feat: configure CI workflow builder through WorkflowConfig and func.yaml

pkg/ci/github/common.go

@@ -1,8 +1,31 @@
 package github
 
-import "fmt"
+import (
+	"fmt"
+	"slices"
 
-func determineBuilder(runtime string, remote bool) (string, error) {
+	"knative.dev/func/pkg/builders"
+)
+
+func determineBuilder(runtime, builder string, remote bool) (string, error) {
+	defaultBuilder, err := runtimeDefaultBuilder(runtime, remote)
+	if err != nil {
+		return "", err
+	}
+	if builder == "" {
+		return defaultBuilder, nil
+	}
+	all := builders.All()
+	if !slices.Contains(all, builder) {
+		return "", builders.ErrUnknownBuilder{Name: builder, Known: all}
+	}
+	if remote && builder == builders.Host {
+		return "", fmt.Errorf("builder %q is incompatible with remote builds", builders.Host)
+	}
+	return builder, nil
+}
+
+func runtimeDefaultBuilder(runtime string, remote bool) (string, error) {
 	switch runtime {
 	case "go":
 		if remote {

pkg/ci/github/generator.go

@@ -78,23 +78,28 @@ func (g *workflowGenerator) Generate(ctx context.Context, f fn.Function) error {
 		return fmt.Errorf("function root path can not be empty")
 	}
 
-	githubWorkflow, err := newGitHubWorkflow(g.cfg, f.Runtime, g.messageWriter)
+	cfg := g.cfg
+	if cfg.Builder == "" {
+		cfg.Builder = f.Build.Builder
+	}
+
+	githubWorkflow, err := newGitHubWorkflow(cfg, f.Runtime, g.messageWriter)
 	if err != nil {
 		return err
 	}
 
-	if err := githubWorkflow.Export(g.cfg.fnGitHubWorkflowFilepath(f.Root), g.workflowWriter, g.cfg.Force, g.messageWriter); err != nil {
+	if err := githubWorkflow.Export(cfg.fnGitHubWorkflowFilepath(f.Root), g.workflowWriter, cfg.Force, g.messageWriter); err != nil {
 		return err
 	}
 
 	if g.verbose {
 		// best-effort user message; errors are non-critical
-		_ = PrintConfiguration(g.cfg, f.Runtime, g.messageWriter)
+		_ = PrintConfiguration(cfg, f.Runtime, g.messageWriter)
 		return nil
 	}
 
 	// best-effort user message; errors are non-critical
-	_ = PrintPostExportMessage(g.cfg, g.messageWriter)
+	_ = PrintPostExportMessage(cfg, g.messageWriter)
 	return nil
 }
 

pkg/ci/github/generator_test.go

@@ -9,6 +9,7 @@ import (
 
 	"gotest.tools/v3/assert"
 	"gotest.tools/v3/assert/cmp"
+	"knative.dev/func/pkg/builders"
 	"knative.dev/func/pkg/ci/github"
 	fn "knative.dev/func/pkg/functions"
 )
@@ -518,6 +519,74 @@ func TestCIGenerator_BuilderForRuntime(t *testing.T) {
 	}
 }
 
