cgroup prefix matching for Amazon ECS missing

[Ristovski]

When running coroot-node-agent directly on an EC2 instance thats part of an ECS cluster, the following message is spammed:
W0905 11:42:31.320648 1826000 registry.go:305] failed to read proc cgroup: unknown container: /ecstasks.slice/ecstasks-[UID].slice/docker-[UID].scope

This seems to stem from the fact that the prefix matching is hardcoded and doesn't match ecstasks.slice:

coroot-node-agent/cgroup/cgroup.go

Lines 130 to 172 in 8f1ee26

	if prefix == "user.slice" || prefix == "init.scope" {
	return ContainerTypeStandaloneProcess, "", nil
	}
	if prefix == "docker" || (prefix == "system.slice" && strings.HasPrefix(parts[1], "docker-")) {
	matches := dockerIdRegexp.FindStringSubmatch(path)
	if matches == nil {
	return ContainerTypeUnknown, "", fmt.Errorf("invalid docker cgroup %s", path)
	}
	return ContainerTypeDocker, matches[1], nil
	}
	if strings.Contains(path, "kubepods") {
	crioMatches := crioIdRegexp.FindStringSubmatch(path)
	if crioMatches != nil {
	return ContainerTypeCrio, crioMatches[1], nil
	}
	if strings.Contains(path, "crio-conmon-") {
	return ContainerTypeUnknown, "", nil
	}
	containerdMatches := containerdIdRegexp.FindStringSubmatch(path)
	if containerdMatches != nil {
	return ContainerTypeContainerd, containerdMatches[1], nil
	}
	matches := dockerIdRegexp.FindStringSubmatch(path)
	if matches == nil {
	return ContainerTypeSandbox, "", nil
	}
	return ContainerTypeDocker, matches[1], nil
	}
	if prefix == "lxc" {
	matches := lxcIdRegexp.FindStringSubmatch(path)
	if matches == nil {
	return ContainerTypeUnknown, "", fmt.Errorf("invalid lxc cgroup %s", path)
	}
	return ContainerTypeLxc, matches[1], nil
	}
	if prefix == "system.slice" || prefix == "runtime.slice" {
	matches := systemSliceIdRegexp.FindStringSubmatch(path)
	if matches == nil {
	return ContainerTypeUnknown, "", fmt.Errorf("invalid systemd cgroup %s", path)
	}
	return ContainerTypeSystemdService, strings.Replace(matches[1], "\\x2d", "-", -1), nil
	}
	return ContainerTypeUnknown, "", fmt.Errorf("unknown container: %s", path)