Deploy a Dockerized ASP.NET Core Application to Kubernetes on Azure Using a VSTS CI/CD Pipeline: Part 2
If you need to provision a new environment for your deployment pipeline, what's your process and how long does it take? For many of us the process probably starts with a request to an infrastructure team for new virtual machines. If the new VMs are in Azure the request might be completed quite quickly; if they are on premises it might take much longer. In both scenarios you might have to justify your request: there will be actual cost in Azure and on premises it's another chunk of the datacentre ‘gone'.
With the help of containers and container orchestrators I predict (and sincerely hope) that this sort of pain will become a distant memory for much of the software development community for whom it is currently an issue. The reason is that container orchestration technologies abstract away the virtual (or physical) server layer and allow you to focus on configuring services and how they communicate with each other—all through configuration files. The only time you'd need to think of virtual (or physical) servers is if the cluster running your orchestrator needed more capacity, in which case someone will need to add more nodes. A whole new environment for your pipeline just by doing some work with a configuration file? What's not to like?
In this blog post I hope to make my prediction come alive by showing you how new environments can be quickly created using Kubernetes running in Microsoft's Azure Container Service (AKS), crucially using declarative configuration files that get deployed as part of a VSTS release pipeline. This post follows directly on from a previous post, both in terms of understanding and also the components that were built in that first post, so if you haven't already done so I recommend working your way through that post before going further.
In the previous post we deployed to the default namespace so it probably makes sense to clean all this up. This can all be done by the command line of course but to mix it up a bit I'll illustrate using the Kubernetes Dashboard. You can start the dashboard using the following command, substituting in the name of your resource group and the name of the cluster:
az aks browse --resource-group <resource-group> --name <cluster-name>
This should open the dashboard in a browser displaying the default namespace. Navigate to Workloads > Deployments and using the hamburger menu delete the deployment:
Navigate to Discovery and Load Balancing > Services and delete the service:
Navigate to Config and Storage > Secret and delete the secret:
Environments and Namespaces
The Kubernetes feature that we'll use to create environments that together form part of our pipeline is Namespaces. You can think of namespaces as a way to divide the Kubernetes cluster in to virtual clusters. Within a namespace resource names need to be unique but they don't have to be across namespaces. This is great because effectively we have network isolation so that across each environment resource names stay the same. Say goodbye to having to append the environment name to all the resources in your environment to make them unique.
In this post I'll make a pipeline consisting of two environments. I'm sticking with a convention I established several years ago so I'll be creating DAT (developer automated test) and PRD (production) environments. In a complete pipeline I might also create a DQC (developer quality control) environment to sit between DAT and PRD but that won't really add anything extra to this exercise.
First up is to create the namespaces. There is an argument for saying that namespace creation should be part of the release pipeline however in this post I'm going to create everything manually as I think it helps to understand what's going on. Create a file called namespaces.yaml and add the following contents:
Note that namespace name needs to be in lower case as it needs to be DNS compatible. Open a command prompt at the same location as namespaces.yaml and execute the the following command: kubectl create -f namespaces.yaml. You should get a message back advising the namespaces have been created and at one level that's all there is to it. However there's a couple of extra bits worth knowing.
When you first start working with kubectl at the command line you are working in the default namespace. To work with other namespaces needs some configuration.
To return details of the configuration stored in C:\Users\<username>\.kube\config use:
kubectl config view
My cluster returned the following output:
- name: clusterUser_k8sResourceGroup_k8sCluster
From this output you need to determine your cluster name (which you probably already know) as well as the name of the user. These details are fed in to the following command for creating a new context for an environment (in this case the DAT environment):
kubectl config set-context dat --namespace=dat --cluster=k8sCluster --user=clusterUser_k8sResourceGroup_k8sCluster
To switch to working to this context (and hence the dat namespace) use:
kubectl config use-context dat
To confirm (or check) the current context use:
kubectl config current-context
To get back to the default namespace use:
kubectl config use-context <name-of-cluster>
Normally that would be most of what you need to know to work with namespaces, however as of the time of writing there is a bug in the VSTS Deploy to Kubernetes task which requires some extra work. The bug may be fixed by the time you read this however it's handy to examine the issue to further understand what is going on behind the scenes.
Each namespace needs to access the Azure Container Registry (ACR) we created in the previous post to pull down images. This is a private registry so we don't want open access and so some form of authentication is required. This is provided by the creation of a Kubernetes secret that holds the authentication details to the ACR. The VSTS Deploy to Kubernetes task can create this secret for us however the bug is that it only creates the secret for the default namespace and fails to create the secret when a different namespace is specified. The workaround is to create the secret manually in each namespace using the following command:
kubectl create secret docker-registry <secret-name> --namespace=<namespace> --docker-server=<acr-name>.azurecr.io --docker-username=<acr-name> --docker-password=<acr-admin-password> --docker-email=<any-valid-email-address>
In the above command secret-name is any arbitrary name you choose for the secret, namespace is the namespace in which to create the secret, acr-name is the name of your ACR, acr-admin-password is the password from the Access keys panel of your ACR and any-valid-email-address is just that. You'll need to run this command for each namespace of course. One final thing: you'll need to make sure that in the codebase the imagePullSecrets name in deployment.yaml matches the name of the secret you just created.
Amend the VSTS Pipeline to Support Multiple Environments
In this section we amend the release pipeline that was built in the previous post to support multiple environments.
- In the Pipeline tab rename Environment 1 to DAT:
- In the Variables tab create a variable to hold the name of the secret created above to authenticate with ACR. Create a second variable for the DAT environment namespace and change its scope to DAT. Remember that the value needs to be lower case:
- In the Tasks tab amend all three Deploy to Kubernetes tasks so that the Namespace field contains the $(DatEnvironment) variable. At the same time ensure that Secret name field matches the name of the secret variable created above:
- In order to test that deploying to DAT works, either trigger a build or, if you updated deployment.yaml above on your workstation commit your code. If the deployment was successful find the external IP address of the LoadBalancer by executing kubectl get services --namespace=dat and paste in to a browser to confirm that the ASP.NET Core website is running.
Amend the VSTS Pipeline to Support a New Environment
Now for the fun bit where we see just how easy it is to configure a new, network-isolated environment.
- In the Pipeline tab use the arrow next to Environments > Add to show and then select Clone environment:
- Rename the cloned environment to PRD. Create a new variable (ie PrdEnvironment) scoped to PRD to hold the prd namespace and amend each of the three Deploy to Kubernetes tasks so that the Namespace field contains the $(PrdEnvironment) variable.
- Trigger a build and check the deployment was successful by executing kubectl get services --namespace=prd to get the external IP address of the LoadBalancer which you can paste in to a browser to confirm that the ASP.NET Core website is running.
And That's It!
Yep—that really is all there is to it! Okay, this is just a trivial example, however even with more services the procedure would be the same. Granted, in a more complex application there might be some environment variables or secrets that might change but even so, it's just configuration.
I'm thrilled by the power that Kubernetes gives to developers—no more thinking about VMs or tin, no more having to append resources with environment names, and the ability to create a new environment in the blink of an eye—wow!
There's lots more I'm planning to cover in the deployment pipeline space however next time I'll be looking at the development inner loop and the options for running Kubernetes whilst developing code.