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https://github.com/atmos/camo
:lock: an http proxy to route images through SSL
https://github.com/atmos/camo
Last synced: about 2 months ago
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:lock: an http proxy to route images through SSL
- Host: GitHub
- URL: https://github.com/atmos/camo
- Owner: atmos
- License: mit
- Archived: true
- Created: 2010-11-13T02:56:46.000Z (almost 14 years ago)
- Default Branch: master
- Last Pushed: 2021-04-04T19:59:16.000Z (over 3 years ago)
- Last Synced: 2024-09-21T22:04:00.081Z (about 2 months ago)
- Language: CoffeeScript
- Homepage:
- Size: 210 KB
- Stars: 1,802
- Watchers: 106
- Forks: 370
- Open Issues: 25
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.md
Awesome Lists containing this project
- awesome-list - camo
README
# camo [](https://travis-ci.org/atmos/camo)
Camo is all about making insecure assets look secure. This is an SSL image proxy to prevent mixed content warnings on secure pages served from [GitHub](https://github.com).
We want to allow people to keep embedding images in comments/issues/READMEs.
[There's more info on the GitHub blog](https://github.com/blog/743-sidejack-prevention-phase-3-ssl-proxied-assets).
Using a shared key, proxy URLs are authenticated with [hmac](http://en.wikipedia.org/wiki/HMAC) so we can bust caches/ban/rate limit if needed.
Camo currently runs on node version 0.10.29 at GitHub on [heroku](http://heroku.com).
[](https://heroku.com/deploy?template=https://github.com/atmos/camo)
Features
--------
* Max size for proxied images
* Follow redirects to a certain depth
* Restricts proxied images content-types to a whitelist
* Forward images regardless of HTTP status code
At GitHub we render markdown and replace all of the `src` attributes on the `img` tags with the appropriate URL to hit the proxies. There's example code for creating URLs in [the tests](https://github.com/atmos/camo/blob/master/test/proxy_test.rb).
## URL Formats
Camo supports two distinct URL formats:
http://example.org/?url=
http://example.org//
The `` is a 40 character hex encoded HMAC digest generated with a shared
secret key and the unescaped `` value. The `` is the
absolute URL locating an image. In the first format, the `` should be
URL escaped aggressively to ensure the original value isn't mangled in transit.
In the second format, each byte of the `` should be hex encoded such
that the resulting value includes only characters `[0-9a-f]`.
## Configuration
Camo is configured through environment variables.
* `PORT`: The port number Camo should listen on. (default: 8081)
* `CAMO_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 `)
* `CAMO_KEY`: A shared key consisting of a random string, used to generate the HMAC digest.
* `CAMO_LENGTH_LIMIT`: The maximum `Content-Length` Camo will proxy. (default: 5242880)
* `CAMO_LOGGING_ENABLED`: The logging level used for reporting debug or error information. Options are `debug` and `disabled`. (default: `disabled`)
* `CAMO_MAX_REDIRECTS`: The maximum number of redirects Camo will follow while fetching an image. (default: 4)
* `CAMO_SOCKET_TIMEOUT`: The maximum number of seconds Camo will wait before giving up on fetching an image. (default: 10)
* `CAMO_TIMING_ALLOW_ORIGIN`: The string for Camo to include in the [`Timing-Allow-Origin` header](http://www.w3.org/TR/resource-timing/#cross-origin-resources) it sends in responses to clients. The header is omitted if this environment variable is not set. (default: not set)
* `CAMO_HOSTNAME`: The `Camo-Host` header value that Camo will send. (default: `unknown`)
* `CAMO_KEEP_ALIVE`: Whether or not to enable keep-alive session. (default: `false`)
## Testing Functionality
### Bundle Everything
% rake bundle
### Start the server
% coffee server.coffee
### In another shell
% rake
### Debugging
To see the full URL restclient is hitting etc, try this.
% RESTCLIENT_LOG=stdout rake
### Deployment
You should run this on heroku.
To enable useful line numbers in stacktraces you probably want to compile the server.coffee file to native javascript when deploying.
% coffee -c server.coffee
% /usr/bin/env PORT=9090 CAMO_KEY="" node server.js
### Docker
A `Dockerfile` is included, you can build and run it with:
```bash
docker build -t camo .
docker run --env CAMO_KEY=YOUR_KEY -t camo
```
## Examples
* Ruby - https://github.com/ankane/camo
* PHP - https://github.com/willwashburn/Phpamo