📄 Templating

Helmwave using go templates for templating.

Helmwave supports all built-in functions / sprig / gomplate and several custom functions. We recommend using gomplate.

Flags

--templater value   Select template engine: sprig or gomplate (default: "sprig") [$HELMWAVE_TEMPLATER, $HELMWAVE_TEMPLATE_ENGINE]`

Explain context helm vs helmwave

There is a different context between helm and helmwave. You can't pass variables from helmwave to your helm chart templates. You should use helmwave to render values of your chart.

Sprig

• masterminds/sprig
• documentations

If you've ever written helm charts, then you're already familiar with it.

Gomplate

• hairyhenderson/gomplate
• documentations

Gomplate is a template renderer which supports a growing list of datasources, such as JSON (including EJSON - encrypted JSON), YAML, AWS EC2 metadata, BoltDB, Hashicorp Consul and Hashicorp Vault secrets.

Custom

Custom functions will work with any template engine.

env

The env function allows you to declare a particular environment variable as an optional for template rendering. If the environment variable is unset or empty, the template rendering will continue with an empty string as a value.

{{ $envValue := env "envName" }}

requiredEnv

The requiredEnv function allows you to declare a particular environment variable as required for template rendering. If the environment variable is unset or empty, the template rendering will fail with an error message.

{{ $envValue := requiredEnv "envName" }}

If the environment variable value starts with '/' (forward slash) and Git for Windows is used, you must set MSYS_NO_PATHCONV=1 to preserve values as-is, or the environment variable value will be prefixed with the C:\Program Files\Git. Reference

exec

The exec function allows you to run a command, returning the stdout of the command. When the command fails, the template rendering will fail with an error message.

{{ $cmdOutpot := exec "./mycmd" (list "arg1" "arg2" "--flag1") }}

readFile

The readFile function allows you to read a file and return its content as the function output. On failure, the template rendering will fail with an error message.

{{ $fileContent := readFile "./myfile" }}

toYaml

The toYaml function allows you to convert a value to YAML string. When has failed, the template rendering will fail with an error message.

{{ $yaml :=  $value | toYaml }}

fromYaml

The fromYaml function allows you to convert a YAML string to a value. When has failed, the template rendering will fail with an error message.

{{ $value :=  $yamlString | fromYaml }}

setValueAtPath

The setValueAtPath function allows you to set a value at a path. When has failed, the template rendering will fail with an error message.

{{ $value | setValueAtPath "path.key" $newValue }}

get

The get function allows you to get a value at a path. when defaultValue not set. It will return nil. When has failed, the template rendering will fail with an error message.

{{ $Getvalue :=  $value | get "path.key" "defaultValue" }}

required

The required function returns the second argument as-is only if it is not empty. If empty, the template rendering will fail with an error message containing the first argument.

{{ $requiredValue :=  $value | required "value not set" }}