feat: Add global env

Supports configuring global `env` variables that will be applied to all builds.

Modifies the `builder` function to accept a `buildContext` structure. This will simplify similar modifications in the future.

Fixes #1305

Signed-off-by: Nathan Mittler <[email protected]>

docs/configuration.md

@@ -104,6 +104,31 @@ You can also use the `KO_DEFAULTPLATFORMS` environment variable to set the defau
 KO_DEFAULTPLATFORMS=linux/arm64,linux/amd64
 ```
 
+### Setting build environment variables
+
+By default, `ko` builds use the ambient environment from the system (i.e. `os.Environ()`).
+These values can be overridden globally or per-build (or both).
+
+```yaml
+env:
+- FOO=foo
+builds:
+- id: foo
+  dir: .
+  main: ./foobar/foo
+  env:
+  - FOO=bar # Overrides the global value.
+- id: bar
+  dir: ./bar
+  main: .
+```
+
+For a given build, the environment variables are merged in the following order:
+
+- System `os.Environ` (lowest precedence)
+- Global `env`
+- Build `env` (highest precedence)
+
 ### Environment Variables (advanced)
 
 For ease of use, backward compatibility and advanced use cases, `ko` supports the following environment variables to

pkg/build/gobuild.go

@@ -61,7 +61,16 @@ const (
 // GetBase takes an importpath and returns a base image reference and base image (or index).
 type GetBase func(context.Context, string) (name.Reference, Result, error)
 
-type builder func(context.Context, string, string, v1.Platform, Config) (string, error)
+// buildContext provides parameters for a builder function.
+type buildContext struct {
+	ip       string
+	dir      string
+	env      []string
+	platform v1.Platform
+	config   Config
+}
+
+type builder func(context.Context, buildContext) (string, error)
 
 type sbomber func(context.Context, string, string, string, oci.SignedEntity, string) ([]byte, types.MediaType, error)
 
@@ -81,6 +90,7 @@ type gobuild struct {
 	disableOptimizations bool
 	trimpath             bool
 	buildConfigs         map[string]Config
+	env                  []string
 	platformMatcher      *platformMatcher
 	dir                  string
 	labels               map[string]string
@@ -103,6 +113,7 @@ type gobuildOpener struct {
 	disableOptimizations bool
 	trimpath             bool
 	buildConfigs         map[string]Config
+	env                  []string
 	platforms            []string
 	labels               map[string]string
 	dir                  string
@@ -131,6 +142,7 @@ func (gbo *gobuildOpener) Open() (Interface, error) {
 		disableOptimizations: gbo.disableOptimizations,
 		trimpath:             gbo.trimpath,
 		buildConfigs:         gbo.buildConfigs,
+		env:                  gbo.env,
 		labels:               gbo.labels,
 		dir:                  gbo.dir,
 		platformMatcher:      matcher,
@@ -251,8 +263,8 @@ func getGoBinary() string {
 	return defaultGoBin
 }
 
-func build(ctx context.Context, ip string, dir string, platform v1.Platform, config Config) (string, error) {
-	buildArgs, err := createBuildArgs(config)
+func build(ctx context.Context, buildCtx buildContext) (string, error) {
+	buildArgs, err := createBuildArgs(buildCtx.config)
 	if err != nil {
 		return "", err
 	}
@@ -261,9 +273,9 @@ func build(ctx context.Context, ip string, dir string, platform v1.Platform, con
 	args = append(args, "build")
 	args = append(args, buildArgs...)
 
-	env, err := buildEnv(platform, os.Environ(), config.Env)
+	env, err := buildEnv(buildCtx.platform, os.Environ(), buildCtx.env, buildCtx.config.Env)
 	if err != nil {
-		return "", fmt.Errorf("could not create env for %s: %w", ip, err)
