scaffold script flow

Dockerfile

@@ -12,9 +12,7 @@ FROM alpine:3.14
 
 WORKDIR /root
 
-RUN apk add --update ca-certificates docker openrc gnupg
+RUN apk add --update ca-certificates
-RUN update-ca-certificates
-RUN rc-update add docker boot
 
 COPY --from=builder /app/backup /usr/bin/backup
 

src/main.go

@@ -2,8 +2,10 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
+	"time"
 
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
@@ -13,63 +15,138 @@ import (
 )
 
 func main() {
-	if err := godotenv.Load("/etc/backup.env"); err != nil {
+	s := &script{}
+	defer func() {
+		for _, thunk := range s.cleanupTasks {
+			thunk()
+		}
+	}()
+
+	s.lock()
+	defer s.unlock()
+
+	if err := s.init(); err != nil {
 		panic(err)
 	}
 
-	ctx := context.Background()
+	if err := s.stopContainers(); err != nil {
-	cli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
-	if err != nil {
 		panic(err)
 	}
 
+	if err := s.takeBackup(); err != nil {
+		panic(err)
+	}
+
+	if err := s.restartContainers(); err != nil {
+		panic(err)
+	}
+
+	if err := s.encryptBackup(); err != nil {
+		panic(err)
+	}
+
+	if err := s.copyBackup(); err != nil {
+		panic(err)
+	}
+
+	if err := s.cleanBackup(); err != nil {
+		panic(err)
+	}
+
+	if err := s.pruneBackups(); err != nil {
+		panic(err)
+	}
+}
+
+type script struct {
+	ctx               context.Context
+	cli               *client.Client
+	stoppedContainers []types.Container
+	file              string
+	cleanupTasks      []func()
+}
+
+func (s *script) lock()   {}
+func (s *script) unlock() {}
+
+func (s *script) init() error {
+	s.ctx = context.Background()
+	if timeout, ok := os.LookupEnv("BACKUP_TIMEOUT_DURATION"); ok {
+		d, err := time.ParseDuration(timeout)
+		if err != nil {
+			return fmt.Errorf("init: error parsing given timeout duration: %w", err)
+		}
+		withTimeout, cancelFunc := context.WithTimeout(context.Background(), d)
+		s.ctx = withTimeout
+		s.cleanupTasks = append(s.cleanupTasks, cancelFunc)
+	}
+
+	if err := godotenv.Load("/etc/backup.env"); err != nil {
+		return fmt.Errorf("init: failed to load env file: %w", err)
+	}
+
 	socketExists, err := fileExists("/var/run/docker.sock")
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("init: error checking whether docker.sock is available: %w", err)
 	}
-
-	var containersToStop []types.Container
 	if socketExists {
-		containersToStop, err = cli.ContainerList(ctx, types.ContainerListOptions{
+		cli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
+		if err != nil {
+			return fmt.Errorf("init: failied to create docker client")
+		}
+		s.cli = cli
+	}
+	return nil
+}
+
+func (s *script) stopContainers() error {
+	if s.cli == nil {
+		return nil
+	}
+	stoppedContainers, err := s.cli.ContainerList(s.ctx, types.ContainerListOptions{
 		Quiet: true,
 		Filters: filters.NewArgs(filters.KeyValuePair{
 			Key:   "label",
 			Value: fmt.Sprintf("docker-volume-backup.stop-during-backup=%s", os.Getenv("BACKUP_STOP_CONTAINER_LABEL")),
 		}),
 	})
+
+	s.stoppedContainers = stoppedContainers
 	if err != nil {
-			panic(err)
+		return fmt.Errorf("stopContainers: error querying for containers to stop: %w", err)
-		}
-		fmt.Printf("Stopping %d containers\n", len(containersToStop))
 	}
+	fmt.Printf("Stopping %d containers\n", len(s.stoppedContainers))
 
-	if len(containersToStop) != 0 {
+	if len(s.stoppedContainers) != 0 {
 		fmt.Println("Stopping containers")
-		for _, container := range containersToStop {
+		for _, container := range s.stoppedContainers {
-			if err := cli.ContainerStop(ctx, container.ID, nil); err != nil {
+			if err := s.cli.ContainerStop(s.ctx, container.ID, nil); err != nil {
-				panic(err)
+				return fmt.Errorf("stopContainers: error stopping container %s: %w", container.Names[0], err)
 			}
 		}
 	}
+	return nil
+}
 
-	fmt.Println("Creating backup")
+func (s *script) takeBackup() error {
-	// TODO: Implement backup
+	return errors.New("takeBackup: not implemented yet")
+}
 
-	if len(containersToStop) != 0 {
+func (s *script) restartContainers() error {
 	fmt.Println("Starting containers/services back up")
 	servicesRequiringUpdate := map[string]struct{}{}
-		for _, container := range containersToStop {
+	for _, container := range s.stoppedContainers {
 		if swarmServiceName, ok := container.Labels["com.docker.swarm.service.name"]; ok {
 			servicesRequiringUpdate[swarmServiceName] = struct{}{}
 			continue
 		}
-			if err := cli.ContainerStart(ctx, container.ID, types.ContainerStartOptions{}); err != nil {
+		if err := s.cli.ContainerStart(s.ctx, container.ID, types.ContainerStartOptions{}); err != nil {
 			panic(err)
 		}
 	}
 
 	if len(servicesRequiringUpdate) != 0 {
-			services, _ := cli.ServiceList(ctx, types.ServiceListOptions{})
+		services, _ := s.cli.ServiceList(s.ctx, types.ServiceListOptions{})
 		for serviceName := range servicesRequiringUpdate {
 			var serviceMatch swarm.Service
 			for _, service := range services {
@@ -79,16 +156,40 @@ func main() {
 				}
 			}
 			if serviceMatch.ID == "" {
-					panic(fmt.Sprintf("Couldn't find service with name %s", serviceName))
+				return fmt.Errorf("restartContainers: Couldn't find service with name %s", serviceName)
 			}
 			serviceMatch.Spec.TaskTemplate.ForceUpdate = 1
-				cli.ServiceUpdate(
+			s.cli.ServiceUpdate(
-					ctx, serviceMatch.ID,
+				s.ctx, serviceMatch.ID,
 				serviceMatch.Version, serviceMatch.Spec, types.ServiceUpdateOptions{},
 			)
 		}
 	}
+	return nil
+}
+
+func (s *script) encryptBackup() error {
+	_, ok := os.LookupEnv("GPG_PASSPHRASE")
+	if !ok {
+		return nil
 	}
+	return errors.New("encryptBackup: not implemented yet")
+}
+
+func (s *script) copyBackup() error {
+	return errors.New("copyBackup: not implemented yet")
+}
+
+func (s *script) cleanBackup() error {
+	return errors.New("cleanBackup: not implemented yet")
+}
+
+func (s *script) pruneBackups() error {
+	_, ok := os.LookupEnv("BACKUP_RETENTION_DAYS")
+	if !ok {
+		return nil
+	}
+	return errors.New("pruneBackups: not implemented yet")
 }
 
 func fileExists(location string) (bool, error) {