cmd/kpod/parse.go: Provided by Urvashi Mohnani

Signed-off-by: baude <bbaude@redhat.com>

cmd/kpod/parse.go

@@ -0,0 +1,872 @@
+// most of these validate and parse functions have been taken from projectatomic/docker
+// and modified for cri-o
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"os"
+	"os/user"
+	"path"
+	"regexp"
+	"strconv"
+	"strings"
+
+	units "github.com/docker/go-units"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+	pb "k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
+)
+
+// Note: for flags that are in the form <number><unit>, use the RAMInBytes function
+// from the units package in docker/go-units/size.go
+
+var (
+	whiteSpaces  = " \t"
+	alphaRegexp  = regexp.MustCompile(`[a-zA-Z]`)
+	domainRegexp = regexp.MustCompile(`^(:?(:?[a-zA-Z0-9]|(:?[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9]))(:?\.(:?[a-zA-Z0-9]|(:?[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])))*)\.?\s*$`)
+)
+
+// validateExtraHost validates that the specified string is a valid extrahost and returns it.
+// ExtraHost is in the form of name:ip where the ip has to be a valid ip (ipv4 or ipv6).
+// for add-host flag
+func validateExtraHost(val string) (string, error) {
+	// allow for IPv6 addresses in extra hosts by only splitting on first ":"
+	arr := strings.SplitN(val, ":", 2)
+	if len(arr) != 2 || len(arr[0]) == 0 {
+		return "", fmt.Errorf("bad format for add-host: %q", val)
+	}
+	if _, err := validateIPAddress(arr[1]); err != nil {
+		return "", fmt.Errorf("invalid IP address in add-host: %q", arr[1])
+	}
+	return val, nil
+}
+
+// validateIPAddress validates an Ip address.
+// for dns, ip, and ip6 flags also
+func validateIPAddress(val string) (string, error) {
+	var ip = net.ParseIP(strings.TrimSpace(val))
+	if ip != nil {
+		return ip.String(), nil
+	}
+	return "", fmt.Errorf("%s is not an ip address", val)
+}
+
+// validateAttach validates that the specified string is a valid attach option.
+// for attach flag
+func validateAttach(val string) (string, error) {
+	s := strings.ToLower(val)
+	for _, str := range []string{"stdin", "stdout", "stderr"} {
+		if s == str {
+			return s, nil
+		}
+	}
+	return val, fmt.Errorf("valid streams are STDIN, STDOUT and STDERR")
+}
+
+// validate the blkioWeight falls in the range of 10 to 1000
+// for blkio-weight flag
+func validateBlkioWeight(val int64) (int64, error) {
+	if val >= 10 && val <= 1000 {
+		return val, nil
+	}
+	return -1, errors.Errorf("invalid blkio weight %q, should be between 10 and 1000", val)
+}
+
+// weightDevice is a structure that holds device:weight pair
+type weightDevice struct {
+	path   string
+	weight uint16
+}
+
+func (w *weightDevice) String() string {
+	return fmt.Sprintf("%s:%d", w.path, w.weight)
+}
+
+// validateweightDevice validates that the specified string has a valid device-weight format
+// for blkio-weight-device flag
+func validateweightDevice(val string) (*weightDevice, error) {
+	split := strings.SplitN(val, ":", 2)
+	if len(split) != 2 {
+		return nil, fmt.Errorf("bad format: %s", val)
+	}
+	if !strings.HasPrefix(split[0], "/dev/") {
+		return nil, fmt.Errorf("bad format for device path: %s", val)
+	}
+	weight, err := strconv.ParseUint(split[1], 10, 0)
+	if err != nil {
+		return nil, fmt.Errorf("invalid weight for device: %s", val)
+	}
+	if weight > 0 && (weight < 10 || weight > 1000) {
+		return nil, fmt.Errorf("invalid weight for device: %s", val)
+	}
+
+	return &weightDevice{
+		path:   split[0],
+		weight: uint16(weight),
+	}, nil
+}
+
+// parseDevice parses a device mapping string to a container.DeviceMapping struct
+// for device flag
+func parseDevice(device string) (*pb.Device, error) {
+	_, err := validateDevice(device)
+	if err != nil {
+		return nil, errors.Wrapf(err, "device string not valid %q", device)
+	}
+
+	src := ""
+	dst := ""
+	permissions := "rwm"
+	arr := strings.Split(device, ":")
+	switch len(arr) {
+	case 3:
+		permissions = arr[2]
+		fallthrough
+	case 2:
+		if validDeviceMode(arr[1]) {
+			permissions = arr[1]
+		} else {
+			dst = arr[1]
+		}
+		fallthrough
+	case 1:
+		src = arr[0]
+	default:
+		return nil, fmt.Errorf("invalid device specification: %s", device)
+	}
+
+	if dst == "" {
+		dst = src
+	}
+
+	deviceMapping := &pb.Device{
+		ContainerPath: dst,
+		HostPath:      src,
+		Permissions:   permissions,
+	}
+	return deviceMapping, nil
+}
+
+// validDeviceMode checks if the mode for device is valid or not.
