add support for build-arg files

Signed-off-by: Avi Deitcher <avi@deitcher.net>

src/cmd/linuxkit/pkg_build.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bufio"
 	"errors"
 	"fmt"
 	"os"
@@ -46,6 +47,7 @@ func addCmdRunPkgBuildPush(cmd *cobra.Command, withPush bool) *cobra.Command {
 		cacheDir       = flagOverEnvVarOverDefaultString{def: defaultLinuxkitCache(), envVar: envVarCacheDir}
 		sbomScanner    string
 		dockerfile     string
+		buildArgFiles  []string
 	)
 
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
@@ -95,6 +97,24 @@ func addCmdRunPkgBuildPush(cmd *cobra.Command, withPush bool) *cobra.Command {
 		}
 		opts = append(opts, pkglib.WithDockerfile(dockerfile))
 
+		// read any build arg files
+		var buildArgs []string
+		for _, filename := range buildArgFiles {
+			f, err := os.Open(filename)
+			if err != nil {
+				return fmt.Errorf("error opening build args file %s: %w", filename, err)
+			}
+			defer f.Close()
+			scanner := bufio.NewScanner(f)
+			for scanner.Scan() {
+				buildArgs = append(buildArgs, scanner.Text())
+			}
+			if err := scanner.Err(); err != nil {
+				return fmt.Errorf("error reading build args file %s: %w", filename, err)
+			}
+		}
+		opts = append(opts, pkglib.WithBuildArgs(buildArgs))
+
 		// skipPlatformsMap contains platforms that should be skipped
 		skipPlatformsMap := make(map[string]bool)
 		if skipPlatforms != "" {
@@ -205,6 +225,7 @@ func addCmdRunPkgBuildPush(cmd *cobra.Command, withPush bool) *cobra.Command {
 	cmd.Flags().BoolVar(&manifest, "manifest", true, "Create and push multi-arch manifest")
 	cmd.Flags().StringVar(&sbomScanner, "sbom-scanner", "", "SBOM scanner to use, must match the buildkit spec; set to blank to use the buildkit default; set to 'false' for no scanning")
 	cmd.Flags().StringVar(&dockerfile, "dockerfile", "", "Dockerfile to use for building the image, must be in this directory or below, overrides what is in build.yml")
+	cmd.Flags().StringArrayVar(&buildArgFiles, "build-arg-file", nil, "Files containing build arguments, one key=value per line, contents augment and override buildArgs in build.yml. Can be specified multiple times. File is relative to working directory when running `linuxkit pkg build`")
 
 	return cmd
 }

src/cmd/linuxkit/pkglib/build.go

@@ -44,6 +44,7 @@ type buildOpts struct {
 	sbomScan         bool
 	sbomScannerImage string
 	dockerfile       string
+	buildArgs        []string
 }
 
 // BuildOpt allows callers to specify options to Build
@@ -195,6 +196,16 @@ func WithDockerfile(dockerfile string) BuildOpt {
 	}
 }
 
+// WithBuildArgs add build args to use when building the package
+func WithBuildArgs(args []string) BuildOpt {
+	return func(bo *buildOpts) error {
+		// we copy the contents, rather than the reference to the slice, to be safe
+		bo.buildArgs = make([]string, len(args))
+		copy(bo.buildArgs, args)
+		return nil
+	}
+}
+
 // Build builds the package
 func (p Pkg) Build(bos ...BuildOpt) error {
 	var bo buildOpts
@@ -380,6 +391,7 @@ func (p Pkg) Build(bos ...BuildOpt) error {
 		imageBuildOpts.Labels["org.mobyproject.linuxkit.version"] = version.Version
 		imageBuildOpts.Labels["org.mobyproject.linuxkit.revision"] = version.GitCommit
 
