Removing obsolete package from metricbeat

[amitkanfer]

github.com/pkg/errors is deprecated since 2021.
Furthermore, it's at least 100% worse in terms of performance compared to the native errors and fmt packages, (probably due to the fact every error log comes with a stack trace)

Another interesting benchmark: https://g4s8.wtf/posts/go-errors-performance/

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @amitkanfer? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

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• Start Time: 2023-06-22T16:36:26.183+0000

• Duration: 88 min 33 sec

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Failed	0
Passed	27454
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Total	29477

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[amitkanfer]

Special attention here

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[cmacknz]

Everything LGTM, the one place the error was unused feels like it is a bug that could be improved but within the scope of what this PR is trying to do it could also be left as is.

[cmacknz]

Seems like it might be a bug that this is just getting dropped.

This is called from the following function which does allow returning an error:

beats/metricbeat/module/docker/healthcheck/healthcheck.go

Lines 67 to 76 in 3325ba1

	func (m *MetricSet) Fetch(r mb.ReporterV2) error {
	// Fetch a list of all containers.
	containers, err := m.dockerClient.ContainerList(context.TODO(), types.ContainerListOptions{})
	if err != nil {
	return errors.Wrap(err, "failed to get docker containers list")
	}
	eventsMapping(r, containers, m)
	return nil
	}

The only trick would be that you don't want to just return an error and immediately stop if one of many containers has an error.

beats/metricbeat/module/docker/healthcheck/data.go

Lines 33 to 37 in 3325ba1

	func eventsMapping(r mb.ReporterV2, containers []types.Container, m *MetricSet) {
	for _, container := range containers {
	eventMapping(r, &container, m)
	}
	}

For this you could use https://github.com/hashicorp/go-multierror there's an example here

beats/x-pack/libbeat/management/blacklist.go

Line 69 in 3325ba1

err = multierror.Append(err, fmt.Errorf("Config for '%s' is blacklisted", configs.Type))

This multierr package itself can probably be replaced with standard library functionality once we upgrade to Go 1.20.

If you don't want to deal with all that, you can just delete this. It isn't making the code any worse and it was unused before.

[amitkanfer]

ok, deleting. will open a follow up issue to fix this.

[amitkanfer]

Team,
We're making an exception and not going to wait for approvals from all CODEOWNERS for this "find and replace" type of PRs. @cmacknz 's review will be enough.