+// Valid mode is a composition of r (read), w (write), and m (mknod).
+func validDeviceMode(mode string) bool {
+	var legalDeviceMode = map[rune]bool{
+		'r': true,
+		'w': true,
+		'm': true,
+	}
+	if mode == "" {
+		return false
+	}
+	for _, c := range mode {
+		if !legalDeviceMode[c] {
+			return false
+		}
+		legalDeviceMode[c] = false
+	}
+	return true
+}
+
+// validateDevice validates a path for devices
+// It will make sure 'val' is in the form:
+//    [host-dir:]container-path[:mode]
+// It also validates the device mode.
+func validateDevice(val string) (string, error) {
+	return validatePath(val, validDeviceMode)
+}
+
+func validatePath(val string, validator func(string) bool) (string, error) {
+	var containerPath string
+	var mode string
+
+	if strings.Count(val, ":") > 2 {
+		return val, fmt.Errorf("bad format for path: %s", val)
+	}
+
+	split := strings.SplitN(val, ":", 3)
+	if split[0] == "" {
+		return val, fmt.Errorf("bad format for path: %s", val)
+	}
+	switch len(split) {
+	case 1:
+		containerPath = split[0]
+		val = path.Clean(containerPath)
+	case 2:
+		if isValid := validator(split[1]); isValid {
+			containerPath = split[0]
+			mode = split[1]
+			val = fmt.Sprintf("%s:%s", path.Clean(containerPath), mode)
+		} else {
+			containerPath = split[1]
+			val = fmt.Sprintf("%s:%s", split[0], path.Clean(containerPath))
+		}
+	case 3:
+		containerPath = split[1]
+		mode = split[2]
+		if isValid := validator(split[2]); !isValid {
+			return val, fmt.Errorf("bad mode specified: %s", mode)
+		}
+		val = fmt.Sprintf("%s:%s:%s", split[0], containerPath, mode)
+	}
+
+	if !path.IsAbs(containerPath) {
+		return val, fmt.Errorf("%s is not an absolute path", containerPath)
+	}
+	return val, nil
+}
+
+// throttleDevice is a structure that holds device:rate_per_second pair
+type throttleDevice struct {
+	path string
+	rate uint64
+}
+
+func (t *throttleDevice) String() string {
+	return fmt.Sprintf("%s:%d", t.path, t.rate)
+}
+
+// validateBpsDevice validates that the specified string has a valid device-rate format
+// for device-read-bps and device-write-bps flags
+func validateBpsDevice(val string) (*throttleDevice, error) {
+	split := strings.SplitN(val, ":", 2)
+	if len(split) != 2 {
+		return nil, fmt.Errorf("bad format: %s", val)
+	}
+	if !strings.HasPrefix(split[0], "/dev/") {
+		return nil, fmt.Errorf("bad format for device path: %s", val)
+	}
+	rate, err := units.RAMInBytes(split[1])
+	if err != nil {
+		return nil, fmt.Errorf("invalid rate for device: %s. The correct format is <device-path>:<number>[<unit>]. Number must be a positive integer. Unit is optional and can be kb, mb, or gb", val)
+	}
+	if rate < 0 {
+		return nil, fmt.Errorf("invalid rate for device: %s. The correct format is <device-path>:<number>[<unit>]. Number must be a positive integer. Unit is optional and can be kb, mb, or gb", val)
+	}
+
+	return &throttleDevice{
+		path: split[0],
+		rate: uint64(rate),
+	}, nil
+}
+
+// validateIOpsDevice validates that the specified string has a valid device-rate format
+// for device-write-iops and device-read-iops flags
+func validateIOpsDevice(val string) (*throttleDevice, error) {
+	split := strings.SplitN(val, ":", 2)
+	if len(split) != 2 {
+		return nil, fmt.Errorf("bad format: %s", val)
+	}
+	if !strings.HasPrefix(split[0], "/dev/") {
+		return nil, fmt.Errorf("bad format for device path: %s", val)
+	}
+	rate, err := strconv.ParseUint(split[1], 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("invalid rate for device: %s. The correct format is <device-path>:<number>. Number must be a positive integer", val)
+	}
+	if rate < 0 {
+		return nil, fmt.Errorf("invalid rate for device: %s. The correct format is <device-path>:<number>. Number must be a positive integer", val)
+	}
+
+	return &throttleDevice{
+		path: split[0],
+		rate: uint64(rate),
+	}, nil
+}
+
+// validateDNSSearch validates domain for resolvconf search configuration.
