Struct BaseImage 

pub struct BaseImage {
    pub name: String,
    pub docker_ref: String,
    pub working_dir: String,
}

A base image: the platform ARN, the Dockerfile FROM that pairs with it, and whether it declares a WORKDIR.

All three together because the first two must agree and used to be able to disagree: the Python client’s DEFAULT_BASE_IMAGE named the managed base for baseImageArn while default_dockerfile hardcoded an unrelated registry literal in its FROM, so changing either left the other pointing somewhere else (sandbox.py:410-444). Pairing them means a caller selects one thing and both fields follow.

Fields

name: String

Goes into baseImageArn — the platform’s managed base, not a registry ref.

docker_ref: String

Goes into the Dockerfile FROM — the registry ref measured alongside name.

working_dir: String

What docker inspect reports for WorkingDir. Empty means it declares none.

A field rather than a lookup because a caller with a purpose-built image is the only one who can say what their image declares, and this client cannot read it without pulling the manifest.

Implementations

impl BaseImage

pub fn al2023() -> BaseImage

The managed base every docs/PLATFORM.md measurement from 2026-08-06 onward used, paired with the registry ref those same builds used as FROM.

working_dir is empty, and that is measured rather than assumed: al2023-minimal, python:3.12-slim, and node:20-slim all leave WorkingDir empty (2026-08-05), which is what makes require_workdir necessary.

pub fn from_dockerfile(dockerfile: &str) -> Result<BaseImage, Error>

The base image a task Dockerfile pairs with: the managed base’s name (so baseImageArn is unchanged) and the Dockerfile’s own first FROM as docker_ref (IMAGE-4).

The pairing the other way round

require_matching_from refuses a Dockerfile whose first FROM is not the base’s docker_ref. That is the right guard where this client derives the Dockerfile from the base; a task Dockerfile chooses its own FROM, so the pairing has to run from the Dockerfile to the base, and every harness wrote the same inversion by hand (#220). Here the ref is taken whole — --platform and AS decoration dropped by dockerfile_from_ref, a digest pin kept — so the guard’s comparison is the ref against itself and it passes by construction.

working_dir is empty: this cannot read the FROM image’s WorkingDir without pulling its manifest, and empty is what every measured public base declares (see BaseImage::al2023). A task that relies on one sets WORKDIR, which require_workdir reads from the Dockerfile.

Refuses a Dockerfile with no FROM: there is no ref to take.

pub fn arn(&self, region: &Region) -> String

The baseImageArn for this base in region.

microvm-image:<name>, with a colon, and it is not just the managed base

This was the only place in the repo building the colon form; the fakes and the encoding test all used microvm-image/<name>, so the repo held two beliefs about the shape of the identifier every image call takes. The model’s TaggableResource pattern admits only (capacity-provider|network-connector|microvm-image):[a-zA-Z0-9-_]+, and a live read settled it: ListMicrovmImages in us-east-1 returns arn:aws:lambda:us-east-1:<account>:microvm-image:coding-agents-on-bedrock for a customer image, and GetMicrovmImage accepts exactly that (measured 2026-08-15).

So the colon is right for both the managed base and a customer image; there is no two-form rule, and this comment used to imply there was. The slash form fails as AccessDeniedException rather than as a validation error, because IAM evaluates the malformed ARN as a resource with no matching policy — a permissions message for a resource that exists.

Trait Implementations

impl Clone for BaseImage

fn clone(&self) -> BaseImage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BaseImage

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for BaseImage

fn default() -> BaseImage

Returns the “default value” for a type.

impl Eq for BaseImage

impl PartialEq for BaseImage

fn eq(&self, other: &BaseImage) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BaseImage