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Development

This doc explains how to setup a development environment so you can get started contributing to Knative Serving. Also take a look at:

Prerequisites

Follow the instructions below to set up your development environment. Once you meet these requirements, you can make changes and deploy your own version of Knative Serving!

Before submitting a PR, see also CONTRIBUTING.md.

Sign up for GitHub

Start by creating a GitHub account, then setup GitHub access via SSH.

Install requirements

You must install these tools:

  1. go: The language Knative Serving is built in (1.14 or later)
  2. git: For source control
  3. ko: For development.
  4. kubectl: For managing development environments.

If you're working on and changing .proto files:

  1. protoc: For compiling protocol buffers.
  2. protoc-gen-gogofaster: For generating efficient golang code out of protocol buffers.

Create a cluster and a repo

  1. Set up a kubernetes cluster
    • Follow an install guide up through "Creating a Kubernetes Cluster"
    • You do not need to install Istio or Knative using the instructions in the guide. Simply create the cluster and come back here.
    • If you did install Istio/Knative following those instructions, that's fine too, you'll just redeploy over them, below.
  2. Set up a docker repository for pushing images. You can use any container image registry by adjusting the authentication methods and repository paths mentioned in the sections below.

Note: You'll need to be authenticated with your KO_DOCKER_REPO before pushing images. Run gcloud auth configure-docker if you are using Google Container Registry or docker login if you are using Docker Hub.

Setup your environment

To start your environment you'll need to set these environment variables (we recommend adding them to your .bashrc):

  1. GOPATH: If you don't have one, simply pick a directory and add export GOPATH=...
  2. $GOPATH/bin on PATH: This is so that tooling installed via go get will work properly.
  3. KO_DOCKER_REPO: The docker repository to which developer images should be pushed (e.g. gcr.io/[gcloud-project]).
  • Note: if you are using docker hub to store your images your KO_DOCKER_REPO variable should be docker.io/<username>.
  • Note: Currently Docker Hub doesn't let you create subdirs under your username.

.bashrc example:

export GOPATH="$HOME/go"
export PATH="${PATH}:${GOPATH}/bin"
export KO_DOCKER_REPO='gcr.io/my-gcloud-project-id'

Checkout your fork

The Go tools require that you clone the repository to the src/knative.dev/serving directory in your GOPATH.

To check out this repository:

  1. Create your own fork of this repo
  2. Clone it to your machine:
mkdir -p ${GOPATH}/src/knative.dev
cd ${GOPATH}/src/knative.dev
git clone [email protected]:${YOUR_GITHUB_USERNAME}/serving.git
cd serving
git remote add upstream https://github.com/knative/serving.git
git remote set-url --push upstream no_push

Adding the upstream remote sets you up nicely for regularly syncing your fork.

Once you reach this point you are ready to do a full build and deploy as described below.

Starting Knative Serving

Once you've setup your development environment, stand up Knative Serving. Note that if you already installed Knative to your cluster, redeploying the new version should work fine, but if you run into trouble, you can easily clean your cluster up and try again.

Setup cluster admin

Your user must be a cluster admin to perform the setup needed for Knative. This should be the case by default if you've provisioned your own Kubernetes cluster. In particular, you'll need to be able to create Kubernetes cluster-scoped Namespace, CustomResourceDefinition, ClusterRole, and ClusterRoleBinding objects.

Resource allocation for Kubernetes

Please allocate sufficient resources for Kubernetes, especially when you run a Kubernetes cluster on your local machine. We recommend allocating at least 6 CPUs and 8G memory assuming a single node Kubernetes installation, and allocating at least 4 CPUs and 8G memory for each node assuming a 3-node Kubernetes installation. Please go back to your cluster setup to reconfigure your Kubernetes cluster in your designated environment, if necessary.

Deploy Istio

kubectl apply -f ./third_party/istio-stable/istio-crds.yaml
while [[ $(kubectl get crd gateways.networking.istio.io -o jsonpath='{.status.conditions[?(@.type=="Established")].status}') != 'True' ]]; do
  echo "Waiting on Istio CRDs"; sleep 1
done
kubectl apply -f ./third_party/istio-stable/istio-minimal.yaml

Follow the instructions if you need to set up static IP for Ingresses in the cluster.

If you want to adopt preinstalled Istio, please check whether the cluster-local-gateway Service is deployed in namespace istio-system or not (you can check by running kubectl get service cluster-local-gateway -n istio-system). If it's not installed, please install it with following command. You could also adjust parameters if needed.

kubectl apply -f ./third_party/istio-stable/istio-knative-extras.yaml

If you want to customize the istio*.yaml files you can refer to third_party/istio-<VERSION>-latest/download-istio.sh how these templates were generated.

