node.js - Cannot invoke Google Cloud Function from GCP Scheduler

Question

I've been trying to invoke a GCP function (--runtime nodejs8 --trigger-http) from GCP scheduler, both located within the same project. I can only make it work, if I grant unauthenticated access by adding the allUsers member to the functions permissions, with the Cloud Functions-Invoker role applied to it. However, when I only use the service account of the scheduler as the Cloud Functions-Invoker, I get a PERMISSION DENIED Error.

I created a hello world example, to show in detail, how my setup looks like.

1. I set up a service account:

gcloud iam service-accounts create scheduler --display-name="Task Schedule Runner"

2. Setting the role:

svc_policy.json:
{
    "bindings": [
      {
        "members": [
          "serviceAccount:[email protected]"
        ],
        "role": "roles/cloudscheduler.serviceAgent"
      }    
    ]
  }

gcloud iam service-accounts set-iam-policy [email protected] svc_policy.json  -q

3. Deploying the Cloud Function:

gcloud functions deploy helloworld --runtime nodejs8 --trigger-http --entry-point=helloWorld

4. Adding the service account as a member to the function:

gcloud functions add-iam-policy-binding helloworld --member serviceAccount:[email protected] --role roles/cloudfunctions.invoker

5. Creating the scheduler job:

gcloud beta scheduler jobs create http test-job --schedule "5 * * * *" --http-method=GET --uri=https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld --oidc-service-account-email=scheduler@mwsdata-1544225920485.iam.gserviceaccount.com --oidc-token-audience=https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld

Log: PERMISSION DENIED

{
 httpRequest: {
 }
 insertId: "1ny5xuxf69w0ck"  
 jsonPayload: {
  @type: "type.googleapis.com/google.cloud.scheduler.logging.AttemptFinished"   
  jobName: "projects/mwsdata-1544225920485/locations/europe-west1/jobs/test-job"   
  status: "PERMISSION_DENIED"   
  targetType: "HTTP"   
  url: "https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld"   
 }
 logName: "projects/mwsdata-1544225920485/logs/cloudscheduler.googleapis.com%2Fexecutions"  
 receiveTimestamp: "2020-02-04T22:05:05.248707989Z"  
 resource: {
  labels: {
   job_id: "test-job"    
   location: "europe-west1"    
   project_id: "mwsdata-1544225920485"    
  }
  type: "cloud_scheduler_job"   
 }
 severity: "ERROR"  
 timestamp: "2020-02-04T22:05:05.248707989Z"  
}

Update

Here are the corresponding settings.

Scheduler Service Account

gcloud iam service-accounts get-iam-policy [email protected]

bindings:
- members:
  - serviceAccount:[email protected]
  role: roles/cloudscheduler.serviceAgent
etag: BwWdxuiGNv4=
version: 1

IAM Policy of the function:

gcloud functions get-iam-policy helloworld    
bindings:
- members:
  - serviceAccount:[email protected]
  role: roles/cloudfunctions.invoker
etag: BwWdxyDGOAY=
version: 1

Function Description

gcloud functions describe helloworld
availableMemoryMb: 256
entryPoint: helloWorld
httpsTrigger:
  url: https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld
ingressSettings: ALLOW_ALL
labels:
  deployment-tool: cli-gcloud
name: projects/mwsdata-1544225920485/locations/us-central1/functions/helloworld
runtime: nodejs8
serviceAccountEmail: [email protected]
sourceUploadUrl: https://storage.googleapis.com/gcf-upload-us-central1-671641e6-3f1b-41a1-9ac1-558224a1638a/b4a0e407-69b9-4f3d-a00d-7543ac33e013.zip?GoogleAccessId=service-617967399269@gcf-admin-robot.iam.gserviceaccount.com&Expires=1580854835&Signature=S605ODVtOpnU4LIoRT2MnU4OQN3PqhpR0u2CjgcpRcZZUXstQ5kC%2F1rT6Lv2SusvUpBrCcU34Og2hK1QZ3dOPluzhq9cXEvg5MX1MMDyC5Y%2F7KGTibnV4ztFwrVMlZNTj5N%2FzTQn8a65T%2FwPBNUJWK0KrIUue3GemOQZ4l4fCf9v4a9h6MMjetLPCTLQ1BkyFUHrVnO312YDjSC3Ck7Le8OiXb7a%2BwXjTDtbawR20NZWfgCCVvL6iM9mDZSaVAYDzZ6l07eXHXPZfrEGgkn7vXN2ovMF%2BNGvwHvTx7pmur1yQaLM4vRRprjsnErU%2F3p4JO3tlbbFEf%2B69Wd9dyIKVA%3D%3D
status: ACTIVE
timeout: 60s
updateTime: '2020-02-04T21:51:15Z'
versionId: '1'

Scheduler Job Description

gcloud scheduler jobs describe test-job
attemptDeadline: 180s
httpTarget:
  headers:
    User-Agent: Google-Cloud-Scheduler
  httpMethod: GET
  oidcToken:
    audience: https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld
    serviceAccountEmail: [email protected]
  uri: https://us-central1-mwsdata-1544225920485.cloudfunctions.net/helloworld
lastAttemptTime: '2020-02-05T09:05:00.054111Z'
name: projects/mwsdata-1544225920485/locations/europe-west1/jobs/test-job
retryConfig:
  maxBackoffDuration: 3600s
  maxDoublings: 16
  maxRetryDuration: 0s
  minBackoffDuration: 5s
schedule: 5 * * * *
scheduleTime: '2020-02-05T10:05:00.085854Z'
state: ENABLED
status:
  code: 7
timeZone: Etc/UTC
userUpdateTime: '2020-02-04T22:02:31Z'

Answer 1

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