Can I use buildpacks task to build Knative functions?

[Khodesaeed]

I have a situation which I want to create a FaaS system with the help of Knative. So far, I have developed some sample Knative function which perfectly build, run, and, deployed on local and dev cluster. So, I want to build these functions via a Tekton pipeline. I think I have to create a Tekton pipeline that clone the function code, store it in a shared workspace and then build the image with buildpacks task and push it to private OCI container registry.

Here is my pipeline and pipelinerun so far:

apiVersion: tekton.dev/v1
kind: Pipeline
metadata:
  name: knative-function-pipeline
spec:
  description: A pipeline to build and deploy a Knative Function from a git repo
  params:
    - name: repo-url
      type: string
      description: The git repository URL
    - name: repo-revision
      type: string
      description: The git repository revision (branch, tag, commit)
      default: main
    - name: ssh-port
      type: string
      description: The SSH port for git cloning
      default: "227"
      # The buildpacks parameters 
    - name: app-image-name
      type: string
      description: The name of the Knative function image to build and deploy
    - name: app-private-repo
      type: string
      description: The private repository to push the function image to (without trailing slash)
    - name: cluster-name
      type: string
      description: The name of the target Kubernetes cluster also used as a function repo subpath
    - name: client-namespace
      type: string
      description: The client namespace also used as a function repo subpath and create it on cluster
    - name: builder-image
      type: string
      description: The builder image to use for building the function
  workspaces:
    - name: source-ws
      description: A workspace shared between tasks
    - name: ssh-keys-ws
      description: Secret workspace to mount SSH private key and known_hosts (mounted at /workspace/ssh-keys)
    - name: dockerconfig-ws
      description: Secret workspace to mount Docker config.json for image push
  tasks:
    - name: git-clone-ssh
      taskRef:
        name: git-clone-ssh
      params:
        - name: url
          value: $(params.repo-url)
        - name: revision
          value: $(params.repo-revision)
        - name: sshPort
          value: $(params.ssh-port)
      workspaces:
        - name: source
          workspace:  source-ws
        - name: ssh-keys
          workspace: ssh-keys-ws
    - name: build-knative-function
      runAfter:
        - git-clone-ssh
      taskRef:
        name: buildpacks
      params:
        - name: APP_IMAGE
          value: "$(params.app-private-repo)/$(params.app-image-name)"
        - name: BUILDER_IMAGE
          value: "$(params.builder-image)"
        - name: SOURCE_SUBPATH
          value: "$(params.cluster-name)/$(params.client-namespace)"
      workspaces: 
        - name: source
          workspace: source-ws
        - name: dockerconfig
          workspace: dockerconfig-ws
---

apiVersion: tekton.dev/v1
kind: PipelineRun
metadata:
  generateName: knative-function-pipelinerun-
spec:
  pipelineRef:
    name: knative-function-pipeline
  params:
    - name: repo-url
      value: <private-repo>
    - name: repo-revision
      value: main
    - name: ssh-port
      value: "227"

    - name: app-private-repo
      value: <private-registry>
    - name: app-image-name
      value: tekton-knative-ipinfo
    - name: builder-image
      value: gcr.io/buildpacks/builder:v1
    - name: cluster-name
      value: cluster-alpha
    - name: client-namespace
      value: knative-tenant-customer1
  workspaces:
    - name: source-ws
      volumeClaimTemplate:
        spec:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 100Mi
    - name: ssh-keys-ws
      secret:
        secretName: git-credentials
        items:
          - key: id_rsa
            path: id_rsa
          - key: known_hosts
            path: known_hosts
    - name: dockerconfig-ws
      secret:
        secretName: dockerconfig-secret    

here is the log of the build-knative-function taskrun:

task build-knative-function has failed: "step-create" exited with code 21: Error
[prepare] > Setting permissions on '/tekton/home'...
[prepare] > Setting permissions on '/layers'...
[prepare] > Setting permissions on '/workspace/source'...
[prepare] > Parsing additional configuration...
[prepare] -> Parsing env variables...
[prepare] > Processing any environment variables...
[prepare] --> Creating 'env' directory: /platform/env

