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changed struct to policyMapper
change "image" to "registry" in multiple locations

Updated documentation with registry alias & autoupdate local

Added relevant test

Signed-off-by: Parker Van Roy <[email protected]>
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@ParkerVR
ParkerVR committed Apr 29, 2021
1 parent 150e2a3 commit caf19ef
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55 changes: 48 additions & 7 deletions docs/source/markdown/podman-auto-update.1.md
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Original file line number Diff line number Diff line change
Expand Up @@ -9,21 +9,25 @@ podman-auto-update - Auto update containers according to their auto-update polic
## 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.
If the label is present and set to "registry", Podman reaches out to the corresponding registry to check if the image has been updated.
The label "image" is an alternative to "registry" maintained for backwards compatibility.
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.

The registry policy requires a 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 an image ID was used, Podman would not know which image to check/pull anymore.

Alternatively, if the autoupdate label is set to "local", Podman will compare the image a container is using to the image with it's raw name in local storage.
If an image is updated locally, Podman simply restarts the systemd unit executing the container.

If "io.containers.autoupdate.authfile" label is present, Podman reaches out to corresponding authfile when pulling images.

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 `podman auto-update` 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 an image ID was used, Podman would not know which image to check/pull anymore.

Moreover, the systemd units are expected to be generated with `podman-generate-systemd --new`, or similar units that create new containers in order to run the updated images.
Note that`podman auto-update` relies on systemd. The systemd units are expected to be generated with `podman-generate-systemd --new`, or similar units that create new containers in order to run the updated images.
Systemd units that start and stop a container cannot run a new image.


Expand All @@ -44,9 +48,11 @@ environment variable. `export REGISTRY_AUTH_FILE=path`

## EXAMPLES

Autoupdate with registry policy

```
# Start a container
$ podman run --label "io.containers.autoupdate=image" \
$ podman run --label "io.containers.autoupdate=registry" \
--label "io.containers.autoupdate.authfile=/some/authfile.json" \
-d busybox:latest top
bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d
Expand All @@ -70,5 +76,40 @@ $ podman auto-update
container-bc219740a210455fa27deacc96d50a9e20516492f1417507c13ce1533dbdcd9d.service
```

Autoupdate with local policy

```
# Start a container
$ podman run --label "io.containers.autoupdate=local" \
-d busybox:latest top
be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338
# Generate a systemd unit for this container
$ podman generate systemd --new --files be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338
/home/user/containers/libpod/container-be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338.service
# Load the new systemd unit and start it
$ mv ./container-be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338.service ~/.config/systemd/user
$ systemctl --user daemon-reload
# If the previously created containers or pods are using shared resources, such as ports, make sure to remove them before starting the generated systemd units.
$ podman stop be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338
$ podman rm be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338
$ systemctl --user start container-be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338.service
# Get the name of the container
$ podman ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
01f5c8113e84 docker.io/library/busybox:latest top 2 seconds ago Up 3 seconds ago inspiring_galileo
# Modify the image
$ podman commit --change CMD=/bin/bash inspiring_galileo busybox:latest
# Auto-update the container
$ podman auto-update
container-be0889fd06f252a2e5141b37072c6bada68563026cb2b2649f53394d87ccc338.service
```

## SEE ALSO
podman(1), podman-generate-systemd(1), podman-run(1), systemd.unit(5)
109 changes: 52 additions & 57 deletions pkg/autoupdate/autoupdate.go
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ const (
// PolicyDefault is the default policy denoting no auto updates.
PolicyDefault Policy = "disabled"
// PolicyRegistryImage is the policy to update as soon as there's a new image found.
PolicyRegistryImage = "image"
PolicyRegistryImage = "registry"
// PolicyLocalImage is the policy to run auto-update based on a local image
PolicyLocalImage = "local"
)
Expand All @@ -48,11 +48,8 @@ var supportedPolicies = map[string]Policy{
"local": PolicyLocalImage,
}

// Struct for tying a container to it's autoupdate policy
type PolicyContainer struct {
p Policy
ctr *libpod.Container
}
// policyMapper is used for tying a container to it's autoupdate policy
type policyMapper map[Policy][]*libpod.Container

