Support --pull for build/publish commands

The --pull flag is supported by Docker and forces a pull
attempt to be made for base images for the case that there
is a newer version available.

The main use-case for this is when teams are publishing
production or internal images directly from their own machines
which accumulate older images.

This is not needed in CI pipelines which start with an empty
library, so always pull the base images fresh from source.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

Author: alexellis

builder/build.go

@@ -30,7 +30,7 @@ const AdditionalPackageBuildArg = "ADDITIONAL_PACKAGE"
 
 // BuildImage construct Docker image from function parameters
 // TODO: refactor signature to a struct to simplify the length of the method header
-func BuildImage(image string, handler string, functionName string, language string, nocache bool, squash bool, shrinkwrap bool, buildArgMap map[string]string, buildOptions []string, tagFormat schema.BuildFormat, buildLabelMap map[string]string, quietBuild bool, copyExtraPaths []string, remoteBuilder, payloadSecretPath string) error {
+func BuildImage(image string, handler string, functionName string, language string, nocache bool, squash bool, shrinkwrap bool, buildArgMap map[string]string, buildOptions []string, tagFormat schema.BuildFormat, buildLabelMap map[string]string, quietBuild bool, copyExtraPaths []string, remoteBuilder, payloadSecretPath string, forcePull bool) error {
 
 	if stack.IsValidTemplate(language) {
 		pathToTemplateYAML := fmt.Sprintf("./template/%s/template.yml", language)
@@ -127,6 +127,7 @@ func BuildImage(image string, handler string, functionName string, language stri
 				BuildArgMap:      buildArgMap,
 				BuildOptPackages: buildOptPackages,
 				BuildLabelMap:    buildLabelMap,
+				ForcePull:        forcePull,
 			}
 
 			command, args := getDockerBuildCommand(dockerBuildVal)
@@ -135,6 +136,7 @@ func BuildImage(image string, handler string, functionName string, language stri
 			if mountSSH {
 				envs = append(envs, "DOCKER_BUILDKIT=1")
 			}
+			log.Printf("Build flags: %+v\n", args)
 
 			task := v2execute.ExecTask{
 				Cwd:         tempPath,
@@ -260,7 +262,7 @@ func hashFolder(contextPath string) (string, error) {
 }
 
 func getDockerBuildCommand(build dockerBuild) (string, []string) {
-	flagSlice := buildFlagSlice(build.NoCache, build.Squash, build.HTTPProxy, build.HTTPSProxy, build.BuildArgMap, build.BuildOptPackages, build.BuildLabelMap)
+	flagSlice := buildFlagSlice(build.NoCache, build.Squash, build.HTTPProxy, build.HTTPSProxy, build.BuildArgMap, build.BuildOptPackages, build.BuildLabelMap, build.ForcePull)
 	args := []string{"build"}
 	args = append(args, flagSlice...)
 
@@ -287,6 +289,8 @@ type dockerBuild struct {
 
 	// ExtraTags for published images like :latest
 	ExtraTags []string
+
+	ForcePull bool
 }
 
 var defaultDirPermissions os.FileMode = 0700
@@ -409,7 +413,7 @@ func pathInScope(path string, scope string) (string, error) {
 	return "", fmt.Errorf("forbidden path appears to be outside of the build context: %s (%s)", path, abs)
 }
 
-func buildFlagSlice(nocache bool, squash bool, httpProxy string, httpsProxy string, buildArgMap map[string]string, buildOptionPackages []string, buildLabelMap map[string]string) []string {
+func buildFlagSlice(nocache bool, squash bool, httpProxy string, httpsProxy string, buildArgMap map[string]string, buildOptionPackages []string, buildLabelMap map[string]string, forcePull bool) []string {
 
 	var spaceSafeBuildFlags []string
 
@@ -445,6 +449,10 @@ func buildFlagSlice(nocache bool, squash bool, httpProxy string, httpsProxy stri
 		spaceSafeBuildFlags = append(spaceSafeBuildFlags, "--label", fmt.Sprintf("%s=%s", k, v))
 	}
 
+	if forcePull {
+		spaceSafeBuildFlags = append(spaceSafeBuildFlags, "--pull")
+	}
+
 	return spaceSafeBuildFlags
 }
 

builder/build_test.go

@@ -302,7 +302,8 @@ func Test_buildFlagSlice(t *testing.T) {
 
 		t.Run(test.title, func(t *testing.T) {
 
-			flagSlice := buildFlagSlice(test.nocache, test.squash, test.httpProxy, test.httpsProxy, test.buildArgMap, test.buildPackages, test.buildLabelMap)
+			forcePull := false
+			flagSlice := buildFlagSlice(test.nocache, test.squash, test.httpProxy, test.httpsProxy, test.buildArgMap, test.buildPackages, test.buildLabelMap, forcePull)
 			fmt.Println(flagSlice)
 			if len(flagSlice) != len(test.expectedSlice) {
 				t.Errorf("Slices differ in size - wanted: %d, found %d", len(test.expectedSlice), len(flagSlice))

