rubasace/drone-helm-k8s repository overview

⁠Drone Helm K8s

⁠Description

Generic Drone⁠ extension for deploying applications to Kubernetes clusters using a generic Helm chart.

This extension acts as a simple interface between the Helm chart and a CI/CD pipeline. All details of the chart can be found here⁠.

Inspired by TicketMaster's talk at KubeCon (2017)⁠, this extension pretends to be the one used on the deployment process of our applications. This way a team/company can centralize all good-practices and standardize their deployment process in a friction-less manner.

⁠How to use

⁠Pipeline definition

To use it, first you have to plug the step on the drone pipeline. An example where we bake an image and deploy it would look like this:

kind: pipeline
name: default

steps:
    # Create the docker image
  - name: bake
    image: plugins/docker
    settings:
      username: *******
      password: *******
      repo: registry.mycompany.com/v2/team1/demo
      registry: registry.mycompany.com/v2
      tags: 1.0.0.${CI_BUILD_NUMBER}
    when:
      branch:
        - master
    # Deploy the docker image using the extension
  - name: deploy
    image: rubasace/drone-helm-k8s
    environment:
      CHART_VERSION_ARGUMENT: 0.1.24
      K8S_CERT_AUTHORITY_DATA:
        from_secret: K8S_CERT_AUTHORITY_DATA
      K8S_SERVER:
        from_secret: K8S_SERVER
      K8S_USER:
        from_secret: K8S_USER
      K8S_PASSWORD:
        from_secret: K8S_PASSWORD
      NAMESPACE: production
      IMAGE_TAG: 1.0.0.${CI_BUILD_NUMBER}
    when:
      branch:
        - master

In order to configure the deployment, we have to specify a few environment variables:

• It's recomended to specify the chart version, to ensure the deployment is reproducible and to avoid surprises when the chart evolves independently of the application.

⁠General values

This extension will look for a values.yaml file in the directory .k8s of the repository. This is the way the chart can be customized for a specific deployment. One example of .k8s/values.yaml would be:

ingress:
  enabled: true
  domain: mycompany.com
deployment:
  image: registry.mycompany.com/v2/team1/demo
  containerPort: 8080
  imagePullSecrets:
    - regcred

Those are the values that will be passed to the Helm chart when deploying the application. For a full list of the supported values, have a look at the chart documentation.

⁠Namespace-specific values

This extension supports overlaying of values, by creating additional values-{namespace}.yaml files. While it isn't mandatory, this mechanism is key in order to avoid repetition of values: all common values for every environment can be specified in the values.yaml file, only putting the environment-specific values in separate files

Following the previous example, we might want to override the domain as well as specify a subdomain for the deployment to the namespace staging. We can create the file .k8s/values-staging.yaml as follows:

ingress:
  domain: mycompanystaging.com
  subdomain: demo

We could as well specify a different subdomain and enable OAuth2 authentication for production with the file .k8s/values-production.yml:

ingress:
  subdomain: demo
  oauth2Enabled: true

The application repository would look something like this:

├── .k8s
│   └── values.yaml
│   └── values-production.yaml
│   └── values-staging.yaml
├── Dockerfile
├── README.md
├── ...

In both cases, all values in values.yaml will be set first and then will be complemented/overriden by the ones in the environment-specific files.

⁠Usage with other tools

This extension was created to be used with Drone, but it can be easily adapted to any other Docker based CI/CD tool such as CircleCI. It's as simple as replacing the few Drone specific environment variables with the ones provided by the tool of your choice.

⁠Notes

While this extension works out-of-the-box, it's too generic for being used as it is. Things like the domain are left in the air, so it's a good practice to just extend/fork the Helm chart⁠ in order to adapt it to your specific scenario, instead of having to provide the same values over and over again. Then it would be a matter of making this extension point to your forked chart.