npm URLs are re-downloaded despite caching in dockerfile

[GJZwiers]

I am having an issue when using Deno Lambda together with npm: URLs. It seems the npm dependencies are being re-downloaded on executing the function even though they have already been cached during the Docker build.

src/listFunctions.ts:

import {
  APIGatewayProxyEventV2,
  APIGatewayProxyResultV2,
  Context,
} from "https://deno.land/x/lambda@1.28.1/mod.ts";
import { LambdaClient, ListFunctionsCommand } from "npm:@aws-sdk/client-lambda";
 
export async function handler(
  _event: APIGatewayProxyEventV2,
  _context: Context,
): Promise<APIGatewayProxyResultV2> {

  const client = new LambdaClient({ region: "eu-west-3" });

  const funs = await client.send(new ListFunctionsCommand({
    MaxItems: 10,
  }));
  console.log(funs);

  return {
    statusCode: 200,
    headers: { "content-type": "text/html;charset=utf8" },
    body: JSON.stringify(funs.Functions),
  };
}

src/Dockerfile:

FROM hayd/deno-lambda:1.28.2

COPY listFunctions.ts .
RUN deno cache listFunctions.ts

CMD ["listFunctions.handler"]

The lambda is deployed from an AWS CDK project inside an infra folder using this stack:

import * as cdk from "aws-cdk-lib";
import * as iam from "aws-cdk-lib/aws-iam";
import * as lambda from "aws-cdk-lib/aws-lambda";
import { Construct } from "constructs";

export class LambdaStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const fn = new lambda.DockerImageFunction(this, "DockerHandler", {
      code: lambda.DockerImageCode.fromImageAsset("../src"),
    });

    fn.role?.attachInlinePolicy(
      new iam.Policy(this, "allow-lambda-list-functions", {
        statements: [
          new iam.PolicyStatement({
            actions: ["lambda:ListFunctions"],
            resources: ["*"],
          }),
        ],
      }),
    );
  }
}

During the docker build in my pipeline I can see the npm dependencies are downloaded:

 Status: Downloaded newer image for hayd/deno-lambda:1.28.2
 ---> 0306bd607a84
Step 2/4 : COPY listFunctions.ts .
 ---> 855fc54db93f
Step 3/4 : RUN deno cache listFunctions.ts
 ---> Running in cdeb25b45f93
Download https://deno.land/x/lambda@1.28.1/mod.ts
Download https://deno.land/x/lambda@1.28.1/types.d.ts
Download https://registry.npmjs.org/@aws-sdk/client-lambda
Download https://registry.npmjs.org/@aws-crypto/sha256-browser
Download https://registry.npmjs.org/@aws-crypto/sha256-js
Download https://registry.npmjs.org/@aws-sdk/client-sts
Download https://registry.npmjs.org/@aws-sdk/config-resolver
Download https://registry.npmjs.org/@aws-sdk/credential-provider-node
Download https://registry.npmjs.org/@aws-sdk/fetch-http-handler
Download https://registry.npmjs.org/@aws-sdk/hash-node
Download https://registry.npmjs.org/@aws-sdk/invalid-dependency
Download https://registry.npmjs.org/@aws-sdk/middleware-content-length
Download https://registry.npmjs.org/@aws-sdk/middleware-endpoint
Download https://registry.npmjs.org/@aws-sdk/middleware-host-header
Download https://registry.npmjs.org/@aws-sdk/middleware-logger
Download https://registry.npmjs.org/@aws-sdk/middleware-recursion-detection
...

But when invoking the lambda it times out and I can see in the logs that the npm dependencies are being downloaded again:

warn: unable to import '.deno_dir/' as DENO_DIR
Download https://registry.npmjs.org/@aws-sdk/client-lambda
Download https://registry.npmjs.org/@aws-crypto/sha256-browser
Download https://registry.npmjs.org/@aws-crypto/sha256-js
Download https://registry.npmjs.org/@aws-sdk/client-sts
Download https://registry.npmjs.org/@aws-sdk/config-resolver
Download https://registry.npmjs.org/@aws-sdk/credential-provider-node
Download https://registry.npmjs.org/@aws-sdk/fetch-http-handler
Download https://registry.npmjs.org/@aws-sdk/hash-node
Download https://registry.npmjs.org/@aws-sdk/invalid-dependency
Download https://registry.npmjs.org/@aws-sdk/middleware-content-length
Download https://registry.npmjs.org/@aws-sdk/middleware-endpoint
Download https://registry.npmjs.org/@aws-sdk/middleware-host-header
Download https://registry.npmjs.org/@aws-sdk/middleware-logger
Download https://registry.npmjs.org/@aws-sdk/middleware-recursion-detection

If I change dependencies to use the aws_api module from deno.land/x I don't get this issue at all (although I do get the same warning about being unable to import .deno_dir)

import {
  APIGatewayProxyEventV2,
  APIGatewayProxyResultV2,
  Context,
} from "https://deno.land/x/lambda@1.28.1/mod.ts";
import { ApiFactory } from "https://deno.land/x/aws_api@v0.7.0/client/mod.ts";
import { Lambda } from "https://deno.land/x/aws_api@v0.7.0/services/lambda/mod.ts";
 
export async function handler(
  _event: APIGatewayProxyEventV2,
  _context: Context,
): Promise<APIGatewayProxyResultV2> {
  const lambda = new ApiFactory({
    region: "eu-west-3",
  }).makeNew(Lambda);

  const funs = await lambda.listFunctions({
    MaxItems: 10,
  });
  console.log(funs);

  return {
    statusCode: 200,
    headers: { "content-type": "text/html;charset=utf8" },
    body: JSON.stringify(funs.Functions),
  };
}

warn: unable to import '.deno_dir/' as DENO_DIR
--
START RequestId: 4c3c8794-3800-4708-8fb2-98d757bb4f56 Version: $LATEST
INFO	RequestId: 4c3c8794-3800-4708-8fb2-98d757bb4f56{  Functions: [    {      Description: "",      TracingConfig: { Mode: "PassThrough" },      VpcConfig: null,      SigningJobArn: null,      RevisionId: "3f9fbe00-d293-4df9-a8c9-4055e2b5cf49",      LastModified: "2022-11-27T11:55:16.000+0000",      FileSystemConfigs: null,      FunctionName: "LambdaStack-DockerHandlerE16963D5-RJq8TsfCxSsm",      Runtime: null,      Version: "$LATEST",      PackageType: "Image",      LastUpdateStatus: null,      Layers: null,      FunctionArn: "arn:aws:lambda:eu-west-3:305747223196:function:LambdaStack-DockerHandlerE16963D5-RJq8TsfCxSsm",      KMSKeyArn: null,      MemorySize: 128,      ImageConfigResponse: null,      LastUpdateStatusReason: null,      DeadLetterConfig: null,      Timeout: 30,      Handler: null,      CodeSha256: "0b8ada40dfe0610a0720f995ca8a7b271213678e616111451c952a226c8557ca",      Role: "arn:aws:iam::305747223196:role/LambdaStack-DockerHandlerServiceRole5A884A94-1WWHCIXLKC63E",      SigningProfileVersionArn: null,      MasterArn: null,      CodeSize: 0,      State: null,      StateReason: null,      Environment: null,      StateReasonCode: null,      LastUpdateStatusReasonCode: null,      Architectures: [ "x86_64" ]    }  ],  NextMarker: null}
END RequestId: 4c3c8794-3800-4708-8fb2-98d757bb4f56
REPORT RequestId: 4c3c8794-3800-4708-8fb2-98d757bb4f56	Duration: 363.21 ms	Billed Duration: 928 ms	Memory Size: 128 MB	Max Memory Used: 71 MB	Init Duration: 563.89 ms