builder/publish.go

@@ -44,7 +44,7 @@ const BuilderConfigFilename = "com.openfaas.docker.config"
 // PublishImage will publish images as multi-arch
 // TODO: refactor signature to a struct to simplify the length of the method header
 func PublishImage(image string, handler string, functionName string, language string, nocache bool, squash bool, shrinkwrap bool, buildArgMap map[string]string,
-	buildOptions []string, tagMode schema.BuildFormat, buildLabelMap map[string]string, quietBuild bool, copyExtraPaths []string, platforms string, extraTags []string, remoteBuilder, payloadSecretPath string) error {
+	buildOptions []string, tagMode schema.BuildFormat, buildLabelMap map[string]string, quietBuild bool, copyExtraPaths []string, platforms string, extraTags []string, remoteBuilder, payloadSecretPath string, forcePull bool) error {
 
 	if stack.IsValidTemplate(language) {
 		pathToTemplateYAML := fmt.Sprintf("./template/%s/template.yml", language)
@@ -81,6 +81,11 @@ func PublishImage(image string, handler string, functionName string, language st
 		fmt.Printf("Building: %s with %s template. Please wait..\n", imageName, language)
 
 		if remoteBuilder != "" {
+
+			if forcePull {
+				return fmt.Errorf("--pull is not supported with --remote-builder")
+			}
+
 			tempDir, err := os.MkdirTemp(os.TempDir(), "builder-*")
 			if err != nil {
 				return fmt.Errorf("failed to create temporary directory for %s, error: %w", functionName, err)
@@ -139,6 +144,7 @@ func PublishImage(image string, handler string, functionName string, language st
 				BuildLabelMap:    buildLabelMap,
 				Platforms:        platforms,
 				ExtraTags:        extraTags,
+				ForcePull:        forcePull,
 			}
 
 			command, args := getDockerBuildxCommand(dockerBuildVal)
@@ -173,7 +179,7 @@ func PublishImage(image string, handler string, functionName string, language st
 
 func getDockerBuildxCommand(build dockerBuild) (string, []string) {
 	flagSlice := buildFlagSlice(build.NoCache, build.Squash, build.HTTPProxy, build.HTTPSProxy, build.BuildArgMap,
-		build.BuildOptPackages, build.BuildLabelMap)
+		build.BuildOptPackages, build.BuildLabelMap, build.ForcePull)
 
 	// pushOnly defined at https://github.com/docker/buildx
 	const pushOnly = "--output=type=registry,push=true"

commands/build.go

@@ -37,6 +37,7 @@ var (
 	envsubst         bool
 	quietBuild       bool
 	disableStackPull bool
+	forcePull        bool
 )
 
 func init() {
@@ -59,6 +60,7 @@ func init() {
 	buildCmd.Flags().BoolVar(&envsubst, "envsubst", true, "Substitute environment variables in stack.yml file")
 	buildCmd.Flags().BoolVar(&quietBuild, "quiet", false, "Perform a quiet build, without showing output from Docker")
 	buildCmd.Flags().BoolVar(&disableStackPull, "disable-stack-pull", false, "Disables the template configuration in the stack.yml")
+	buildCmd.Flags().BoolVar(&forcePull, "pull", false, "Force a re-pull of base images in template during build, useful for publishing images")
 
 	// Set bash-completion.
 	_ = buildCmd.Flags().SetAnnotation("handler", cobra.BashCompSubdirsInDir, []string{})
@@ -80,7 +82,8 @@ var buildCmd = &cobra.Command{
                  [--build-arg KEY=VALUE]
                  [--build-option VALUE]
                  [--copy-extra PATH]
-                 [--tag <sha|branch|describe>]`,
+                 [--tag <sha|branch|describe>]
+				 [--forcePull]`,
 	Short: "Builds OpenFaaS function containers",
 	Long: `Builds OpenFaaS function containers either via the supplied YAML config using
 the "--yaml" flag (which may contain multiple function definitions), or directly
@@ -207,6 +210,7 @@ func runBuild(cmd *cobra.Command, args []string) error {
 			copyExtra,
 			remoteBuilder,
 			payloadSecretPath,
+			forcePull,
 		); err != nil {
 			return err
 		}
@@ -263,6 +267,7 @@ func build(services *stack.Services, queueDepth int, shrinkwrap, quietBuild bool
 						combinedExtraPaths,
 						remoteBuilder,
 						payloadSecretPath,
+						forcePull,
 					)
 
 					if err != nil {

commands/publish.go

@@ -52,6 +52,7 @@ func init() {
 	publishCmd.Flags().BoolVar(&resetQemu, "reset-qemu", false, "Runs \"docker run multiarch/qemu-user-static --reset -p yes\" to enable multi-arch builds. Compatible with AMD64 machines only.")
 	publishCmd.Flags().StringVar(&remoteBuilder, "remote-builder", "", "URL to the builder")
 	publishCmd.Flags().StringVar(&payloadSecretPath, "payload-secret", "", "Path to payload secret file")
+	publishCmd.Flags().BoolVar(&forcePull, "pull", false, "Force a re-pull of base images in template during build, useful for publishing images")
 
 	// Set bash-completion.
 	_ = publishCmd.Flags().SetAnnotation("handler", cobra.BashCompSubdirsInDir, []string{})
@@ -257,6 +258,7 @@ func publish(services *stack.Services, queueDepth int, shrinkwrap, quietBuild, m
 						extraTags,
 						remoteBuilder,
 						payloadSecretPath,
+						forcePull,
 					)
 
 					if err != nil {