(5.5) Add command for updating teleport node auth servers

[r0mant]

Description

Add a system CLI command for manipulating another part of teleport configuration - auth servers, to provide a manual recovery way for #1515.

Type of change

• New feature (non-breaking change which adds functionality)

Linked tickets and other PRs

• Closes Provide a way to update auth servers in teleport node config #1943.

TODOs

• Self-review the change
• Perform manual testing
• Write documentation
• Address review feedback

Testing done

Install a cluster. Check teleport config:

ubuntu@node-1:~/installer$ sudo gravity system teleport show-config --package=node
Using Teleport node config from test/teleport-node-config-19216899102test:3.0.5
teleport:
  ...
  auth_servers:
  - 127.0.0.1:3025
  - 192.168.99.102:3025
  ...

Update auth servers:

ubuntu@node-1:~/installer$ sudo gravity system teleport set-auth-servers --auth-server=192.168.99.103
Using Teleport node config from test/teleport-node-config-19216899102test:3.0.5
Teleport node auth servers updated. Please restart Teleport service using 'sudo systemctl restart *teleport*'

Check config again and make sure new auth server is there:

ubuntu@node-1:~/installer$ sudo gravity system teleport show-config --package=node
Using Teleport node config from test/teleport-node-config-19216899102test:3.0.5
teleport:
  ...
  auth_servers:
  - 127.0.0.1:3025
  - 192.168.99.102:3025
  - 192.168.99.103:3025
  ...

Additional information

Will also need to write a KB article for this.

[a-palchikov]

Looks like we should offer the ability to replace the whole configuration file?

[r0mant]

@a-palchikov I thought exactly the same. On the other hand, having commands to update specific things leaves less room for error for the users (esp. given this is a last resort workaround). I still think having a command to update teleport node config will be definitely useful, even for ourselves, maybe will do it in newer branches.