helmfile/docs/templating_funcs.md

Template Functions

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") }}

envExec

The envExec function allows you to run a command with environment variables declared on-the-fly in addition to existing environment variables, returning the stdout of the command. When the command fails, the template rendering will fail with an error message.

{{ $cmdOutpot := envExec (dict "envKey" "envValue") "./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" }}

readDir

The readDir function returns a list of the relative paths to the files contained within the directory. (No folders included. Use readDirEntries if you need folders too)

{{ range $index,$item := readDir "./testdata/tmpl/sample_folder/" }}
  {{- $itemSplit := splitList  "/" $item -}}
  {{- if contains "\\" $item -}}
  {{- $itemSplit = splitList "\\" $item -}}
  {{- end -}}
  {{- $itemValue := $itemSplit | last -}}
  {{- $itemValue -}}
{{- end -}}

readDirEntries

The readDirEntries function returns a list of DirEntry contained within the directory

{{ range $index,$item := readDirEntries "./testdata/tmpl/sample_folder/" }}
  {{- if $item.IsDir -}}
  {{- $item.Name -}}
  {{- end -}}
{{- end -}}

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" }}

getOrNil

The getOrNil 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.

{{ $GetOrNlvalue :=  $value | getOrNil "path.key" }}

tpl

The tpl function allows you to render a template. When has failed, the template rendering will fail with an error message.

{{ $tplValue :=  $value | tpl "{{ .Value.key }}" }}

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" }}

fetchSecretValue

The fetchSecretValue function parses the argument as a vals ref URL, retrieves and returns the remote secret value referred by the URL. In case it failed to access the remote secret backend for whatever reason or the URL was invalid, the template rendering will fail with an error message.

{{ $fetchSecretValue :=  fetchSecretValue "secret/path" }}

expandSecretRefs

The expandSecretRefs function takes an object as the argument and expands every vals secret reference URL embedded in the object's values. See "Remote Secrets" page in our documentation for more information.

{{ $expandSecretRefs :=  $value | expandSecretRefs }}