Hound is an extremely fast source code search engine. The core is based on this article (and code) from Russ Cox: Regular Expression Matching with a Trigram Index. Hound itself is a static React frontend that talks to a Go backend. The backend keeps an up-to-date index for each repository and answers searches through a minimal API. Here it is in action:

1. Use the Go tools to install Hound. The binaries houndd (server) and hound (cli) will be installed in your $GOPATH.

go get github.com/etsy/hound/cmds/...

2. Create a config.json in a directory with your list of repositories.

3. Run the Hound server with houndd and you should see output similar to:

2015/03/13 09:07:42 Searcher started for statsd
2015/03/13 09:07:42 Searcher started for Hound
2015/03/13 09:07:42 All indexes built!
2015/03/13 09:07:42 running server at http://localhost:6080...

1. Create a config.json in a directory with your list of repositories.

2. Run

docker run -d -p 6080:6080 --name hound -v $(pwd):/data etsy/hound

You should be able to navigate to http://localhost:6080/ as usual.

There are no special flags to run Hound in production. You can use the --addr=:6880 flag to control the port to which the server binds. Currently, Hound does not supports SSL/TLS as most users simply run Hound behind either Apache or nginx. Adding TLS support is pretty straight forward though if anyone wants to add it.

We've used many similar tools in the past, and most of them are either too slow, too hard to configure, or require too much software to be installed. Which brings us to...

• Go 1.3+

Yup, that's it. You can proxy requests to the Go service through Apache/nginx/etc., but that's not required.

Currently Hound is only tested on MacOS and CentOS, but it should work on any *nix system. Hound on Windows is not supported but we've heard it compiles and runs just fine.

Hound supports the following version control systems:

• Git - This is the default
• Mercurial - use "vcs" : "hg" in the config
• SVN - use "vcs" : "svn" in the config
• Bazaar - use "vcs" : "bzr" in the config

See config-example.json for examples of how to use each VCS.

There are a couple of ways to get Hound to index private repositories:

• Use the file:// protocol. This allows you to index a local clone of a repository. The downside here is that the polling to keep the repo up to date will not work. (This also doesn't work on local folders that are not of a supported repository type.)
• Use SSH style URLs in the config: "url" : "git@github.com:foo/bar.git". As long as you have your SSH keys set up on the box where Hound is running this will work.

By default Hound polls the URL in the config for updates every 30 seconds. You can override this value by setting the ms-between-poll key on a per repo basis in the config. If you are indexing a large number of repositories, you may also be interested in tweaking the max-concurrent-indexers property. You can see how these work in the example config.

Currently the following editors have plugins that support Hound:

• Sublime Text
• Vim
• Emacs

• make
• Node.js (Installation Instructions)
• React-tools (install w/ npm -g install react-tools)

Hound includes tools to make building locally easy. It is recommended that you use these tools if you are working on Hound. To get setup and build, just run the following commands:

git clone https://github.com/etsy/hound.git hound/src/github.com/etsy/hound
cd hound
src/github.com/etsy/hound/tools/setup
make

There are an increasing number of tests in each of the packages in Hound. Please make sure these pass before uploading your Pull Request. You can run the tests with the following command.

make test

Hound includes a web UI that is composed of several files (html, css, javascript, etc.). To make sure hound works seamlessly with the standard Go tools, these resources are all bundled inside of the houndd binary. Note that changes to the UI will result in local changes to the ui/bindata.go file. You must include these changes in your Pull Request.

To make development easier, there is a flag that will read the files from the file system (allowing the much-loved edit/refresh cycle).

bin/houndd --dev

Created at Etsy by:

• Kelly Norton
• Jonathan Klein