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Submodule box.info

Submodule box.info

The box.info submodule provides access to information about server instance variables.

  • version is the Tarantool version. This value is also shown by tarantool –version.
  • id corresponds to replication.id (see below).
  • ro is true if the instance is in “read-only” mode (same as read_only in box.cfg{}).
  • vclock corresponds to replication.downstream.vclock (see below).
  • uptime is the number of seconds since the instance started. This value can also be retrieved with tarantool.uptime().
  • lsn corresponds to replication.lsn (see below).
  • vinyl returns runtime statistics for vinyl storage engine.
  • cluster.uuid is the UUID of the replica set. Every instance in a replica set will have the same cluster.uuid value. This value is also stored in box.space._schema system space.
  • pid is the process ID. This value is also shown by tarantool module and by the Linux command ps -A.
  • status corresponds to replication.upstream.status (see below).
  • signature is the sum of all lsn values from the vector clocks (vclock) of all instances in the replica set.
  • uuid corresponds to replication.uuid (see below).

replication part contains statistics for all instances in the replica set in regard to the current instance (see an example in the section “Monitoring a replica set”):

  • replication.id is a short numeric identifier of the instance within the replica set.

  • replication.uuid is a globally unique identifier of the instance. This value is also stored in box.space._cluster system space.

  • replication.lsn is the log sequence number (LSN) for the latest entry in the instance’s write ahead log (WAL).

  • replication.upstream contains statistics for the replication data uploaded by the instance.

  • replication.upstream.status is the replication status of the instance.

    • auth means that the instance is getting authenticated to connect to a replication source.
    • connecting means that the instance is trying to connect to the replications source(s) listed in its replication parameter.
    • disconnected means that the instance is not connected to the replica set (due to network problems, not replication errors).
    • follow means that the instance’s role is “replica” (read-only) and replication is in progress.
    • running means the instance’s role is “master” (non read-only) and replication is in progress.
    • stopped means that replication was stopped due to a replication error (e.g. duplicate key).
  • replication.upstream.idle is the time (in seconds) since the instance received the last event from a master.

  • replication.upstream.lag is the time difference between the local time at the instance, recorded when the event was received, and the local time at another master recorded when the event was written to the write ahead log on that master.

    Since lag calculation uses operating system clock from two different machines, don’t be surprised if it’s negative: a time drift may lead to the remote master clock being consistently behind the local instance’s clock.

    For multi-master configurations, this is the maximal lag.

  • replication.downstream contains statistics for the replication data requested and downloaded from the instance.

  • replication.downstream.vclock is the instance’s vector clock, which contains a pair ‘id, lsn’.

box.info()

Since box.info contents are dynamic, it’s not possible to iterate over keys with the Lua pairs() function. For this purpose, box.info() builds and returns a Lua table with all keys and values provided in the submodule.

Return:keys and values in the submodule.
Rtype:table

Example:

tarantool> box.info
---
- version: 1.7.4-52-g980d30092
  id: 1
  ro: false
  vclock: {1: 8}
  uptime: 7280
  lsn: 8
  vinyl: []
  cluster:
    uuid: f7c0c1c6-f9d8-4df7-82ff-d4bd00610a6c
  pid: 16162
  status: running
  signature: 8
  replication:
    1:
      id: 1
      uuid: 1899631e-6369-40a1-81c9-7d170e909276
      lsn: 8
    2:
      id: 2
      uuid: bd949e5d-7ff9-413e-b4f2-c9b0149fdda6
      lsn: 0
      upstream:
        status: follow
        idle: 7256.7571430206
        lag: 0
      downstream:
        vclock: {1: 8}
    3:
      id: 3
      uuid: c5cb61d5-fa48-460d-abd7-3f13709d07a7
      lsn: 0
      upstream:
        status: follow
        idle: 7255.7510120869
        lag: 0
      downstream:
        vclock: {1: 8}
  uuid: 1899631e-6369-40a1-81c9-7d170e909276
...