Step 2.1: Create the deployment package

Currently the example code for the Lambda function is only supplied in Python.

Python

The following example Python code reads and writes an item to your ElastiCache cluster. Copy the code and save it into a file named app.py. Be sure to replace the elasticache_config_endpoint value in the code with the endpoint address you copied in step 1.


import uuid
import ssl
from pymemcache.client.base import Client

elasticache_config_endpoint = "serverlesscacheforlambda-ces85m.serverless.use1.cache.amazonaws.com"
target_port = 11211

context = ssl.create_default_context()

memcached_client = Client((elasticache_config_endpoint, target_port), tls_context=context)

def lambda_handler(event, context):
    
    # create a random UUID - this will be the sample element we add to the cache
    uuid_in = uuid.uuid4().hex
    
    # put the UUID to the cache
    memcached_client.set("uuid", uuid_in, expire=500, noreply=False)
    
    # get the item (UUID) from the cache
    result = memcached_client.get("uuid")
    decoded_result = result.decode("utf-8")
    
    # check the retrieved item matches the item added to the cache and print
    # the results
    if decoded_result == uuid_in:
        print(f"Success: Inserted {uuid_in}. Fetched {decoded_result} from Memcached.")
    else:
        raise Exception(f"Bad value retrieved. Expected {uuid_in}, got {decoded_result}")
        
    return "Fetched value from Memcached"

This code uses the Python pymemcache library to put items into your cache and retrieve them. To create a deployment package containing pymemcache, carry out the following steps.

In your project directory containing the app.py source code file, create a folder package to install the pymemacache library into.
```
mkdir package
```

Install pymemcache using pip.


pip install --target ./package pymemcache

Create a .zip file containing the pymemcache library. In Linux and macOS, run the following command. In Windows, use your preferred zip utility to create a .zip file with the pymemache library at the root.
```
cd package
zip -r ../my_deployment_package.zip .
```
Add your function code to the .zip file. In Linux and macOS, run the following command. In Windows, use your preferred zip utility to add app.py to the root of your .zip file.
```
cd ..
zip my_deployment_package.zip app.py
```

Next Step

Step 2.2: Create the IAM role (execution role)

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Step 2: Create a Lambda function

Step 2.2: Create the IAM role (execution role)