CLI config

[amorey]

Overview

We would like to add support for a CLI config file so that users can configure their default settings when using CLI commands. For example, users should be able to set the default columns they would like to see when tailing logs or the default port number to use when running the web dashboard.

Goals

• Allow users to set defaults for logs sub-command
• Allow users to set defaults for serve sub-command
• By default look for config file in ~/.config/kubetail/config
• Add a global flag to the CLI tool to support custom config file paths (e.g. -c, --config)
• Support yaml by default with other formats as indicated by file extension

Non-Goals

• We don't need to support multiple config file versions
• We don't need to support features beyond the ones listed above

Design Overview

We want to support the following config schema:

## Kubetail CLI Configuration
#

## version ##
#
# Sets the version of the config schema
#
# Default value: 1
#
version: 1

## general ##
#
general:

  ## kubeconfig ##
  #
  # Overrides the default kubeconfig path ($HOMEDIR/.kube/config)
  #
  # Default value: __empty__
  #
  kubeconfig:

## commands ##
#
commands:

  ## logs ##
  #
  logs:

    ## head ##
    #
    # Sets the default number of log records to return for `head`
    #
    # Default value: 10
    #
    head: 10

    ## tail ##
    #
    # Sets the default number of log records to return for `tail`
    #
    # Default value: 10
    #
    tail: 10

    ## columns ##
    #
    # Sets the default columns to show when displaying log records
    #
    # Default value: [ts, dot, message]
    #
    columns:
      - ts
      - dot
      - message

  ## serve ##
  #
  serve:

    ## port ##
    #
    # The port to use for the dashboard server
    # 
    # Default: 7500
    #
    port: 7500

Alternatives Considered

No response

Risks and Mitigations

No response

Open Questions

No response

Future Work

Here are some ideas for other features we can support in the future:
https://github.com/kubetail-org/cli-config-proposal/blob/main/config.yaml