feat: add template params for platform info

This restructures the build logic in order to expand the buildArgs to include:

- `Env`: the actual environment variables used to execute the build. This includes platform info (e.g. `GOOS`, `GOARCH`).
- `GoEnv`: the map of variables from `go env`, but overridden with any platform-specific values defined in `Env`.

Fixes ko-build#1301

Signed-off-by: Nathan Mittler <nmittler@aviatrix.com>

docs/configuration.md

@@ -84,20 +84,21 @@ The `ko` builds supports templating of `flags` and `ldflags`, similar to the
 
 The table below lists the supported template parameters.
 
-| Template param        | Description                                           |
-|-----------------------|-------------------------------------------------------|
-| `Env`                 | Map of system environment variables from `os.Environ` |
-| `Date`                | The UTC build date in RFC 3339 format                 |
-| `Timestamp`           | The UTC build date as Unix epoc seconds               |
-| `Git.Branch`          | The current git branch                                |
-| `Git.Tag`             | The current git tag                                   |
-| `Git.ShortCommit`     | The git commit short hash                             |
-| `Git.FullCommit`      | The git commit full hash                              |
-| `Git.CommitDate`      | The UTC commit date in RFC 3339 format                |
-| `Git.CommitTimestamp` | The UTC commit date in Unix format                    |
-| `Git.IsDirty`         | Whether or not current git state is dirty             |
-| `Git.IsClean`         | Whether or not current git state is clean.            |
-| `Git.TreeState`       | Either `clean` or `dirty`                             |
+| Template param        | Description                                              |
+|-----------------------|----------------------------------------------------------|
+| `Env`                 | Map of environment variables used for the build          |
+| `GoEnv`               | Map of `go env` environment variables used for the build |
+| `Date`                | The UTC build date in RFC 3339 format                    |
+| `Timestamp`           | The UTC build date as Unix epoc seconds                  |
+| `Git.Branch`          | The current git branch                                   |
+| `Git.Tag`             | The current git tag                                      |
+| `Git.ShortCommit`     | The git commit short hash                                |
+| `Git.FullCommit`      | The git commit full hash                                 |
+| `Git.CommitDate`      | The UTC commit date in RFC 3339 format                   |
+| `Git.CommitTimestamp` | The UTC commit date in Unix format                       |
+| `Git.IsDirty`         | Whether or not current git state is dirty                |
+| `Git.IsClean`         | Whether or not current git state is clean.               |
+| `Git.TreeState`       | Either `clean` or `dirty`                                |
 
 ### Setting default platforms
 

pkg/build/gobuild.go

@@ -16,6 +16,7 @@ package build
 
 import (
 	"archive/tar"
+	"bufio"
 	"bytes"
 	"context"
 	"errors"
@@ -68,7 +69,7 @@ type buildContext struct {
 	creationTime v1.Time
 	ip           string
 	dir          string
-	env          []string
+	mergedEnv    []string
 	platform     v1.Platform
 	config       Config
 }
@@ -267,6 +268,8 @@ func getGoBinary() string {
 }
 
 func build(ctx context.Context, buildCtx buildContext) (string, error) {
+	// Create the set of build arguments from the config flags/ldflags with any
+	// template parameters applied.
 	buildArgs, err := createBuildArgs(ctx, buildCtx)
 	if err != nil {
 		return "", err
@@ -275,12 +278,6 @@ func build(ctx context.Context, buildCtx buildContext) (string, error) {
 	args := make([]string, 0, 4+len(buildArgs))
 	args = append(args, "build")
 	args = append(args, buildArgs...)
-
-	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", buildCtx.ip, err)
-	}
-
 	tmpDir := ""
 
 	if dir := os.Getenv("KOCACHE"); dir != "" {
@@ -316,7 +313,7 @@ func build(ctx context.Context, buildCtx buildContext) (string, error) {
 	gobin := getGoBinary()
 	cmd := exec.CommandContext(ctx, gobin, args...)
 	cmd.Dir = buildCtx.dir
-	cmd.Env = env
+	cmd.Env = buildCtx.mergedEnv
 
