Consolidate config value resolution at top level (#705)

* Consolidate env expansion at top level

* Move handling of deprecated config into resolve method

* Handle template interpolation in resolve method

* Clean up and document resolve function

cmd/backup/config.go

@@ -4,12 +4,15 @@
 package main
 
 import (
+	"bytes"
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
 	"os"
 	"regexp"
 	"strconv"
+	"strings"
+	"text/template"
 	"time"
 
 	"github.com/offen/docker-volume-backup/internal/errwrap"
@@ -225,3 +228,92 @@ func (c *Config) applyEnv() (func() error, error) {
 	}
 	return unset, nil
 }
+
+// resolve is responsible for performing all implicit logic that transforms a configuration object
+// into what is actually being used at runtime. E.g. environment variables are expanded or
+// deprecated config options are transposed into their up to date successors. The caller is
+// responsible for calling the returned reset function after usage of the config is done.
+func (c *Config) resolve() (reset func() error, warnings []string, err error) {
+	reset, aErr := c.applyEnv()
+	if aErr != nil {
+		err = errwrap.Wrap(aErr, "error applying env")
+		return
+	}
+
+	if c.BackupFilenameExpand {
+		c.BackupFilename = os.ExpandEnv(c.BackupFilename)
+		c.BackupLatestSymlink = os.ExpandEnv(c.BackupLatestSymlink)
+		c.BackupPruningPrefix = os.ExpandEnv(c.BackupPruningPrefix)
+	}
+
+	if c.EmailNotificationRecipient != "" {
+		emailURL := fmt.Sprintf(
+			"smtp://%s:%s@%s:%d/?from=%s&to=%s",
+			c.EmailSMTPUsername,
+			c.EmailSMTPPassword,
+			c.EmailSMTPHost,
+			c.EmailSMTPPort,
+			c.EmailNotificationSender,
+			c.EmailNotificationRecipient,
+		)
+		c.NotificationURLs = append(c.NotificationURLs, emailURL)
+		warnings = append(warnings,
+			"Using EMAIL_* keys for providing notification configuration has been deprecated and will be removed in the next major version.",
+			"Please use NOTIFICATION_URLS instead. Refer to the README for an upgrade guide.",
+		)
+	}
+
+	if c.BackupFromSnapshot {
+		warnings = append(warnings,
+			"Using BACKUP_FROM_SNAPSHOT has been deprecated and will be removed in the next major version.",
+			"Please use `archive-pre` and `archive-post` commands to prepare your backup sources. Refer to the documentation for an upgrade guide.",
+		)
+	}
+
+	if c.BackupStopDuringBackupLabel != "" && c.BackupStopContainerLabel != "" {
+		err = errwrap.Wrap(nil, "both BACKUP_STOP_DURING_BACKUP_LABEL and BACKUP_STOP_CONTAINER_LABEL have been set, cannot continue")
+		return
+	}
+	if c.BackupStopContainerLabel != "" {
+		warnings = append(warnings,
+			"Using BACKUP_STOP_CONTAINER_LABEL has been deprecated and will be removed in the next major version.",
+			"Please use BACKUP_STOP_DURING_BACKUP_LABEL instead. Refer to the docs for an upgrade guide.",
+		)
+		c.BackupStopDuringBackupLabel = c.BackupStopContainerLabel
+	}
+
+	tmplFileName, tErr := template.New("extension").Parse(c.BackupFilename)
+	if tErr != nil {
+		err = errwrap.Wrap(tErr, "unable to parse backup file extension template")
+		return
+	}
+
+	var bf bytes.Buffer
+	if tErr := tmplFileName.Execute(&bf, map[string]string{
+		"Extension": func() string {
+			if c.BackupCompression == "none" {
+				return "tar"
+			}
+			return fmt.Sprintf("tar.%s", c.BackupCompression)
+		}(),
+	}); tErr != nil {
+		err = errwrap.Wrap(tErr, "error executing backup file extension template")
+		return
+	}
+	c.BackupFilename = bf.String()
+
+	if c.AzureStorageEndpoint != "" {
+		endpointTemplate, tErr := template.New("endpoint").Parse(c.AzureStorageEndpoint)
+		if tErr != nil {
+			err = errwrap.Wrap(tErr, "error parsing endpoint template")
+			return
+		}
+		var ep bytes.Buffer
+		if tErr := endpointTemplate.Execute(&ep, map[string]string{"AccountName": c.AzureStorageAccountName}); tErr != nil {
+			err = errwrap.Wrap(tErr, "error executing endpoint template")
+			return
+		}
+		c.AzureStorageEndpoint = fmt.Sprintf("%s/", strings.TrimSuffix(ep.String(), "/"))
+	}
+	return
+}

