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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 (1.13 or later)
  2. git: For source control
  3. dep: For managing external Go dependencies.
  4. ko: For development.
  5. kubectl: For managing development environments.

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 [email protected]: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.

The value you use depends on your cluster setup: when using Minikube or Kubernetes on Docker Desktop, the user is your local user; when using GKE, the user is your GCP user.

# For GCP
kubectl create clusterrolebinding cluster-admin-binding \
  --clusterrole=cluster-admin \
  --user=$(gcloud config get-value core/account)

# For minikube or Kubernetes on Docker Desktop
kubectl create clusterrolebinding cluster-admin-binding \
  --clusterrole=cluster-admin \
  --user=$USER

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-1.2-latest/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-1.2-latest/istio-lean.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 cluster-local-gateway is deployed in namespace istio-system or not. If it's not installed, please install it with following commands. You could also adjust parameters if needed.

kubectl apply -f ./third_party/istio-1.2-latest/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-0.9.1/cert-manager-crds.yaml
while [[ $(kubectl get crd certificates.certmanager.k8s.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.

    # For kubernetes version 1.13 or above, --validate=false is not needed.
kubectl apply -f ./third_party/cert-manager-0.9.1/cert-manager.yaml --validate=false

Deploy Knative Serving

This step includes building Knative Serving, creating and pushing developer images and deploying them to your Kubernetes cluster.

First, edit config-network.yaml as instructed within the file. If this file is edited and deployed after Knative Serving installation, the changes in it will be effective only for newly created revisions. Alternatively, if you are developing on GKE, you can skip the editing and use the patching tool in hack/dev-patch-config-gke.sh after deploying knative.

Edited config-network.yaml example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: config-network
  namespace: knative-serving
  labels:
    serving.knative.dev/release: devel

data:
  istio.sidecar.includeOutboundIPRanges: "172.30.0.0/16,172.20.0.0/16,10.10.10.0/24"
  ingress.class: "istio.ingress.networking.knative.dev"

You should keep the default value for "istio.sidecar.includeOutboundIPRanges", when you use Minikube or Docker Desktop as the Kubernetes environment.

Next, run:

ko apply -f config/

# Optional steps

# Configure outbound network for GKE.
export PROJECT_ID="my-gcp-project-id"
# Set K8S_CLUSTER_ZONE if using a zonal cluster
export K8S_CLUSTER_ZONE="my-cluster-zone"
# Set K8S_CLUSTER_REGION if using a regional cluster
export K8S_CLUSTER_REGION="my-cluster-region"
./hack/dev-patch-config-gke.sh my-k8s-cluster-name

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

The above step is equivalent to applying the serving.yaml for released versions of Knative Serving.

You can see things running with:

kubectl -n knative-serving get pods
NAME                                READY   STATUS      RESTARTS   AGE
activator-5b87795885-f8t7k          2/2     Running     0          18m
autoscaler-6495f7f79d-86jsr         2/2     Running     0          18m
controller-5fd7fddc58-klmt4         1/1     Running     0          18m
default-domain-6hs98                0/1     Completed   0          13s
networking-istio-6755db495d-wtj4d   1/1     Running     0          18m
webhook-84b8c9886d-dsqqv            1/1     Running     0          18m

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)

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:

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 "dep ensure" command. In some cases, if newer dependencies are required, you need to run "dep ensure -update package-name" 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.

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-1.2-latest/istio.yaml \
  -f ./third_party/istio-1.2-latest/istio-crds.yaml \
  -f ./third_party/cert-manager-0.9.1/cert-manager-crds.yaml \
  -f ./third_party/cert-manager-0.9.1/cert-manager.yaml

Telemetry

To access Telemetry see: