SAM local lambda prevent rebuilding image on every invocation

[tobyloki]

I am trying to test my Lambda locally using sam local start-lambda. It is attached to a local Lambda Layer called MyLambdaLayer. However, whenever I try to invoke the Lambda, it always rebuilds the image. Is there a way to cache the build or prevent it from rebuilding on every invocation?

Here is my setup procedure:

1. Start the local Lambda server

sam local start-lambda --template Lambda.yaml --skip-pull-image

2. Invoke the Lambda via JS test script

const { LambdaClient, InvokeCommand } = require('@aws-sdk/client-lambda');
const lambda = new LambdaClient({
    endpoint: 'http://127.0.0.1:3001',
    tls: false,
    region: 'us-east-1',
    credentials: {
        accessKeyId: 'any',
        secretAccessKey: 'any'
    }
});
const invoke = async (funcName, payload) => {
    const command = new InvokeCommand({
        FunctionName: funcName,
        Payload: JSON.stringify(payload)
    });
    const ret = await lambda.send(command);
    const { Payload, StatusCode } = ret;
    const result = Buffer.from(Payload).toString();
    return {
        payload: result,
        statusCode: StatusCode
    };
};

test('test', async () => {
    const event = {
        data: 'some data'
    };
    const result = await invoke('MyLambda', event);
    console.log(result);
}, 25000);

npm test lambdaInvoke.test.js

Here are the logs from the local Lambda server every time I invoke the Lambda:

2023-11-15 20:11:46 127.0.0.1 - - [15/Nov/2023 20:11:46] "POST /2015-03-31/functions/MyLambda/invocations HTTP/1.1" 200 -
Invoking index.handler (nodejs16.x)                                                                                                                         
MyLambdaLayer is a local Layer in the template                                                                                                
Building image.....................
Requested to skip pulling images ...                                                                                                                        
                                                                                                                                                            
Mounting /path/MyLambda as /var/task:ro,delegated, inside runtime container                                    
START RequestId: 76f26199-64cf-4def-959a-97afd4a10951 Version: $LATEST
END RequestId: 76f26199-64cf-4def-959a-97afd4a10951
REPORT RequestId: 76f26199-64cf-4def-959a-97afd4a10951  Init Duration: 0.13 ms  Duration: 1290.95 ms    Billed Duration: 1291 ms        Memory Size: 256 MBMax Memory Used: 256 MB

2023-11-15 20:12:14 127.0.0.1 - - [15/Nov/2023 20:12:14] "POST /2015-03-31/functions/MyLambda/invocations HTTP/1.1" 200 -
Invoking index.handler (nodejs16.x)                                                                                                                         
MyLambdaLayer is a local Layer in the template                                                                                                
Building image.....................
Requested to skip pulling images ...                                                                                                                        
                                                                                                                                                            
Mounting /path/MyLambda as /var/task:ro,delegated, inside runtime container                                    
START RequestId: b5b2e638-1d45-48a8-8d13-e3118c50f4bc Version: $LATEST
END RequestId: b5b2e638-1d45-48a8-8d13-e3118c50f4bc
REPORT RequestId: b5b2e638-1d45-48a8-8d13-e3118c50f4bc  Init Duration: 0.07 ms  Duration: 1348.59 ms    Billed Duration: 1349 ms        Memory Size: 256 MBMax Memory Used: 256 MB

[mildaniel]

Hi @tobyloki, can you try running the command using the --warm-containers EAGER flag and see if this works for you?

[hnnasit]

Closing as this issue has been inactive for a while. Feel free to try @mildaniel's suggestion and open a new issue if you still have questions or concerns.

[github-actions]

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