Skip to content

Expressions

Expressions produce values for inputs, locals, node bodies, constraints, and outputs.

Literals

'web'
3
1.5
true
false
null
['a', 'b']
{ name: 'web', port: 443 }

References

Factory expressions can read these roots:

  • input.<name> for factory or composite inputs.
  • local.<name> for file locals.
  • resource.<name> for resource outputs.
  • data-source.<name> for data source outputs.
  • action.<name> for action outputs.
  • asset.<name> for a file or directory captured by the current body.
  • @each.key and @each.value inside @for-each and iterating constraints.
  • @core.<name>(...) for builtin functions.
  • <alias>.<name>(...) for imported functions, where <alias> is the import alias.
resource.web.id
input.instances[0]
input.tags['Name']

A node with @for-each gets one @each value per item:

resources: {
  file: std.fs-file {
    @for-each: input.files
    path:      $'/tmp/{{ @each.key }}.txt'
    content:   @each.value
  }
}

Asset references

An asset reference starts with the asset root and a name declared in the current factory or composite body:

asset.lambda.path
asset.lambda.content
asset.lambda.content-sha256
asset.lambda.mode

For a directory asset, one bracket may select a descendant. Put the complete canonical relative path in that bracket:

asset.lambda['main.go'].content
asset.lambda['internal/helpers.go'].path
asset.lambda['internal'].content-sha256

The selection must be a string literal using /, with no empty, . or .. segments. Computed selection, repeated brackets, and selection from a file asset are invalid.

Asset paths support == and != with other path or string expressions. The comparison uses the logical reference, not a host cache path. Asset content compares as bytes and can be passed to byte-compatible functions such as @core.b64-encode. Equality between disjoint types, such as asset content and a string, is a type mismatch.

Operators

Common operators include arithmetic, comparisons, boolean operators, ?., and ??:

input.count + 1
input.environment == 'prod'
input.enabled && input.count > 0
input.tls?.cert ?? 'self-signed'

Infix operators must have even spacing. Write a - b or a + b, not a -b or a+ b. Due to kebab-casing in identifiers, a-b would be evaluated as an identifier, not subtraction.

Function calls

Functions are qualified by their import alias. Builtins use the @core namespace:

@core.length(input.names)
@core.join(input.names, ',')

Imported Go library functions are qualified by their import alias:

imports: { text: 'github.com/example/text' }

locals: {
  slug: text.slug(input.name)
}