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get-started.md

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Installing Weave Flux Manually
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Get started with Flux

This short guide shows a self-contained example of Flux and just takes a couple of minutes to get set up. By the end you will have Flux running in your cluster and it will be deploying any code changes for you.

Note: If you would like to install Flux using Helm, refer to the Helm section.

Prerequisites

You will need to have Kubernetes set up. For a quick local test, you can use minikube or kubeadm. Any other Kubernetes setup will work as well though.

When using a cluster in the cloud (e.g. GKE), use nodes with at least 2 CPU's. When using nodes with only 1 CPU (like n1-standard-1), an upgrade may be stuck with not enough CPU resources. This issue usually manifests itself in the form of pods hanging in the PENDING state, which looks something like:

$ kubectl describe pod/helloworld-... | tail -3
Events:
  Type     Reason            Age                From               Message
  ----     ------            ----               ----               -------
  Warning  FailedScheduling  3m (x37 over 13m)  default-scheduler  0/2 nodes are available: 2 Insufficient cpu.

A Note on GKE with RBAC enabled

If working on e.g. GKE with RBAC enabled, you will need to add a clusterrolebinding:

kubectl create clusterrolebinding "cluster-admin-$(whoami)" --clusterrole=cluster-admin --user="$(gcloud config get-value core/account)"

to avoid an error along the lines of

Error from server (Forbidden): error when creating "deploy/flux-account.yaml": clusterroles.rbac.authorization.k8s.io "flux" is forbidden: attempt to grant extra privileges:

Set up Flux

Get Flux:

git clone https://github.com/weaveworks/flux
cd flux

Now you can go ahead and edit Flux's deployment manifest. At the very least you will have to change the --git-url parameter to point to the config repository for the workloads you want Flux to deploy for you. You are going to need access to this repository.

$EDITOR deploy/flux-deployment.yaml

In our example we are going to use flux-example. If you want to use that too, be sure to create a fork of it on Github and add the git URL to the config file above.

Deploying Flux to the cluster

In the next step, deploy Flux to the cluster:

kubectl apply -f deploy

Allow some time for all containers to get up and running. If you're impatient, run the following command and see the pod creation process.

watch kubectl get pods --all-namespaces

Giving write access

At startup Flux generates a SSH key and logs the public key. Find the SSH public key with:

kubectl logs deployment/flux | grep identity.pub | cut -d '"' -f2

Note: If you have downloaded fluxctl already, you can use fluxctl identity as well.

In order to sync your cluster state with git you need to copy the public key and create a deploy key with write access on your GitHub repository.

Open GitHub, navigate to your fork, go to Setting > Deploy keys, click on Add deploy key, give it a name, check Allow write access, paste the Flux public key and click Add key.

(Or replace YOURUSER with your Github ID in this url: https://github.com/YOURUSER/flux-example/settings/keys/new and paste the key there.)

Committing a small change

In this example we are using a simple example of a webservice and change its configuration to use a different message. The easiest way is to edit your fork of flux-example and change the msg argument.

Replace YOURUSER in https://github.com/YOURUSER/flux-example/blob/master/helloworld-deploy.yaml with your Github ID), open the URL in your browser, edit the file, change the argument value and commit the file.

You can check out the Flux logs with:

kubectl -n default logs deployment/flux -f

The default sync frequency is 5 minutes. This can be tweaked easily. By observing the logs you can see when the change landed in in the cluster.

Confirm the change landed

To access our webservice and check out its welcome message, simply run:

kubectl port-forward deployment/helloworld 8080:80 &
curl localhost:8080

Conclusion

As you can see, the actual steps to set up Flux, get our app deployed, give Flux access to it and see modifications land are very straight-forward and are a quite natural work-flow.

As a next step, you might want to dive deeper into how to control Flux or check out more sophisticated setups.