A critical topic in Cloud Native applications is the deployment strategy. We are no longer dealing with one monolithic application. We have several applications that have dependencies on each other and also have other dependencies like brokers or databases.
Applications have their own life cycle, so we should be able to execute independent Blue/Green deployment. All the applications and dependencies will not change their version at the same time.
Another important topic in the Cloud Native is Continuous Delivery. If we are going to have several applications doing Blue/Green deployment independently we have to automate it. We will use Helm, Argo Rollouts, Openshift GitOps, and of course Red Hat Openshift to help us.
Argo Rollouts is a Kubernetes controller and set of CRDs which provide advanced deployment capabilities such as blue-green, canary, canary analysis, experimentation, and progressive delivery features to Kubernetes. In this demo we are going to use blue-green capabilities.
In the next steps, we will see a real example of how to install, deploy and manage the life cycle of Cloud Native applications doing Blue/Green deployment using Argo Rollouts.
If you want to know more about Blue/Green deployment please read Blue/Green Deployment
Let's start with some theory...after that, we will have a hands-on example.
We are going to use very simple applications to test Blue/Green deployment. We have created two Quarkus applications Products and Discounts
Products call Discounts to get the product`s discount and expose an API with a list of products with its discounts.
To achieve Blue/Green deployment with Cloud Native applications using Argo Rollouts, we have designed this architecture.
OpenShift Components - Online
- Routes and Services declared with the suffix -online
- Routes mapped only to the online services
- Services mapped to the rollout.
OpenShift Components - Offline
- Routes and Services declared with the suffix -offline
- Routes mapped only to the offline services
- Services mapped to the rollout
This is an example of products rollout manifest:
strategy:
blueGreen:
activeService: products-umbrella-online
previewService: products-umbrella-offline
autoPromotionEnabled: false
prePromotionAnalysis:
templates:
- templateName: products-analysis-templateWe have defined an active or online service 'products-umbrella-online' and a preview or offline service 'products-umbrella-offline'. Final user will always use 'products-umbrella-online'. We have created an AnalysisTemplate 'products-analysis-template' that just validates the health of the application, for production environments a better analysis should be done. Argo Rollouts use this AnalysisTemplate to validate a new version and set it ready to be promoted or not. To learn more, please read this.
One of the best ways to package Cloud Native applications is Helm. In Blue/Green deployment it makes even more sense.
We have created a chart for each application that does not know anything about Blue/Green. Then we pack everything together in an umbrella helm chart.
In the Shop Umbrella Chart we use several times the same charts as helm dependencies but with different names if they are online/offline. This will allow us to have different configurations for each color.
We have packaged both applications in one chart, but we may have different umbrella charts per application.
- Red Hat Openshift 4.16 with admin rights.
- You can download Red Hat Openshift Local for OCP 4.16.
- Getting Started Guide
- Git
- GitHub account
- [oc 4.16 CLI] (https://docs.openshift.com/container-platform/4.16/cli_reference/openshift_cli/getting-started-cli.html)
- Argo Rollouts CLI
We have a GitHub repository for this demo. As part of the demo, you will have to do some changes and commits. So it is important that you fork the repository and clone it in your local.
git clone https://github.com/your_user/cloud-native-deployment-strategies
If we want to have a Cloud Native deployment we can not forget CI/CD. Red Hat OpenShift GitOps will help us.
Go to the folder where you have cloned your forked repository and create a new branch rollouts
git checkout -b rollouts
git push origin rollouts
Log into OpenShift as a cluster admin and install the OpenShift GitOps operator with the following command. This may take some minutes.
oc apply -f gitops/gitops-operator.yaml
Once OpenShift GitOps is installed, an instance of Argo CD is automatically installed on the cluster in the openshift-gitops namespace and a link to this instance is added to the application launcher in OpenShift Web Console.
Argo CD upon installation generates an initial admin password which is stored in a Kubernetes secret. In order to retrieve this password, run the following command to decrypt the admin password:
oc extract secret/openshift-gitops-cluster -n openshift-gitops --to=-
Click on Argo CD from the OpenShift Web Console application launcher and then log into Argo CD with admin username and the password retrieved from the previous step.
We are going to follow, as much as we can, a GitOps methodology in this demo. So we will have everything in our Git repository and use ArgoCD to deploy it in the cluster.
