Add option to specify Golang default version

config/serverless-operator.yaml

@@ -33,6 +33,7 @@ config:
       - onDemand: true
         version: "4.14"
       promotion: {}
+      golangVersion: "1.25"
     release-1.35:
       konflux:
         enabled: true
@@ -161,6 +162,7 @@ config:
       promotion: {}
       prowgen:
         disabled: true
+      golangVersion: "1.25"
 repositories:
 - customConfigs:
   - name: 420-aws-ovn

pkg/dockerfilegen/generator.go

@@ -17,6 +17,7 @@ import (
 	"strings"
 	"text/template"
 
+	"github.com/openshift-knative/hack/config"
 	"github.com/openshift-knative/hack/pkg/soversion"
 
 	"github.com/coreos/go-semver/semver"
@@ -150,11 +151,11 @@ func generateDockerfile(params Params, mainPackagesPaths sets.Set[string]) error
 	if err != nil {
 		return err
 	}
-	goVersion := goMod.Go.Version
+	goModGoVersion := goMod.Go.Version
 
 	// The builder images are distinguished by golang major.minor, so we ignore the rest of the goVersion
-	if strings.Count(goVersion, ".") > 1 {
-		goVersion = strings.Join(strings.Split(goVersion, ".")[0:2], ".")
+	if strings.Count(goModGoVersion, ".") > 1 {
+		goModGoVersion = strings.Join(strings.Split(goModGoVersion, ".")[0:2], ".")
 	}
 
 	metadata, err := project.ReadMetadataFile(params.ProjectFilePath)
@@ -167,6 +168,15 @@ func generateDockerfile(params Params, mainPackagesPaths sets.Set[string]) error
 		metadata = project.DefaultMetadata()
 	}
 
+	// get target go version
+	goVersion, err := goVersionFromConfig(metadata)
+	if err != nil {
+		return fmt.Errorf("failed to get Go version from config: %w", err)
+	}
+	if goVersion == nil {
+		goVersion = &goModGoVersion
+	}
+
 	rhelVersion := RHEL9
 	templateFilePattern := "dockerfile-templates/rhel-9/*.tmpl"
 	var soVersion string
@@ -210,7 +220,7 @@ func generateDockerfile(params Params, mainPackagesPaths sets.Set[string]) error
 
 	builderImage := params.DockerfileImageBuilderFmt
 	if builderImage == "" {
-		builderImage = builderImageForGoVersion(goVersion, rhelVersion)
+		builderImage = builderImageForGoVersion(*goVersion, rhelVersion)
 	} else {
 		// Builder image might be provided without formatting '%s' string as plain value
 		if strings.Count(params.DockerfileImageBuilderFmt, "%s") == 1 {
@@ -408,6 +418,95 @@ func generateDockerfile(params Params, mainPackagesPaths sets.Set[string]) error
 	return nil
 }
 
