docker-volume-backup/cmd/backup/docker.go

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package main
import (
"context"
"errors"
"fmt"
"io"
"sync"
"time"
"github.com/docker/cli/cli/command/service/progress"
"github.com/docker/docker/api/types"
ctr "github.com/docker/docker/api/types/container"
"github.com/docker/docker/api/types/filters"
"github.com/docker/docker/api/types/swarm"
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"github.com/docker/docker/client"
)
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func scaleService(cli *client.Client, serviceID string, replicas uint64) ([]string, error) {
service, _, err := cli.ServiceInspectWithRaw(context.Background(), serviceID, types.ServiceInspectOptions{})
if err != nil {
return nil, fmt.Errorf("scaleService: error inspecting service %s: %w", serviceID, err)
}
serviceMode := &service.Spec.Mode
switch {
case serviceMode.Replicated != nil:
serviceMode.Replicated.Replicas = &replicas
default:
return nil, fmt.Errorf("scaleService: service to be scaled %s has to be in replicated mode", service.Spec.Name)
}
response, err := cli.ServiceUpdate(context.Background(), service.ID, service.Version, service.Spec, types.ServiceUpdateOptions{})
if err != nil {
return nil, fmt.Errorf("scaleService: error updating service: %w", err)
}
discardWriter := &noopWriteCloser{io.Discard}
if err := progress.ServiceProgress(context.Background(), cli, service.ID, discardWriter); err != nil {
return nil, err
}
return response.Warnings, nil
}
func awaitContainerCountForService(cli *client.Client, serviceID string, count int) error {
for {
containers, err := cli.ContainerList(context.Background(), types.ContainerListOptions{
Filters: filters.NewArgs(filters.KeyValuePair{
Key: "label",
Value: fmt.Sprintf("com.docker.swarm.service.id=%s", serviceID),
}),
})
if err != nil {
return fmt.Errorf("awaitContainerCount: error listing containers: %w", err)
}
if len(containers) == count {
break
}
time.Sleep(time.Second)
}
return nil
}
// stopContainersAndServices stops all Docker containers that are marked as to being
// stopped during the backup and returns a function that can be called to
// restart everything that has been stopped.
func (s *script) stopContainersAndServices() (func() error, error) {
if s.cli == nil {
return noop, nil
}
dockerInfo, err := s.cli.Info(context.Background())
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error getting docker info: %w", err)
}
isDockerSwarm := dockerInfo.Swarm.LocalNodeState != "inactive"
filterMatchLabel := fmt.Sprintf(
"docker-volume-backup.stop-during-backup=%s",
s.c.BackupStopContainerLabel,
)
allContainers, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{})
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error querying for containers: %w", err)
}
containersToStop, err := s.cli.ContainerList(context.Background(), types.ContainerListOptions{
Filters: filters.NewArgs(filters.KeyValuePair{
Key: "label",
Value: filterMatchLabel,
}),
})
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error querying for containers to stop: %w", err)
}
var allServices []swarm.Service
var servicesToScaleDown []handledSwarmService
if isDockerSwarm {
allServices, err = s.cli.ServiceList(context.Background(), types.ServiceListOptions{})
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error querying for services: %w", err)
}
matchingServices, err := s.cli.ServiceList(context.Background(), types.ServiceListOptions{
Filters: filters.NewArgs(filters.KeyValuePair{
Key: "label",
Value: filterMatchLabel,
}),
Status: true,
})
for _, s := range matchingServices {
servicesToScaleDown = append(servicesToScaleDown, handledSwarmService{
serviceID: s.ID,
initialReplicaCount: *s.Spec.Mode.Replicated.Replicas,
})
}
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error querying for services to scale down: %w", err)
}
}
if len(containersToStop) == 0 && len(servicesToScaleDown) == 0 {
return noop, nil
}
if isDockerSwarm {
for _, container := range containersToStop {
if swarmServiceID, ok := container.Labels["com.docker.swarm.service.id"]; ok {
parentService, _, err := s.cli.ServiceInspectWithRaw(context.Background(), swarmServiceID, types.ServiceInspectOptions{})
if err != nil {
return noop, fmt.Errorf("(*script).stopContainersAndServices: error querying for parent service with ID %s: %w", swarmServiceID, err)
}
for label := range parentService.Spec.Labels {
if label == "docker-volume-backup.stop-during-backup" {
return noop, fmt.Errorf(
"(*script).stopContainersAndServices: container %s is labeled to stop but has parent service %s which is also labeled, cannot continue",
container.Names[0],
parentService.Spec.Name,
)
}
}
}
}
}
s.logger.Info(
fmt.Sprintf(
"Stopping %d out of %d running container(s) and scaling down %d out of %d active service(s) as they were labeled %s.",
