Experiment with running command in spawned container

cmd/backup/command.go

@@ -36,8 +36,17 @@ func (c *command) runAsCommand() error {
 	}
 
 	for _, config := range configurations {
-		if err := runScript(config); err != nil {
-			return errwrap.Wrap(err, "error running script")
+		switch config.ExecutionMode {
+		case "process":
+			if err := runScript(config); err != nil {
+				return errwrap.Wrap(err, "error running script")
+			}
+		case "container":
+			if err := runInContainer(config); err != nil {
+				return errwrap.Wrap(err, "error spawning container")
+			}
+		default:
+			return errwrap.Wrap(nil, fmt.Sprintf("unknown execution mode %s", config.ExecutionMode))
 		}
 	}
 
@@ -110,16 +119,39 @@ func (c *command) schedule(strategy configStrategy) error {
 				),
 			)
 
-			if err := runScript(config); err != nil {
+			switch config.ExecutionMode {
+			case "process":
+				if err := runScript(config); err != nil {
+					c.logger.Error(
+						fmt.Sprintf(
+							"Unexpected error running schedule %s: %v",
+							config.BackupCronExpression,
+							errwrap.Unwrap(err),
+						),
+						"error",
+						err,
+					)
+				}
+			case "container":
+				if err := runInContainer(config); err != nil {
+					c.logger.Error(
+						fmt.Sprintf(
+							"Unexpected error running schedule %s in container: %v",
+							config.BackupCronExpression,
+							errwrap.Unwrap(err),
+						),
+						"error",
+						err,
+					)
+				}
+			default:
 				c.logger.Error(
 					fmt.Sprintf(
-						"Unexpected error running schedule %s: %v",
-						config.BackupCronExpression,
-						errwrap.Unwrap(err),
+						"Unkown execution mode %s, please check your configuration",
+						config.ExecutionMode,
 					),
-					"error",
-					err,
 				)
+				return
 			}
 		})
 

cmd/backup/config.go

@@ -30,7 +30,6 @@ type Config struct {
 	AwsIamRoleEndpoint            string          `split_words:"true"`
 	AwsPartSize                   int64           `split_words:"true"`
 	BackupCompression             CompressionType `split_words:"true" default:"gz"`
-	GzipParallelism               WholeNumber     `split_words:"true" default:"1"`
 	BackupSources                 string          `split_words:"true" default:"/backup"`
 	BackupFilename                string          `split_words:"true" default:"backup-%Y-%m-%dT%H-%M-%S.{{ .Extension }}"`
 	BackupFilenameExpand          bool            `split_words:"true"`
@@ -46,6 +45,7 @@ type Config struct {
 	BackupFromSnapshot            bool            `split_words:"true"`
 	BackupExcludeRegexp           RegexpDecoder   `split_words:"true"`
 	BackupSkipBackendsFromPrune   []string        `split_words:"true"`
+	GzipParallelism               WholeNumber     `split_words:"true" default:"1"`
 	GpgPassphrase                 string          `split_words:"true"`
 	GpgPublicKeyRing              string          `split_words:"true"`
 	AgePassphrase                 string          `split_words:"true"`
@@ -73,6 +73,7 @@ type Config struct {
 	ExecLabel                     string          `split_words:"true"`
 	ExecForwardOutput             bool            `split_words:"true"`
 	LockTimeout                   time.Duration   `split_words:"true" default:"60m"`
+	ExecutionMode                 string          `split_words:"true" default:"process"`
 	AzureStorageAccountName       string          `split_words:"true"`
 	AzureStoragePrimaryAccountKey string          `split_words:"true"`
 	AzureStorageConnectionString  string          `split_words:"true"`

cmd/backup/container.go

@@ -0,0 +1,5 @@
+package main
+
+func runInContainer(config *Config) error {
+	return nil
+}

test/container/docker-compose.yml

@@ -0,0 +1,22 @@
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    restart: always
+    environment:
+      BACKUP_FILENAME: test.tar.gz
+      BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      EXECUTION_MODE: container
+    volumes:
+      - app_data:/backup/app_data:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - ${LOCAL_DIR:-./local}:/archive
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/container/run.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+set -e
+
+cd "$(dirname "$0")"
+. ../util.sh
+current_test=$(basename $(pwd))
+
+export LOCAL_DIR=$(mktemp -d)
+
+docker compose up -d --quiet-pull
+sleep 5
+
+# A symlink for a known file in the volume is created so the test can check
+# whether symlinks are preserved on backup.
+docker compose exec offen ln -s /var/opt/offen/offen.db /var/opt/offen/db.link
+docker compose exec backup backup
+
+sleep 5
+
+expect_running_containers "2"
+
+tmp_dir=$(mktemp -d)
+tar -xvf "$LOCAL_DIR/test.tar.gz" -C $tmp_dir
+if [ ! -f "$tmp_dir/backup/app_data/offen.db" ]; then
+  fail "Could not find expected file in untared archive."
+fi
+rm -f "$LOCAL_DIR/test-hostnametoken.tar.gz"