On cluster s2i build for Go (alternative version) (#2471)

* Prepare util image to accomodate multiple cmds

As of now func-util image has only one command of our own -- "deploy".
This commits prepares grounds for one additional command named "scaffolding".
The commands will be implemented in one binary and dispatched over
argv[0] using symlinks. Kinda like busybox does.

Signed-off-by: Matej Vašek <[email protected]>

* Add scaffolding for on-cluster build

Added new build step in tekton pipeline that scaffolds main() for Go
porject when using s2i builder.

Signed-off-by: Matej Vašek <[email protected]>

* Better docker build caching

This will cache dependencies between docker builds.

Signed-off-by: Matej Vašek <[email protected]>

* fixup: perms

Signed-off-by: Matej Vašek <[email protected]>

* fixup: remove broken check

Signed-off-by: Matej Vašek <[email protected]>

* fixup: remove test because of 'no space left on device'

Signed-off-by: Matej Vašek <[email protected]>

* Make func-util rootfull

Signed-off-by: Matej Vašek <[email protected]>

---------

Signed-off-by: Matej Vašek <[email protected]>

Dockerfile.utils

@@ -4,24 +4,29 @@ ARG BUILDPLATFORM
 ARG TARGETPLATFORM
 ARG TARGETARCH
 
+WORKDIR /workspace
+
+COPY go.mod go.sum ./
+RUN go mod download -x
+
 COPY . .
 
-RUN GOARCH=$TARGETARCH go build -o deploy -trimpath -ldflags '-w -s' ./cmd/func-deployer
+RUN GOARCH=$TARGETARCH go build -o func-util -trimpath -ldflags '-w -s' ./cmd/func-util
 
 #########################
 
 FROM --platform=$TARGETPLATFORM index.docker.io/library/alpine:latest
 
-RUN apk add --no-cache socat tar \
-  && addgroup func -g 1000 \
-  && adduser func -u 1001 -D -G func
+RUN apk add --no-cache socat tar
 
-COPY --from=builder /go/deploy /usr/local/bin/
+COPY --from=builder /workspace/func-util /usr/local/bin/
+RUN ln -s /usr/local/bin/func-util /usr/local/bin/deploy && \
+    ln -s /usr/local/bin/func-util /usr/local/bin/scaffold
 
 LABEL \
    org.opencontainers.image.description="Knative Func Utils Image" \
    org.opencontainers.image.source="https://github.com/knative/func" \
    org.opencontainers.image.vendor="https://github.com/knative/func" \
    org.opencontainers.image.url="https://github.com/knative/func/pkgs/container/func-utils"
 
-USER func:func
+USER 0:0

cmd/func-deployer/main.go → cmd/func-util/main.go

@@ -5,11 +5,14 @@ import (
 	"fmt"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"syscall"
 
+	"knative.dev/func/pkg/builders/s2i"
 	fn "knative.dev/func/pkg/functions"
 	"knative.dev/func/pkg/k8s"
 	"knative.dev/func/pkg/knative"
+	"knative.dev/func/pkg/scaffolding"
 )
 
 func main() {
@@ -25,12 +28,68 @@ func main() {
 		os.Exit(137)
 	}()
 
-	err := deploy(ctx)
+	var cmd func(context.Context) error = unknown
+
+	switch os.Args[0] {
+	case "deploy":
+		cmd = deploy
+	case "scaffold":
+		cmd = scaffold
+	}
+
+	err := cmd(ctx)
 	if err != nil {
 		_, _ = fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
 		os.Exit(1)
 	}
 }
+
+func unknown(_ context.Context) error {
+	return fmt.Errorf("unknown command: " + os.Args[0])
+}
+
+func scaffold(ctx context.Context) error {
+
+	if len(os.Args) != 2 {
+		return fmt.Errorf("expected exactly one positional argument (function project path)")
+	}
+
+	path := os.Args[1]
+
+	f, err := fn.NewFunction(path)
+	if err != nil {
+		return fmt.Errorf("cannot load func project: %w", err)
+	}
+
+	if f.Runtime != "go" {
+		// Scaffolding is for now supported/needed only for Go.
+		return nil
+	}
+
+	embeddedRepo, err := fn.NewRepository("", "")
+	if err != nil {
+		return fmt.Errorf("cannot initialize repository: %w", err)
+	}
+
+	appRoot := filepath.Join(f.Root, ".s2i", "builds", "last")
+	_ = os.RemoveAll(appRoot)
+
+	err = scaffolding.Write(appRoot, f.Root, f.Runtime, f.Invoke, embeddedRepo.FS())
+	if err != nil {
+		return fmt.Errorf("cannot write the scaffolding: %w", err)
+	}
+
+	if err := os.MkdirAll(filepath.Join(f.Root, ".s2i", "bin"), 0755); err != nil {
+		return fmt.Errorf("unable to create .s2i bin dir. %w", err)
+	}
+
+	if err := os.WriteFile(filepath.Join(f.Root, ".s2i", "bin", "assemble"), []byte(s2i.GoAssembler), 0755); err != nil {
+		return fmt.Errorf("unable to write go assembler. %w", err)
+	}
+
+	return nil
+}
+
 func deploy(ctx context.Context) error {
 	var err error
 	deployer := knative.NewDeployer(

pkg/pipelines/tekton/tasks.go

@@ -321,7 +321,7 @@ spec:
         cat /env-vars/env-file
         echo "------------------------------"
 
