auto updates

Add support to auto-update containers running in systemd units as
generated with `podman generate systemd --new`.

`podman auto-update` looks up containers with a specified
"io.containers.autoupdate" label (i.e., the auto-update policy).

If the label is present and set to "image", Podman reaches out to the
corresponding registry to check if the image has been updated.  We
consider an image to be updated if the digest in the local storage is
different than the one of the remote image.  If an image must be
updated, Podman pulls it down and restarts the container.  Note that the
restarting sequence relies on systemd.

At container-creation time, Podman looks up the "PODMAN_SYSTEMD_UNIT"
environment variables and stores it verbatim in the container's label.
This variable is now set by all systemd units generated by
`podman-generate-systemd` and is set to `%n` (i.e., the name of systemd
unit starting the container).  This data is then being used in the
auto-update sequence to instruct systemd (via DBUS) to restart the unit
and hence to restart the container.

Note that this implementation of auto-updates relies on systemd and
requires a fully-qualified image reference to be used to create the
container.  This enforcement is necessary to know which image to
actually check and pull.  If we used an image ID, we would not know
which image to check/pull anymore.

Fixes: containers#3575
Signed-off-by: Valentin Rothberg <[email protected]>

cmd/podman/autoupdate.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/containers/libpod/cmd/podman/cliconfig"
+	"github.com/containers/libpod/pkg/adapter"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+var (
+	autoUpdateCommand     cliconfig.AutoUpdateValues
+	autoUpdateDescription = `Auto update containers according to their auto-update policy.
+
+Auto-update policies are specified with the "io.containers.autoupdate" label.`
+	_autoUpdateCommand = &cobra.Command{
+		Use:   "auto-update [flags]",
+		Short: "Auto update containers according to their auto-update policy",
+		Long:  autoUpdateDescription,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			restartCommand.InputArgs = args
+			restartCommand.GlobalFlags = MainGlobalOpts
+			return autoUpdateCmd(&restartCommand)
+		},
+		Example: `podman auto-update`,
+	}
+)
+
+func init() {
+	autoUpdateCommand.Command = _autoUpdateCommand
+	autoUpdateCommand.SetHelpTemplate(HelpTemplate())
+	autoUpdateCommand.SetUsageTemplate(UsageTemplate())
+}
+
+func autoUpdateCmd(c *cliconfig.RestartValues) error {
+	runtime, err := adapter.GetRuntime(getContext(), &c.PodmanCommand)
+	if err != nil {
+		return errors.Wrapf(err, "error creating libpod runtime")
+	}
+	defer runtime.DeferredShutdown(false)
+
+	units, failures := runtime.AutoUpdate()
+	for _, unit := range units {
+		fmt.Println(unit)
+	}
+	var finalErr error
+	if len(failures) > 0 {
+		finalErr = failures[0]
+		for _, e := range failures[1:] {
+			finalErr = errors.Errorf("%v\n%v", finalErr, e)
+		}
+	}
+	return finalErr
+}

cmd/podman/cliconfig/config.go

@@ -54,6 +54,10 @@ type AttachValues struct {
 	SigProxy   bool
 }
 
+type AutoUpdateValues struct {
+	PodmanCommand
+}
+
 type ImagesValues struct {
 	PodmanCommand
 	All       bool
@@ -470,10 +474,11 @@ type RefreshValues struct {
 
 type RestartValues struct {
 	PodmanCommand
-	All     bool
-	Latest  bool
-	Running bool
-	Timeout uint
+	All        bool
+	AutoUpdate bool
+	Latest     bool
+	Running    bool
+	Timeout    uint
 }
 
 type RestoreValues struct {

cmd/podman/commands.go

@@ -11,6 +11,7 @@ const remoteclient = false
 // Commands that the local client implements
 func getMainCommands() []*cobra.Command {
 	rootCommands := []*cobra.Command{
+		_autoUpdateCommand,
 		_cpCommand,
 		_playCommand,
 		_loginCommand,

cmd/podman/shared/create.go

@@ -18,13 +18,15 @@ import (
 	"github.com/containers/libpod/libpod"
 	"github.com/containers/libpod/libpod/image"
 	ann "github.com/containers/libpod/pkg/annotations"
+	"github.com/containers/libpod/pkg/autoupdate"
 	envLib "github.com/containers/libpod/pkg/env"
 	"github.com/containers/libpod/pkg/errorhandling"
 	"github.com/containers/libpod/pkg/inspect"
 	ns "github.com/containers/libpod/pkg/namespaces"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/libpod/pkg/seccomp"
 	cc "github.com/containers/libpod/pkg/spec"
+	systemdGen "github.com/containers/libpod/pkg/systemd/generate"
 	"github.com/containers/libpod/pkg/util"
 	"github.com/docker/go-connections/nat"
 	"github.com/docker/go-units"
@@ -69,6 +71,7 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 	}
 
 	imageName := ""
+	rawImageName := ""
 	var imageData *inspect.ImageData = nil
 
 	// Set the storage if there is no rootfs specified
@@ -78,9 +81,8 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 			writer = os.Stderr
 		}
 