 	var output bytes.Buffer
 	cmd.Stderr = &output
@@ -325,13 +322,49 @@ func build(ctx context.Context, buildCtx buildContext) (string, error) {
 	log.Printf("Building %s for %s", buildCtx.ip, buildCtx.platform)
 	if err := cmd.Run(); err != nil {
 		if os.Getenv("KOCACHE") == "" {
-			os.RemoveAll(tmpDir)
+			_ = os.RemoveAll(tmpDir)
 		}
 		return "", fmt.Errorf("go build: %w: %s", err, output.String())
 	}
 	return file, nil
 }
 
+func goenv(ctx context.Context) (map[string]string, error) {
+	gobin := getGoBinary()
+	cmd := exec.CommandContext(ctx, gobin, "env")
+	var output bytes.Buffer
+	cmd.Stdout = &output
+	cmd.Stderr = &output
+	if err := cmd.Run(); err != nil {
+		return nil, fmt.Errorf("go env: %w: %s", err, output.String())
+	}
+
+	env := make(map[string]string)
+	scanner := bufio.NewScanner(bytes.NewReader(output.Bytes()))
+
+	line := 0
+	for scanner.Scan() {
+		line++
+		kv := strings.SplitN(scanner.Text(), "=", 2)
+		if len(kv) != 2 {
+			return nil, fmt.Errorf("go env: failed parsing line: %d", line)
+		}
+		key := strings.TrimSpace(kv[0])
+		value := strings.TrimSpace(kv[1])
+
+		// Unquote the value. Handle single or double quoted strings.
+		if len(value) > 1 && ((value[0] == '\'' && value[len(value)-1] == '\'') ||
+			(value[0] == '"' && value[len(value)-1] == '"')) {
+			value = value[1 : len(value)-1]
+		}
+		env[key] = value
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("go env: failed parsing: %w", err)
+	}
+	return env, nil
+}
+
 func goversionm(ctx context.Context, file string, appPath string, appFileName string, se oci.SignedEntity, dir string) ([]byte, types.MediaType, error) {
 	gobin := getGoBinary()
 
@@ -724,15 +757,31 @@ func (g *gobuild) tarKoData(ref reference, platform *v1.Platform) (*bytes.Buffer
 	return buf, walkRecursive(tw, root, chroot, creationTime, platform)
 }
 
-func createTemplateData(ctx context.Context, buildCtx buildContext) map[string]interface{} {
+func createTemplateData(ctx context.Context, buildCtx buildContext) (map[string]interface{}, error) {
 	envVars := map[string]string{
 		"LDFLAGS": "",
 	}
-	for _, entry := range os.Environ() {
+	for _, entry := range buildCtx.mergedEnv {
 		kv := strings.SplitN(entry, "=", 2)
+		if len(kv) != 2 {
+			return nil, fmt.Errorf("invalid environment variable entry: %q", entry)
+		}
 		envVars[kv[0]] = kv[1]
 	}
 
+	// Get the go environment.
+	goEnv, err := goenv(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	// Override go env with any matching values from the environment variables.
+	for k, v := range envVars {
+		if _, ok := goEnv[k]; ok {
+			goEnv[k] = v
+		}
+	}
+
 	// Get the git information, if available.
 	info, err := git.GetInfo(ctx, buildCtx.dir)
 	if err != nil {
@@ -747,10 +796,11 @@ func createTemplateData(ctx context.Context, buildCtx buildContext) map[string]i
 
 	return map[string]interface{}{
 		"Env":       envVars,
+		"GoEnv":     goEnv,
 		"Git":       info.TemplateValue(),
 		"Date":      date.Format(time.RFC3339),
 		"Timestamp": date.UTC().Unix(),
-	}
+	}, nil
 }
 
 func applyTemplating(list []string, data map[string]interface{}) ([]string, error) {
@@ -775,7 +825,10 @@ func applyTemplating(list []string, data map[string]interface{}) ([]string, erro
 func createBuildArgs(ctx context.Context, buildCtx buildContext) ([]string, error) {
 	var args []string
 