In the current Git repository, the gitops/cluster-config directory contains OpenShift cluster configurations such as:
- namespaces
gitops. - role binding for ArgoCD to the namespace
gitops. - namespaces
argo-rollouts. - Argo Rollouts
RolloutManager.
Let's configure Argo CD to recursively sync the content of the gitops/cluster-config directory into the OpenShift cluster.
Execute this command to add a new Argo CD application that syncs a Git repository containing cluster configurations with the OpenShift cluster.
oc apply -f blue-green-argo-rollouts/application-cluster-config.yaml
Looking at the Argo CD dashboard, you would notice that an application has been created.
You can click on the cluster-configuration application to check the details of sync resources and their status on the cluster.
We are going to create the application shop, that we will use to test Blue/Green deployment. Because we will make changes in the application's GitHub repository, we have to use the repository that you have just forked. Please edit the file blue-green-argo-rollouts/application-shop-blue-green-rollouts.yaml and set your own GitHub repository in the reportURL.
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: shop
namespace: openshift-gitops
spec:
destination:
name: ''
namespace: gitops
server: 'https://kubernetes.default.svc'
source:
path: helm/quarkus-helm-umbrella/chart
repoURL: https://github.com/change_me/cloud-native-deployment-strategies.git
targetRevision: rollouts
helm:
parameters:
- name: "global.namespace"
value: gitops
valueFiles:
- values/values-rollouts-blue-green.yaml
project: default
syncPolicy:
automated:
prune: true
selfHeal: trueoc apply -f blue-green-argo-rollouts/application-shop-blue-green-rollouts.yaml
Looking at the Argo CD dashboard, you would notice that we have a new shop application.
We have deployed the shop with ArgoCD. We can test that it is up and running.
We have to get the Online route
curl -k "$(oc get routes products-umbrella-online -n gitops --template='https://{{.spec.host}}')/products"
And the Offline route
curl -k "$(oc get routes products-umbrella-offline -n gitops --template='https://{{.spec.host}}')/products"
Notice that in each microservice response we have added metadata information to see better the version of each application. This will help us to see the changes while we do the Blue/Green deployment.
Because right now we have both routers against the same rollout revision we will have the same response with version v1.0.1:
{
"products":[
{
...
"name":"TV 4K",
"price":"1500€"
}
],
"metadata":{
"version":"v1.0.1", <--
"colour":"none",
"mode":"online"
}
}We can also see the rollout`s status1.
kubectl argo rollouts get rollout products --watch -n gitops
NAME KIND STATUS AGE INFO
⟳ products Rollout ✔ Healthy 12m
└──# revision:1
└──⧉ products-67fc9fb79b ReplicaSet ✔ Healthy 12m stable,active
├──□ products-67fc9fb79b-49k25 Pod ✔ Running 12m ready:1/1
└──□ products-67fc9fb79b-p7jk9 Pod ✔ Running 12m ready:1/1
We have split a Cloud Native Blue/Green deployment into two steps:
- Deploy a new version.
- Promote a new version
We have already deployed the products version v1.0.1, and we are ready to use a new products version v1.1.1 that has a new description attribute.
This is our current status:
We will deploy a new version v1.1.1. To do it, we have to edit the file helm/quarkus-helm-umbrella/chart/values/values-rollouts-blue-green.yaml under products-blue set tag value to v.1.1.1
products-blue:
mode: online
image:
tag: v1.1.1And push the changes
git add .
git commit -m "Change products version to v1.1.1"
git push origin rollouts
ArgoCD will refresh the status after some minutes. If you don't want to wait you can refresh it manually from ArgoCD UI or configure the Argo CD Git Webhook.2.
Argo Rollouts will automatically deploy the new products version and execute the prePromotionAnalysis.
NAME KIND STATUS AGE INFO
⟳ products Rollout ॥ Paused 27m
├──# revision:2
│ ├──⧉ products-9dc6f576f ReplicaSet ✔ Healthy 36s preview
│ │ ├──□ products-9dc6f576f-6vqp5 Pod ✔ Running 36s ready:1/1
│ │ └──□ products-9dc6f576f-lmgd7 Pod ✔ Running 36s ready:1/1
│ └──α products-9dc6f576f-2-pre AnalysisRun ✔ Successful 31s ✔ 1
└──# revision:1
└──⧉ products-67fc9fb79b ReplicaSet ✔ Healthy 27m stable,active
├──□ products-67fc9fb79b-49k25 Pod ✔ Running 27m ready:1/1
└──□ products-67fc9fb79b-p7jk9 Pod ✔ Running 27m ready:1/1
If the prePromotionAnalysis goes well, we can see that offline applications have version v1.1.1 and the new attribute description, but the online version has not changed.
