refactor dockerDiscoverBackupTargets() to support having different kinds of producers

Author: joonas-fi

cmd/ubackup/backup.go

@@ -74,18 +74,32 @@ func runBackup(ctx context.Context, logger *log.Logger) error {
 		}
 
 		for _, containerTarget := range containerTargets {
-			if err := backupOneContainer(ctx, containerTarget, *conf, logger); err != nil {
-				handleOneFailure(containerTarget, err)
+			if err := ubbackup.BackupAndStore(
+				ctx,
+				ubtypes.BackupForTarget(containerTarget.BackupTarget),
+				*conf,
+				containerTarget.Produce,
+				logger,
+			); err != nil {
+				handleOneFailure(containerTarget.BackupTarget, err)
 			}
 		}
 	}
 
 	for _, staticTarget := range conf.StaticTargets {
 		staticTarget := staticTarget // pin
 
-		if err := ubbackup.BackupAndStore(ctx, ubtypes.BackupForTarget(staticTarget), *conf, func(backupSink io.Writer) error {
-			return copyCommandStdout(exec.Command(staticTarget.BackupCommand[0], staticTarget.BackupCommand[1:]...), backupSink)
-		}, logger); err != nil {
+		if err := ubbackup.BackupAndStore(
+			ctx,
+			ubtypes.BackupForTarget(staticTarget),
+			*conf,
+			func(backupSink io.Writer) error {
+				return copyCommandStdout(
+					exec.Command(staticTarget.BackupCommand[0], staticTarget.BackupCommand[1:]...),
+					backupSink)
+			},
+			logger,
+		); err != nil {
 			handleOneFailure(staticTarget, err)
 		}
 	}
@@ -116,25 +130,6 @@ func runBackup(ctx context.Context, logger *log.Logger) error {
 	return nil
 }
 
-func backupOneContainer(
-	ctx context.Context,
-	target ubtypes.BackupTarget,
-	conf ubconfig.Config,
-	logger *log.Logger,
-) error {
-	return ubbackup.BackupAndStore(ctx, ubtypes.BackupForTarget(target), conf, func(backupSink io.Writer) error {
-		dockerExecCmd := append([]string{
-			"docker",
-			"exec",
-			target.TaskId,
-		}, target.BackupCommand...)
-
-		return copyCommandStdout(
-			exec.Command(dockerExecCmd[0], dockerExecCmd[1:]...),
-			backupSink)
-	}, logger)
-}
-
 func copyCommandStdout(cmd *exec.Cmd, backupSink io.Writer) error {
 	cmd.Stderr = os.Stderr
 	stdout, err := cmd.StdoutPipe()

cmd/ubackup/dockerdiscovery.go

@@ -7,16 +7,23 @@ import (
 	"github.com/function61/gokit/ezhttp"
 	"github.com/function61/gokit/udocker"
 	"github.com/function61/ubackup/pkg/ubtypes"
+	"io"
 	"net/http"
+	"os/exec"
 	"strings"
 )
 
 const (
 	backupCommandEnvKey = "BACKUP_COMMAND"
 )
 
+type DockerTarget struct {
+	BackupTarget ubtypes.BackupTarget
+	Produce      func(backupSink io.Writer) error
+}
+
 // returns containers that have ENV var "BACKUP_COMMAND" defined
-func dockerDiscoverBackupTargets(ctx context.Context, dockerEndpoint string) ([]ubtypes.BackupTarget, error) {
+func dockerDiscoverBackupTargets(ctx context.Context, dockerEndpoint string) ([]DockerTarget, error) {
 	dockerClient, base, err := udocker.Client(dockerEndpoint, nil, false)
 	if err != nil {
 		return nil, fmt.Errorf("udocker.Client: %v", err)
@@ -41,29 +48,54 @@ func dockerDiscoverBackupTargets(ctx context.Context, dockerEndpoint string) ([]
 		return nil, err
 	}
 
-	targets := []ubtypes.BackupTarget{}
+	targets := []DockerTarget{}
 
 	for _, inspected := range inspecteds {
+		foundBackupCommand := ""
+
 		for _, envSerialized := range inspected.Config.Env {
 			key, value := envvar.Parse(envSerialized)
-			if key != backupCommandEnvKey {
-				continue
+			if key == backupCommandEnvKey {
+				foundBackupCommand = value
 			}
+		}
 
-			serviceName := inspected.Config.Labels[udocker.SwarmServiceNameLabelKey]
-			if serviceName == "" {
-				serviceName = "none"
-			}
+		if foundBackupCommand == "" {
+			continue
+		}
 
-			// FIXME
-			backupCommandParsed := strings.Split(value, " ")
+		serviceName := inspected.Config.Labels[udocker.SwarmServiceNameLabelKey]
+		if serviceName == "" {
+			serviceName = "none"
+		}
+
+		// FIXME
+		backupCommandParsed := strings.Split(foundBackupCommand, " ")
 
-			targets = append(targets, ubtypes.BackupTarget{
-				ServiceName:   serviceName,
-				TaskId:        inspected.Id[0:12], // Docker CLI truncates ids to this long. using same here to shorten filenames
-				BackupCommand: backupCommandParsed,
-			})
+		target := ubtypes.BackupTarget{
+			ServiceName:   serviceName,
+			TaskId:        inspected.Id[0:12], // Docker CLI truncates ids to this long. using same here to shorten filenames
+			BackupCommand: backupCommandParsed,
 		}
+
+		producer := func(target ubtypes.BackupTarget) func(io.Writer) error {
+			return func(backupSink io.Writer) error {
+				dockerExecCmd := append([]string{
+					"docker",
+					"exec",
+					target.TaskId,
+				}, target.BackupCommand...)
+
+				return copyCommandStdout(
+					exec.Command(dockerExecCmd[0], dockerExecCmd[1:]...),
+					backupSink)
+			}
+		}(target)
+
+		targets = append(targets, DockerTarget{
+			Produce:      producer,
+			BackupTarget: target,
+		})
 	}
 
 	return targets, nil