docker-s3-cache

Docker image with Varnish cache for use in Elastic Beanstalk — caching for sites deployed to S3.

• Ready to deploy to Elastic Beanstalk.
• Caches requests to websites deployed to S3.
• Alters 302 (Moved Temporarily) responses from S3 to 301's (Moved Permanently).
• Optional datadog reporting (see below).

Try It

docker run \
  --env VARNISH_BACKEND_HOST=example.com \
  --env VARNISH_BACKEND_ELB=example.com.s3-website-us-east-1.amazonaws.com \
  adzerk/s3-cache

Overview

This container provides three main components:

• The Varnish caching HTTP proxy configured to listen on port 80 and pass HTTP requests to localhost port 8080. Any 302 status response is changed to a 301 status before being sent to the client.

• An Nginx reverse proxy configured to listen on localhost port 8080 and pass HTTP requests to an S3 website hosting bucket ELB. Nginx is needed to resolve the ELB's IP address at runtime (Varnish can't do this).

• The DataDog agent daemon for container metrics.

Runtime Configuration

The image configures itself via environment variables:

Environment Variable	Description
VARNISH_BACKEND_ELB	The hostname of the S3 ELB (e.g. example.com.s3-website-us-east-1.amazonaws.com).
VARNISH_BACKEND_HOST	The hostname to be sent to the backend as the Host header (e.g. example.com).
VARNISH_BACKEND_PORT	The port the backend will listening on (optional, defaults to 80).
VARNISH_BACKEND_FORCE_SSL	When set to "true", rewrite requests to SSL
VARNISH_BACKEND_FORCE_SSL_HOST	For use with VARNISH_BACKEND_FORCE_SSL. https host to redirect to.
DATADOG_API_KEY	Your datadog API key (datadog agent won't be started if this isn't provided).
DATADOG_TAGS	An optional, comma-delimited list of tags for datadog.

These env variables can be set in the Beanstalk environment configuration.

Build & Test Locally

Then build the image:

make build

Create a docker.env file for testing (loaded via the --env-file option to docker), e.g.

VARNISH_BACKEND_HOST=example.com
VARNISH_BACKEND_ELB=example.com.s3-website-us-east-1.amazonaws.com
...

and start the container:

make run

Deploy to Beanstalk

You just need a Dockerrun.aws.json file with the following contents:

{
  "AWSEBDockerrunVersion": "1",
  "Image": {
    "Name": "adzerk/s3-cache",
    "Update": "true"
  },
  "Ports": [
    {
      "ContainerPort": "80"
    }
  ],
  "Volumes": [],
  "Logging": "/var/log/nginx"
}