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chore: bind lambda RIE to 0.0.0.0 for durable functions#8483

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valerena merged 2 commits into
aws:developfrom
bchampp:fix/durable-lambda-rie-container-interface
Dec 3, 2025
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chore: bind lambda RIE to 0.0.0.0 for durable functions#8483
valerena merged 2 commits into
aws:developfrom
bchampp:fix/durable-lambda-rie-container-interface

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@bchampp

@bchampp bchampp commented Dec 3, 2025

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Which issue(s) does this change fix?

Why is this change necessary?

The Lambda RIE container gets bound to 127.0.0.1 (localhost) by default. The durable executions emulator needs to interact with the RIE endpoint directly - so we're making HTTP calls from within the emulator container across to the RIE endpoint.

In some environments, this isn't accessible by default, and we see errors like Could not connect to endpoint: host.docker.internal... We need to bind the RIE container to 0.0.0.0 instead so it's accessible on any interface. Users can work around this by using --container-host-interface 0.0.0.0, but this should by default.

How does it address the issue?

Updating the DurableLambdaContainer class to override the lambda container container_host_interface parameter to 0.0.0.0.

What side effects does this change have?

Lambda container is always bound to 0.0.0.0 for durable executions.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

@bchampp
bchampp requested a review from a team as a code owner December 3, 2025 07:22
@github-actions github-actions Bot added area/local/start-api sam local start-api command area/local/invoke sam local invoke command area/local/start-invoke pr/external stage/needs-triage Automatically applied to new issues and PRs, indicating they haven't been looked at. labels Dec 3, 2025
Comment thread samcli/local/docker/durable_lambda_container.py
@valerena
valerena enabled auto-merge December 3, 2025 17:11
@valerena
valerena added this pull request to the merge queue Dec 3, 2025
Merged via the queue into aws:develop with commit d48ca94 Dec 3, 2025
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3 participants