cmd/backup/create_archive.go

@@ -18,12 +18,6 @@ func (s *script) createArchive() error {
 	backupSources := s.c.BackupSources
 
 	if s.c.BackupFromSnapshot {
-		s.logger.Warn(
-			"Using BACKUP_FROM_SNAPSHOT has been deprecated and will be removed in the next major version.",
-		)
-		s.logger.Warn(
-			"Please use `archive-pre` and `archive-post` commands to prepare your backup sources. Refer to the documentation for an upgrade guide.",
-		)
 		backupSources = filepath.Join("/tmp", s.c.BackupSources)
 		// copy before compressing guard against a situation where backup folder's content are still growing.
 		s.registerHook(hookLevelPlumbing, func(error) error {

cmd/backup/run_script.go

@@ -43,7 +43,7 @@ func runScript(c *Config) (err error) {
 		}
 	}()
 
-	unset, err := s.c.applyEnv()
+	unset, warnings, err := s.c.resolve()
 	if err != nil {
 		return errwrap.Wrap(err, "error applying env")
 	}
@@ -52,6 +52,9 @@ func runScript(c *Config) (err error) {
 			err = errors.Join(err, errwrap.Wrap(derr, "error unsetting environment variables"))
 		}
 	}()
+	for _, w := range warnings {
+		s.logger.Warn(w)
+	}
 
 	if s.c != nil && s.c.BackupJitter > 0 {
 		max := s.c.BackupJitter

cmd/backup/script.go

@@ -4,7 +4,6 @@
 package main
 
 import (
-	"bytes"
 	"fmt"
 	"log/slog"
 	"os"
@@ -79,24 +78,6 @@ func (s *script) init() error {
 		return nil
 	})
 	// Register notifications first so they can fire in case of other init errors.
-	if s.c.EmailNotificationRecipient != "" {
-		emailURL := fmt.Sprintf(
-			"smtp://%s:%s@%s:%d/?from=%s&to=%s",
-			s.c.EmailSMTPUsername,
-			s.c.EmailSMTPPassword,
-			s.c.EmailSMTPHost,
-			s.c.EmailSMTPPort,
-			s.c.EmailNotificationSender,
-			s.c.EmailNotificationRecipient,
-		)
-		s.c.NotificationURLs = append(s.c.NotificationURLs, emailURL)
-		s.logger.Warn(
-			"Using EMAIL_* keys for providing notification configuration has been deprecated and will be removed in the next major version.",
-		)
-		s.logger.Warn(
-			"Please use NOTIFICATION_URLS instead. Refer to the README for an upgrade guide.",
-		)
-	}
 
 	hookLevel, ok := hookLevels[s.c.NotificationLevel]
 	if !ok {
@@ -143,30 +124,6 @@ func (s *script) init() error {
 	}
 
 	s.file = path.Join("/tmp", s.c.BackupFilename)
-
-	tmplFileName, tErr := template.New("extension").Parse(s.file)
-	if tErr != nil {
-		return errwrap.Wrap(tErr, "unable to parse backup file extension template")
-	}
-
-	var bf bytes.Buffer
-	if tErr := tmplFileName.Execute(&bf, map[string]string{
-		"Extension": func() string {
-			if s.c.BackupCompression == "none" {
-				return "tar"
-			}
-			return fmt.Sprintf("tar.%s", s.c.BackupCompression)
-		}(),
-	}); tErr != nil {
-		return errwrap.Wrap(tErr, "error executing backup file extension template")
-	}
-	s.file = bf.String()
-
-	if s.c.BackupFilenameExpand {
-		s.file = os.ExpandEnv(s.file)
-		s.c.BackupLatestSymlink = os.ExpandEnv(s.c.BackupLatestSymlink)
-		s.c.BackupPruningPrefix = os.ExpandEnv(s.c.BackupPruningPrefix)
-	}
 	s.file = timeutil.Strftime(&s.stats.StartTime, s.file)
 
 	_, err := os.Stat("/var/run/docker.sock")

cmd/backup/stop_restart.go

@@ -8,7 +8,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
 	"sync"
 	"time"
 
@@ -113,23 +112,9 @@ func (s *script) stopContainersAndServices() (func() error, error) {
 		return noop, errwrap.Wrap(err, "error determining swarm state")
 	}
 