+// goVersionFromConfig returns the target go version for the project.
+// First it checks if a dedicated go version is defined for the repositories branch in the config.
+// If no repo-branch specific config is set, it uses the one from the coresponding SO branch config.
+// If SO does not have a default go version in it's config neither it returns nil to let the caller
+// decide.
+func goVersionFromConfig(metadata *project.Metadata) (*string, error) {
+	// get repo config
+	if imagePrefix := metadata.Project.ImagePrefix; imagePrefix != "" {
+
+		// this is a component repo
+		branch := ""
+		if metadata.Project.Tag == "knative-nightly" {
+			branch = "release-next"
+		} else {
+			branch = fmt.Sprintf("release-%s", strings.TrimPrefix(metadata.Project.Tag, "knative-"))
+		}
+
+		configFiles, err := fs.ReadDir(config.Configs, ".")
+		if err != nil {
+			return nil, fmt.Errorf("failed to read config directory: %w", err)
+		}
+
+		for _, configFile := range configFiles {
+			if configFile.IsDir() {
+				continue
+			}
+
+			content, err := fs.ReadFile(config.Configs, configFile.Name())
+			if err != nil {
+				return nil, fmt.Errorf("failed to load config from %s: %w", configFile.Name(), err)
+			}
+
+			cfg, err := prowgen.UnmarshalConfig(content)
+			if err != nil {
+				return nil, fmt.Errorf("failed to parse config from %s: %w", configFile.Name(), err)
+			}
+
+			for _, repo := range cfg.Repositories {
+				if repo.ImagePrefix == imagePrefix {
+					// this is the repo we are generating the dockerfile for
+
+					if branchConfig, ok := cfg.Config.Branches[branch]; ok {
+						if branchConfig.GolangVersion != nil && *branchConfig.GolangVersion != "" {
+							return branchConfig.GolangVersion, nil
+						}
+						// we didn't find a repo-branch specific default --> fall back to SO default
+					}
+				}
+			}
+		}
+	}
+
+	// check SO config
+	soBranch := ""
+	if metadata.Project.Tag != "" {
+		// this is a component repo (-> we falled through, as we didn't find a repo-branch specific default
+		if metadata.Project.Tag == "knative-nightly" || metadata.Project.Tag == "main" {
+			soBranch = "main"
+		} else {
+			soVersion := soversion.FromUpstreamVersion(strings.TrimPrefix(metadata.Project.Tag, "knative-"))
+			soBranch = soversion.BranchName(soVersion)
+		}
+	} else if metadata.Project.Version != "" {
+		majorMinor := strings.TrimSuffix(metadata.Project.Version, ".0")
+		soBranch = fmt.Sprintf("release-v%s", majorMinor)
+	}
+
+	if soBranch != "" {
+		soYaml, err := config.Configs.ReadFile("serverless-operator.yaml")
+		if err != nil {
+			return nil, fmt.Errorf("failed to load config for serverless-operator: %w", err)
+		}
+
+		soConfig, err := prowgen.UnmarshalConfig(soYaml)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse config for serverless-operator: %w", err)
+		}
+
+		if cfg, ok := soConfig.Config.Branches[soBranch]; ok {
+			if cfg.GolangVersion != nil && *cfg.GolangVersion != "" {
+				return cfg.GolangVersion, nil
+			}
+			// we didn't find a repo-branch specific default --> fall back to go.mod version
+		}
+	}
+
+	return nil, nil
+}
+
 func hasVendorFolder(dir string) (bool, error) {
 	info, err := os.Stat(path.Join(dir, "vendor"))
 	if err == nil {

pkg/project/testoutput/openshift/ci-operator/build-image/Dockerfile

@@ -3,7 +3,7 @@
 FROM registry.ci.openshift.org/ocp/4.19:cli-artifacts as tools
 
 # Dockerfile to bootstrap build and test in openshift-ci
-FROM registry.ci.openshift.org/openshift/release:rhel-9-release-golang-1.22-openshift-4.17 as builder
+FROM registry.ci.openshift.org/openshift/release:rhel-9-release-golang-1.25-openshift-4.21 as builder
 
 ARG TARGETARCH
 

pkg/project/testoutput/openshift/ci-operator/knative-images/discover/Dockerfile

@@ -1,5 +1,5 @@
 # DO NOT EDIT! Generated Dockerfile for cmd/discover.
-ARG GO_BUILDER=registry.ci.openshift.org/openshift/release:rhel-9-release-golang-1.22-openshift-4.17
+ARG GO_BUILDER=registry.ci.openshift.org/openshift/release:rhel-9-release-golang-1.25-openshift-4.21
 ARG GO_RUNTIME=registry.access.redhat.com/ubi9/ubi-minimal
 
 FROM $GO_BUILDER as builder

pkg/prowgen/prowgen_config.go

@@ -91,6 +91,7 @@ type Branch struct {
 	SkipE2EMatches         []string    `json:"skipE2EMatches,omitempty" yaml:"skipE2EMatches,omitempty"`
 	SkipDockerFilesMatches []string    `json:"skipDockerFilesMatches,omitempty" yaml:"skipDockerFilesMatches,omitempty"`
 	Konflux                *Konflux    `json:"konflux,omitempty" yaml:"konflux,omitempty"`
+	GolangVersion          *string     `json:"golangVersion,omitempty" yaml:"golangVersion,omitempty"`
 
 	// DependabotEnabled enabled if `nil`.
 	DependabotEnabled *bool `json:"dependabotEnabled,omitempty" yaml:"dependabotEnabled,omitempty"`