-	data := createTemplateData(ctx, buildCtx)
+	data, err := createTemplateData(ctx, buildCtx)
+	if err != nil {
+		return nil, err
+	}
 
 	if len(buildCtx.config.Flags) > 0 {
 		flags, err := applyTemplating(buildCtx.config.Flags, data)
@@ -865,13 +918,21 @@ func (g *gobuild) buildOne(ctx context.Context, refStr string, base v1.Image, pl
 	if !g.platformMatcher.matches(platform) {
 		return nil, fmt.Errorf("base image platform %q does not match desired platforms %v", platform, g.platformMatcher.platforms)
 	}
-	// Do the build into a temporary file.
+
 	config := g.configForImportPath(ref.Path())
+
+	// Merge the system, global, and build config environment variables.
+	mergedEnv, err := buildEnv(*platform, os.Environ(), g.env, config.Env)
+	if err != nil {
+		return nil, fmt.Errorf("could not create env for %s: %w", ref.Path(), err)
+	}
+
+	// Do the build into a temporary file.
 	file, err := g.build(ctx, buildContext{
 		creationTime: g.creationTime,
 		ip:           ref.Path(),
 		dir:          g.dir,
-		env:          g.env,
+		mergedEnv:    mergedEnv,
 		platform:     *platform,
 		config:       config,
 	})
@@ -1101,7 +1162,7 @@ func (g *gobuild) buildAll(ctx context.Context, ref string, baseRef name.Referen
 		return nil, err
 	}
 
-	matches := []v1.Descriptor{}
+	var matches []v1.Descriptor
 	for _, desc := range im.Manifests {
 		// Nested index is pretty rare. We could support this in theory, but return an error for now.
 		if desc.MediaType != types.OCIManifestSchema1 && desc.MediaType != types.DockerManifestSchema2 {
@@ -1226,7 +1287,7 @@ func parseSpec(spec []string) (*platformMatcher, error) {
 		return &platformMatcher{spec: spec}, nil
 	}
 
-	platforms := []v1.Platform{}
+	var platforms []v1.Platform
 	for _, s := range spec {
 		p, err := v1.ParsePlatform(s)
 		if err != nil {

pkg/build/gobuild_test.go

@@ -315,16 +315,25 @@ func TestBuildEnv(t *testing.T) {
 	}
 }
 
-func TestCreateTemplateData(t *testing.T) {
-	t.Run("env", func(t *testing.T) {
-		t.Setenv("FOO", "bar")
-		params := createTemplateData(context.TODO(), buildContext{dir: t.TempDir()})
-		vars := params["Env"].(map[string]string)
-		require.Equal(t, "bar", vars["FOO"])
-	})
+func TestGoEnv(t *testing.T) {
+	goVars, err := goenv(context.TODO())
+	if err != nil {
+		t.Fatalf("unexpected error running goenv(): %v", err)
+	}
 
+	// Just check some basic values.
+	if goVars["GOOS"] != runtime.GOOS {
+		t.Fatalf("goenv(): invalid GOOS value: '%s', expected: '%s'", goVars["GOOS"], runtime.GOOS)
+	}
+	if goVars["GOARCH"] != runtime.GOARCH {
+		t.Fatalf("goenv(): invalid GOARCH value: '%s', expected: '%s'", goVars["GOARCH"], runtime.GOARCH)
+	}
+}
+
+func TestCreateTemplateData(t *testing.T) {
 	t.Run("empty creation time", func(t *testing.T) {
-		params := createTemplateData(context.TODO(), buildContext{dir: t.TempDir()})
+		params, err := createTemplateData(context.TODO(), buildContext{dir: t.TempDir()})
+		require.NoError(t, err)
 
