Managing Chart Dependencies

1. Declaring Dependencies

Property	Values	Description
dependencies	`[]`	List of chart dependencies
name	`string`	Name of the dependency chart
alias	`string`	Alias to use for the dependency
version	`string`	Version of the dependency chart
repository	`string`	Repository URL or alias for the dependency chart
condition	`string`	Condition to enable the dependency
tags	`[]`	Tags to include the dependency
import-values	`[]`	Import values from the dependency chart

Example: Declaring a dependency in Chart.yaml

apiVersion: v2
name: my-app
version: 1.0.0
dependencies:
  - name: nginx
    version: "1.2.3"
    repository: "https://charts.bitnami.com/bitnami"
  - name: postgresql
    version: "10.1.2"
    repository: "@bitnami"
    condition: postgresql.enabled

2. Specifying Dependency Version

Field	Description	Example
version	Version of the dependency chart to use	`"1.2.3"`
repository	Repository URL or alias where the chart is located	`"https://example.com/charts"`
condition	Conditional value to enable or disable the dependency	`"server.enabled"`
tags	List of tags to include or exclude dependencies	`["frontend", "backend"]`
import-values	Import values from parent chart to child chart	`[{"childKey": "server.port", "parentKey": "port"}]`

Example: Specifying Chart Version in requirements.yaml

dependencies:
- name: nginx
  version: "1.2.3"
  repository: "https://kubernetes-charts.storage.googleapis.com"

Note: The version field supports semantic versioning (SemVer) and can use wildcards like * or >=1.0.0.

3. Setting Dependency Repository

Repository Name	URL	Notes
stable	`https://charts.helm.sh/stable`	Official stable Helm charts repository
bitnami	`https://charts.bitnami.com/bitnami`	Bitnami charts repository
incubator	`https://charts.helm.sh/incubator`	Community incubated charts

Example: Adding a Repository

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

Example: Listing Repositories

helm repo list

Note: After adding a repository, run helm repo update to refresh the local cache.

4. Using Local Dependencies

Dependency Type	Specification	Notes
local	`local: ./my-local-chart`	Path to local chart directory relative to `Chart.yaml`

Example: Local Dependency in Chart.yaml

apiVersion: v2
name: my-app
version: 1.0.0
dependencies:
  - name: my-local-chart
    alias: local-chart
    version: 0.1.0
    repository: "@local"
    condition: local-chart.enabled
    tags:
      - frontend

Example: Using Local Dependency in Values

local-chart:
  enabled: true
  config:
    port: 8080

Note: Local dependencies must be placed in the charts/ directory or referenced via a relative path from Chart.yaml.

5. Enabling Conditional Dependencies

Conditional dependencies in Helm charts allow you to include or exclude chart dependencies based on specific conditions. This is useful for enabling features only when certain criteria are met, such as environment-specific configurations or feature flags.

Field	Description	Example
condition	Specifies the path to a boolean value in the values file that determines whether to include the dependency.	`server.enabled`
tags	Allows dependencies to be included based on tags defined in the values file.	`["frontend", "backend"]`

Example: Using condition in Chart.yaml

dependencies:
  - name: nginx
    version: 1.2.3
    condition: server.enabled

Example: Using tags in Chart.yaml

dependencies:
  - name: redis
    version: 4.5.6
    tags:
      - cache

Note: The condition field checks for a boolean value in the values file. If the value is false, the dependency will not be included in the release.

Note: Tags are useful for grouping dependencies and enabling them collectively. They can be used in combination with conditions.

6. Using Tag-based Dependencies

Dependency	Tag	Notes
name	`my-app`	Unique identifier for the dependency
alias	`app`	Optional alias to use in templates
version	`1.2.3`	Version of the chart to use
repository	`https://example.com/charts`	URL to the chart repository
condition	`app.enabled`	Conditional rendering based on values
tags	`frontend,production`	Tags to filter dependencies

Example: Tag-based dependency in requirements.yaml

dependencies:
- name: my-app
  version: 1.2.3
  repository: https://example.com/charts
  tags:
    - frontend
    - production

Note: Tag-based dependencies are useful for organizing and filtering chart dependencies in complex environments.

