Migrating to Tanka

At Cloudflight we were previously using kubecfg to deploy our applications. As of 2022-02-21, tanka is our recommended tool for Kubernetes configurations. Reasoning for this can be found in ADR-0077.

If you're still using kubecfg you're in Luck! The migration to Tanka is very simple and can be done in under five minutes.

Tip

TL;DR:

• Move stage files to environments/$NAME/main.jsonnet
• Create environments/$NAME/spec.json
• Fix Imports

Verifying your current setup

Before we can start to migrate to the new setup, we should be confident in the old one to avoid issues further down the line.

As a requirement, you should be able to view your configuration in the yaml format by running

kubecfg show $YOUR_STAGE_FILE

Restructuring

The main change required for a smooth workflow in Tanka, is a small restructuring of the directory. Our old layout prescribes a flat structure with everything in the root directory. Tanka on the other hand expects a folder per environment. To perform this step, you need to go from this:

.
├── jsonnetfile.json
├── production.jsonnet
├── resources
│   └── application.jsonnet
└── staging.jsonnet

to

.
├── jsonnetfile.json
├── environments
│   ├── production
│   │   └── main.jsonnet # (1)
│   └── staging
│       └── main.jsonnet # (2)
└── lib
    └── application.libsonnet

1. The old production.jsonnet
2. The old staging.jsonnet

Configuring

Instead of relying on the current Kubernetes context, Tanka needs explicit information on the API Server as well as the namespace.

This information is saved in the spec.json file, contained in the respective environment. The complete layout can be found in the Tanka documentation

The syntax is as follows:

{
  "apiVersion": "tanka.dev/v1alpha1",
  "kind": "Environment",
  "metadata": {
    "name": "environments/staging"
  },
  "spec": {
    "apiServer": "openshift-dev.internal.cloudflight.io:6443", // (1)
    "namespace": "762-example-staging", // (2)
    "resourceDefaults": {},
    "expectVersions": {},
    "injectLabels": true
  }
}

1. API server URL. Excluding theh protocol, including the port
2. Namespace of your project. Will be injected to all resources

Fixing Imports

Now that you moved around the files, you will also need to fix the imports contained within them. For convenience, Tanka automatically includes the lib and vendor directory in the jsonnet path. So instead of having to write ../../lib/application.libsonnet you can simply import application.libsonnet.

Verifying the new configuration

After fixing the imports, you can show the new configuration with the following command:

tk show environments/staging

TeamCity

Tanka integration from TeamCity is supported from version 3.0.0 of the cloudflight-teamcity-dsl onwards.

Example:

subCloudflightProject {
  name = "Deployment"
  tankaApply {
    openShiftConfig {
        serviceAccountToken = "credentialsJSON:..."
    }
    contextDir = ".openshift" // (1)
  }
}

1. Default: deployment as is the case with our new configuration skeleton

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Last update: 2022-07-08