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File Marks


ytt allows to control certain metadata about files via --file-mark flag.

$ ytt ... --file-mark <path>:<mark>=<value>


  • path — location to the file(s) being marked
    • exact path (use --files-inspect to see paths as seen by ytt)
    • path with * to match files in a directory
    • path with **/* to match files and directories recursively
  • mark — metadata to modify on the file(s) selected by path
  • value — the value for the mark

Note that this flag can be specified multiple times.


ytt -f . \
  --file-mark 'alt-example**/*:type=data' \
  --file-mark 'example**/*:type=data' \
  --file-mark 'generated.go.txt:exclusive-for-output=true' \
  --output-files ../../tmp/

Available Marks


Changes the relative path.

--file-mark '<path>:path=<new-path>'


--file-mark 'generated.go.txt:path=gen.go.txt'

renames generated.go.txt to gen.go.txt


Exclude file from any kind of processing.

--file-mark '<path>:exclude=true'


Change type of file, affecting how ytt processes it.

--file-mark '<path>:type=<file-type>'

By default file-type is determined based on file extension and — as of v0.32.0 — content.

file-type can be:

  • yaml-template (default for: .yml or .yaml) — parsed as a YAML document and evaluated for templating.
  • yaml-plain — parsed as a simple YAML document (not evaluated for templating).
  • text-template (default for: .txt) — parsed as a text document containing text templating.
  • text-plain — included in output, as is.
  • starlark (default for: .star) — a Starlark source file (executed)
  • data (default for all other files) — a text file that can be loaded by


--file-mark 'config.yml:type=data'

indicates that config.yml is not a yaml-template, but is data. This file will not be parsed, evaluated, or included in the output, but can be loaded using

type detection for YAML files

(as of v0.32.0)

First, ytt determines the type of each YAML file:

  1. if it has a .yml or .yaml extension, it’s assumed to be a yaml-template
  2. if it is yaml-template but does not contain any ytt templating, it is treated as if it were yaml-plain
  3. if it is marked with type=yaml-plain, it is treated as yaml-plain

and then processes each:

  • yaml-template files are:
    1. parsed as YAML,
    2. evaluated (i.e. executes ytt the template), and
    3. linted (i.e. detects when non-ytt comments are included)
      • this catches errors where the @ is accidentally omitted,
      • if the --ignore-unknown-comments flag is included, this “linting” is disabled.
  • yaml-plain files are simply parsed as YAML (with no evaluation or linting).


Marks a file to be included in the output.

Files of type yaml-template, yaml-plain, text-template, and text-plain are part of the output by default.

--file-mark '<path>:for-output=true'


--file-mark 'config.lib.yml:for-output=true'

By default, .lib.yml files are not included in the rendered output (they are loaded by other templates). With this file mark, config.lib.yml is included in the output.


Limits output to only marked files.

If there is at least one file marked this way, only these files will be used in output.

--file-mark '<path>:exclusive-for-output=true'


--file-mark 'config.lib.yml:exclusive-for-output=true'

Causes output to only include config.lib.yml.

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