+// A zero length domain is represented by a dot (.).
+// for dns-search flag
+func validateDNSSearch(val string) (string, error) {
+	if val = strings.Trim(val, " "); val == "." {
+		return val, nil
+	}
+	return validateDomain(val)
+}
+
+func validateDomain(val string) (string, error) {
+	if alphaRegexp.FindString(val) == "" {
+		return "", fmt.Errorf("%s is not a valid domain", val)
+	}
+	ns := domainRegexp.FindSubmatch([]byte(val))
+	if len(ns) > 0 && len(ns[1]) < 255 {
+		return string(ns[1]), nil
+	}
+	return "", fmt.Errorf("%s is not a valid domain", val)
+}
+
+// validateEnv validates an environment variable and returns it.
+// If no value is specified, it returns the current value using os.Getenv.
+// for env flag
+func validateEnv(val string) (string, error) {
+	arr := strings.Split(val, "=")
+	if len(arr) > 1 {
+		return val, nil
+	}
+	if !doesEnvExist(val) {
+		return val, nil
+	}
+	return fmt.Sprintf("%s=%s", val, os.Getenv(val)), nil
+}
+
+func doesEnvExist(name string) bool {
+	for _, entry := range os.Environ() {
+		parts := strings.SplitN(entry, "=", 2)
+		if parts[0] == name {
+			return true
+		}
+	}
+	return false
+}
+
+// reads a file of line terminated key=value pairs, and overrides any keys
+// present in the file with additional pairs specified in the override parameter
+// for env-file and labels-file flags
+func readKVStrings(files []string, override []string) ([]string, error) {
+	envVariables := []string{}
+	for _, ef := range files {
+		parsedVars, err := parseEnvFile(ef)
+		if err != nil {
+			return nil, err
+		}
+		envVariables = append(envVariables, parsedVars...)
+	}
+	// parse the '-e' and '--env' after, to allow override
+	envVariables = append(envVariables, override...)
+
+	return envVariables, nil
+}
+
+// parseEnvFile reads a file with environment variables enumerated by lines
+func parseEnvFile(filename string) ([]string, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return []string{}, err
+	}
+	defer fh.Close()
+
+	lines := []string{}
+	scanner := bufio.NewScanner(fh)
+	for scanner.Scan() {
+		// trim the line from all leading whitespace first
+		line := strings.TrimLeft(scanner.Text(), whiteSpaces)
+		// line is not empty, and not starting with '#'
+		if len(line) > 0 && !strings.HasPrefix(line, "#") {
+			data := strings.SplitN(line, "=", 2)
+
+			// trim the front of a variable, but nothing else
+			variable := strings.TrimLeft(data[0], whiteSpaces)
+			if strings.ContainsAny(variable, whiteSpaces) {
+				return []string{}, errors.Errorf("variable %q has white spaces, poorly formatted environment", variable)
+			}
+
+			if len(data) > 1 {
+
+				// pass the value through, no trimming
+				lines = append(lines, fmt.Sprintf("%s=%s", variable, data[1]))
+			} else {
+				// if only a pass-through variable is given, clean it up.
+				lines = append(lines, fmt.Sprintf("%s=%s", strings.TrimSpace(line), os.Getenv(line)))
+			}
+		}
+	}
+	return lines, scanner.Err()
+}
+
+// NsIpc represents the container ipc stack.
+// for ipc flag
+type NsIpc string
+
+// IsPrivate indicates whether the container uses its private ipc stack.
+func (n NsIpc) IsPrivate() bool {
+	return !(n.IsHost() || n.IsContainer())
+}
+
+// IsHost indicates whether the container uses the host's ipc stack.
+func (n NsIpc) IsHost() bool {
+	return n == "host"
+}
+
+// IsContainer indicates whether the container uses a container's ipc stack.
+func (n NsIpc) IsContainer() bool {
+	parts := strings.SplitN(string(n), ":", 2)
+	return len(parts) > 1 && parts[0] == "container"
+}
+
+// Valid indicates whether the ipc stack is valid.
+func (n NsIpc) Valid() bool {
+	parts := strings.Split(string(n), ":")
+	switch mode := parts[0]; mode {
+	case "", "host":
+	case "container":
+		if len(parts) != 2 || parts[1] == "" {
+			return false
+		}
+	default:
+		return false
+	}
+	return true
+}
+
+// Container returns the name of the container ipc stack is going to be used.
+func (n NsIpc) Container() string {
+	parts := strings.SplitN(string(n), ":", 2)
+	if len(parts) > 1 {
+		return parts[1]
+	}
+	return ""
+}
+
+// validateLabel validates that the specified string is a valid label, and returns it.
+// Labels are in the form on key=value.
+// for label flag
+func validateLabel(val string) (string, error) {
+	if strings.Count(val, "=") < 1 {
+		return "", fmt.Errorf("bad attribute format: %s", val)
+	}
+	return val, nil
+}
+
+// validateMACAddress validates a MAC address.
+// for mac-address flag
+func validateMACAddress(val string) (string, error) {
+	_, err := net.ParseMAC(strings.TrimSpace(val))
+	if err != nil {
+		return "", err
+	}
+	return val, nil
+}
+
+// validateLink validates that the specified string has a valid link format (containerName:alias).
+func validateLink(val string) (string, error) {
+	if _, _, err := parseLink(val); err != nil {
+		return val, err
+	}
+	return val, nil
+}
+
+// parseLink parses and validates the specified string as a link format (name:alias)
+func parseLink(val string) (string, string, error) {
+	if val == "" {
+		return "", "", fmt.Errorf("empty string specified for links")
+	}
+	arr := strings.Split(val, ":")
+	if len(arr) > 2 {
+		return "", "", fmt.Errorf("bad format for links: %s", val)
+	}
+	if len(arr) == 1 {
+		return val, val, nil
+	}
+	// This is kept because we can actually get a HostConfig with links
+	// from an already created container and the format is not `foo:bar`
+	// but `/foo:/c1/bar`
+	if strings.HasPrefix(arr[0], "/") {
+		_, alias := path.Split(arr[1])
+		return arr[0][1:], alias, nil
+	}
+	return arr[0], arr[1], nil
+}
+
+// parseLoggingOpts validates the logDriver and logDriverOpts
+// for log-opt and log-driver flags
+func parseLoggingOpts(logDriver string, logDriverOpt []string) (map[string]string, error) {
+	logOptsMap := convertKVStringsToMap(logDriverOpt)
+	if logDriver == "none" && len(logDriverOpt) > 0 {
+		return map[string]string{}, errors.Errorf("invalid logging opts for driver %s", logDriver)
+	}
+	return logOptsMap, nil
+}
+
+// NsPid represents the pid namespace of the container.
+//for pid flag
+type NsPid string
+
+// IsPrivate indicates whether the container uses its own new pid namespace.
+func (n NsPid) IsPrivate() bool {
+	return !(n.IsHost() || n.IsContainer())
+}
+
+// IsHost indicates whether the container uses the host's pid namespace.
+func (n NsPid) IsHost() bool {
+	return n == "host"
+}
+
+// IsContainer indicates whether the container uses a container's pid namespace.