 		// Make sure the date was set to time.Now().
 		actualDateStr := params["Date"].(string)
@@ -346,10 +355,11 @@ func TestCreateTemplateData(t *testing.T) {
 		expectedTime, err := time.Parse(time.RFC3339, "2012-11-01T22:08:00Z")
 		require.NoError(t, err)
 
-		params := createTemplateData(context.TODO(), buildContext{
+		params, err := createTemplateData(context.TODO(), buildContext{
 			creationTime: v1.Time{Time: expectedTime},
 			dir:          t.TempDir(),
 		})
+		require.NoError(t, err)
 
 		// Check the date.
 		actualDateStr := params["Date"].(string)
@@ -365,9 +375,10 @@ func TestCreateTemplateData(t *testing.T) {
 
 	t.Run("no git available", func(t *testing.T) {
 		dir := t.TempDir()
-		params := createTemplateData(context.TODO(), buildContext{dir: dir})
-		gitParams := params["Git"].(map[string]interface{})
+		params, err := createTemplateData(context.TODO(), buildContext{dir: dir})
+		require.NoError(t, err)
 
+		gitParams := params["Git"].(map[string]interface{})
 		require.Equal(t, "", gitParams["Branch"])
 		require.Equal(t, "", gitParams["Tag"])
 		require.Equal(t, "", gitParams["ShortCommit"])
@@ -384,13 +395,54 @@ func TestCreateTemplateData(t *testing.T) {
 		gittesting.GitCommit(t, dir, "commit1")
 		gittesting.GitTag(t, dir, "v0.0.1")
 
-		params := createTemplateData(context.TODO(), buildContext{dir: dir})
-		gitParams := params["Git"].(map[string]interface{})
+		params, err := createTemplateData(context.TODO(), buildContext{dir: dir})
+		require.NoError(t, err)
 
+		gitParams := params["Git"].(map[string]interface{})
 		require.Equal(t, "main", gitParams["Branch"])
 		require.Equal(t, "v0.0.1", gitParams["Tag"])
 		require.Equal(t, "clean", gitParams["TreeState"])
 	})
+
+	t.Run("env", func(t *testing.T) {
+		params, err := createTemplateData(context.TODO(), buildContext{
+			dir:       t.TempDir(),
+			mergedEnv: []string{"FOO=bar"},
+		})
+		require.NoError(t, err)
+		vars := params["Env"].(map[string]string)
+		require.Equal(t, "bar", vars["FOO"])
+	})
+
+	t.Run("bad env", func(t *testing.T) {
+		_, err := createTemplateData(context.TODO(), buildContext{
+			dir:       t.TempDir(),
+			mergedEnv: []string{"bad var"},
+		})
+		require.Error(t, err)
+	})
+
+	t.Run("default go env", func(t *testing.T) {
+		params, err := createTemplateData(context.TODO(), buildContext{dir: t.TempDir()})
+		require.NoError(t, err)
+		vars := params["GoEnv"].(map[string]string)
+		require.Equal(t, runtime.GOOS, vars["GOOS"])
+		require.Equal(t, runtime.GOARCH, vars["GOARCH"])
+	})
+
+	t.Run("env overrides go env", func(t *testing.T) {
+		params, err := createTemplateData(context.TODO(), buildContext{
+			dir: t.TempDir(),
+			mergedEnv: []string{
+				"GOOS=testgoos",
+				"GOARCH=testgoarch",
+			},
+		})
+		require.NoError(t, err)
+		vars := params["GoEnv"].(map[string]string)
+		require.Equal(t, "testgoos", vars["GOOS"])
+		require.Equal(t, "testgoarch", vars["GOARCH"])
+	})
 }
 
 func TestBuildConfig(t *testing.T) {