+		return "", fmt.Errorf("could not create env for %s: %w", buildCtx.ip, err)
 	}
 
 	tmpDir := ""
@@ -282,7 +294,7 @@ func build(ctx context.Context, ip string, dir string, platform v1.Platform, con
 		}
 
 		// TODO(#264): if KOCACHE is unset, default to filepath.Join(os.TempDir(), "ko").
-		tmpDir = filepath.Join(dir, "bin", ip, platform.String())
+		tmpDir = filepath.Join(dir, "bin", buildCtx.ip, buildCtx.platform.String())
 		if err := os.MkdirAll(tmpDir, os.ModePerm); err != nil {
 			return "", fmt.Errorf("creating KOCACHE bin dir: %w", err)
 		}
@@ -296,18 +308,18 @@ func build(ctx context.Context, ip string, dir string, platform v1.Platform, con
 	file := filepath.Join(tmpDir, "out")
 
 	args = append(args, "-o", file)
-	args = append(args, ip)
+	args = append(args, buildCtx.ip)
 
 	gobin := getGoBinary()
 	cmd := exec.CommandContext(ctx, gobin, args...)
-	cmd.Dir = dir
+	cmd.Dir = buildCtx.dir
 	cmd.Env = env
 
 	var output bytes.Buffer
 	cmd.Stderr = &output
 	cmd.Stdout = &output
 
-	log.Printf("Building %s for %s", ip, platform)
+	log.Printf("Building %s for %s", buildCtx.ip, buildCtx.platform)
 	if err := cmd.Run(); err != nil {
 		if os.Getenv("KOCACHE") == "" {
 			os.RemoveAll(tmpDir)
@@ -440,7 +452,7 @@ func cycloneDX() sbomber {
 // buildEnv creates the environment variables used by the `go build` command.
 // From `os/exec.Cmd`: If Env contains duplicate environment keys, only the last
 // value in the slice for each duplicate key is used.
-func buildEnv(platform v1.Platform, userEnv, configEnv []string) ([]string, error) {
+func buildEnv(platform v1.Platform, osEnv, globalEnv, configEnv []string) ([]string, error) {
 	// Default env
 	env := []string{
 		"CGO_ENABLED=0",
@@ -464,7 +476,8 @@ func buildEnv(platform v1.Platform, userEnv, configEnv []string) ([]string, erro
 		}
 	}
 
-	env = append(env, userEnv...)
+	env = append(env, osEnv...)
+	env = append(env, globalEnv...)
 	env = append(env, configEnv...)
 	return env, nil
 }
@@ -836,7 +849,13 @@ func (g *gobuild) buildOne(ctx context.Context, refStr string, base v1.Image, pl
 	}
 	// Do the build into a temporary file.
 	config := g.configForImportPath(ref.Path())
-	file, err := g.build(ctx, ref.Path(), g.dir, *platform, config)
+	file, err := g.build(ctx, buildContext{
+		ip:       ref.Path(),
+		dir:      g.dir,
+		env:      g.env,
+		platform: *platform,
+		config:   config,
+	})
 	if err != nil {
 		return nil, fmt.Errorf("build: %w", err)
 	}

pkg/build/gobuild_test.go

@@ -217,7 +217,8 @@ func TestBuildEnv(t *testing.T) {
 	tests := []struct {
 		description  string
 		platform     v1.Platform
-		userEnv      []string
+		osEnv        []string
+		globalEnv    []string
 		configEnv    []string
 		expectedEnvs map[string]string
 	}{{
@@ -233,13 +234,28 @@ func TestBuildEnv(t *testing.T) {
 		},
 	}, {
 		description: "override a default value",
+		osEnv:       []string{"CGO_ENABLED=0"},
+		configEnv:   []string{"CGO_ENABLED=1"},
+		expectedEnvs: map[string]string{
+			"CGO_ENABLED": "1",
+		},
+	}, {
+		description: "global override a default value",
+		osEnv:       []string{"CGO_ENABLED=0"},
+		globalEnv:   []string{"CGO_ENABLED=1"},
+		expectedEnvs: map[string]string{
+			"CGO_ENABLED": "1",
+		},
+	}, {
+		description: "override a global value",
+		globalEnv:   []string{"CGO_ENABLED=0"},
 		configEnv:   []string{"CGO_ENABLED=1"},
 		expectedEnvs: map[string]string{
 			"CGO_ENABLED": "1",
 		},
 	}, {
 		description: "override an envvar and add an envvar",
-		userEnv:     []string{"CGO_ENABLED=0"},
+		osEnv:       []string{"CGO_ENABLED=0"},
 		configEnv:   []string{"CGO_ENABLED=1", "GOPRIVATE=git.internal.example.com,source.developers.google.com"},
