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Sender Identity for Knative Eventing

Flag name: authentication-oidc

Stage: Alpha, disabled by default

Tracking issue: #6806

Overview

Currently, event delivery within the cluster is unauthenticated, and an addressable event consumer cannot determine the identity of any sender.

Knative Eventing Addressables expose their OIDC Audience in their status as part of their address (e.g. .status.address.audience) and require requests containing an OIDC access token issued for this audience.

Knative Eventing Souces request an OIDC access token for the targets audience and add them to the request. A per-source dedicated Service Account is used as the identity for the request.

Prerequisites

Note

To not provide the access token in cleartext over the wire, transport-encryption should be enabled as well. Take a look at Transport-Encryption, which explains how to enable the transport encryption feature flag.

Compatibility

OIDC authentication is currently supported for the following components:

Sender Identity Configuration

The possible values for authentication-oidc are:

  • disabled
    • No change in behaviour
  • enabled
    • Addressables announce their audience in their status
    • Sources add an Authorization Header to their request containing an access token for their target

For example, to enable sender identity, the config-features ConfigMap will look like the following:

apiVersion: v1
kind: ConfigMap
metadata:
  name: config-features
  namespace: knative-eventing
data:
  authentication-oidc: "enabled"

Verifying that the feature is working

Save the following YAML into a file called default-broker-example.yaml

# default-broker-example.yaml

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: br

---
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: tr
spec:
  broker: br
  subscriber:
    ref:
      apiVersion: v1
      kind: Service
      name: event-display

---
apiVersion: v1
kind: Service
metadata:
  name: event-display
spec:
  selector:
    app: event-display
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

---
apiVersion: v1
kind: Pod
metadata:
  name: event-display
  labels:
    app: event-display
spec:
  containers:
    - name: event-display
      image: gcr.io/knative-releases/knative.dev/eventing/cmd/event_display
      imagePullPolicy: Always
      ports:
        - containerPort: 8080

Apply the default-broker-example.yaml file into a test namespace authentication-oidc-test:

kubectl create namespace authentication-oidc-test

kubectl apply -n authentication-oidc-test -f default-broker-example.yaml

Verify that the Broker announces its audience: 

kubectl -n authentication-oidc-test get broker br -o yaml

Example output:

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: br
  namespace: authentication-oidc-test
spec:
  config:
    # ...
  delivery:
    # ...
status:
  address:
    audience: eventing.knative.dev/broker/authentication-oidc-test/br
    name: http
    url: http://broker-ingress.knative-eventing.svc.cluster.local/authentication-oidc-test/br
  annotations:
  # ...

Send events to the Broker using OIDC authentication:

  1. Create an OIDC token (access token): 

    kubectl -n authentication-oidc-test create serviceaccount oidc-test-user; kubectl -n authentication-oidc-test create token oidc-test-user --audience eventing.knative.dev/broker/authentication-oidc-test/br

    Example output: 

    serviceaccount/oidc-test-user created
eyJhbGciOiJSUzI1NiIsImtpZCI6IlZBWmppNEVJZkVSVDZoYTA4dU1xTWJxSHFYQTgtbE00VU1tMmpFZUNuakUifQ.eyJhdWQiOlsiZXZlbnRpbmcua25hdGl2ZS5kZXYvYnJva2VyL2F1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdC9iciJdLCJleHAiOjE3MDU5MzQyMTQsImlhdCI6MTcwNTkzMDYxNCwiaXNzIjoiaHR0cHM6Ly9rdWJlcm5ldGVzLmRlZmF1bHQuc3ZjIiwia3ViZXJuZXRlcy5pbyI6eyJuYW1lc3BhY2UiOiJhdXRoZW50aWNhdGlvbi1vaWRjLXRlc3QiLCJzZXJ2aWNlYWNjb3VudCI6eyJuYW1lIjoib2lkYy10ZXN0LXVzZXIiLCJ1aWQiOiJkNGM5MjkzMy1kZThlLTRhNDYtYjkxYS04NjRjNTZkZDU4YzIifX0sIm5iZiI6MTcwNTkzMDYxNCwic3ViIjoic3lzdGVtOnNlcnZpY2VhY2NvdW50OmF1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdDpvaWRjLXRlc3QtdXNlciJ9.Taqk11LRC7FKMbt_1VvmRjMolJL54CFGbRT85ZgNdG8YT6MXiw_S2rMHxLyC9RyX0hb720szHhiVIPj15jbz597egSBbcuk-f_MCsUFMyK1Nb95blo6UNDFKIQxC5_aleoT-qaGtXlt4OEE6RjA28mFeeSCjcJUCRdLGLuSiQT47lxLqNK5OfKjd4wGMiUsbBzOcXor9ouJc1lr4gFlCzzIMJNLfXU0O_AB8J--yh6wP07Q-2AWwwv7J1CtZCrIqaPBFjWnplLqtBgo33ZNbqomXyYVdO_0HlEN9XtlK_y_2veEvKOkINzpic_ipf5ZhTxEpXWaztZzdkWd-e2mHMg