+func (n NsPid) IsContainer() bool {
+	parts := strings.SplitN(string(n), ":", 2)
+	return len(parts) > 1 && parts[0] == "container"
+}
+
+// Valid indicates whether the pid namespace is valid.
+func (n NsPid) Valid() bool {
+	parts := strings.Split(string(n), ":")
+	switch mode := parts[0]; mode {
+	case "", "host":
+	case "container":
+		if len(parts) != 2 || parts[1] == "" {
+			return false
+		}
+	default:
+		return false
+	}
+	return true
+}
+
+// Container returns the name of the container whose pid namespace is going to be used.
+func (n NsPid) Container() string {
+	parts := strings.SplitN(string(n), ":", 2)
+	if len(parts) > 1 {
+		return parts[1]
+	}
+	return ""
+}
+
+// parsePortSpecs receives port specs in the format of ip:public:private/proto and parses
+// these in to the internal types
+// for publish, publish-all, and expose flags
+func parsePortSpecs(ports []string) ([]*pb.PortMapping, error) {
+	var portMappings []*pb.PortMapping
+	for _, rawPort := range ports {
+		portMapping, err := parsePortSpec(rawPort)
+		if err != nil {
+			return nil, err
+		}
+
+		portMappings = append(portMappings, portMapping...)
+	}
+	return portMappings, nil
+}
+
+func validateProto(proto string) bool {
+	for _, availableProto := range []string{"tcp", "udp"} {
+		if availableProto == proto {
+			return true
+		}
+	}
+	return false
+}
+
+// parsePortSpec parses a port specification string into a slice of PortMappings
+func parsePortSpec(rawPort string) ([]*pb.PortMapping, error) {
+	var proto string
+	rawIP, hostPort, containerPort := splitParts(rawPort)
+	proto, containerPort = splitProtoPort(containerPort)
+
+	// Strip [] from IPV6 addresses
+	ip, _, err := net.SplitHostPort(rawIP + ":")
+	if err != nil {
+		return nil, fmt.Errorf("Invalid ip address %v: %s", rawIP, err)
+	}
+	if ip != "" && net.ParseIP(ip) == nil {
+		return nil, fmt.Errorf("Invalid ip address: %s", ip)
+	}
+	if containerPort == "" {
+		return nil, fmt.Errorf("No port specified: %s<empty>", rawPort)
+	}
+
+	startPort, endPort, err := parsePortRange(containerPort)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid containerPort: %s", containerPort)
+	}
+
+	var startHostPort, endHostPort uint64 = 0, 0
+	if len(hostPort) > 0 {
+		startHostPort, endHostPort, err = parsePortRange(hostPort)
+		if err != nil {
+			return nil, fmt.Errorf("Invalid hostPort: %s", hostPort)
+		}
+	}
+
+	if hostPort != "" && (endPort-startPort) != (endHostPort-startHostPort) {
+		// Allow host port range iff containerPort is not a range.
+		// In this case, use the host port range as the dynamic
+		// host port range to allocate into.
+		if endPort != startPort {
+			return nil, fmt.Errorf("Invalid ranges specified for container and host Ports: %s and %s", containerPort, hostPort)
+		}
+	}
+
+	if !validateProto(strings.ToLower(proto)) {
+		return nil, fmt.Errorf("invalid proto: %s", proto)
+	}
+
+	protocol := pb.Protocol_TCP
+	if strings.ToLower(proto) == "udp" {
+		protocol = pb.Protocol_UDP
+	}
+
+	var ports []*pb.PortMapping
+	for i := uint64(0); i <= (endPort - startPort); i++ {
+		containerPort = strconv.FormatUint(startPort+i, 10)
+		if len(hostPort) > 0 {
+			hostPort = strconv.FormatUint(startHostPort+i, 10)
+		}
+		// Set hostPort to a range only if there is a single container port
+		// and a dynamic host port.
