Camo-rb

Camo-rb is a ruby version of camo

A camo server is a special type of image proxy that proxies non-secure images over SSL/TLS, in order to prevent mixed content warnings on secure pages. The server works in conjunction with back-end code that rewrites image URLs and signs them with an HMAC.

Usage

Install Camo-rb as a ruby gem:

gem install camo-rb

Run it:

CAMORB_KEY=<some key> camorb

Configuration

Use the next environment variables to configure the server:

• CAMORB_PORT — the port number Camo should listen on (default: 9292)
• CAMORB_KEY — a shared key consisting of a random string, used to generate the HMAC digest (default: none)
• CAMORB_HEADER_VIA — the string for Camo to include in the Via and User-Agent headers it sends in requests to origin servers (default: Camo Asset Proxy <version>)
• CAMORB_LOG_LEVEL — severity of logging, available levels: debug, info, error (default: info)
• CAMORB_KEEP_ALIVE — whether or not to enable keep-alive session (default: false)
• CAMORB_MAX_REDIRECTS — the maximum number of redirects Camo will follow while fetching an image (default: 4)
• CAMORB_SOCKET_TIMEOUT — the maximum number of seconds Camo will wait before giving up on fetching an image (default: 10)
• CAMORB_LENGTH_LIMIT — the maximum Content-Length Camo will proxy (default: 5242880)
• CAMORB_TIMING_ALLOW_ORIGIN — the string for Camo to include in the Timing-Allow-Origin header it sends in responses to clients. The header is omitted if this environment variable is not set (default: none)
• CAMORB_HOSTNAME — the Camo-Host header value that Camo will send (default: unknown)

URL Formats

Camo supports two distinct URL formats:

http://example.org/<digest>?url=<image-url>
http://example.org/<digest>/<image-url>

The <digest> is a 40 character hex encoded HMAC digest generated with a shared secret key and the unescaped <image-url> value. The <image-url> is the absolute URL locating an image. In the first format, the <image-url> should be URL escaped aggressively to ensure the original value isn't mangled in transit. In the second format, each byte of the <image-url> should be hex encoded such that the resulting value includes only characters [0-9a-f].

Tasks to do

• Create MVP
• Allow use SSL/TLS certificates
• Add logging in JSON format
• Allow to customize requests and the server
• Support metrics (Prometheus)
• Allow to customize logging

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