// LookupPolicy looks up the corresponding Policy for the specified
// string. If none is found, an errors is returned including the list of
Expand Down Expand Up @@ -150,7 +147,7 @@ func AutoUpdate(runtime *libpod.Runtime, options Options) ([]string, []error) {
// Update images.
containersToRestart := []*libpod.Container{}
updatedRawImages := make(map[string]bool)
for imageID, policyContainers := range containerMap {
for imageID, policyMapper := range containerMap {
image, exists := imageMap[imageID]
if !exists {
errs = append(errs, errors.Errorf("container image ID %q not found in local storage", imageID))
Expand All @@ -159,52 +156,49 @@ func AutoUpdate(runtime *libpod.Runtime, options Options) ([]string, []error) {
// Now we have to check if the image of any containers must be updated.
// Note that the image ID is NOT enough for this check as a given image
// may have multiple tags.
for i, pc := range policyContainers {
cid := pc.ctr.ID()
rawImageName := pc.ctr.RawImageName()
for _, registryCtr := range policyMapper[PolicyRegistryImage] {
cid := registryCtr.ID()
rawImageName := registryCtr.RawImageName()
if rawImageName == "" {
errs = append(errs, errors.Errorf("error auto-updating container %q: raw-image name is empty", pc.ctr.ID()))
errs = append(errs, errors.Errorf("error registry auto-updating container %q: raw-image name is empty", cid))
}
readAuthenticationPath(registryCtr, options)
needsUpdate, err := newerRemoteImageAvailable(runtime, image, rawImageName, options)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error registry auto-updating container %q: image check for %q failed", cid, rawImageName))
continue
}

switch pc.p {
// Sanity Check, should be unreachable code
case PolicyDefault:
errs = append(errs, errors.Errorf("error auto-updating container %q: invalid policy", cid))

// Registry Autoupdate Containers pull new images and are flagged for restart.
case PolicyRegistryImage:
readAuthenticationPath(pc.ctr, options)
needsUpdate, err := newerRemoteImageAvailable(runtime, image, rawImageName, options)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error auto-updating container %q: image check for %q failed", cid, rawImageName))
continue
}

if needsUpdate {
logrus.Infof("Auto-updating container %q using registry image %q", cid, rawImageName)
if _, updated := updatedRawImages[rawImageName]; !updated {
_, err = updateImage(runtime, rawImageName, options)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error auto-updating container %q: image update for %q failed", cid, rawImageName))
continue
}
updatedRawImages[rawImageName] = true
if needsUpdate {
logrus.Infof("Auto-updating container %q using registry image %q", cid, rawImageName)
if _, updated := updatedRawImages[rawImageName]; !updated {
_, err = updateImage(runtime, rawImageName, options)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error registry auto-updating container %q: image update for %q failed", cid, rawImageName))
continue
}
containersToRestart = append(containersToRestart, policyContainers[i].ctr)
}
// Local Autoupdate Containers with an update are flagged for restart.
case PolicyLocalImage:
// This avoids restarting containers unnecessarily.
needsUpdate, err := newerLocalImageAvailable(image, rawImageName)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error auto-updating container %q: image check for %q failed", cid, rawImageName))
continue
updatedRawImages[rawImageName] = true
}
containersToRestart = append(containersToRestart, registryCtr)
}
}

if needsUpdate {
logrus.Infof("Auto-updating container %q using local image %q", cid, rawImageName)
containersToRestart = append(containersToRestart, policyContainers[i].ctr)
}
for _, localCtr := range policyMapper[PolicyLocalImage] {
cid := localCtr.ID()
rawImageName := localCtr.RawImageName()
if rawImageName == "" {
errs = append(errs, errors.Errorf("error locally auto-updating container %q: raw-image name is empty", cid))
}
// This avoids restarting containers unnecessarily.
needsUpdate, err := newerLocalImageAvailable(image, rawImageName)
if err != nil {
errs = append(errs, errors.Wrapf(err, "error locally auto-updating container %q: image check for %q failed", cid, rawImageName))
continue
}

if needsUpdate {
logrus.Infof("Auto-updating container %q using local image %q", cid, rawImageName)
containersToRestart = append(containersToRestart, localCtr)
}
}
}
Expand Down Expand Up @@ -233,15 +227,15 @@ func AutoUpdate(runtime *libpod.Runtime, options Options) ([]string, []error) {

