Reuse Connections with Keep-Alive

By default, the default Node.js HTTP/HTTPS agent creates a new TCP connection for every new request. To avoid the cost of establishing a new connection, you can reuse an existing connection.

The easiest way to configure SDK for JavaScript to reuse TCP connections is to set the AWS_NODEJS_CONNECTION_REUSE_ENABLED environment variable to 1.

Using Serverless Framework, this can be set as an environment variable in the serverless.yml file.

  environment:
    AWS_NODEJS_CONNECTION_REUSE_ENABLED	: "1"

Running a test for 5 mins using artillery, CloudWatch Insights produced the following with no keep-alive set:

Max Duration	Average Duration	Min Duration	95th Percentile
439.89ms	78.2102ms	52.35ms	115.182ms

When keep-alive is turned on, this was reduced to:

Max Duration	Average Duration	Min Duration	95th Percentile
334.15ms	34.3112ms	24.06ms	49.0142ms