PBM-1472 sanitize double slashes in storage config parts

[jcechace]

Ticket: https://perconadev.atlassian.net/browse/PBM-1472

[jcechace]

@boris-ilijic sanitizing in Cast() works well but...

• pbm config --file will properly sanitize when creating config
• pbm config --set storage.s3.bucket=bcp/ will not

PBM will still work fine (as Cast will normalize it before storage is used). However there are few weaknesses

pbm backup
Starting backup "2026-02-17T12:14:35Z"....Backup "2026-02-17T12:14:35Z" saved to remote store (path: "http://minio:9000/bcp//pbme2etest")

pbm status

Main storage:
  Type:       S3
  Region:     us-east-1
  Path:       http://minio:9000/bcp//pbme2etest

Here Path() still prints the path based on users actual configuration. Not neccessarily bad -- at least users can see their typo

A fix for pbm config --set storage.s3.bucket=bcp/ would be slightly akward as it owuld have to check the possible suffixes for which to trim the slashes. So in config.SetConfigVar we would need something like

if strings.HasSuffix(key, ".bucket") || strings.HasSuffix(key, ".container") || strings.HasSuffix(key, ".prefix") {
    s := strings.Trim(v.(string), "/")
}

which seems a bit fragile -- but that is the case for the entire function

[boris-ilijic]

It's better to avoid having invalid config setting (eg. t1/ in example) and then mutate it all the time before the usage. That will be potential source of bugs, so that needs to be fixed.

$ pbm config --set storage.s3.prefix=t1/
[storage.s3.prefix=t1/]
$ pbm config
storage:
  type: s3
  s3:
    bucket: abc
    prefix: t1/

That check doesn't need to be fragile, it can be just case like existing one:

percona-backup-mongodb/pbm/config/config.go

Lines 624 to 627 in 01eb998

	case "storage.filesystem.path":
	if v.(string) == "" {
	return errors.New("storage.filesystem.path can't be empty")
	}

	case "storage.s3.prefix", "storage.s3.bucket":

Optionally:
I'd prefer to fail if param is invalid within the file, more than adjust, so from the ticket maybe better fix should be:

PBM validates bucket/prefix options and returns error about incorrect format

So something like this:
https://github.com/percona/percona-backup-mongodb/blob/01eb9981f58a6875f634eba60dc15b51b2d24037/pbm/storage/mio/config.go#L102C2-L104C3

[jcechace]

@boris-ilijic

That check doesn't need to be fragile, it can be just case like existing one:
There is 6x2=12 cases which need to be either validated or sanitized -- I'm for sanitization since it's basically the same step, just less bothersome for the user.

But overall I agree that this shouldn't likely be in Cast(). Will change that part

[boris-ilijic]

But overall I agree that this shouldn't likely be in Cast(). Will change that part

While you are changing, it should be clearer and easier to report the error than to sanitize.

[boris-ilijic]

@jcechace

I'm for sanitization since it's basically the same step, just less bothersome for the user.

Sorry I missed your comment, it's hidden by formatting in gray, see it above.
User doesn't care imo, he/she will be informed, and then correction will be made. I would do it as it is easier for maintenance, but it's up to you.