  2. Send a curl request to the Broker 

    kubectl -n authentication-oidc-test run curl --image=curlimages/curl -i --tty -- sh

# Send unauthenticated request (should result in a 401)
curl -v http://broker-ingress.knative-eventing.svc.cluster.local/authentication-oidc-test/br -H "Content-Type:application/json" -H "Ce-Id:1" -H "Ce-Source:cloud-event-example" -H "Ce-Type:myCloudEventGreeting" -H "Ce-Specversion:1.0" -d "{\"name\": \"unauthenticated\"}"

# Send authenticated request (should request in 202)
curl -v http://broker-ingress.knative-eventing.svc.cluster.local/authentication-oidc-test/br -H "Content-Type:application/json" -H "Ce-Id:1" -H "Ce-Source:cloud-event-example" -H "Ce-Type:myCloudEventGreeting" -H "Ce-Specversion:1.0" -H "Authorization: Bearer <YOUR-TOKEN-FROM-STEP-1>" -d "{\"name\": \"authenticated\"}"

    Example output: 

    $ curl -v http://broker-ingress.knative-eventing.svc.cluster.local/authentication-oidc-test/br -H "Content-Type:application/json" -H "Ce-Id:1" -H "Ce-Source:cloud-event-example" -H "Ce-Type:myCloudEventGreeting" -H "Ce-Specversion:1.0" -d "{\"name\": \"unauthenticated\"}"

* Host broker-ingress.knative-eventing.svc.cluster.local:80 was resolved.
* IPv6: (none)
* IPv4: 10.96.110.167
*   Trying 10.96.110.167:80...
* Connected to broker-ingress.knative-eventing.svc.cluster.local (10.96.110.167) port 80
> POST /authentication-oidc-test/br HTTP/1.1
> Host: broker-ingress.knative-eventing.svc.cluster.local
> User-Agent: curl/8.5.0
> Accept: */*
> Content-Type:application/json
> Ce-Id:1
> Ce-Source:cloud-event-example
> Ce-Type:myCloudEventGreeting
> Ce-Specversion:1.0
> Content-Length: 27
> 
< HTTP/1.1 401 Unauthorized
< Allow: POST, OPTIONS
< Date: Mon, 22 Jan 2024 13:33:57 GMT
< Content-Length: 0
< 
* Connection #0 to host broker-ingress.knative-eventing.svc.cluster.local left intact

