func newDockerContainerHandler()

in container/docker/handler.go [113:249]
103 lines of code
18 McCabe index (conditional complexity)

func newDockerContainerHandler(
	client *docker.Client,
	name string,
	machineInfoFactory info.MachineInfoFactory,
	fsInfo fs.FsInfo,
	storageDriver StorageDriver,
	storageDir string,
	cgroupSubsystems map[string]string,
	inHostNamespace bool,
	metadataEnvAllowList []string,
	dockerVersion []int,
	includedMetrics container.MetricSet,
	thinPoolName string,
	thinPoolWatcher *devicemapper.ThinPoolWatcher,
	zfsWatcher *zfs.ZfsWatcher,
) (container.ContainerHandler, error) {
	// Create the cgroup paths.
	cgroupPaths := common.MakeCgroupPaths(cgroupSubsystems, name)

	// Generate the equivalent cgroup manager for this container.
	cgroupManager, err := containerlibcontainer.NewCgroupManager(name, cgroupPaths)
	if err != nil {
		return nil, err
	}

	rootFs := "/"
	if !inHostNamespace {
		rootFs = "/rootfs"
		storageDir = path.Join(rootFs, storageDir)
	}

	id := dockerutil.ContainerNameToId(name)

	// Add the Containers dir where the log files are stored.
	// FIXME: Give `otherStorageDir` a more descriptive name.
	otherStorageDir := path.Join(storageDir, pathToContainersDir, id)

	rwLayerID, err := getRwLayerID(id, storageDir, storageDriver, dockerVersion)
	if err != nil {
		return nil, err
	}

	// Determine the rootfs storage dir OR the pool name to determine the device.
	// For devicemapper, we only need the thin pool name, and that is passed in to this call
	rootfsStorageDir, zfsFilesystem, zfsParent, err := DetermineDeviceStorage(storageDriver, storageDir, rwLayerID)
	if err != nil {
		return nil, fmt.Errorf("unable to determine device storage: %v", err)
	}

	// We assume that if Inspect fails then the container is not known to docker.
	ctnr, err := client.ContainerInspect(context.Background(), id)
	if err != nil {
		return nil, fmt.Errorf("failed to inspect container %q: %v", id, err)
	}

	// Do not report network metrics for containers that share netns with another container.
	metrics := common.RemoveNetMetrics(includedMetrics, ctnr.HostConfig.NetworkMode.IsContainer())

	// TODO: extract object mother method
	handler := &dockerContainerHandler{
		machineInfoFactory: machineInfoFactory,
		cgroupPaths:        cgroupPaths,
		fsInfo:             fsInfo,
		storageDriver:      storageDriver,
		poolName:           thinPoolName,
		rootfsStorageDir:   rootfsStorageDir,
		envs:               make(map[string]string),
		labels:             ctnr.Config.Labels,
		includedMetrics:    metrics,
		zfsParent:          zfsParent,
	}
	// Timestamp returned by Docker is in time.RFC3339Nano format.
	handler.creationTime, err = time.Parse(time.RFC3339Nano, ctnr.Created)
	if err != nil {
		// This should not happen, report the error just in case
		return nil, fmt.Errorf("failed to parse the create timestamp %q for container %q: %v", ctnr.Created, id, err)
	}
	handler.libcontainerHandler = containerlibcontainer.NewHandler(cgroupManager, rootFs, ctnr.State.Pid, metrics)

	// Add the name and bare ID as aliases of the container.
	handler.reference = info.ContainerReference{
		Id:        id,
		Name:      name,
		Aliases:   []string{strings.TrimPrefix(ctnr.Name, "/"), id},
		Namespace: DockerNamespace,
	}
	handler.image = ctnr.Config.Image
	// Only adds restartcount label if it's greater than 0
	if ctnr.RestartCount > 0 {
		handler.labels["restartcount"] = strconv.Itoa(ctnr.RestartCount)
	}

	// Obtain the IP address for the container.
	// If the NetworkMode starts with 'container:' then we need to use the IP address of the container specified.
	// This happens in cases such as kubernetes where the containers doesn't have an IP address itself and we need to use the pod's address
	ipAddress := ctnr.NetworkSettings.IPAddress
	networkMode := string(ctnr.HostConfig.NetworkMode)
	if ipAddress == "" && strings.HasPrefix(networkMode, "container:") {
		containerID := strings.TrimPrefix(networkMode, "container:")
		c, err := client.ContainerInspect(context.Background(), containerID)
		if err != nil {
			return nil, fmt.Errorf("failed to inspect container %q: %v", id, err)
		}
		ipAddress = c.NetworkSettings.IPAddress
	}

	handler.ipAddress = ipAddress

	if includedMetrics.Has(container.DiskUsageMetrics) {
		handler.fsHandler = &FsHandler{
			FsHandler:       common.NewFsHandler(common.DefaultPeriod, rootfsStorageDir, otherStorageDir, fsInfo),
			ThinPoolWatcher: thinPoolWatcher,
			ZfsWatcher:      zfsWatcher,
			DeviceID:        ctnr.GraphDriver.Data["DeviceId"],
			ZfsFilesystem:   zfsFilesystem,
		}
	}

	// split env vars to get metadata map.
	for _, exposedEnv := range metadataEnvAllowList {
		if exposedEnv == "" {
			// if no dockerEnvWhitelist provided, len(metadataEnvAllowList) == 1, metadataEnvAllowList[0] == ""
			continue
		}

		for _, envVar := range ctnr.Config.Env {
			if envVar != "" {
				splits := strings.SplitN(envVar, "=", 2)
				if len(splits) == 2 && strings.HasPrefix(splits[0], exposedEnv) {
					handler.envs[strings.ToLower(splits[0])] = splits[1]
				}
			}
		}
	}

	return handler, nil
}