Warning: Ensure that tags are consistently applied across all charts to avoid misconfigurations.

7. Downloading Dependencies

Command	Description	Options
helm dependency get	Downloads chart dependencies from `Chart.yaml`	`--cert-file`, `--key-file`, `--ca-file`
helm dependency update	Updates dependencies and regenerates `Chart.lock`	`--skip-refresh`, `--verify`

Example: Downloading Dependencies

helm dependency get

Example: Updating Dependencies

helm dependency update

8. Building Dependency Charts

Field	Description	Example
name	Name of the dependency chart	`nginx`
version	Version of the dependency chart	`1.2.3`
repository	Repository URL or alias for the chart	`https://charts.example.com`
condition	Conditional value to enable/disable the chart	`server.enabled`
tags	Tags to include or exclude charts	`["frontend", "backend"]`
import-values	Import values from parent chart to child chart	`[{"child": "server.port", "parent": "port"}]`

Example: Defining a dependency in Chart.yaml

apiVersion: v2
name: my-app
version: 1.0.0
dependencies:
  - name: nginx
    version: 1.2.3
    repository: https://charts.example.com
    condition: nginx.enabled
    tags:
      - frontend

Note: The repository field can be an alias defined in repositories.yaml.

Example: Using import-values to pass values

apiVersion: v2
name: my-app
version: 1.0.0
dependencies:
  - name: mysql
    version: 8.0.0
    repository: https://charts.bitnami.com/bitnami
    import-values:
      - child: "auth.rootPassword"
        parent: "mysqlRootPassword"

9. Listing Dependencies

Command	Description	Flags
helm dependency list	Lists all dependencies defined in the `Chart.yaml` file	`--chart-repo-url`, `--output`

Example: Listing Dependencies

helm dependency list my-chart

Note: The helm dependency list command reads from the Chart.yaml and requirements.yaml files to display the chart dependencies.

10. Importing Child Values

Property	Description	Example
values.yaml	Defines values that can be overridden by child charts	`{ "child": { "config": "value" } }`
import	Used to import values from child charts into parent chart	`{ "import": { "childValues": "{{ .Values.child.config }}" } }`

Example: Importing Values from Child Chart

child:
  config: "example-value"
import:
  childValues: "{{ .Values.child.config }}"

Note: The import key allows parent charts to access values defined in child charts, enabling shared configuration.

11. Overriding Subchart Values

When a Helm chart depends on subcharts (defined in Chart.yaml), you can override the values of those subcharts using the values.yaml file or command-line flags.

Override Path	Description	Example
parent.subchart.key	Override a value in a subchart by prefixing the key with the subchart name.	`mysql: auth: rootPassword: "secret"`

Example: Overriding MySQL Subchart Values

mysql:
  auth:
    rootPassword: "secret"
    username: "admin"
  resources:
    limits:
      cpu: "500m"

Note: Values must be valid YAML and follow the structure defined by the subchart's values.yaml.

12. Managing Chart.lock File

Property	Description	Values
apiVersion	API version of the lock file	`v2`
entries	List of dependencies and their resolved versions	Array of dependency objects
entries.name	Name of the dependency chart	String
entries.version	Resolved version of the dependency chart	String
entries.repository	Repository URL where the dependency is located	String
entries.digest	SHA256 digest of the chart archive	String

Example: Chart.lock content

apiVersion: v2
entries:
- name: nginx
  version: 15.2.0
  repository: https://charts.bitnami.com/bitnami
  digest: sha256:1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef
- name: postgresql
  version: 12.1.10
  repository: https://charts.bitnami.com/bitnami
  digest: sha256:abcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890

Note: The Chart.lock file is automatically generated and managed by Helm. It ensures reproducible deployments by locking dependency versions.