feat(update): make image pruning mode configurable

Add pacman.prune_unused_images configuration key and
GetImagePruningFlag() helper to control pruning behavior
during update completion.

By default, only application images are pruned. When the
flag is enabled, all unused images are pruned instead.

Apply the selected prune mode consistently across retry
attempts in completeUpdate().

Signed-off-by: Mike Sul <mike.sul@foundries.io>

Author: mike-sul

pkg/config/config.go

@@ -41,14 +41,15 @@ type (
 )
 
 const (
-	TagKey                = "pacman.tags"
-	ServerBaseUrlKey      = "tls.server"
-	StorageDirKey         = "storage.path"
-	StorageDBPathKey      = "storage.sqldb_path"
-	HardwareIDKey         = "provision.primary_ecu_hardware_id"
-	StorageUsageWatermark = "pacman.storage_watermark" // in percentage of overall storage, the maximum allowed to be used by apps
-	ComposeAppsProxyKey   = "pacman.compose_apps_proxy"
-	ComposeAppsProxyCaKey = "import.tls_cacert_path"
+	TagKey                          = "pacman.tags"
+	ServerBaseUrlKey                = "tls.server"
+	StorageDirKey                   = "storage.path"
+	StorageDBPathKey                = "storage.sqldb_path"
+	HardwareIDKey                   = "provision.primary_ecu_hardware_id"
+	StorageUsageWatermark           = "pacman.storage_watermark" // in percentage of overall storage, the maximum allowed to be used by apps
+	ComposeAppsProxyKey             = "pacman.compose_apps_proxy"
+	ComposeAppsProxyCaKey           = "import.tls_cacert_path"
+	ComposeAppsPruneUnusedImagesKey = "pacman.prune_unused_images"
 
 	StorageDefaultDir               = "/var/sota"
 	StorageDefaultDBPath            = "sql.db"
@@ -194,6 +195,10 @@ func (c *Config) SetClientForProxy(client proxyHTTPClient) {
 	}
 }
 
+func (c *Config) GetImagePruningFlag() bool {
+	return c.tomlConfig.GetDefault(ComposeAppsPruneUnusedImagesKey, "0") == "1"
+}
+
 func newComposeConfig(config *sotatoml.AppConfig, proxyProvider compose.ProxyProvider) (*compose.Config, error) {
 	// TODO: set the defaults in cmd/fioup package instead of here
 	return v1.NewDefaultConfig(

pkg/state/start.go

@@ -57,13 +57,17 @@ func (s *Start) Execute(ctx context.Context, updateCtx *UpdateContext) error {
 
 func (u *UpdateContext) completeUpdate(ctx context.Context) {
 	var err error
-	// 1. First attempt with pruning
-	if err = u.UpdateRunner.Complete(ctx, update.CompleteWithPruning()); err == nil {
+	// 1. First attempt with app pruning, prune images based on the prune type configured by the user
+	imagePruneType := compose.PruneTypeOnlyAppImages
+	if u.Config.GetImagePruningFlag() {
+		imagePruneType = compose.PruneTypeAllUnusedImages
+	}
+	if err = u.UpdateRunner.Complete(ctx, update.CompleteWithPruning(imagePruneType)); err == nil {
 		return
 	}
 	slog.Debug("update completion with pruning failed; retrying", "error", err)
 	// 2. Second attempt with pruning
-	if err = u.UpdateRunner.Complete(ctx, update.CompleteWithPruning()); err == nil {
+	if err = u.UpdateRunner.Complete(ctx, update.CompleteWithPruning(imagePruneType)); err == nil {
 		return
 	}
 	slog.Error("update completion with pruning failed; trying without pruning", "error", err)