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Databend Meta Service Configuration

A databend-meta server is configured with a config file in toml: databend-meta --config-file databend-meta.toml.

databend-meta.toml

#
# Logging
#
log_dir                  = "metadata/_logs1"
log_level                = "DEBUG"
#
# Metric API endpoint
#
metric_api_address       = "0.0.0.0:28100"
#
# Admin API endpoint
#
admin_api_address        = "0.0.0.0:28101"
admin_tls_server_cert    = "admin.cert" 
admin_tls_server_key     = "admin.key" 
#
# GRPC client API endpoint
#
grpc_api_address         = "0.0.0.0:9191"
grpc_tls_server_cert     = "grpc.cert" 
grpc_tls_server_key      = "grpc.key"
#
# Internal raft communication
#
[raft_config]
id                       = 1
raft_dir                 = "metadata/datas1"
raft_api_port            = 28103
raft_listen_host         = "127.0.0.1"
raft_advertise_host      = "localhost"
#
# Raft internal config
#
heartbeat_interval       = 1000 # milli second 
install_snapshot_timeout = 4000 # milli second
max_applied_log_to_keep  = 1000 # N.O. raft logs
snapshot_logs_since_last = 1024 # N.O. raft logs
#
# Startup config
#
single                   = false
join                     = ["127.0.0.1:28103", "127.0.0.1:28203"]

1. Logging config​

  • log_id is the path to a directory for storing hourly-rolling debug log.
  • log_level is the log level. By default, it is DEBUG.

2. Metric service config​

Metric API provides service metrics data for other component such as prometheus.

  • metric_api_address is the HTTP service for metrics collection.

3. Admin config​

Admin API provides cluster information such as node list, the currently active leader.

  • admin_api_address is the HTTP service for retrieving cluster status.
  • admin_tls_server_cert specifies the path to load tls certificate for admin service
  • admin_tls_server_key specifies the path to load tls key for admin service

4. GRPC config​

GRPC API is application API a databend-meta client connects to, for reading and writing metadata.

  • grpc_api_address is the HTTP server address for reading and writing metadata.
  • grpc_tls_server_cert specifies the path to load tls certificate.
  • grpc_tls_server_key specifies the path to load tls key.

5. Raft config​

  • raft_config.id is the globally unique id for this node; it is a u64.

  • raft_config.raft_dir is the local dir to store metadata, including raft log and state machine etc.

  • raft_config.raft_api_port,raft_config.raft_listen_host and raft_config.raft_advertise_host defines the service for internal raft communication. Application should never touch this port.

    raft_listen_host is the host the internal raft server listens on. raft_advertise_host is the host the internal raft client to connect to.

6. Raft internal config​

Defines raft behaviors on raft-storage and the state machine.

  • heartbeat_interval specifies the interval between two heartbeat in milliseconds.

  • install_snapshot_timeout specifies the max time for installing a snapshot in milliseconds.

  • max_applied_log_to_keep specifies the max number of applied raft-log to keep.

  • snapshot_logs_since_last specifies the number of raft-logs since the last snapshot beyond which a snapshot will be generated.

7. Startup config​

  • single tells the node to initialize a single node cluster if it is not initialized. Otherwise, this arg is just ignored.

  • join specifies a list of address(<raft_advertise_host>:<raft_api_port>) of nodes in an existing cluster a new node is joint to.

    join is only used for an uninitialized node. join will be ignored if the node is already initialized.