-	labelValue := s.c.BackupStopDuringBackupLabel
-	if s.c.BackupStopContainerLabel != "" {
-		s.logger.Warn(
-			"Using BACKUP_STOP_CONTAINER_LABEL has been deprecated and will be removed in the next major version.",
-		)
-		s.logger.Warn(
-			"Please use BACKUP_STOP_DURING_BACKUP_LABEL instead. Refer to the docs for an upgrade guide.",
-		)
-		if _, ok := os.LookupEnv("BACKUP_STOP_DURING_BACKUP_LABEL"); ok {
-			return noop, errwrap.Wrap(nil, "both BACKUP_STOP_DURING_BACKUP_LABEL and BACKUP_STOP_CONTAINER_LABEL have been set, cannot continue")
-		}
-		labelValue = s.c.BackupStopContainerLabel
-	}
-
 	stopDuringBackupLabel := fmt.Sprintf(
 		"docker-volume-backup.stop-during-backup=%s",
-		labelValue,
+		s.c.BackupStopDuringBackupLabel,
 	)
 
 	stopDuringBackupNoRestartLabel := fmt.Sprintf(
@@ -144,7 +129,7 @@ func (s *script) stopContainersAndServices() (func() error, error) {
 
 	var containersToStop []handledContainer
 	for _, c := range allContainers.Items {
-		hasStopDuringBackupLabel, hasStopDuringBackupNoRestartLabel, err := checkStopLabels(c.Labels, labelValue, s.c.BackupStopDuringBackupNoRestartLabel)
+		hasStopDuringBackupLabel, hasStopDuringBackupNoRestartLabel, err := checkStopLabels(c.Labels, s.c.BackupStopDuringBackupLabel, s.c.BackupStopDuringBackupNoRestartLabel)
 		if err != nil {
 			return noop, errwrap.Wrap(err, "error querying for containers to stop")
 		}
@@ -169,7 +154,7 @@ func (s *script) stopContainersAndServices() (func() error, error) {
 		}
 
 		for _, service := range allServices {
-			hasStopDuringBackupLabel, hasStopDuringBackupNoRestartLabel, err := checkStopLabels(service.Spec.Labels, labelValue, s.c.BackupStopDuringBackupNoRestartLabel)
+			hasStopDuringBackupLabel, hasStopDuringBackupNoRestartLabel, err := checkStopLabels(service.Spec.Labels, s.c.BackupStopDuringBackupLabel, s.c.BackupStopDuringBackupNoRestartLabel)
 			if err != nil {
 				return noop, errwrap.Wrap(err, "error querying for services to scale down")
 			}

internal/storage/azure/azure.go

@@ -4,16 +4,13 @@
 package azure
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"os"
 	"path"
 	"path/filepath"
-	"strings"
 	"sync"
-	"text/template"
 	"time"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
@@ -49,16 +46,6 @@ func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error
 		return nil, errwrap.Wrap(nil, "using primary account key and connection string are mutually exclusive")
 	}
 
-	endpointTemplate, err := template.New("endpoint").Parse(opts.Endpoint)
-	if err != nil {
-		return nil, errwrap.Wrap(err, "error parsing endpoint template")
-	}
-	var ep bytes.Buffer
-	if err := endpointTemplate.Execute(&ep, opts); err != nil {
-		return nil, errwrap.Wrap(err, "error executing endpoint template")
-	}
-	normalizedEndpoint := fmt.Sprintf("%s/", strings.TrimSuffix(ep.String(), "/"))
-
 	var client *azblob.Client
 	if opts.PrimaryAccountKey != "" {
 		cred, err := azblob.NewSharedKeyCredential(opts.AccountName, opts.PrimaryAccountKey)
@@ -66,11 +53,12 @@ func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error
 			return nil, errwrap.Wrap(err, "error creating shared key Azure credential")
 		}
 
-		client, err = azblob.NewClientWithSharedKeyCredential(normalizedEndpoint, cred, nil)
+		client, err = azblob.NewClientWithSharedKeyCredential(opts.Endpoint, cred, nil)
 		if err != nil {
 			return nil, errwrap.Wrap(err, "error creating azure client from primary account key")
 		}
 	} else if opts.ConnectionString != "" {
+		var err error
 		client, err = azblob.NewClientFromConnectionString(opts.ConnectionString, nil)
 		if err != nil {
 			return nil, errwrap.Wrap(err, "error creating azure client from connection string")
@@ -80,7 +68,7 @@ func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error
 		if err != nil {
 			return nil, errwrap.Wrap(err, "error creating managed identity credential")
 		}
-		client, err = azblob.NewClient(normalizedEndpoint, cred, nil)
+		client, err = azblob.NewClient(opts.Endpoint, cred, nil)
 		if err != nil {
 			return nil, errwrap.Wrap(err, "error creating azure client from managed identity")
 		}