Deploy an AWS Lambda Function from the Terminal

My last article gave a quick run-down on how you can invoke a Lambda function from your terminal. I've had a few people message me asking how I deploy / upload my Lambda functions to AWS.

Here is how I do it.

Zipping up your code

When you upload your Lambda function, you'll want to provide a ZIP file that contains all of the necessary code. I mostly write Node functions these days, so my ZIP files generally contain a node_modules folder, an index.js file and a package.json file too so I can quickly check what dependencies I'm using from the Lambda UI.

On UNIX machines, you can use the zip command to generate a ZIP file. As an example, you might run something like this:

zip -r function.zip .

This command will create a new function.zip file, compressing the contents of the current directory (or .).

If you need to exclude some files, you can use the -x option. This is handy if you have a generic input.json or output.json file, as described in my other article.

zip -r function.zip . -x output.json input.json

Deploying to AWS

Now that we've got a ZIP file with our Lambda function's dependencies and handler, we can finally deploy to AWS. AWS have, surprisingly, made this very simple using the AWS CLI.

aws lambda update-function-code --function-name NameOfFunctionHere

We haven't told the AWS CLI what to deploy though. In our case it will be a ZIP file, so let's use the --zip-file option and specify the correct file.

aws lambda update-function-code --function-name NameOfFunctionHere --zip-file fileb://function.zip

The fileb:// protocol is used because we're uploading binary data.

Condensing this down

You might have already guessed it, but I don't actually type out this entire command each time. I like putting these commands inside of NPM "scripts" so that I can quickly run them with npm run or yarn.

{
    "scripts": {
        "zip": "zip -r function.zip . -x output.json input.json",
        "deploy": "npm run zip && aws lambda update-function-code --function-name NameOfFunctionHere --zip-file fileb://function.zip"
    }
}