+		if startPort == endPort && startHostPort != endHostPort {
+			hostPort = fmt.Sprintf("%s-%s", hostPort, strconv.FormatUint(endHostPort, 10))
+		}
+
+		ctrPort, err := strconv.ParseInt(containerPort, 10, 32)
+		if err != nil {
+			return nil, err
+		}
+		hPort, err := strconv.ParseInt(hostPort, 10, 32)
+		if err != nil {
+			return nil, err
+		}
+
+		port := &pb.PortMapping{
+			Protocol:      protocol,
+			ContainerPort: int32(ctrPort),
+			HostPort:      int32(hPort),
+			HostIp:        ip,
+		}
+
+		ports = append(ports, port)
+	}
+	return ports, nil
+}
+
+// parsePortRange parses and validates the specified string as a port-range (8000-9000)
+func parsePortRange(ports string) (uint64, uint64, error) {
+	if ports == "" {
+		return 0, 0, fmt.Errorf("empty string specified for ports")
+	}
+	if !strings.Contains(ports, "-") {
+		start, err := strconv.ParseUint(ports, 10, 16)
+		end := start
+		return start, end, err
+	}
+
+	parts := strings.Split(ports, "-")
+	start, err := strconv.ParseUint(parts[0], 10, 16)
+	if err != nil {
+		return 0, 0, err
+	}
+	end, err := strconv.ParseUint(parts[1], 10, 16)
+	if err != nil {
+		return 0, 0, err
+	}
+	if end < start {
+		return 0, 0, fmt.Errorf("Invalid range specified for the Port: %s", ports)
+	}
+	return start, end, nil
+}
+
+// splitParts separates the different parts of rawPort
+func splitParts(rawport string) (string, string, string) {
+	parts := strings.Split(rawport, ":")
+	n := len(parts)
+	containerport := parts[n-1]
+
+	switch n {
+	case 1:
+		return "", "", containerport
+	case 2:
+		return "", parts[0], containerport
+	case 3:
+		return parts[0], parts[1], containerport
+	default:
+		return strings.Join(parts[:n-2], ":"), parts[n-2], containerport
+	}
+}
+
+// splitProtoPort splits a port in the format of port/proto
+func splitProtoPort(rawPort string) (string, string) {
+	parts := strings.Split(rawPort, "/")
+	l := len(parts)
+	if len(rawPort) == 0 || l == 0 || len(parts[0]) == 0 {
+		return "", ""
+	}
+	if l == 1 {
+		return "tcp", rawPort
+	}
+	if len(parts[1]) == 0 {
+		return "tcp", parts[0]
+	}
+	return parts[1], parts[0]
+}
+
+// takes a local seccomp file and reads its file contents
+// for security-opt flag
+func parseSecurityOpts(securityOpts []string) ([]string, error) {
+	for key, opt := range securityOpts {
+		con := strings.SplitN(opt, "=", 2)
+		if len(con) == 1 && con[0] != "no-new-privileges" {
+			if strings.Index(opt, ":") != -1 {
+				con = strings.SplitN(opt, ":", 2)
+			} else {
+				return securityOpts, fmt.Errorf("Invalid --security-opt: %q", opt)
+			}
+		}
+		if con[0] == "seccomp" && con[1] != "unconfined" {
+			f, err := ioutil.ReadFile(con[1])
+			if err != nil {
+				return securityOpts, fmt.Errorf("opening seccomp profile (%s) failed: %v", con[1], err)
+			}
+			b := bytes.NewBuffer(nil)
+			if err := json.Compact(b, f); err != nil {
+				return securityOpts, fmt.Errorf("compacting json for seccomp profile (%s) failed: %v", con[1], err)
+			}
+			securityOpts[key] = fmt.Sprintf("seccomp=%s", b.Bytes())
+		}
+	}
+
+	return securityOpts, nil
+}
+
+// parses storage options per container into a map
+// for storage-opt flag
+func parseStorageOpts(storageOpts []string) (map[string]string, error) {
+	m := make(map[string]string)
+	for _, option := range storageOpts {
+		if strings.Contains(option, "=") {
+			opt := strings.SplitN(option, "=", 2)
+			m[opt[0]] = opt[1]
+		} else {
+			return nil, errors.Errorf("invalid storage option %q", option)
+		}
+	}
+	return m, nil
+}
+
+// parseUser parses the the uid and gid in the format <name|uid>[:<group|gid>]
+// for user flag
+// FIXME: Issue from https://github.com/projectatomic/buildah/issues/66
+func parseUser(rootdir, userspec string) (specs.User, error) {
+	var gid64 uint64
+	var gerr error = user.UnknownGroupError("error looking up group")
+
+	spec := strings.SplitN(userspec, ":", 2)
+	userspec = spec[0]
+	groupspec := ""
+	if userspec == "" {
+		return specs.User{}, nil
+	}
+	if len(spec) > 1 {
+		groupspec = spec[1]
+	}
+
+	uid64, uerr := strconv.ParseUint(userspec, 10, 32)
+	if uerr == nil && groupspec == "" {
+		// We parsed the user name as a number, and there's no group
+		// component, so we need to look up the user's primary GID.
