add a 'flags' subcommand to list global flags

[LeGEC]

Database name

I work with PostgreSQL, right now I only added this flags subcommand to main/pg

Pull request description

in main/pg binary :

add a 'flags' subcommand to list global flags

additionally :

• remove this list from the default list of options,
• change default doc template to mention :
  "list available flags with 'wal-g flags'"

fixes #1032 (for main/pg)

[usernamedt]

Hi! This is a cool idea. The amount of auto-generated flags is definitely overwhelming.

Currently, when I run the wal-g flags command with no configuration, I get the following error:

➜  pg git:(1032-pg-help-flags) ./wal-g flags                                                                                                                                                                   
ERROR: 2021/08/18 16:15:03.156199 Failed to find any configured storage

I guess that this command should not depend on any configuration parameters, but simply output the available flags.

This happens because of the AssertRequiredSettingsSet() call in the PersistentPreRun of the pg command. Maybe there is another way to add the flags subcommand?

[usernamedt]

needs changes

[LeGEC]

@usernamedt yes ; FWIW ./wal-g help has the same issue

[LeGEC]

update :

• fix the linting error
• commands 'help' and 'flags' don't need to have a configured storage, don't fail with "Failed to find any configured storage" error

[usernamedt]

Command itself looks good, but I think that flags should be a global subcommand for any database. Can you move it to a separate package, for example cmd/flags/flags.go? You can use storage tools global subcommand as a reference.

[usernamedt]

I moved the flags subcommand and all common cmd init logic to the common. Now it should work fine for all databases.

[mialinx]

LGTM