01-directive.md

Directive

In omnifests directives are sections of the document that get transformed by otk into something else.

otk has various directives that can be used in an omnifest. Generally these directives can appear anywhere in the tree unless otherwise specified (see below) and they are replaced with other trees or values as produced by the directive.

There are example omnifests for various distributions and images in a source checkout.

otk.version

Example

otk.version: "1"

otk.target.<consumer>.<name>

Only act on this sub-tree if producing output for the specified consumer. Anything specific to the pipelines of e.g. osbuild would be put under otk.target.osbuild. This allows otk to infer context for the omnifest that is being processed.

A target is necessary for otk to generate any outputs. The target is namespaced to a specific application. otk tries to keep little context but it does need to know what it is outputting for. This allows us to scope otk.external things to only be allowed within specific targets and for those externals to assume certain things will be in the tree.

The following values are valid for the <consumer> part of the key, this list can grow as other image build tooling is supported:

• osbuild

The <name> part of the key is free form and allows you to use a descriptive name for the export. Note that there MUST be no duplication of the <consumer>.<name> tuple.

otk.target.osbuild.tree:
  pipelines:
    - otk.include: pipelines/root.yaml
    - otk.include: pipelines/tree.yaml

---

otk.define

Defines variables that can be used through the ${} directive in other parts of the omnifest.

Variable scope is global, an otk.define directive anywhere in the omnifest tree will result in the defined names being hoisted to the global scope.

Redefinitions of variables are allowed. This allows for setting up default values. If -W duplicate-definition is passed as an argument to otk then otk will warn on all duplicate definitions.

Expects a map for its value.

otk.define:
  packages:
    include:
      - @core
      - kernel
    exclude:
      - linux-util
  boot_mode: uefi

Valid variable names must start with [a-zA-Z] and after that initial char can also contain [a-zA-Z0-9_]. E.g. foo is valid but f? is not.

Usage of ${}

Use a previously defined variable. String values can be used inside other string values, non-string values must stand on their own.

otk.define:
  variable: "foo"

otk.include: ${variable}

Using the above packages map example you can refer to the include and exclude lists using ${packages.include} and ${packages.exclude}.

If a ${} appears in a str value then its string value as it appears in otk.define is replaced into the string. Note that substitutions in this form require the value to be a string in the otk.define.

# this is OK
otk.define:
  variable: aarch64

otk.include: path/${variable}.yaml

The following example is an error as the value of variable is a seq, which is not allowed inside a string format.

# this is NOT OK
otk.define:
  variable:
    - 1
    - 2

otk.include: path/${variable}.yaml

This is okay because ${variable} is there on it's own so it's unambiguous.

# this is OK
otk.define:
  variable:
    - 1
    - 2

some:
 thing: ${variable}

otk.include

Include a file at this position in the tree, replacing the directive with the contents of the file.

Note that cyclical includes are forbidden and will cause an error.

It expects a str for its value and as with other strings variable substitution is performed before using it.

otk.include: file.yaml

otk.op

Perform various operations on variables.

otk.op.join

Join two or more variables of type sequence or map together, trying to join other types or mix types will cause an error. Duplicate keys in maps are considered an error.

Expects a map for its value that contains a values key with a value of type seq or map.

Example when using with a sequence as input:

otk.define:
  a:
    - 1
    - 2
  b:
    - 3
    - 4
  c:
    otk.op.join:
      values:
        - ${a}
        - ${b}

-> Result c: [1, 2, 3, 4]

Example when using with a map as input:

otk.define:
  a:
    a: 1
  b:
    b: 2
  c:
    otk.op.join:
      values:
        - ${a}
        - ${b}

-> Result
  c:
   a: 1
   b: 2

otk.external

External directives. Directives starting with otk.external are redirected to /usr/libexec/otk/external-binaries. For example the directive otk.external.osbuild-depsolve-dnf4 will execute osbuild-depsolve-dnf4 with the tree under the directive on stdin and expect a new tree to replace the directive with on stdout.

Read more about external directives in their specific documentation section.