// imageContainersMap generates a map[image ID] -> [containers using the image]
// of all containers with a valid auto-update policy.
func imageContainersMap(runtime *libpod.Runtime) (map[string][]PolicyContainer, []error) {
func imageContainersMap(runtime *libpod.Runtime) (map[string]policyMapper, []error) {
allContainers, err := runtime.GetAllContainers()
if err != nil {
return nil, []error{err}
}

errors := []error{}
containerMap := make(map[string][]PolicyContainer)
for i, ctr := range allContainers {
containerMap := make(map[string]policyMapper)
for _, ctr := range allContainers {
state, err := ctr.State()
if err != nil {
errors = append(errors, err)
Expand All @@ -266,16 +260,17 @@ func imageContainersMap(runtime *libpod.Runtime) (map[string][]PolicyContainer,
}

// Skip labels not related to autoupdate
if policy != PolicyDefault {
if policy == PolicyDefault {
continue
} else {
id, _ := ctr.Image()
pc := PolicyContainer{
p: policy,
ctr: allContainers[i],
policyMap, exists := containerMap[id]
if !exists {
policyMap = make(map[Policy][]*libpod.Container)
}
containerMap[id] = append(containerMap[id], pc)
policyMap[policy] = append(policyMap[policy], ctr)
containerMap[id] = policyMap
// Now we know that `ctr` is configured for auto updates.
} else {
continue
}
}

Expand Down
70 changes: 57 additions & 13 deletions test/system/250-systemd.bats
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Original file line number Diff line number Diff line change
Expand Up @@ -27,23 +27,23 @@ function teardown() {
run '?' $SYSTEMCTL stop "$SERVICE_NAME"
rm -f "$UNIT_FILE"
$SYSTEMCTL daemon-reload
run_podman rmi -a

basic_teardown
}

# This test can fail in dev. environment because of SELinux.
# quick fix: chcon -t container_runtime_exec_t ./bin/podman
@test "podman generate - systemd - basic" {
# Helper to setup xdg runtime for rootless
function xdg_rootless() {
# podman initializes this if unset, but systemctl doesn't
if is_rootless; then
if [ -z "$XDG_RUNTIME_DIR" ]; then
export XDG_RUNTIME_DIR=/run/user/$(id -u)
fi
fi
}

cname=$(random_string)
# See #7407 for --pull=always.
run_podman create --pull=always --name $cname --label "io.containers.autoupdate=image" $IMAGE top

# Helper to start a systemd service running a container
function service_setup() {
run_podman generate systemd --new $cname
echo "$output" > "$UNIT_FILE"
run_podman rm $cname
Expand All @@ -59,6 +59,30 @@ function teardown() {
if [ $status -ne 0 ]; then
die "Non-zero status of systemd unit $SERVICE_NAME, output: $output"
fi
}

# Helper to stop a systemd service running a container
function service_cleanup() {
run $SYSTEMCTL stop "$SERVICE_NAME"
if [ $status -ne 0 ]; then
die "Error stopping systemd unit $SERVICE_NAME, output: $output"
fi

rm -f "$UNIT_FILE"
$SYSTEMCTL daemon-reload
}

# These tests can fail in dev. environment because of SELinux.
# quick fix: chcon -t container_runtime_exec_t ./bin/podman
@test "podman generate - systemd - basic" {
xdg_rootless

cname=$(random_string)
# See #7407 for --pull=always.
run_podman create --pull=always --name $cname --label "io.containers.autoupdate=registry" $IMAGE top

# Start systemd service to run this container
service_setup

# Give container time to start; make sure output looks top-like
sleep 2
Expand All @@ -72,13 +96,33 @@ function teardown() {
run_podman auto-update

# All good. Stop service, clean up.
run $SYSTEMCTL stop "$SERVICE_NAME"
if [ $status -ne 0 ]; then
die "Error stopping systemd unit $SERVICE_NAME, output: $output"
fi
service_cleanup
}

rm -f "$UNIT_FILE"
$SYSTEMCTL daemon-reload
@test "podman autoupdate local" {
xdg_rootless

cname=$(random_string)
run_podman create --name $cname --label "io.containers.autoupdate=local" $IMAGE top

# Start systemd service to run this container
service_setup

# Give container time to start; make sure output looks top-like
sleep 2
run_podman logs $cname
is "$output" ".*Load average:.*" "running container 'top'-like output"

# Save the container id before updating
run_podman ps --format '{{.ID}}'

# Run auto-update and check that it restarted the container
run_podman commit --change "CMD=/bin/bash" $cname $IMAGE
run_podman auto-update
is $output $SERVICE_NAME "autoupdate local restarted container"

# All good. Stop service, clean up.
service_cleanup
}

# vim: filetype=sh

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