+		var name string
+		name, gid64, gerr = lookupGroupForUIDInContainer(rootdir, uid64)
+		if gerr == nil {
+			userspec = name
+		} else {
+			if userrec, err := user.LookupId(userspec); err == nil {
+				gid64, gerr = strconv.ParseUint(userrec.Gid, 10, 32)
+				userspec = userrec.Name
+			}
+		}
+	}
+	if uerr != nil {
+		uid64, gid64, uerr = lookupUserInContainer(rootdir, userspec)
+		gerr = uerr
+	}
+	if uerr != nil {
+		if userrec, err := user.Lookup(userspec); err == nil {
+			uid64, uerr = strconv.ParseUint(userrec.Uid, 10, 32)
+			gid64, gerr = strconv.ParseUint(userrec.Gid, 10, 32)
+		}
+	}
+
+	if groupspec != "" {
+		gid64, gerr = strconv.ParseUint(groupspec, 10, 32)
+		if gerr != nil {
+			gid64, gerr = lookupGroupInContainer(rootdir, groupspec)
+		}
+		if gerr != nil {
+			if group, err := user.LookupGroup(groupspec); err == nil {
+				gid64, gerr = strconv.ParseUint(group.Gid, 10, 32)
+			}
+		}
+	}
+
+	if uerr == nil && gerr == nil {
+		u := specs.User{
+			UID:      uint32(uid64),
+			GID:      uint32(gid64),
+			Username: userspec,
+		}
+		return u, nil
+	}
+
+	err := errors.Wrapf(uerr, "error determining run uid")
+	if uerr == nil {
+		err = errors.Wrapf(gerr, "error determining run gid")
+	}
+	return specs.User{}, err
+}
+
+// convertKVStringsToMap converts ["key=value"] to {"key":"value"}
+func convertKVStringsToMap(values []string) map[string]string {
+	result := make(map[string]string, len(values))
+	for _, value := range values {
+		kv := strings.SplitN(value, "=", 2)
+		if len(kv) == 1 {
+			result[kv[0]] = ""
+		} else {
+			result[kv[0]] = kv[1]
+		}
+	}
+
+	return result
+}
+
+// NsUser represents userns mode in the container.
+// for userns flag
+type NsUser string
+
+// IsHost indicates whether the container uses the host's userns.
+func (n NsUser) IsHost() bool {
+	return n == "host"
+}
+
+// IsPrivate indicates whether the container uses the a private userns.
+func (n NsUser) IsPrivate() bool {
+	return !(n.IsHost())
+}
+
+// Valid indicates whether the userns is valid.
+func (n NsUser) Valid() bool {
+	parts := strings.Split(string(n), ":")
+	switch mode := parts[0]; mode {
+	case "", "host":
+	default:
+		return false
+	}
+	return true
+}
+
+// NsUts represents the UTS namespace of the container.
+// for uts flag
+type NsUts string
+
+// IsPrivate indicates whether the container uses its private UTS namespace.
+func (n NsUts) IsPrivate() bool {
+	return !(n.IsHost())
+}
+
+// IsHost indicates whether the container uses the host's UTS namespace.
+func (n NsUts) IsHost() bool {
+	return n == "host"
+}
+
+// Valid indicates whether the UTS namespace is valid.
+func (n NsUts) Valid() bool {
+	parts := strings.Split(string(n), ":")
+	switch mode := parts[0]; mode {
+	case "", "host":
+	default:
+		return false
+	}
+	return true
+}