~ $ curl -v http://broker-ingress.knative-eventing.svc.cluster.local/authentication-oidc-test/br -H "Content-Type:application/json" -H "Ce-Id:1" -H "Ce-Source:cloud-event-example" -H "Ce-Type:myCloudEventGreeting" -H "Ce-Specversion:1.0" -H "Authorization: Bearer eyJhbGciOiJSUzI1NiIsImtpZCI6IlZBWmppNEVJZkVSV
DZoYTA4dU1xTWJxSHFYQTgtbE00VU1tMmpFZUNuakUifQ.eyJhdWQiOlsiZXZlbnRpbmcua25hdGl2ZS5kZXYvYnJva2VyL2F1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdC9iciJdLCJleHAiOjE3MDU5MzQwMDgsImlhdCI6MTcwNTkzMDQwOCwiaXNzIjoiaHR0cHM6Ly9rdWJlcm5ldGVzLmRlZmF1bHQuc3ZjIiwia3ViZXJuZXRlcy5pbyI6eyJuYW1lc3BhY2UiOiJhdXRoZW50aWNhdGlvbi1vaWRjLXRlc3QiLCJ
zZXJ2aWNlYWNjb3VudCI6eyJuYW1lIjoib2lkYy10ZXN0LXVzZXIiLCJ1aWQiOiI3MTlkMWI3ZC1hZjBkLTQzMDAtOGUxNy1lNTk4YmZmN2VmYTIifX0sIm5iZiI6MTcwNTkzMDQwOCwic3ViIjoic3lzdGVtOnNlcnZpY2VhY2NvdW50OmF1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdDpvaWRjLXRlc3QtdXNlciJ9.UrleSi54mxgThesyrC4kzG7rO3-Fic1B3kPOY8k1l-oslhvw3dbT0n24bvP96m7Ke4ZGoXE3Efo
966LZM_61-bfntFbw8kTRe_w6wGXVGpadrBSZsIChVgFYqsPNX_7r1LSNTy5tFXze9phVz6EpO7XeUct_PXyYLASNw0LNXWyqbcEqBNtgWmDKHaS_1pIscFP6MaoGVj968hpVqli8O6okQUQitIoPwFEGAIbaBlIX6Z5ZqlGwL9eqbIiNEMEgjlduv9dyZVmpDc0hsF6GHk2RnAhLeOniUNdUo4VO3z27TJY5JYK7xIMBD6Z5dUAhud9ofA8VWEl7Mziw4fsdCw" -d "{\"name\": \"authenticated\"}"
* Host broker-ingress.knative-eventing.svc.cluster.local:80 was resolved.
* IPv6: (none)
* IPv4: 10.96.110.167
*   Trying 10.96.110.167:80...
* Connected to broker-ingress.knative-eventing.svc.cluster.local (10.96.110.167) port 80
> POST /authentication-oidc-test/br HTTP/1.1
> Host: broker-ingress.knative-eventing.svc.cluster.local
> User-Agent: curl/8.5.0
> Accept: */*
> Content-Type:application/json
> Ce-Id:1
> Ce-Source:cloud-event-example
> Ce-Type:myCloudEventGreeting
> Ce-Specversion:1.0
> Authorization: Bearer eyJhbGciOiJSUzI1NiIsImtpZCI6IlZBWmppNEVJZkVSVDZoYTA4dU1xTWJxSHFYQTgtbE00VU1tMmpFZUNuakUifQ.eyJhdWQiOlsiZXZlbnRpbmcua25hdGl2ZS5kZXYvYnJva2VyL2F1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdC9iciJdLCJleHAiOjE3MDU5MzQwMDgsImlhdCI6MTcwNTkzMDQwOCwiaXNzIjoiaHR0cHM6Ly9rdWJlcm5ldGVzLmRlZmF1bHQuc3ZjIiwia3ViZXJuZXRlcy5pbyI6eyJuYW1lc3BhY2UiOiJhdXRoZW50aWNhdGlvbi1vaWRjLXRlc3QiLCJzZXJ2aWNlYWNjb3VudCI6eyJuYW1lIjoib2lkYy10ZXN0LXVzZXIiLCJ1aWQiOiI3MTlkMWI3ZC1hZjBkLTQzMDAtOGUxNy1lNTk4YmZmN2VmYTIifX0sIm5iZiI6MTcwNTkzMDQwOCwic3ViIjoic3lzdGVtOnNlcnZpY2VhY2NvdW50OmF1dGhlbnRpY2F0aW9uLW9pZGMtdGVzdDpvaWRjLXRlc3QtdXNlciJ9.UrleSi54mxgThesyrC4kzG7rO3-Fic1B3kPOY8k1l-oslhvw3dbT0n24bvP96m7Ke4ZGoXE3Efo966LZM_61-bfntFbw8kTRe_w6wGXVGpadrBSZsIChVgFYqsPNX_7r1LSNTy5tFXze9phVz6EpO7XeUct_PXyYLASNw0LNXWyqbcEqBNtgWmDKHaS_1pIscFP6MaoGVj968hpVqli8O6okQUQitIoPwFEGAIbaBlIX6Z5ZqlGwL9eqbIiNEMEgjlduv9dyZVmpDc0hsF6GHk2RnAhLeOniUNdUo4VO3z27TJY5JYK7xIMBD6Z5dUAhud9ofA8VWEl7Mziw4fsdCw
> Content-Length: 25
> 
< HTTP/1.1 202 Accepted
< Allow: POST, OPTIONS
< Date: Mon, 22 Jan 2024 13:34:27 GMT
< Content-Length: 0
< 
* Connection #0 to host broker-ingress.knative-eventing.svc.cluster.local left intact
~ $
    3. Verify the 2nd event reached the event-display pod 
    kubectl -n authentication-oidc-test logs event-display

    Example output: 

    ☁️  cloudevents.Event
Context Attributes,
  specversion: 1.0
  type: myCloudEventGreeting
  source: cloud-event-example
  id: 1
  datacontenttype: application/json
Extensions,
  knativearrivaltime: 2024-01-22T13:34:26.032199371Z
Data,
  {
    "name": "authenticated"
  }

Limitations with Istio

You might experience issues with the eventing integration with Istio and having the authentication-oidc feature flag enabeled, when the JWKS URI is represented via an IP. E.g. like in the following case:

$ kubectl get --raw /.well-known/openid-configuration | jq
{
  "issuer": "https://kubernetes.default.svc",
  "jwks_uri": "https://172.18.0.3:6443/openid/v1/jwks",
  ...
}

In this case you need to add the traffic.sidecar.istio.io/excludeOutboundIPRanges: <JWKS IP>/32 annotation to the pod templates of the following deployments:

  • imc-dispatcher
  • mt-broker-ingress
  • mt-broker-filter

For example:

$ kubectl -n knative-eventing patch deploy imc-dispatcher --patch '{"spec":{"template":{"metadata":{"annotations":{"traffic.sidecar.istio.io/excludeOutboundIPRanges":"172.18.0.3/32"}}}}}'
deployment.apps/imc-dispatcher patched

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