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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 (1.12rc1 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.

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 and DOCKER_REPO_OVERRIDE: 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}:${GOPATH}/bin"
export KO_DOCKER_REPO='gcr.io/my-gcloud-project-name'
export DOCKER_REPO_OVERRIDE="${KO_DOCKER_REPO}"
export K8S_CLUSTER_OVERRIDE='my-k8s-cluster-name'

Make sure to configure authentication for your KO_DOCKER_REPO if required. To be able to push images to gcr.io/<project>, you need to run this once:

gcloud auth configure-docker

For K8S_CLUSTER_OVERRIDE, we expect that this name matches a cluster with authentication configured with kubectl. You can list the clusters you currently have configured via: kubectl config get-contexts. For the cluster you want to target, the value in the CLUSTER column should be put in this variable.

Checkout your fork

The Go tools require that you clone the repository to the src/github.com/knative/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/github.com/knative
cd ${GOPATH}/src/github.com/knative
git clone git@github.com:${YOUR_GITHUB_USERNAME}/serving.git
cd serving
git remote add upstream git@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 $K8S_USER_OVERRIDE must be a cluster admin to perform the setup needed for Knative.

The value you use depends on your cluster setup:

# When using Minikube, the K8s user is your local user.
export K8S_USER_OVERRIDE=$USER

# When using GKE, the K8s user is your GCP user.
export K8S_USER_OVERRIDE=$(gcloud config get-value core/account)

kubectl create clusterrolebinding cluster-admin-binding \
  --clusterrole=cluster-admin \
  --user="${K8S_USER_OVERRIDE?}"

Deploy Istio

kubectl apply -f ./third_party/istio-1.0.2/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-1.0.2/istio.yaml

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

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.

Next, run:

ko apply -f config/
./hack/dev-patch-config-gke.sh my-k8s-cluster-name  # optional

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-c8495dc9-z7xpz      2/2       Running   0          6d
autoscaler-66897845df-t5cwg   2/2       Running   0          6d
controller-699fb46bb5-xhlkg   1/1       Running   0          6d
webhook-76b87b8459-tzj6r      1/1       Running   0          6d

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/config/build/release.yaml \
  -f ./third_party/istio-1.0.2/istio.yaml \
  -f ./third_party/istio-1.0.2/istio-crds.yaml

Telemetry

To access Telemetry see: