahead log configuration. | map | See below | ||
| clustering | Broker cluster configuration. | map | See below |
NATS Configuration Settings
Below is the list of the configuration settings for the nats part of
the configuration file.
| Name | Flag | Description | Type | Default | Valid Values |
|---|---|---|---|---|---|
| servers | nats-servers | List of NATS hosts to connect to. | list | nats://localhost:4222 | |
| user | Username to use to connect to NATS servers. | string | |||
| password | Password to use to connect to NATS servers. | string |
Log Configuration Settings
Below is the list of the configuration settings for the log part of
the configuration file.
| Name | Flag | Description | Type | Default | Valid Values |
|---|---|---|---|---|---|
| retention.max.bytes | The maximum size a stream's log can grow to, in bytes, before we will discard old log segments to free up space. A value of 0 indicates no limit. | int64 | 0 | ||
| retention.max.messages | The maximum size a stream's log can grow to, in number of messages, before we will discard old log segments to free up space. A value of 0 indicates no limit. | int64 | 0 | ||
| retention.max.age | The TTL for stream log segment files, after which they are deleted. A value of 0 indicates no TTL. | duration | 168h | ||
| cleaner.interval | The frequency to check if a new stream log segment file should be rolled and whether any segments are eligible for deletion based on the retention policy or compaction if enabled. | duration | 5m | ||
| log.roll.time | The maximum time before a new stream log segment is rolled out. A value of 0 means new segments will only be rolled when segment.max.bytes is reached. Retention is always done a file at a time, so a larger value means fewer files but less granular control over retention. | duration | value of retention.max.age | ||
| segment.max.bytes | The maximum size of a single stream log segment file in bytes. Retention is always done a file at a time, so a larger segment size means fewer files but less granular control over retention. | int64 | 268435456 | ||
| compact | Enables stream log compaction. Compaction works by retaining only the latest message for each key and discarding older messages. The frequency in which compaction runs is controlled by cleaner.interval. | bool | false | ||
| compact.max.goroutines | The maximum number of concurrent goroutines to use for compaction on a stream log (only applicable if compact is enabled). | int | 10 |
Clustering Configuration Settings
Below is the list of the configuration settings for the clustering part of
the configuration file.
| Name | Flag | Description | Type | Default | Valid Values |
|---|---|---|---|---|---|
| server.id | server-id | ID of the server in the cluster. | string | random id | string with no spaces or periods |
| namespace | namespace | Cluster namespace. | string | liftbridge-default | string with no spaces or periods |
| raft.snapshot.retain | The number Raft log snapshots to retain on disk. | int | 2 | ||
| raft.snapshot.threshold | Controls how many outstanding logs there must be before taking a snapshot. This prevents excessive snapshots when a small set of logs can be replayed. | int | 8192 | ||
| raft.cache.size | The number of Raft logs to hold in memory for quick lookup. | int | 512 | ||
| raft.bootstrap.seed | raft-bootstrap-seed | Bootstrap the Raft cluster by electing self as leader if there is no existing state. If this is enabled, raft.bootstrap.peers should generally not be used, either on this node or peer nodes, since cluster topology is not being explicitly defined. Instead, peers should be started without bootstrap flags which will cause them to automatically discover the bootstrapped leader and join the cluster. | bool | false | |
| raft.bootstrap.peers | raft-bootstrap-peers | Bootstrap the Raft cluster with the provided list of peer IDs if there is no existing state. This should generally not be used in combination with raft.bootstrap.seed since it is explicitly defining cluster topology and the configured topology will elect a leader. Note that once the cluster is established, new nodes can join without setting bootstrap flags since they will automatically discover the elected leader and join the cluster. | list | ||
| raft.logging | Enables logging in the Raft subsystem. | bool | false | ||
| replica.max.lag.time | If a follower hasn't sent any replication requests or hasn't caught up to the leader's log end offset for at least this time, the leader will remove the follower from ISR. | duration | 15s | ||
| replica.max.leader.timeout | If a leader hasn't sent any replication responses for at least this time, the follower will report the leader to the controller. If a majority of the replicas report the leader, a new leader is selected by the controller. | duration | 15s | ||
| replica.max.idle.wait | The maximum amount of time a follower will wait before making a replication request once the follower is caught up with the leader. This value should always be less than replica.max.lag.time to avoid frequent shrinking of ISR for low-throughput streams. | duration | 10s | ||
| replica.fetch.timeout | Timeout duration for follower replication requests. | duration | 3s | ||
| min.insync.replicas | Specifies the minimum number of replicas that must acknowledge a stream write before it can be committed. If the ISR drops below this size, messages cannot be committed. | int | 1 | [1,...] |