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Driving Weave Flux - automations, locks and annotations

In this tutorial we want to get a better feel for what we can do with Weave Flux. We won't spend too much time with getting it up and running, so let's get that out of the way first.

In our example we are going to use the flux-get-started example deployment. So as your first step, please head to our example deployment and click on the "Fork" button.

Setup

Get the source code of Weave Flux:

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

In the next step, let's change the Git URL of Flux to point to our fork:

EDITOR deploy/flux-deployment.yaml

And update the following line

    [email protected]:weaveworks/flux-get-started

to point to your fork, e.g. if your Github Login is baloothebear, the line above should be

    [email protected]:baloothebear/flux-get-started

Save the file. For our simple case, that's all the configuration we need. Now it's time to deploy Flux. Simply run

kubectl apply -f deploy

Alternative: Using Helm for the setup

If you have never used Helm, you first need to

  • Download/install Helm

  • Set up Tiller. First create a service account and a cluster role binding for Tiller:

    kubectl -n kube-system create sa tiller
kubectl create clusterrolebinding tiller-cluster-rule \
  --clusterrole=cluster-admin \
  --serviceaccount=kube-system:tiller

    Deploy Tiller in the kube-system namespace:

    helm init --skip-refresh --upgrade --service-account tiller

Now you can take care of the actual installation. First add the Flux repository of Weaveworks:

helm repo add weaveworks https://weaveworks.github.io/flux

Apply the Helm Release CRD:

kubectl apply -f https://raw.githubusercontent.com/weaveworks/flux/master/deploy-helm/flux-helm-release-crd.yaml

Install Weave Flux and its Helm Operator by specifying your fork URL. Just make sure you replace YOURUSER with your GitHub username in the command below:

helm upgrade -i flux \
--set helmOperator.create=true \
--set helmOperator.createCRD=false \
--set [email protected]:YOURUSER/flux-get-started \
--namespace default \
weaveworks/flux

Note: In this tutorial we keep things simple, so we deploy Flux into the default namespace. Normally you would pick a separate namespace for it. fluxctl has the k8s-fwd-ns option for specifying the right namespace.

Connecting to your git config

The first step is done. Flux is now and up running (you can confirm by running kubectl get pods --all-namespaces).

In the second step we will use fluxctl to talk to Flux in the cluster and interact with the deployments. First, please install fluxctl. (It enables you to drive all of Weave Flux, so have a look at the output of fluxctl -h to get a better idea.)

Note: Another option (without installing fluxctl is to take a look at the resulting annotation changes and make the changes in Git. This is GitOps after all. :-)

To enable Weave Flux to sync your config, you need to add the deployment key to your fork.

Get your Flux deployment key by running

fluxctl identity

Copy/paste the key and add it to https://github.com/YOUR-USER-ID/flux-get-started/settings/keys/new and enable write access for it.

Wait for sync to happen or run

fluxctl sync

Driving Weave Flux

After syncing, Weave Flux will find out which workloads there are, which images are available and what needs doing. To find out which workloads are managed by Weave Flux, run

fluxctl list-workloads -a

Notice that podinfo is on v1.3.2 and in state automated.

To check which images are avaible for podinfo run

fluxctl list-images -c demo:deployment/podinfo

Now let's change the policy for podinfo to target 1.4.* releases:

fluxctl policy -c demo:deployment/podinfo --tag-all='1.4.*'

On the command-line you should see a message just like this one:

CONTROLLER               STATUS   UPDATES
demo:deployment/podinfo  success
Commit pushed:  4755a3b

If you now go back to https://github.com/YOUR-USER-ID/flux-get-started in your browser, you will notice that Weave Flux has made a commit on your behalf. The policy change is now in Git, which is great for transparency and for defining expected state.

It should look a little something like this:

--- a/workloads/podinfo-dep.yaml
+++ b/workloads/podinfo-dep.yaml
@@ -8,8 +8,8 @@ metadata:
     app: podinfo
   annotations:
     flux.weave.works/automated: "true"
-    flux.weave.works/tag.init: regexp:^3.*
-    flux.weave.works/tag.podinfod: semver:~1.3
+    flux.weave.works/tag.init: glob:1.4.*
+    flux.weave.works/tag.podinfod: glob:1.4.*
 spec:
   strategy:
     rollingUpdate:

If you have a closer look at the last change which was committed, you'll see that the image filtering pattern has been changed. (Our docs explain how to use semver, glob, regex filtering.)

Again, wait for the sync to happen or run

fluxctl sync

To check which image is current, run

fluxctl list-images -c demo:deployment/podinfo

In our case this is 1.4.2 (it could be a later image too). Let's say an engineer found that 1.4.2 was faulty and we have to go back to 1.4.1. That's easy.

Rollback to 1.4.1:

fluxctl release -c demo:deployment/podinfo -i stefanprodan/podinfo:1.4.1

The response should be

Submitting release ...
CONTROLLER               STATUS   UPDATES
demo:deployment/podinfo  success  podinfod: stefanprodan/podinfo:1.4.2 -> 1.4.1
Commit pushed:  426d723
Commit applied: 426d723

and the diff for this is going to look like this:

--- a/workloads/podinfo-dep.yaml
+++ b/workloads/podinfo-dep.yaml
@@ -33,7 +33,7 @@ spec:
         - "1"
       containers:
       - name: podinfod
-        image: stefanprodan/podinfo:1.3.2
+        image: stefanprodan/podinfo:1.4.1
         imagePullPolicy: IfNotPresent
         ports:
         - containerPort: 9898

Lock to 1.4.1 with a message describing why:

fluxctl lock -c demo:deployment/podinfo -m "1.4.2 does not work for us"

The resulting diff should look like this

--- a/workloads/podinfo-dep.yaml
+++ b/workloads/podinfo-dep.yaml
@@ -10,6 +10,7 @@ metadata:
     app: podinfo
   annotations:
     flux.weave.works/automated: "true"
     flux.weave.works/tag.init: glob:1.4.*
     flux.weave.works/tag.podinfod: glob:1.4.*
+    flux.weave.works/locked: 'true'
 spec:
   strategy:
     rollingUpdate:

And that's it. At the end of this tutorial, you have automated, locked and annotated deployments with Weave Flux.

Another tip, if you should get stuck anywhere: check what Flux is doing. You can do that by simply running

kubectl logs -n default deploy/flux -f

If you should have any questions, find us on Slack in the #flux channel, get an invite to it here.