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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.

tip

You can find sample configuration files on GitHub that set up Databend for various deployment environments. These files were created for internal testing ONLY. Please do NOT modify them for your own purposes. But if you have a similar deployment, it is a good idea to reference them when editing your own configuration files.

databend-meta.toml

#
# Logging
#
log_dir                  = "metadata/_logs1"
log_level                = "DEBUG"
#
# 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_api_advertise_host    = "1.2.3.4"
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_dir is the path to a directory for storing hourly-rolling debug log.
  • log_level is the log level. By default, it is DEBUG.

2. 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

3. 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 to listen for incoming business request, e.g., 0.0.0.0:9191.
  • grpc_api_advertise_host is the HTTP server address published for databend-query to connect to, e.g., 1.2.3.4.
  • grpc_tls_server_cert specifies the path to load tls certificate.
  • grpc_tls_server_key specifies the path to load tls key.

4. 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.

5. 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.

6. 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.