Proxy Image Service

A simple Node.js image proxy service. It can be used by an application to render images hosted on remote servers while protecting users against cross-site request forgery attacks.

• The image content is piped directly from the remote server to the client for efficient usage of memory
• Remote response headers are forwarded to the client response.
• Only responses from remote servers with 200 HTTP status codes are forwarded to the client.
• 301/302 responses from the remote server are followed until a depth allowance is exceeded

Demo

A demo instance of the service has been deployed via Google Cloud.

Here are examples of the image proxy functionality:

• Example 1
• Example 2

Usage

To use the proxy service, simply specify a URL in the format of [proxyServerDomain]/image?url=[remoteImageUrl] as the src attribute of an image element:

<img src="[proxyServerDomain]/image?url=[link]" alt="[link]">

Header Forwarding

All response headers from the remote server are included in the proxy image service's responses when the remote image has been successfully retrieved.

Supported Content Types

The remotely hosted image must have a Content Type response header that begins with image/. Here are a few examples of supported content types:

• image/jpeg
• image/gif
• image/png
• image/svg+xml

The specified url value does not need to include an image file extension such as .jpg, .gif, or .png.

Getting Started

Installation

You can install this package via NPM: npm install -g proxy-image-service.

To setup the package for local development, use commands git clone https://github.com/jamslevy/proxy-image-service.git and cd proxy-image-service to enter the project directory. Use command npm install to install any required development dependencies.

Run the Node.js server locally with command npm start.

Testing

Run tests with command npm test. ESLint will be executed after the tests and run, or you can lint directly with command npm lint.

Quick Gcloud Deployment

To deploy on Google Compute Engine, use command npm run deploy.

Make sure you have first authenticated with command gcloud auth login and logged into an account that has permissions on Google Cloud to deploy to your project's proxy-image-service as specified in the app.yaml file. For more information, refer to the Google Cloud developer documentation. To deploy to an alternative cloud compute provider, modify the deploy script command in the package.json file to use your preferred provider.

You can tail the logs sent to the Google Compute Engine instance with command gcloud app logs tail -s proxy-image-service.

Custom Deployment

The app can also be deployed on an instance hosted by your choice of provider such as AWS or Digital Ocean by completing the following steps:

• Create an instance and use SSH to access the instance via a command line interface.
• Make sure your instance is setup to allow traffic on the port that will be used for the application, the instance is available via a public IP, and required dependencies such as Nodejs are installed,
• Download the source for the package or use npm i -g proxy-image-service to install the package via NPM, and navigate to the installed package location. See the Installation section above for more information on setting up the package for local development.
• Run npm start to run the program, and consider using tools like crontab and forever-service to ensure the Node server continues to run even after the program crashes or the server is restarted.
• Optionally setup DNS forwarding for the server to be available at a web domain or subdomain of your choosing.