 		expectedEnvs: map[string]string{
 			"CGO_ENABLED": "1",
@@ -279,7 +295,7 @@ func TestBuildEnv(t *testing.T) {
 	}}
 	for _, test := range tests {
 		t.Run(test.description, func(t *testing.T) {
-			env, err := buildEnv(test.platform, test.userEnv, test.configEnv)
+			env, err := buildEnv(test.platform, test.osEnv, test.globalEnv, test.configEnv)
 			if err != nil {
 				t.Fatalf("unexpected error running buildEnv(): %v", err)
 			}
@@ -401,7 +417,7 @@ func fauxSBOM(context.Context, string, string, string, oci.SignedEntity, string)
 }
 
 // A helper method we use to substitute for the default "build" method.
-func writeTempFile(_ context.Context, s string, _ string, _ v1.Platform, _ Config) (string, error) {
+func writeTempFile(_ context.Context, buildCtx buildContext) (string, error) {
 	tmpDir, err := os.MkdirTemp("", "ko")
 	if err != nil {
 		return "", err
@@ -412,7 +428,7 @@ func writeTempFile(_ context.Context, s string, _ string, _ v1.Platform, _ Confi
 		return "", err
 	}
 	defer file.Close()
-	if _, err := file.WriteString(filepath.ToSlash(s)); err != nil {
+	if _, err := file.WriteString(filepath.ToSlash(buildCtx.ip)); err != nil {
 		return "", err
 	}
 	return file.Name(), nil

pkg/build/options.go

@@ -85,6 +85,15 @@ func WithConfig(buildConfigs map[string]Config) Option {
 	}
 }
 
+// WithEnv is a functional option for providing a global set of environment
+// variables across all builds.
+func WithEnv(env []string) Option {
+	return func(gbo *gobuildOpener) error {
+		gbo.env = env
+		return nil
+	}
+}
+
 // WithPlatforms is a functional option for building certain platforms for
 // multi-platform base images. To build everything from the base, use "all",
 // otherwise use a list of platform specs, i.e.:

pkg/commands/options/build.go

@@ -47,6 +47,9 @@ type BuildOptions struct {
 	// DefaultPlatforms defines the default platforms when Platforms is not explicitly defined
 	DefaultPlatforms []string
 
+	// Env allows setting environment variables globally and applying them to each build.
+	Env []string
+
 	// WorkingDirectory allows for setting the working directory for invocations of the `go` tool.
 	// Empty string means the current working directory.
 	WorkingDirectory string
@@ -138,6 +141,11 @@ func (bo *BuildOptions) LoadConfig() error {
 		bo.DefaultPlatforms = dp
 	}
 
+	env := v.GetStringSlice("env")
+	if len(env) > 0 {
+		bo.Env = env
+	}
+
 	if bo.BaseImage == "" {
 		ref := v.GetString("defaultBaseImage")
 		if _, err := name.ParseReference(ref); err != nil {

pkg/commands/options/build_test.go

@@ -67,6 +67,21 @@ func TestDefaultPlatformsAll(t *testing.T) {
 	}
 }
 
+func TestEnv(t *testing.T) {
+	bo := &BuildOptions{
+		WorkingDirectory: "testdata/config",
+	}
+	err := bo.LoadConfig()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	wantEnv := []string{"FOO=bar"} // matches value in ./testdata/config/.ko.yaml
+	if !reflect.DeepEqual(bo.Env, wantEnv) {
+		t.Fatalf("wanted Env %s, got %s", wantEnv, bo.Env)
+	}
+}
+
 func TestBuildConfigWithWorkingDirectoryAndDirAndMain(t *testing.T) {
 	bo := &BuildOptions{
 		WorkingDirectory: "testdata/paths",

pkg/commands/options/testdata/config/.ko.yaml

@@ -1,2 +1,3 @@
 defaultBaseImage: alpine
 defaultPlatforms: all
+env: FOO=bar

pkg/commands/resolver.go

@@ -86,6 +86,7 @@ func gobuildOptions(bo *options.BuildOptions) ([]build.Option, error) {
 
 	opts := []build.Option{
 		build.WithBaseImages(getBaseImage(bo)),
+		build.WithEnv(bo.Env),
 		build.WithPlatforms(bo.Platforms...),
 		build.WithJobs(bo.ConcurrentBuilds),
 	}