+		// add build args from the build.yml file
 		if p.buildArgs != nil {
 			for _, buildArg := range *p.buildArgs {
 				parts := strings.SplitN(buildArg, "=", 2)
@@ -389,6 +401,15 @@ func (p Pkg) Build(bos ...BuildOpt) error {
 				imageBuildOpts.BuildArgs[parts[0]] = &parts[1]
 			}
 		}
+		// add build args from other files
+		for _, buildArg := range bo.buildArgs {
+			parts := strings.SplitN(buildArg, "=", 2)
+			if len(parts) != 2 {
+				return fmt.Errorf("invalid build-arg, must be in format 'arg=value': %s", buildArg)
+			}
+			imageBuildOpts.BuildArgs[parts[0]] = &parts[1]
+		}
+
 		// add in information about the build process that might be useful
 		if _, ok := imageBuildOpts.BuildArgs["SOURCE"]; !ok && p.gitRepo != "" {
 			imageBuildOpts.BuildArgs["SOURCE"] = &p.gitRepo

src/cmd/linuxkit/pkglib/docker.go

@@ -473,10 +473,11 @@ func (dr *dockerRunnerImpl) build(ctx context.Context, tag, pkg, dockerfile, doc
 		solveOpts.Session = append(solveOpts.Session, up)
 	} else {
 		solveOpts.LocalDirs = map[string]string{
-			builder.DefaultLocalNameDockerfile: path.Join(pkg, dockerfile),
+			builder.DefaultLocalNameDockerfile: pkg,
 			builder.DefaultLocalNameContext:    pkg,
 		}
 	}
+	frontendAttrs["filename"] = dockerfile
 
 	// go through the dockerfile to see if we have any provided images cached
 	if c != nil {

test/cases/000_build/056_build_args/000_build_arg_yaml/Dockerfile

@@ -0,0 +1,2 @@
+ARG IMAGE
+FROM ${IMAGE}

test/cases/000_build/056_build_args/000_build_arg_yaml/build.yml

@@ -0,0 +1,4 @@
+org: linuxkit
+image: image-in-build-args
+buildArgs:
+- IMAGE=alpine:3.19

test/cases/000_build/056_build_args/000_build_arg_yaml/test.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# SUMMARY: Check that tar output format build is reproducible
+# LABELS:
+
+set -e
+
+# Source libraries. Uncomment if needed/defined
+#. "${RT_LIB}"
+. "${RT_PROJECT_ROOT}/_lib/lib.sh"
+
+linuxkit pkg build --force .
+
+exit 0

test/cases/000_build/056_build_args/001_build_arg_cli/Dockerfile

@@ -0,0 +1,2 @@
+ARG IMAGE
+FROM ${IMAGE}

test/cases/000_build/056_build_args/001_build_arg_cli/build-args

@@ -0,0 +1 @@
+IMAGE=alpine:3.19

test/cases/000_build/056_build_args/001_build_arg_cli/build.yml

@@ -0,0 +1,2 @@
+org: linuxkit
+image: test-image-in-yaml-build-args

test/cases/000_build/056_build_args/001_build_arg_cli/test.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# SUMMARY: Check that tar output format build is reproducible
+# LABELS:
+
+set -e
+
+# Source libraries. Uncomment if needed/defined
+#. "${RT_LIB}"
+. "${RT_PROJECT_ROOT}/_lib/lib.sh"
+
+linuxkit pkg build --force --build-arg-file build-args .
+
+exit 0

test/cases/000_build/056_build_args/002_build_arg_cli_over_yaml/Dockerfile

@@ -0,0 +1,2 @@
+ARG IMAGE
+FROM ${IMAGE}

test/cases/000_build/056_build_args/002_build_arg_cli_over_yaml/build-args

@@ -0,0 +1 @@
+IMAGE=alpine:3.19

test/cases/000_build/056_build_args/002_build_arg_cli_over_yaml/build.yml

@@ -0,0 +1,4 @@
+org: linuxkit
+image: test-image-in-yaml-build-args-with-cli-override
+buildArgs:
+- IMAGE=non-existent:foo

test/cases/000_build/056_build_args/002_build_arg_cli_over_yaml/test.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# SUMMARY: Check that tar output format build is reproducible
+# LABELS:
+
+set -e
+
+# Source libraries. Uncomment if needed/defined
+#. "${RT_LIB}"
+. "${RT_PROJECT_ROOT}/_lib/lib.sh"
+
+linuxkit pkg build --force --build-arg-file build-args .
+
+exit 0