Set machine timezone

Added an option to podman machine init to declare the timezone of the
resulting machine.  the default is to use the value of the host name or
else a given timezone name like America/Chicago.

Fixes: containers#11895

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

[NO NEW TESTS NEEDED]

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

cmd/podman/machine/init.go

@@ -38,7 +38,6 @@ func init() {
 	})
 	flags := initCmd.Flags()
 	cfg := registry.PodmanConfig()
-
 	cpusFlagName := "cpus"
 	flags.Uint64Var(
 		&initOpts.CPUS,
@@ -69,6 +68,13 @@ func init() {
 		"now", false,
 		"Start machine now",
 	)
+	timezoneFlagName := "timezone"
+	defaultTz := cfg.TZ()
+	if len(defaultTz) < 1 {
+		defaultTz = "local"
+	}
+	flags.StringVar(&initOpts.TimeZone, timezoneFlagName, defaultTz, "Set timezone")
+	_ = initCmd.RegisterFlagCompletionFunc(timezoneFlagName, completion.AutocompleteDefault)
 
 	ImagePathFlagName := "image-path"
 	flags.StringVar(&initOpts.ImagePath, ImagePathFlagName, cfg.Machine.Image, "Path to qcow image")

docs/source/markdown/podman-machine-init.1.md

@@ -55,6 +55,12 @@ Memory (in MB).
 
 Start the virtual machine immediately after it has been initialized.
 
+#### **--timezone**
+
+Set the timezone for the machine and containers.  Valid values are `local` or
+a `timezone` such as `America/Chicago`.  A value of `local`, which is the default,
+means to use the timezone of the machine host.
+
 #### **--help**
 
 Print usage statement.

pkg/machine/config.go

@@ -21,6 +21,7 @@ type InitOptions struct {
 	IsDefault    bool
 	Memory       uint64
 	Name         string
+	TimeZone     string
 	URI          url.URL
 	Username     string
 }

pkg/machine/ignition.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/url"
+	"path/filepath"
 )
 
 /*
@@ -44,6 +45,7 @@ func getNodeGrp(grpName string) NodeGroup {
 type DynamicIgnition struct {
 	Name      string
 	Key       string
+	TimeZone  string
 	VMName    string
 	WritePath string
 }
@@ -76,6 +78,37 @@ func NewIgnitionFile(ign DynamicIgnition) error {
 		Links:       getLinks(ign.Name),
 	}
 
+	// Add or set the time zone for the machine
+	if len(ign.TimeZone) > 0 {
+		var (
+			err error
+			tz  string
+		)
+		// local means the same as the host
+		// lookup where it is pointing to on the host
+		if ign.TimeZone == "local" {
+			tz, err = getLocalTimeZone()
+			if err != nil {
+				return err
+			}
+		} else {
+			tz = ign.TimeZone
+		}
+		tzLink := Link{
+			Node: Node{
+				Group:     getNodeGrp("root"),
+				Path:      "/etc/localtime",
+				Overwrite: boolToPtr(false),
+				User:      getNodeUsr("root"),
+			},
+			LinkEmbedded1: LinkEmbedded1{
+				Hard:   boolToPtr(false),
+				Target: filepath.Join("/usr/share/zoneinfo", tz),
+			},
+		}
+		ignStorage.Links = append(ignStorage.Links, tzLink)
+	}
+
 	// ready is a unit file that sets up the virtual serial device
 	// where when the VM is done configuring, it will send an ack
 	// so a listening host knows it can being interacting with it

pkg/machine/ignition_darwin.go

@@ -0,0 +1,16 @@
+//+build darwin
+
+package machine
+
+import (
+	"os"
+	"strings"
+)
+
+func getLocalTimeZone() (string, error) {
+	tzPath, err := os.Readlink("/etc/localtime")
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimPrefix(tzPath, "/var/db/timezone/zoneinfo"), nil
+}

pkg/machine/ignition_linux.go

@@ -0,0 +1,15 @@
+package machine
+
+import (
+	"os/exec"
+	"strings"
+)
+
+func getLocalTimeZone() (string, error) {
+	output, err := exec.Command("timedatectl", "show", "--property=Timezone").Output()
+	if err != nil {
+		return "", err
+	}
+	// Remove prepended field and the newline
+	return strings.TrimPrefix(strings.TrimSuffix(string(output), "\n"), "Timezone="), nil
+}

pkg/machine/qemu/machine.go

@@ -145,6 +145,7 @@ func (v *MachineVM) Init(opts machine.InitOptions) error {
 		// Get image as usual
 		v.ImageStream = opts.ImagePath
 		dd, err := machine.NewFcosDownloader(vmtype, v.Name, opts.ImagePath)
+
 		if err != nil {
 			return err
 		}
@@ -235,6 +236,7 @@ func (v *MachineVM) Init(opts machine.InitOptions) error {
 		Name:      opts.Username,
 		Key:       key,
 		VMName:    v.Name,
+		TimeZone:  opts.TimeZone,
 		WritePath: v.IgnitionFilePath,
 	}
 	return machine.NewIgnitionFile(ign)