Feature: Tooling: "get instances" command

CLI

• Command:

  picodata get instances --address ADDR [--format j[son]|t[able] ]
  picodata g i -a ADDR -f j

  where ADDR is the address of any instance of the cluster

• Output

  The output should be in table format by default and optionally in JSON format

  Table:

  CLUSTER     REPLICASET   INSTANCE   STATUS        ADDRESS
  cluster1    rs1          i1         active        10.0.0.1:3301
  cluster1    rs1          i2         standby       10.0.0.2:3301
  cluster1    rs2          i3         unreachable   10.0.0.3:3301
  cluster1    rs2          i4         starting      10.0.0.4:3301
  cluster1    -            i5         inactive      10.0.0.5:3301

  JSON:

  [
    {"cluster": "cluster1", "replicaset": "rs1", ...},
    ...
  ]

  Status:

  • active - the instance is writable and is OK
  • standby - the instance is read-only and is applying the changes from the active instance and the replication lag <= 10 seconds
  • unreachable - the instance is unable to exchange data with the cluster
  • stale - the instance has stale Raft log and therefore is not up-to date with the cluster
  • lag - the standby instance's replication lag is more than 10 seconds behind the current active instance in the replicaset
  • inactive - the instance is not part of any replicaset (skip this if auto-topology is not implemented yet)
  • starting - Tarantool is loading the snapshot.

DoD

• implemented
• int test with json style output
• the command usage is covered in the docs on the website:
  • a basic example of the command usage
  • output example
  • status variants description

Motivation

• Create a basic command that allows to check the overall cluster health.
• Handy output to use in presentations.
• Create a basis for future CLI tooling development.
• Demonstrate the look and feel of Picodata's CLI tooling in terms of flags usage, commands and subcommands short forms usage.