fix: avoid hardcoded override to avoid durable function failure by lauhon · Pull Request #13354 · serverless/serverless

lauhon · 2026-02-18T11:45:23Z

Summary by CodeRabbit

Release Notes

Improvements
- The serverless development plugin now dynamically detects and uses your local Node.js runtime version instead of enforcing a fixed version, ensuring better compatibility with your development environment.

coderabbitai · 2026-02-18T11:45:31Z

📝 Walkthrough

Walkthrough

The dev command's runtime assignment was updated to use the local Node.js version dynamically instead of enforcing nodejs20.x. This allows projects requiring higher Node versions, such as nodejs22.x for durable functions, to function correctly during development.

Changes

Cohort / File(s)	Summary
Runtime Environment `packages/serverless/lib/plugins/aws/dev/index.js`	Changed hardcoded nodejs20.x runtime to dynamic localRuntime based on current Node.js version for dev environment compatibility.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

🐰 A hop and a skip, the runtime's now free,
No longer locked down to version twenty,
Local Node.js takes the wheel with grace,
Durable functions find their rightful place!
The dev command hops with the system's own pace ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: removing a hardcoded Node.js 20 runtime override that was causing durable function failures.
Linked Issues check	✅ Passed	The code change replaces hardcoded 'nodejs20.x' with dynamic localRuntime, directly addressing the core requirement in `#13355` to prevent runtime override for durable functions.
Out of Scope Changes check	✅ Passed	The change is narrowly scoped to fixing the runtime assignment logic in the dev command, directly related to the linked issue with no extraneous modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Mmarzex · 2026-02-18T11:45:34Z

✅ Snyk checks have passed. No issues have been found so far.

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github-actions · 2026-02-18T11:45:34Z

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

lauhon · 2026-02-18T11:52:58Z

I have read the CLA Document and I hereby sign the CLA

coderabbitai

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

packages/serverless/lib/plugins/aws/dev/index.js (1)

286-288: ⚠️ Potential issue | 🟡 Minor

Stale JSDoc — update step 3 to reflect the dynamic runtime.

The comment at step 3 still reads 'nodejs20.x' as expected by the shim, but the runtime is now derived from the local Node.js version.

📝 Proposed fix

- *   3. Update all AWS Lambda functions' runtime to 'nodejs20.x' as expected by the shim
+ *   3. Update all AWS Lambda functions' runtime to match the local Node.js runtime (e.g. nodejs22.x) as expected by the shim

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@packages/serverless/lib/plugins/aws/dev/index.js` around lines 286 - 288,
Update the stale JSDoc step 3 that currently says "'nodejs20.x' as expected by
the shim" to state that the Lambda runtime is determined dynamically from the
local Node.js version (e.g., "runtime is derived from the local Node.js
version") so it matches the implementation that computes the runtime; search the
file for the JSDoc block containing the bullet list and the literal 'nodejs20.x'
(step 3) and replace that phrase accordingly so the comment reflects the dynamic
runtime behavior.

🧹 Nitpick comments (1)

packages/serverless/lib/plugins/aws/dev/index.js (1)

332-333: localRuntime is not validated against supported AWS Lambda Node.js runtimes.

process.version.split('.')[0].replace('v', '') correctly extracts the major version, but AWS Lambda only supports specific Node.js runtimes (nodejs18.x, nodejs20.x, nodejs22.x). If a developer's local Node.js is an odd/unstable release (e.g., 21 or 23), functionConfig.runtime is set to an unsupported value and the subsequent deploy spawn will fail with an opaque AWS error rather than a clear, actionable message.

Consider validating — or at minimum warning — before proceeding:

🛡️ Proposed improvement

  const localRuntimeVersion = process.version.split('.')[0].replace('v', '')
  const localRuntime = `nodejs${localRuntimeVersion}.x`
+ const supportedNodeRuntimes = ['nodejs18.x', 'nodejs20.x', 'nodejs22.x']
+ if (!supportedNodeRuntimes.includes(localRuntime)) {
+   throw new ServerlessError(
+     `Dev mode requires a locally installed Node.js version that matches a supported AWS Lambda runtime. ` +
+       `Your local version (${localRuntime}) is not supported. Supported runtimes: ${supportedNodeRuntimes.join(', ')}.`,
+     'DEV_MODE_UNSUPPORTED_LOCAL_RUNTIME',
+     { stack: false },
+   )
+ }

Also applies to: 397-397

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@packages/serverless/lib/plugins/aws/dev/index.js` around lines 332 - 333,
Extracting major Node.js version into localRuntimeVersion and building
localRuntime may produce unsupported AWS Lambda runtimes (e.g., nodejs21.x);
update the logic around localRuntimeVersion/localRuntime and where
functionConfig.runtime is assigned to validate against the allowed set
['nodejs18.x','nodejs20.x','nodejs22.x'] and if the computed runtime is not in
that set either (a) throw or return a clear, actionable error message indicating
the unsupported local Node version and listing supported runtimes, or (b) emit a
warning and map/fallback to the nearest supported runtime before proceeding;
make this validation happen before the deploy spawn so the failure is surfaced
early and references functionConfig.runtime, localRuntimeVersion, and
localRuntime when reporting the issue.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@packages/serverless/lib/plugins/aws/dev/index.js`:
- Around line 286-288: Update the stale JSDoc step 3 that currently says
"'nodejs20.x' as expected by the shim" to state that the Lambda runtime is
determined dynamically from the local Node.js version (e.g., "runtime is derived
from the local Node.js version") so it matches the implementation that computes
the runtime; search the file for the JSDoc block containing the bullet list and
the literal 'nodejs20.x' (step 3) and replace that phrase accordingly so the
comment reflects the dynamic runtime behavior.

---

Nitpick comments:
In `@packages/serverless/lib/plugins/aws/dev/index.js`:
- Around line 332-333: Extracting major Node.js version into localRuntimeVersion
and building localRuntime may produce unsupported AWS Lambda runtimes (e.g.,
nodejs21.x); update the logic around localRuntimeVersion/localRuntime and where
functionConfig.runtime is assigned to validate against the allowed set
['nodejs18.x','nodejs20.x','nodejs22.x'] and if the computed runtime is not in
that set either (a) throw or return a clear, actionable error message indicating
the unsupported local Node version and listing supported runtimes, or (b) emit a
warning and map/fallback to the nearest supported runtime before proceeding;
make this validation happen before the deploy spawn so the failure is surfaced
early and references functionConfig.runtime, localRuntimeVersion, and
localRuntime when reporting the issue.

fix: avoid hardcoded override to avoid durable function failure

7e6f641

lauhon marked this pull request as ready for review February 18, 2026 11:49

coderabbitai bot reviewed Feb 18, 2026

View reviewed changes

docs: update comment change as suggested by coderabbit

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Comments

fix: avoid hardcoded override to avoid durable function failure#13354

fix: avoid hardcoded override to avoid durable function failure#13354
lauhon wants to merge 2 commits intoserverless:mainfrom
lauhon:patch-1

lauhon commented Feb 18, 2026 •

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Summary by CodeRabbit

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Walkthrough

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lauhon commented Feb 18, 2026 •

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