-		name := ""
 		if len(c.InputArgs) != 0 {
-			name = c.InputArgs[0]
+			rawImageName = c.InputArgs[0]
 		} else {
 			return nil, nil, errors.Errorf("error, image name not provided")
 		}
@@ -97,7 +99,7 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 			ArchitectureChoice: overrideArch,
 		}
 
-		newImage, err := runtime.ImageRuntime().New(ctx, name, rtc.SignaturePolicyPath, c.String("authfile"), writer, &dockerRegistryOptions, image.SigningOptions{}, nil, pullType)
+		newImage, err := runtime.ImageRuntime().New(ctx, rawImageName, rtc.SignaturePolicyPath, c.String("authfile"), writer, &dockerRegistryOptions, image.SigningOptions{}, nil, pullType)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -174,11 +176,32 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		}
 	}
 
-	createConfig, err := ParseCreateOpts(ctx, c, runtime, imageName, imageData)
+	createConfig, err := ParseCreateOpts(ctx, c, runtime, imageName, rawImageName, imageData)
 	if err != nil {
 		return nil, nil, err
 	}
 
+	// (VR): Ideally we perform the checks _before_ pulling the image but that
+	// would require some bigger code refactoring of `ParseCreateOpts` and the
+	// logic here.  But as the creation code will be consolidated in the future
+	// and given auto updates are experimental, we can live with that for now.
+	// In the end, the user may only need to correct the policy or the raw image
+	// name.
+	autoUpdatePolicy, autoUpdatePolicySpecified := createConfig.Labels[autoupdate.Label]
+	if autoUpdatePolicySpecified {
+		if _, err := autoupdate.LookupPolicy(autoUpdatePolicy); err != nil {
+			return nil, nil, err
+		}
+		// Now we need to make sure we're having a fully-qualified image reference.
+		if rootfs != "" {
+			return nil, nil, errors.Errorf("auto updates do not work with --rootfs")
+		}
+		// Make sure the input image is a docker.
+		if err := autoupdate.ValidateImageReference(rawImageName); err != nil {
+			return nil, nil, err
+		}
+	}
+
 	// Because parseCreateOpts does derive anything from the image, we add health check
 	// at this point. The rest is done by WithOptions.
 	createConfig.HealthCheck = healthCheck
@@ -270,7 +293,7 @@ func configurePod(c *GenericCLIResults, runtime *libpod.Runtime, namespaces map[
 
 // Parses CLI options related to container creation into a config which can be
 // parsed into an OCI runtime spec
-func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.Runtime, imageName string, data *inspect.ImageData) (*cc.CreateConfig, error) {
+func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.Runtime, imageName string, rawImageName string, data *inspect.ImageData) (*cc.CreateConfig, error) {
 	var (
 		inputCommand, command                                    []string
 		memoryLimit, memoryReservation, memorySwap, memoryKernel int64
@@ -481,12 +504,15 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		"container": "podman",
 	}
 
+	// First transform the os env into a map. We need it for the labels later in
+	// any case.
+	osEnv, err := envLib.ParseSlice(os.Environ())
+	if err != nil {
+		return nil, errors.Wrap(err, "error parsing host environment variables")
+	}
+
 	// Start with env-host
 	if c.Bool("env-host") {
-		osEnv, err := envLib.ParseSlice(os.Environ())
-		if err != nil {
-			return nil, errors.Wrap(err, "error parsing host environment variables")
-		}
 		env = envLib.Join(env, osEnv)
 	}
 
@@ -534,6 +560,10 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		}
 	}
 
+	if systemdUnit, exists := osEnv[systemdGen.EnvVariable]; exists {
+		labels[systemdGen.EnvVariable] = systemdUnit
+	}
+
 	// ANNOTATIONS
 	annotations := make(map[string]string)
 