[create] Warning: No cached data will be used, no cache specified.
[create] ===> ANALYZING
[create] Image with name "nexus-faas.abrha.org/repository/faas/tekton-knative-ipinfo" not found
[create] ===> DETECTING
[create] target distro name/version labels not found, reading /etc/os-release file
[create] ======== Results ========
[create] err:  google.dotnet.sdk@0.9.1
[create] err:  google.dotnet.functions-framework@0.0.1
[create] err:  google.dotnet.publish@0.9.0
[create] err:  google.dotnet.runtime@0.9.1
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.dotnet.runtime@0.9.1
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.dart.sdk@1.0.0
[create] err:  google.dart.pub@0.1.0
[create] err:  google.dart.compile@1.0.0
[create] ======== Results ========
[create] err:  google.go.runtime@0.9.1
[create] err:  google.go.functions-framework@0.9.4
[create] err:  google.go.build@0.9.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.go.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.go.runtime@0.9.1
[create] err:  google.go.gomod@0.9.0
[create] err:  google.go.build@0.9.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.go.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.go.runtime@0.9.1
[create] err:  google.go.gopath@0.9.0
[create] err:  google.go.build@0.9.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.go.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.graalvm@0.1.0
[create] err:  google.java.maven@0.9.0
[create] err:  google.java.functions-framework@1.1.0
[create] err:  google.java.native-image@0.1.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.maven@0.9.0
[create] err:  google.java.functions-framework@1.1.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.gradle@0.10.0
[create] err:  google.java.functions-framework@1.1.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.exploded-jar@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.maven@0.9.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.maven@0.9.0
[create] err:  google.java.entrypoint@0.9.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.gradle@0.10.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.java.runtime@0.9.2
[create] err:  google.java.gradle@0.10.0
[create] err:  google.java.entrypoint@0.9.0
[create] err:  google.java.clear-source@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.config.flex@0.9.1
[create] err:  google.python.runtime@0.9.1
[create] err:  google.python.pip@0.9.2
[create] err:  google.python.webserver@0.9.1
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.python.runtime@0.9.1
[create] err:  google.python.functions-framework@0.9.6
[create] err:  google.python.pip@0.9.2
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.python.runtime@0.9.1
[create] err:  google.python.pip@0.9.2
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.ruby.runtime@0.0.1
[create] err:  google.ruby.rubygems@0.9.0
[create] err:  google.ruby.bundle@0.9.0
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.ruby.rails@0.9.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.ruby.runtime@0.0.1
[create] err:  google.utils.archive-source@0.0.1
[create] err:  google.ruby.bundle@0.9.0
[create] err:  google.ruby.functions-framework@0.9.1
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.php.runtime@0.0.2
[create] err:  google.utils.nginx@0.0.1
[create] err:  google.php.composer-install@0.0.1
[create] err:  google.php.composer-gcp-build@0.9.1
[create] err:  google.php.composer@0.9.1
[create] err:  google.utils.label-image@0.0.2
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.php.webconfig@0.0.1
[create] ======== Results ========
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.nodejs.yarn@2.1.0
[create] err:  google.nodejs.functions-framework@0.9.4
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.nodejs.pnpm@0.1.0
[create] err:  google.nodejs.functions-framework@0.9.4
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.nodejs.npm@1.1.0
[create] err:  google.nodejs.functions-framework@0.9.4
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.nodejs.functions-framework@0.9.4
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.nodejs.runtime@1.0.0
[create] err:  google.config.entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.cpp.functions-framework@0.1.0
[create] err:  google.cpp.clear-source@0.1.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.python.runtime@0.9.1
[create] err:  google.python.webserver@0.9.1
[create] err:  google.python.pip@0.9.2
[create] err:  google.python.missing-entrypoint@0.9.0
[create] err:  google.utils.label-image@0.0.2
[create] ======== Results ========
[create] err:  google.ruby.missing-entrypoint@0.0.1
[create] ERROR: No buildpack groups passed detection.
[create] ERROR: failed to detect: buildpack(s) failed with err

[results] 2025/11/17 09:43:24 Skipping step because a previous step failed

container step-results has failed  : [{"key":"StartedAt","value":"2025-11-17T09:43:24.406Z","type":3},{"key":"Reason","value":"Skipped","type":3}]

Does it means that the builder image can't detect my code?
my code is a simple knative structured function which has go.mod, sum.go, and *.go file.
Moreover, I have used the kn func CLI builder image: ghcr.io/knative/builder-jammy-tiny:latest And it has some other problem:
Here is the log of the taskrun with the kn func CLI image:

task build-knative-function has failed: "step-create" exited with code 1: Error
[prepare] > Setting permissions on '/tekton/home'...
[prepare] > Setting permissions on '/layers'...
[prepare] > Setting permissions on '/workspace/source'...
[prepare] > Parsing additional configuration...
[prepare] -> Parsing env variables...
[prepare] > Processing any environment variables...
[prepare] --> Creating 'env' directory: /platform/env

[create] Warning: No cached data will be used, no cache specified.
[create] ERROR: failed to set environment for user 1000: user: unknown userid 1000

container step-create has failed  : [{"key":"StartedAt","value":"2025-11-17T10:02:57.389Z","type":3}]

On this step I edit the builder image USER_ID and GROUP_ID in pipeline:

...
params:
  ...
  - name: builder-user-id
      type: string
      description: The user ID to run the builder image as
      default: "1001"
    - name: builder-group-id
      type: string
      description: The group ID to run the builder image as
      default: "1000"
 ...
tasks:
    ...
    - name: build-knative-function
      runAfter:
        - git-clone-ssh
      taskRef:
        name: buildpacks
      params:
        - name: USER_ID
          value: "$(params.builder-user-id)"
        - name: GROUP_ID
          value: "$(params.builder-group-id)"

And here is the logs:

task build-knative-function has failed: "step-create" exited with code 1: Error
[prepare] > Setting permissions on '/tekton/home'...
[prepare] > Setting permissions on '/layers'...
[prepare] > Setting permissions on '/workspace/source'...
[prepare] > Parsing additional configuration...
[prepare] -> Parsing env variables...
[prepare] > Processing any environment variables...
[prepare] --> Creating 'env' directory: /platform/env

[create] Warning: No cached data will be used, no cache specified.
[create] ERROR: failed to exec as user 1001:1000: operation not permitted

container step-create has failed  : [{"key":"StartedAt","value":"2025-11-17T10:31:51.146Z","type":3}]