len(containersToStop),
len(allContainers),
len(servicesToScaleDown),
len(allServices),
filterMatchLabel,
),
)
var stoppedContainers []types.Container
var stopErrors []error
for _, container := range containersToStop {
if err := s.cli.ContainerStop(context.Background(), container.ID, ctr.StopOptions{}); err != nil {
stopErrors = append(stopErrors, err)
} else {
stoppedContainers = append(stoppedContainers, container)
}
}
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var scaledDownServices []handledSwarmService
var scaleDownErrors concurrentSlice[error]
if isDockerSwarm {
wg := sync.WaitGroup{}
for _, svc := range servicesToScaleDown {
wg.Add(1)
go func(svc handledSwarmService) {
defer wg.Done()
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warnings, err := scaleService(s.cli, svc.serviceID, 0)
if err != nil {
scaleDownErrors.append(err)
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} else {
scaledDownServices = append(scaledDownServices, svc)
}
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for _, warning := range warnings {
s.logger.Warn(
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fmt.Sprintf("The Docker API returned a warning when scaling down service %s: %s", svc.serviceID, warning),
)
}
// progress.ServiceProgress returns too early, so we need to manually check
// whether all containers belonging to the service have actually been removed
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if err := awaitContainerCountForService(s.cli, svc.serviceID, 0); err != nil {
scaleDownErrors.append(err)
}
}(svc)
}
wg.Wait()
}
s.stats.Containers = ContainersStats{
All: uint(len(allContainers)),
ToStop: uint(len(containersToStop)),
Stopped: uint(len(stoppedContainers)),
StopErrors: uint(len(stopErrors)),
}
s.stats.Services = ServicesStats{
All: uint(len(allServices)),
ToScaleDown: uint(len(servicesToScaleDown)),
ScaledDown: uint(len(scaledDownServices)),
ScaleDownErrors: uint(len(scaleDownErrors.value())),
}
var initialErr error
allErrors := append(stopErrors, scaleDownErrors.value()...)
if len(allErrors) != 0 {
initialErr = fmt.Errorf(
"(*script).stopContainersAndServices: %d error(s) stopping containers: %w",
len(allErrors),
errors.Join(allErrors...),
)
}
return func() error {
servicesRequiringForceUpdate := map[string]struct{}{}
var restartErrors []error
for _, container := range stoppedContainers {
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// in case a container was part of a swarm service, teh service requires to
// be force updated instead of restarting the container as it would otherwise
// remain in a "completed" state
if swarmServiceName, ok := container.Labels["com.docker.swarm.service.name"]; ok {
servicesRequiringForceUpdate[swarmServiceName] = struct{}{}
continue
}
if err := s.cli.ContainerStart(context.Background(), container.ID, types.ContainerStartOptions{}); err != nil {
restartErrors = append(restartErrors, err)
}
}
if len(servicesRequiringForceUpdate) != 0 {
services, _ := s.cli.ServiceList(context.Background(), types.ServiceListOptions{})
for serviceName := range servicesRequiringForceUpdate {
var serviceMatch swarm.Service
for _, service := range services {
if service.Spec.Name == serviceName {
serviceMatch = service
break
}
}
if serviceMatch.ID == "" {
restartErrors = append(
restartErrors,
fmt.Errorf("(*script).stopContainersAndServices: couldn't find service with name %s", serviceName),
)
continue
}
serviceMatch.Spec.TaskTemplate.ForceUpdate += 1
if _, err := s.cli.ServiceUpdate(
context.Background(), serviceMatch.ID,
serviceMatch.Version, serviceMatch.Spec, types.ServiceUpdateOptions{},
); err != nil {
restartErrors = append(restartErrors, err)
}
}
}
var scaleUpErrors concurrentSlice[error]
if isDockerSwarm {
wg := &sync.WaitGroup{}
for _, svc := range servicesToScaleDown {
wg.Add(1)
go func(svc handledSwarmService) {
defer wg.Done()
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warnings, err := scaleService(s.cli, svc.serviceID, svc.initialReplicaCount)
if err != nil {
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scaleDownErrors.append(err)
return
}
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for _, warning := range warnings {
s.logger.Warn(
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fmt.Sprintf("The Docker API returned a warning when scaling up service %s: %s", svc.serviceID, warning),
)
}
}(svc)
}
wg.Wait()
}
allErrors := append(restartErrors, scaleUpErrors.value()...)
if len(allErrors) != 0 {
return fmt.Errorf(
"stopContainers: %d error(s) restarting containers and services: %w",
len(allErrors),
errors.Join(allErrors...),
)
}
s.logger.Info(
fmt.Sprintf(
"Restarted %d container(s) and %d service(s).",
len(stoppedContainers),
len(scaledDownServices),
),
)
return nil
}, initialErr
}