@@ -764,11 +794,12 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		Entrypoint:        entrypoint,
 		Env:               env,
 		// ExposedPorts:   ports,
-		Init:        c.Bool("init"),
-		InitPath:    c.String("init-path"),
-		Image:       imageName,
-		ImageID:     imageID,
-		Interactive: c.Bool("interactive"),
+		Init:         c.Bool("init"),
+		InitPath:     c.String("init-path"),
+		Image:        imageName,
+		RawImageName: rawImageName,
+		ImageID:      imageID,
+		Interactive:  c.Bool("interactive"),
 		// IP6Address:     c.String("ipv6"), // Not implemented yet - needs CNI support for static v6
 		Labels: labels,
 		// LinkLocalIP:    c.StringSlice("link-local-ip"), // Not implemented yet

completions/bash/podman

@@ -3334,6 +3334,7 @@ _podman_podman() {
      "
      commands="
     attach
+    auto-update
     build
     commit
     container

contrib/systemd/auto-update/podman-auto-update.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=Podman auto-update service
+Documentation=man:podman-auto-update(1)
+Wants=network.target
+After=network-online.target
+
+[Service]
+ExecStart=/usr/bin/podman auto-update
+
+[Install]
+WantedBy=multi-user.target default.target

contrib/systemd/auto-update/podman-auto-update.timer

@@ -0,0 +1,9 @@
+[Unit]
+Description=Podman auto-update timer
+
+[Timer]
+OnCalendar=daily
+Persistent=true
+
+[Install]
+WantedBy=timers.target

docs/source/markdown/podman-auto-update.1.md

@@ -0,0 +1,46 @@
+% podman-auto-update(1)
+
+## NAME
+podman\-auto-update - Auto update containers according to their auto-update policy
+
+## SYNOPSIS
+**podman auto-update**
+
+## DESCRIPTION
+`podman auto-update` looks up containers with a specified "io.containers.autoupdate" label (i.e., the auto-update policy).
+
+If the label is present and set to "image", Podman reaches out to the corresponding registry to check if the image has been updated.
+An image is considered updated if the digest in the local storage is different than the one of the remote image.
+If an image must be updated, Podman pulls it down and restarts the systemd unit executing the container.
+
+At container-creation time, Podman looks up the "PODMAN_SYSTEMD_UNIT" environment variables and stores it verbatim in the container's label.
+This variable is now set by all systemd units generated by `podman-generate-systemd` and is set to `%n` (i.e., the name of systemd unit starting the container).
+This data is then being used in the auto-update sequence to instruct systemd (via DBUS) to restart the unit and hence to restart the container.
+
+Note that this implementation of auto updates relies on systemd and requires a fully-qualified image reference (e.g., quay.io/podman/stable:latest) to be used to create the container.
+This enforcement is necessary to know which image to actually check and pull.
+If we used an image ID, we would not know which image to check/pull anymore.
+
+## EXAMPLES
+
+```
+# Start a container
+$ podman run -d busybox:latest top
+bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d
+
+# Generate a systemd unit for this container
+$ podman generate systemd --new --files bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d
+/home/user/containers/libpod/container-bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d.service
+
+# Load the new systemd unit and start it
+$ mv ./container-bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d.service ~/.config/systemd/user
+$ systemctl --user daemon-reload
+$ systemctl --user start container-bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d.service
+
+# Auto-update the container
+$ podman auto-update
+container-bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d.service
+```
+
+## SEE ALSO
+podman(1), podman-generate-systemd(1), podman-run(1), systemd.unit(5)

libpod/container.go

@@ -239,6 +239,12 @@ type ContainerConfig struct {
 	// container has been created with.
 	CreateCommand []string `json:"CreateCommand,omitempty"`
 
+	// RawImageName is the raw and unprocessed name of the image when creating
+	// the container (as specified by the user).  May or may not be set.  One
+	// use case to store this data are auto-updates where we need the _exact_
+	// name and not some normalized instance of it.
+	RawImageName string `json:"RawImageName,omitempty"`
+
 	// TODO consider breaking these subsections up into smaller structs
 
 	// UID/GID mappings used by the storage
@@ -503,11 +509,17 @@ func (c *Container) Namespace() string {
 	return c.config.Namespace
 }
 
-// Image returns the ID and name of the image used as the container's rootfs
+// Image returns the ID and name of the image used as the container's rootfs.
 func (c *Container) Image() (string, string) {
 	return c.config.RootfsImageID, c.config.RootfsImageName
 }
 
+// RawImageName returns the unprocessed and not-normalized user-specified image
+// name.
+func (c *Container) RawImageName() string {
+	return c.config.RawImageName
+}
+
 // ShmDir returns the sources path to be mounted on /dev/shm in container
 func (c *Container) ShmDir() string {
 	return c.config.ShmDir