+func TestCIGenerator_BuilderConfiguredInFuncYaml(t *testing.T) {
+	testCases := []struct {
+		name    string
+		runtime string
+		builder string
+	}{
+		{
+			name:    "node function with s2i builder configured",
+			runtime: "node",
+			builder: "s2i",
+		},
+		{
+			name:    "python function with pack builder configured",
+			runtime: "python",
+			builder: "pack",
+		},
+		{
+			name:    "quarkus function with s2i builder configured",
+			runtime: "quarkus",
+			builder: "s2i",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// GIVEN
+			opts := defaultOpts()
+			opts.goFn.Runtime = tc.runtime
+			opts.goFn.Build.Builder = tc.builder
+
+			// WHEN
+			result := runGenerateWorkflow(t, opts)
+
+			// THEN
+			assert.NilError(t, result.executeErr)
+			assert.Assert(t, strings.Contains(result.gwYamlString, "FUNC_BUILDER: "+tc.builder))
+		})
+	}
+}
+
+func TestCIGenerator_WorkflowConfigBuilderTakesPriorityOverFuncYaml(t *testing.T) {
+	// GIVEN
+	opts := defaultOpts()
+	opts.goFn.Runtime = "node"
+	opts.goFn.Build.Builder = "s2i"
+	opts.cfg.Builder = "pack"
+
+	// WHEN
+	result := runGenerateWorkflow(t, opts)
+
+	// THEN
+	assert.NilError(t, result.executeErr)
+	assert.Assert(t, strings.Contains(result.gwYamlString, "FUNC_BUILDER: "+opts.cfg.Builder))
+}
+
+func TestCIGenerator_HostBuilderWithRemoteErrors(t *testing.T) {
+	// GIVEN
+	opts := defaultOpts()
+	opts.cfg.Builder = builders.Host
+	opts.cfg.RemoteBuild = true
+
+	// WHEN
+	result := runGenerateWorkflow(t, opts)
+
+	// THEN
+	assert.Error(t, result.executeErr, `builder "host" is incompatible with remote builds`)
+}
+
 func TestCIGenerator_BuilderForRuntimeError(t *testing.T) {
 	// GIVEN
 	opts := defaultOpts()
@@ -530,6 +599,31 @@ func TestCIGenerator_BuilderForRuntimeError(t *testing.T) {
 	assert.Error(t, result.executeErr, "no builder support for runtime: zig")
 }
 
+func TestCIGenerator_UnsupportedRuntimeErrorsEvenWithExplicitBuilder(t *testing.T) {
+	// GIVEN
+	opts := defaultOpts()
+	opts.goFn.Runtime = "zig"
+	opts.goFn.Build.Builder = "pack"
+
+	// WHEN
+	result := runGenerateWorkflow(t, opts)
+
+	// THEN
+	assert.Error(t, result.executeErr, "no builder support for runtime: zig")
+}
+
+func TestCIGenerator_InvalidBuilderErrors(t *testing.T) {
+	// GIVEN
+	opts := defaultOpts()
+	opts.goFn.Build.Builder = "pakc"
+
+	// WHEN
+	result := runGenerateWorkflow(t, opts)
+
+	// THEN
+	assert.Error(t, result.executeErr, `"pakc" is not a known builder. Available builders are "host", "pack" and "s2i"`)
+}
+
 // ---------------------
 // END: Broad Unit Tests
 

pkg/ci/github/printer.go

@@ -50,7 +50,7 @@ Create the following Secret on github.com: %s
 )
 
 func PrintConfiguration(cfg WorkflowConfig, runtime string, w io.Writer) error {
-	builder, err := determineBuilder(runtime, cfg.RemoteBuild)
+	builder, err := determineBuilder(runtime, cfg.Builder, cfg.RemoteBuild)
 	if err != nil {
 		return err
 	}

pkg/ci/github/workflow.go

@@ -46,7 +46,8 @@ type WorkflowConfig struct {
 	RegistryUserVar,
 	RegistryPassSecret,
 	RegistryUrlVar,
-	FuncCliVersion string
+	FuncCliVersion,
+	Builder string
 	RegistryLogin,
 	SelfHostedRunner,
 	RemoteBuild,
@@ -241,7 +242,7 @@ func createFuncDeployStep(opts WorkflowConfig, runtime string, steps []step) ([]
 	deployFuncStep := newStep("Deploy function").
 		withEnv("FUNC_VERBOSE", "true")
 
-	builder, err := determineBuilder(runtime, opts.RemoteBuild)
+	builder, err := determineBuilder(runtime, opts.Builder, opts.RemoteBuild)
 	if err != nil {
 		return nil, err
 	}