Deploy cert-manager

  1. Deploy cert-manager CRDs

    kubectl apply -f ./third_party/cert-manager-0.12.0/cert-manager-crds.yaml
while [[ $(kubectl get crd certificates.cert-manager.io -o jsonpath='{.status.conditions[?(@.type=="Established")].status}') != 'True' ]]; do
  echo "Waiting on Cert-Manager CRDs"; sleep 1
done

  2. Deploy cert-manager

    If you want to use the feature of automatically provisioning TLS for Knative services, you need to install the full cert-manager.

    kubectl apply -f ./third_party/cert-manager-0.12.0/cert-manager.yaml

Deploy Knative Serving

This step includes building Knative Serving, creating and pushing developer images and deploying them to your Kubernetes cluster. If you're developing locally (for example, using Docker-on-Mac), set KO_DOCKER_REPO=ko.local to avoid needing to push your images to an off-machine registry.

Run:

ko apply --selector knative.dev/crd-install=true -f config/
while [[ $(kubectl get crd images.caching.internal.knative.dev -o jsonpath='{.status.conditions[?(@.type=="Established")].status}') != 'True' ]]; do
  echo "Waiting on Knative CRDs"; sleep 1
done

ko apply -f config/

# Optional steps

# Run post-install job to setup nice XIP.IO domain name.  This only works
# if your Kubernetes LoadBalancer has an IPv4 address.
ko delete -f config/post-install/default-domain.yaml --ignore-not-found
ko apply -f config/post-install/default-domain.yaml

The above step is equivalent to applying the serving-crds.yaml, serving-core.yaml, serving-hpa.yaml and serving-nscert.yaml for released versions of Knative Serving and additionally applying net-istio as the ingress implementation.

You can see things running with:

kubectl -n knative-serving get pods
NAME                                  READY   STATUS    RESTARTS   AGE
activator-7454cd659f-rrz86            1/1     Running   0          105s
autoscaler-58cbfd4985-fl5h7           1/1     Running   0          105s
autoscaler-hpa-77964b9b8c-9sbgq       1/1     Running   0          105s
controller-847b7cc977-5mvvq           1/1     Running   0          105s
istio-webhook-69bf66f869-cgc4l        1/1     Running   0          105s
networking-istio-dcf7944fb-5m25h      1/1     Running   0          105s
networking-ns-cert-56c58544db-sgstd   1/1     Running   0          105s
webhook-6b6c77567f-flr59              1/1     Running   0          105s

You can access the Knative Serving Controller's logs with:

kubectl -n knative-serving logs $(kubectl -n knative-serving get pods -l app=controller -o name) -c controller

If you're using a GCP project to host your Kubernetes cluster, it's good to check the Discovery & load balancing page to ensure that all services are up and running (and not blocked by a quota issue, for example).

Install logging and monitoring backends

Run:

kubectl apply -R -f config/monitoring/100-namespace.yaml \
    -f third_party/config/monitoring/logging/elasticsearch \
    -f config/monitoring/logging/elasticsearch \
    -f third_party/config/monitoring/metrics/prometheus \
    -f config/monitoring/metrics/prometheus \
    -f config/monitoring/tracing/zipkin

Iterating

As you make changes to the code-base, there are two special cases to be aware of:

  • If you change an input to generated code, then you must run ./hack/update-codegen.sh. Inputs include:

    • API type definitions in pkg/apis/serving/v1/.
    • Type definitions annotated with // +k8s:deepcopy-gen=true.
    • The _example value of config maps (to keep the knative.dev/example-checksum label in sync).
    • .proto files. Run ./hack/update-codegen.sh with the --generate-protobufs flag to enable protocol buffer generation.

  • If you change a package's deps (including adding an external dependency), then you must run ./hack/update-deps.sh.

These are both idempotent, and we expect that running these at HEAD to have no diffs. Code generation and dependencies are automatically checked to produce no diffs for each pull request.

update-deps.sh runs go get/mod command. In some cases, if newer dependencies are required, you need to run "go get" manually.

Once the codegen and dependency information is correct, redeploying the controller is simply:

ko apply -f config/controller.yaml

Or you can clean it up completely and completely redeploy Knative Serving.

Updating existing dependencies

To update existing dependencies execute

./hack/update-deps.sh --upgrade && ./hack/update-codegen.sh

Clean up

You can delete all of the service components with:

ko delete --ignore-not-found=true \
  -f config/monitoring/100-namespace.yaml \
  -f config/ \
  -f ./third_party/istio-stable/istio-minimal.yaml \
  -f ./third_party/istio-stable/istio-crds.yaml \
  -f ./third_party/cert-manager-0.12.0/cert-manager-crds.yaml \
  -f ./third_party/cert-manager-0.12.0/cert-manager.yaml

Telemetry

To access Telemetry see: