Working with chart dependencies

The chart can include arbitrary number of dependencies called subcharts.

Subcharts are placed in the directory .helm/charts/SUBCHART_DIR. Each subchart in the SUBCHART_DIR is a chart by itself with the similar files structure (which can also have own recursive subcharts).

During deploy process werf will render, create and track all resources of all subcharts.

Managing subcharts with requirements.yaml

For chart developers, it is often easier to manage a single dependency file which declares all dependencies.

A requirements.yaml file is a YAML file in which developers can declare chart dependencies, along with the location of the chart and the desired version. For example, this requirements file declares two dependencies:

# requirements.yaml
dependencies:
- name: nginx
  version: "1.2.3"
  repository: "https://example.com/charts"
- name: sysdig
  version: "1.4.12"
  repository: "@stable"

• The name should be the name of a chart, where that name must match the name in that chart’s ‘Chart.yaml’ file.
• The version field should contain a semantic version or version range.
• The repository URL should point to a Chart Repository. Helm expects that by appending /index.yaml to the URL, it should be able to retrieve the chart repository’s index. The repository can be an alias. The alias must start with alias: or @.

The requirements.lock file lists the exact versions of immediate dependencies and their dependencies and so forth.

The werf helm dependency commands operate on that file, making it easy to synchronize between the desired dependencies and the actual dependencies stored in the charts directory:

• Use werf helm dependency list to check dependencies and their statuses.
• Use werf helm dependency update to update /charts based on the contents of requirements.yaml.
• Use werf helm dependency build to update /charts based on the requirements.lock file.

All Chart Repositories that are used in requirements.yaml should be configured on the system. The werf helm repo commands can be used to interact with Chart Repositories:

• Use werf helm repo add to add Chart Repository.
• Use werf helm repo update to update local Chart Repositories indexes.
• Use werf helm repo remove to remove Chart Repository.
• Use werf helm repo list to list existing Chart Repositories.
• Use werf helm repo search to search for a keyword in charts of configured Chart Repositories.
• Use werf helm repo fetch to download chart by chart reference.

werf is compatible with Helm settings, so by default werf helm dependency and werf helm repo commands use settings from helm home folder, ~/.helm. But you can change it with --helm-home option. If you do not have helm home folder or want to create another one use werf helm repo init command to initialize necessary settings and configure default Chart Repositories.

Subchart and values

To pass values from parent chart to subchart called mysubchart user must define following values in the parent chart:

mysubchart:
  key1:
    key2:
    - key3: value

In the mysubchart these values should be specified without mysubchart key:

{{ .Values.key1.key2[0].key3 }}

Global values defined by the special toplevel values key global will also be available in the subcharts:

global:
  database:
    mysql:
      user: user
      password: password

In the subcharts these values should be specified as always:

{{ .Values.global.database.mysql.user }}

Only values by keys mysubchart and global will be available in the subchart mysubchart.

NOTE secret-values.yaml files from subcharts will not be used during deploy process. Although secret values from main chart and additional secret values from cli params --secret-values will be available in the .Values as usually.