http-add-on/docs/install.md

Installing the KEDA HTTP Add On

The HTTP Add On is highly modular and, as expected, builds on top of KEDA core. Below are some additional components:

• Operator - watches for ScaledHTTPObject CRD resources and creates necessary backing Kubernetes resources (e.g. Deployments, Services, ScaledObjects, and so forth)
• Scaler - communicates scaling-related metrics to KEDA. By default, the operator will install this for you as necessary.
• Interceptor - a cluster-internal proxy that proxies incoming HTTP requests, communicating HTTP queue size metrics to the scaler, and holding requests in a temporary request queue when there are not yet any available app Pods ready to serve. By default, the operator will install this for you as necessary.

There is pending work in KEDA that will eventually make this component optional. See issue #6 in this repository for even more background

Installing KEDA

Before you install any of these components, you need to install KEDA. Below are simplified instructions for doing so with Helm, but if you need anything more customized, please see the official KEDA deployment documentation.

If you need to install Helm, refer to the installation guide

helm repo add kedacore https://kedacore.github.io/charts
helm repo update
make helm-upgrade-keda

This document will rely on environment variables such as ${NAMESPACE} to indicate a value you should customize and provide to the relevant command. In the above helm install command, ${NAMESPACE} should be the namespace you'd like to install KEDA into. KEDA must be installed in every namespace that you'd like to host KEDA-HTTP powered apps.

Installing HTTP Components

This repository comes with a Helm chart built in. To install the HTTP add on with sensible defaults, first check out this repository and cd into the root directory (if you haven't already):

git clone https://github.com/kedacore/http-add-on.git
cd http-add-on

Next, install the HTTP add on. The below command will install the add on if it doesn't already exist:

make helm-upgrade-operator

Installing the HTTP add on won't affect any running workloads in your cluster. You'll need to install an HTTPScaledObject for each individual Deployment you want to scale. For more on how to do that, please see the walkthrough.

There are a few environment variables in the above command that you can set to customize how it behaves:

• NAMESPACE - which Kubernetes namespace to install KEDA-HTTP. This should be the same as where you installed KEDA itself (required)
• OPERATOR_DOCKER_IMG - the name of the operator's Docker image (optional - falls back to the latest release)
• SCALER_DOCKER_IMG - the name of the scaler's Docker image (optional - falls back to the latest release)
• INTERCEPTOR_DOCKER_IMG - the name of the interceptor's Docker image (optional - falls back to the latest release)

I recommend using direnv to store your environment variables

If You're Installing into a Microk8s Cluster

You might be working with a local development cluster like Microk8s, which offers a local, in-cluster registry. In this case, the previous *_DOCKER_IMG variables won't work for the Helm chart and you'll need to use a custom helm command such as the below:

helm upgrade kedahttp ./charts/keda-http-operator \
    --install \
    --namespace ${NAMESPACE} \
    --create-namespace \
    --set image=localhost:32000/keda-http-operator \
	--set images.scaler=localhost:32000/keda-http-scaler \
	--set images.interceptor=localhost:32000/keda-http-interceptor

In the above command, localhost:32000 is the address of the registry from inside a Microk8s cluster.