How to run lambda function on a schedule in my localhost? - amazon-web-services

Question

I have a task that need to be scheduled on aws lambda function. I wrote a SAM template as below and I see it works when deploying on aws environment (my function get triggered intervally).
But we want to do testing on dev environment first before deploying. I use sam local start-api [OPTIONS] to deploy our functions to dev environment. But the problem is that, every functions configured as rest API work, but the schedule task not. I'm not sure is it possible on local/dev environment or not. If not, please suggest a solution (is it possible?). Thank you
This is template:
aRestApi:
...
...
sendMonthlyReport:
Type: AWS::Serverless::Function
Properties:
Handler: src.monthlyReport
Runtime: nodejs16.x
Events:
ScheduledEvent:
Type: Schedule
Properties:
Schedule: "cron(* * * * *)"

Answer 1

If you search for local testing before deployment of lambda functions you will probably be fed this resource by the quote-unquote "google": https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-using-debugging.html
However, there are other ways to do it.
I personally use the public docker image from aws.
Here is an example of the docker image created for a specific use case of mine.
FROM public.ecr.aws/lambda/python:3.8
RUN yum -y install tar gzip zlib freetype-devel \
gcc \
ghostscript \
lcms2-devel \
libffi-devel \
libimagequant-devel \
.
enter code here
enter code here
and some more dependencies ....
&& yum clean all
COPY requirements.txt ./
RUN python3.8 -m pip install -r requirements.txt
# Replace Pillow with Pillow-SIMD to take advantage of AVX2
RUN pip uninstall -y pillow && CC="cc -mavx2" pip install -U --force-reinstall pillow-simd
COPY <handler>.py ./<handler>.py
# Set the CMD to your handler
ENTRYPOINT [ "python3.8","app5.py" ]
In your case, follow instructions for node and run the docker image locally. If it works, you can then continue with aws lambda creation/update.
I see that you also have a cron job, why not use the cron job to invoke this lambda function separately and not define it in you SAML?
There are a number of ways you can invoke a lambda function based on event.
For example to invoke using cli: (For aws-cliv2)
make sure you configure awscli
# !/bin/bash
export AWS_PROFILE=<your aws profile>
export AWS_REGION=<aws region>
aws lambda invoke --function-name <function name> \
--cli-binary-format raw-in-base64-out \
--log-type Tail \
--payload <your json payload > \
<output filename>
Makes it loosely coupled.
Then you can use carlo's node cronjob suggestion to invoke is as many times you like, free of charge.

Answer 2

I used localstack for the demonstrate. LocalStack is a cloud service emulator that runs in a single container on your laptop or in your CI environment. You can see more detail in this link https://github.com/localstack/localstack

Answer 3

I would use node-cron to set a scheduler on a node file to run.
npm install --save node-cron
var cron = require('node-cron');
cron.schedule('* * * * *', () => {
console.log('running a task every minute');
});
https://www.npmjs.com/package/node-cron
You can also check for this DigitalOcean tutorial!