-        /usr/local/bin/s2i --loglevel=$(params.LOGLEVEL) build $(params.PATH_CONTEXT) $(params.BUILDER_IMAGE) \
+        /usr/local/bin/s2i --loglevel=$(params.LOGLEVEL) build --keep-symlinks $(params.PATH_CONTEXT) $(params.BUILDER_IMAGE) \
         --image-scripts-url $(params.S2I_IMAGE_SCRIPTS_URL) \
         --as-dockerfile /gen-source/Dockerfile.gen --environment-file /env-vars/env-file
 
@@ -413,9 +413,34 @@ spec:
 `, DeployerImage)
 }
 
+func getScaffoldTask() string {
+	return fmt.Sprintf(`apiVersion: tekton.dev/v1
+kind: Task
+metadata:
+  name: func-scaffold
+  labels:
+    app.kubernetes.io/version: "0.1"
+  annotations:
+    tekton.dev/pipelines.minVersion: "0.12.1"
+    tekton.dev/categories: CLI
+    tekton.dev/tags: cli
+    tekton.dev/platforms: "linux/amd64"
+spec:
+  params:
+    - name: path
+      description: Path to the function project
+      default: ""
+  steps:
+    - name: func-scaffold
+      image: %s
+      script: |
+        scaffold $(params.path)
+`, DeployerImage)
+}
+
 // GetClusterTasks returns multi-document yaml containing tekton tasks used by func.
 func GetClusterTasks() string {
-	tasks := getBuildpackTask() + "\n---\n" + getS2ITask() + "\n---\n" + getDeployTask()
+	tasks := getBuildpackTask() + "\n---\n" + getS2ITask() + "\n---\n" + getDeployTask() + "\n---\n" + getScaffoldTask()
 	tasks = strings.Replace(tasks, "kind: Task", "kind: ClusterTask", -1)
 	tasks = strings.ReplaceAll(tasks, "apiVersion: tekton.dev/v1", "apiVersion: tekton.dev/v1beta1")
 	return tasks

pkg/pipelines/tekton/templates.go

@@ -99,6 +99,7 @@ type templateData struct {
 	FuncBuildpacksTaskRef string
 	FuncS2iTaskRef        string
 	FuncDeployTaskRef     string
+	FuncScaffoldTaskRef   string
 
 	// Reference for build task - whether it should run after fetch-sources task or not
 	RunAfterFetchSources string
@@ -128,6 +129,7 @@ func createPipelineTemplatePAC(f fn.Function, labels map[string]string) error {
 		{getBuildpackTask(), &data.FuncBuildpacksTaskRef},
 		{getS2ITask(), &data.FuncS2iTaskRef},
 		{getDeployTask(), &data.FuncDeployTaskRef},
+		{getScaffoldTask(), &data.FuncScaffoldTaskRef},
 	} {
 		ts, err := getTaskSpec(val.ref)
 		if err != nil {
@@ -327,6 +329,7 @@ func createAndApplyPipelineTemplate(f fn.Function, namespace string, labels map[
 		{getBuildpackTask(), &data.FuncBuildpacksTaskRef},
 		{getS2ITask(), &data.FuncS2iTaskRef},
 		{getDeployTask(), &data.FuncDeployTaskRef},
+		{getScaffoldTask(), &data.FuncScaffoldTaskRef},
 	} {
 		ts, err := getTaskSpec(val.ref)
 		if err != nil {

pkg/pipelines/tekton/templates_pack.go

@@ -42,6 +42,15 @@ spec:
       type: array
   tasks:
     {{.GitCloneTaskRef}}
+    - name: scaffold
+      params:
+        - name: path
+          value: $(workspaces.source.path)/$(params.contextDir)
+      workspaces:
+        - name: source
+          workspace: source-workspace
+      {{.RunAfterFetchSources}}
+      {{.FuncScaffoldTaskRef}}
     - name: build
       params:
         - name: APP_IMAGE
@@ -55,7 +64,8 @@ spec:
         - name: ENV_VARS
           value:
             - '$(params.buildEnvs[*])'
-      {{.RunAfterFetchSources}}
+      runAfter:
+        - scaffold
       {{.FuncBuildpacksTaskRef}}
       workspaces:
         - name: source

pkg/pipelines/tekton/templates_s2i.go

@@ -46,6 +46,15 @@ spec:
       default: 'image:///usr/libexec/s2i'
   tasks:
     {{.GitCloneTaskRef}}
+    - name: scaffold
+      params:
+        - name: path
+          value: $(workspaces.source.path)/$(params.contextDir)
+      workspaces:
+        - name: source
+          workspace: source-workspace
+      {{.RunAfterFetchSources}}
+      {{.FuncScaffoldTaskRef}}
     - name: build
       params:
         - name: IMAGE
@@ -61,7 +70,8 @@ spec:
             - '$(params.buildEnvs[*])'
         - name: S2I_IMAGE_SCRIPTS_URL
           value: $(params.s2iImageScriptsUrl)
-      {{.RunAfterFetchSources}}
+      runAfter:
+        - scaffold
       {{.FuncS2iTaskRef}}
       workspaces:
         - name: source