[Refactor] Move containerd client helper from cmd to pkg/clientutil

[Zheaoli]

Signed-off-by: Zheao.Li me@manjusaka.me

[djdongjin]

This snippet is duplicated a lot

	namespace, err := cmd.Flags().GetString("namespace")
	if err != nil {
		return err
	}
	address, err := cmd.Flags().GetString("address")
	if err != nil {
		return err
	}
	client, ctx, cancel, err := clientutil.NewClient(cmd.Context(), namespace, address)

I would suggest that we have a cmd/nerdctl/cmdutil.go which contains this kind of code if they're very common (e.g., read some flags from cmd and call the corresponding pkg functions). So in this case:

// cmd/nerdctl/cmdutil.go, ignore types....
func newClientFromCmd(cmd) client, ctx, cancel, err {
	namespace, err := cmd.Flags().GetString("namespace")
	if err != nil {
		return err
	}
	address, err := cmd.Flags().GetString("address")
	if err != nil {
		return err
	}
	return clientutil.NewClient(cmd.Context(), namespace, address)
}

Personally, I think it still make sense to have 2 functions (newClientFromCmd, and your clientutil.NewClient) compared to the old newClient which does two jobs.

[Zheaoli]

I would suggest that we have a cmd/nerdctl/cmdutil.go which contains this kind of code if they're very common (e.g., read some flags from cmd and call the corresponding pkg functions). So in this case:

This shouldn't be a problem. after the #1680 is completed, all the global flagging processes will share a command helper function getGlobalFlag (like namespace, address etc)(Also this getGlobalFlag helper function would be used at in anywhere need to process the global flag)

I want to make the NewClient out of the cmd package because most of the command logic we want to split into pkg/cmd packages is related to this function. In other words, if we want to split the command logic out of the cmd package, we need to make NewClient out of cmd package first.

Like @AkihiroSuda has said in #1779 (comment), the code in pkg/** should not be related to cobra.

As I have said above, we will have a getGlobalFlag helper function, so the duplicated code here will be replaced by the code below in each command PR

globalFlag,err := getGlobalFlag(cmd)
if err!=nil{
    return err
}
client, ctx, cancel, err := clientutil.NewClient(cmd.Context(), globalFlag.Address, globalFlag.Namespace)

So I think the new wrapper function newClientFromCmd in cmd package should be unnecessary. For personal style, I would like to make the cmd package clean as we can

So IMHO, I think this PR is OK for now. But maybe we can introduce GlobalFlag into this PR? (I'm not sure

[djdongjin]

:) Overall the PR LGTM and I agree both the refactor and the PR is necessary.

My suggestion is more a nit without much context, which can be seen as "add a 10 line helper in cmd side to dedup some duplication code".

Like @AkihiroSuda has said in #1779 (comment), the code in pkg/** should not be related to cobra.

The helper I suggested is also on the cmd side (simply read 2 flags from cmd and call your new function).

Just repeat, it's a nit and the PR is not blocked on me 😉 thanks for your work!

[fahedouch]

I prefer to go through the refacto in small steps even if it introduces unnecessary/redundant code, it would make the process of contributing easier. LGTM to retains redundancy code until progressive introduction of getGlobalFlag

[Laitr0n]

When I refactor the 'compose log' command, I realized that the 'client helper' should be refactored first. After this PR, can the refactoring of the 'compose xxx' command continue?

[AkihiroSuda]

Thanks