feat: add backup compression

.gitignore

@@ -1,4 +1,5 @@
 .idea/
 docker-db-backup
 *.sql
+*.gz
 ./backups

README.md

@@ -78,6 +78,10 @@ Default: `12`
 If provided, the tool will do an empty GET request to this URL to indicate it successfully completed the backup job.
 You can use this with other tools to monitor if backups are completed as they should.
 
+### `BACKUP_COMPRESS`
+
+If set provided and set to `true`, all backups will be compressed using gzip.
+
 ## Building from source
 
 This project uses go modules, so you'll need at least go 1.11 to compile it.

config.go

@@ -18,6 +18,7 @@ type conf struct {
 	Schedule              string
 	MaxBackups            int
 	CompletionWebhookURL  string
+	CompressBackups       bool
 }
 
 var (
@@ -30,6 +31,7 @@ const (
 	envSchedule             = `BACKUP_SCHEDULE`
 	envMax                  = `BACKUP_MAX`
 	envCompletionWebhookURL = `BACKUP_COMPLETION_WEBHOOK_URL`
+	envCompressBackups      = `BACKUP_COMPRESS`
 )
 
 func init() {
@@ -66,6 +68,11 @@ func init() {
 	if has {
 		config.CompletionWebhookURL = webhookURL
 	}
+
+	compress, has := os.LookupEnv(envCompressBackups)
+	if has {
+		config.CompressBackups = compress == "1" || compress == "true"
+	}
 }
 
 func updateFullBackupPath() {

dump_mysql.go

@@ -63,5 +63,5 @@ func (m *MysqlDumper) Dump(c *client.Client) error {
 
 	args := m.buildDumpArgs()
 
-	return runAndSaveCommandInContainer(getDumpFilename(m.Container.Name), c, m.Container, "mysqldump", args...)
+	return runAndSaveCommandInContainer(c, m.Container, "mysqldump", args...)
 }

dump_postgres.go

@@ -26,5 +26,5 @@ func (d *PostgresDumper) Dump(c *client.Client) error {
 		user = u
 	}
 
-	return runAndSaveCommandInContainer(getDumpFilename(d.Container.Name), c, d.Container, "pg_dumpall", "-U", user)
+	return runAndSaveCommandInContainer(c, d.Container, "pg_dumpall", "-U", user)
 }

go.mod

@@ -1,15 +1,31 @@
 module kolaente.dev/konrad/docker-db-backup
 
-go 1.16
+go 1.21
 
 require (
-	github.com/containerd/containerd v1.5.5 // indirect
 	github.com/docker/docker v20.10.8+incompatible
+	github.com/robfig/cron/v3 v3.0.1
+)
+
+require (
+	github.com/Microsoft/go-winio v0.4.17 // indirect
+	github.com/containerd/containerd v1.5.5 // indirect
+	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
+	github.com/docker/go-units v0.4.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.0 // indirect
 	github.com/gorilla/mux v1.8.0 // indirect
 	github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
-	github.com/robfig/cron/v3 v3.0.1
+	github.com/opencontainers/go-digest v1.0.0 // indirect
+	github.com/opencontainers/image-spec v1.0.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/sirupsen/logrus v1.8.1 // indirect
+	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
+	golang.org/x/sys v0.0.0-20210616094352-59db8d763f22 // indirect
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
+	google.golang.org/genproto v0.0.0-20201110150050-8816d57aaa9a // indirect
 	google.golang.org/grpc v1.40.0 // indirect
+	google.golang.org/protobuf v1.26.0 // indirect
 )

save.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"compress/gzip"
 	"context"
 	"fmt"
 	"io"
@@ -10,16 +11,21 @@ import (
 	"github.com/docker/docker/client"
 )
 
-func runAndSaveCommandInContainer(filename string, c *client.Client, container *types.ContainerJSON, command string, args ...string) error {
+func runAndSaveCommandInContainer(c *client.Client, container *types.ContainerJSON, command string, args ...string) error {
 	ctx := context.Background()
 
-	config := types.ExecConfig{
+	filename := getDumpFilename(container.Name)
+	if config.CompressBackups {
+		filename += ".gz"
+	}
+
+	containerConfig := types.ExecConfig{
 		AttachStderr: true,
 		AttachStdout: true,
 		Cmd:          append([]string{command}, args...),
 	}
 
-	r, err := c.ContainerExecCreate(ctx, container.ID, config)
+	r, err := c.ContainerExecCreate(ctx, container.ID, containerConfig)
 	if err != nil {
 		return err
 	}
@@ -36,7 +42,18 @@ func runAndSaveCommandInContainer(filename string, c *client.Client, container *
 	}
 	defer f.Close()
 
-	_, err = io.Copy(f, resp.Reader)
+	var target io.Writer = f
+
+	if config.CompressBackups {
+		gw, err := gzip.NewWriterLevel(f, gzip.BestCompression)
+		if err != nil {
+			return err
+		}
+		defer gw.Close()
+		target = gw
+	}
+
+	_, err = io.Copy(target, resp.Reader)
 	if err != nil {
 		return err
 	}