Dagger module Container arguments accept default addresses
Introduced 2026-02-05 · score 0.97
HOW TO USE IT
When a Dagger Function takes a `Container` argument, set its `defaultAddress` so Dagger loads that image when the caller omits the argument. An explicitly supplied argument value overrides the default.
// +defaultAddress="alpine:latest"
ctr *dagger.Container,{
"function": ["testWithDefaultContainer"],
"argument": "ctr",
"defaultAddress": "alpine:3.18"
}WHY THIS HELPS
Provide a default base image for a Container argument used by a repository build or test function.
REQUIREMENTS AND LIMITATIONS
- Version: v0.19.11
- defaultAddress (required): The container image address to load when this `Container` argument is not set; an explicitly passed argument overrides it.
- function (required): JSON customization field identifying the function by name; shown as an array containing `testWithDefaultContainer`.
- argument (required): JSON customization field naming the argument that receives the default address; shown as `ctr`.
- Prerequisite: The function argument must be of type `Container`; default addresses are only available for `Container` arguments.
- Default addresses are only available for `Container` arguments.
- An explicitly passed value overrides the default address.
FIRST-PARTY EVIDENCE
- https://github.com/dagger/dagger/releases/tag/v0.19.11
- https://github.com/dagger/dagger/pull/11714
- https://docs.dagger.io/0.19.11/getting-started/types/container/#default-addresses
Check the installed version and the source before using it. Entry JSON