Fix support for VolumeId dimension on nitro instances

[montaguethomas]

Description of the issue

Linux allows mounting disks using a device alias (symlink) but the CWAgent is not able to resolve the EBS VolumeId for the device. Fixes #1727.

When PR #1156 implemented support to use ${aws:VolumeId} for a dimension value, it included extensive normalization of the device name:

amazon-cloudwatch-agent/plugins/processors/ec2tagger/internal/volume/volume.go

Lines 109 to 145 in 4123ffc

	func (c *cache) normalizeName(devName string) string {
	normalized := c.fetchBlockName(devName)
	if normalized == "" {
	normalized = devName
	}
	// to match the disk device tag
	return strings.ReplaceAll(normalized, "/dev/", "")
	}
	// find nvme block name by symlink, if symlink doesn't exist, return ""
	func findNvmeBlockNameIfPresent(devName string) string {
	// for nvme(ssd), there is a symlink from devName to nvme block name, i.e. /dev/xvda -> /dev/nvme0n1
	// https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html
	hasRootFs := true
	if _, err := os.Lstat("/rootfs/proc"); os.IsNotExist(err) {
	hasRootFs = false
	}
	nvmeName := ""
	if hasRootFs {
	devName = "/rootfs" + devName
	}
	if info, err := os.Lstat(devName); err == nil {
	if info.Mode()&os.ModeSymlink != 0 {
	if path, err := filepath.EvalSymlinks(devName); err == nil {
	nvmeName = path
	}
	}
	}
	if nvmeName != "" && hasRootFs {
	nvmeName = strings.TrimPrefix(nvmeName, "/rootfs")
	}
	return nvmeName
	}

This linux specific logic runs for all platforms, prevents the device names returned by the describeVolumesProvider (DescribeVolumes.Volumes.Attachments) from being included in the volume cache map. This normalization is not needed for the results of the linux hostProvider as it enumerates the devices registered in /sys/block/.

Description of changes

• Move normalization of device name (trimming prefix /dev/) to describeVolumesProvider.DeviceToSerialMap method.
• Remove normalization from volume provider.
• Enables support for having multiple device names in volume cache with the same device serial (volumeId).

License

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Tests

• Updated and ran unit tests.
• Built linux binary and tested on above system.

Requirements

Before commiting your code, please do the following steps.

• Run make fmt and make fmt-sh
• Run make lint

---

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[montaguethomas]

This PR was marked stale due to lack of activity.

poke

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[montaguethomas]

bump

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