v4.0

Install Helper

There are a lot of charts and components required to be installed and managed for PrimeHub. We need a way to manage common settings across all these components. And provide a way to template the helm value files by feature flags.

Design

In the common helm installation, it may look like the following command.

helm install \
  --name primehub \
  --namespace hub \
  --values primehub-value.yaml \
  modules/charts/primehub

However, it is not convenient to issue this long command for each installation and not easy to be source-controlled as well. To solve this problem, we make use of helmfile. The above command would turn into the yaml file below.

# primehub.yaml
charts:
  - name: primehub
    namespace: primehub
    chart: modules/charts/primehub
    version: ~0.1.0
    values:
      - primehub-values.yaml

and the install command would change to

helmfile -f primehub.yaml

In this way, we make the installation declarative and easy to run. All these helmfiles are located at helm/helmfile.d.

As more and more releases need to be installed, we also categorize these releases by label. There are two labels defined

Here are the available releases

To diff, install/upgrade the helm release, we can use these commands

helmfile -f helm/helmfile.d -l release=<release> diff
helmfile -f helm/helmfile.d -l release=<release> charts
helmfile -f helm/helmfile.d -l app=<app> diff
helmfile -f helm/helmfile.d -l app=<app> charts

or these equivalent make commands

make release-diff-<release>
make release-install-<release>
make component-diff-<app>
make component-install-<app>

Template the Value

Helm provides a great way to template the kubernetes resources. In the helm installation or upgrade, helm consolidates all the values to a single value tree and uses it to generate the final resource YAMLs and apply them to cluster.

However, helm does not provide a way to template the value, this is why helmfile templating comes in. Helmfile provides a way to template the value files by environment valuable.

We can notice that in the helm/<component>/*, these values file have .yaml.gotmpl file extension. When helmfile is run, it would template these value files and output the final plain values.

The environment variable is from the <config-path>/.env. And the config path is searched in the following order

  • ~/.primehub/config/<cluster name>/ ( is kubectl config current-context )

  • ./etc

The helper script bin/phenv would find if ${CONFIG_PATH}/.env is in the folder and determine if it is qualified as a config folder.

Configuration Files

In the previous section, we talk about the config folder. In addition to .env file, the folder also contains these files and folders.

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