This is our current status:
{
"products":[
{
"discountInfo":{...},
"name":"TV 4K",
"price":"1500€",
"description":"The best TV" <--
}
],
"metadata":{
"version":"v1.1.1", <--
}
}Functional testing users can execute Smoke tests to validate this new v1.1.1 version.
We have to be careful with those tests in a production environment because the product microservice will call the online dependencies.
If this dependency is for example a production DB we will create the things that our Smoke tests do.
We are going to open the new version to final users.
Execute this command to promote products:
kubectl argo rollouts promote products -n gitops
First Argo Rollouts will just change the service to use the new release (ReplicaSet). We minimize downtime because it just changes the service label.
NAME KIND STATUS AGE INFO
⟳ products Rollout ✔ Healthy 88m
├──# revision:2
│ ├──⧉ products-9dc6f576f ReplicaSet ✔ Healthy 62m stable,active
│ │ ├──□ products-9dc6f576f-6vqp5 Pod ✔ Running 62m ready:1/1
│ │ └──□ products-9dc6f576f-lmgd7 Pod ✔ Running 62m ready:1/1
│ └──α products-9dc6f576f-2-pre AnalysisRun ✔ Successful 62m ✔ 1
└──# revision:1
└──⧉ products-67fc9fb79b ReplicaSet ✔ Healthy 88m delay:27s
├──□ products-67fc9fb79b-49k25 Pod ✔ Running 88m ready:1/1
└──□ products-67fc9fb79b-p7jk9 Pod ✔ Running 88m ready:1/1
This is our current status:
And after scaleDownDelaySeconds Argo Rollouts will scale down the first replicaSet (v1.0.1).
NAME KIND STATUS AGE INFO
⟳ products Rollout ✔ Healthy 89m
├──# revision:2
│ ├──⧉ products-9dc6f576f ReplicaSet ✔ Healthy 62m stable,active
│ │ ├──□ products-9dc6f576f-6vqp5 Pod ✔ Running 62m ready:1/1
│ │ └──□ products-9dc6f576f-lmgd7 Pod ✔ Running 62m ready:1/1
│ └──α products-9dc6f576f-2-pre AnalysisRun ✔ Successful 62m ✔ 1
└──# revision:1
└──⧉ products-67fc9fb79b ReplicaSet • ScaledDown 89m
This is our final status:
We have in the online environment the new version v1.1.1!!!
{
"products":[
{
"discountInfo":{...},
"name":"TV 4K",
"price":"1500€",
"description":"The best TV" <--
}
],
"metadata":{
"version":"v1.1.1", <--
}
}Imagine that something goes wrong, we know that this never happens but just in case. We can do a very quick rollback just undoing the change in the Products online service.
Argo Rollouts has an undo command to do the rollback. In my opinion, I don't like this procedure because it is not aligned with GitOps. The changes that Argo Rollouts do does not come from git, so git is OutOfSync with what we have in Openshift.
In our case the commit that we have done not only changes the ReplicaSet but also the ConfigMap. The undo command only changes the ReplicaSet, so it does not work for us.
I recommend doing the changes in git. We will revert the last commit
git revert HEAD
git push origin rollouts
ArgoCD will get the changes and apply them. Argo Rollouts will create a new revision with the previous version.
Execute this command to promote products to version v1.0.1:
kubectl argo rollouts promote products -n gitops
The rollback is done!
{
"products":[
{
...
"name":"TV 4K",
"price":"1500€"
}
],
"metadata":{
"version":"v1.0.1", <--
"colour":"none",
"mode":"online"
}
}To delete all the things that we have done for the demo you have to:
- In GitHub delete the branch
rollouts - In ArgoCD delete the application
cluster-configurationandshop - In Openshift, go to project
openshift-operatorsand delete the installed operators Openshift GitOps.
Footnotes
-
Argo Rollouts offers a Kubectl plugin to enrich the experience with Rollouts https://argoproj.github.io/argo-rollouts/installation/#kubectl-plugin-installation ↩
