Example Reloadable Racket Website

Prerequisites

You will need to install the following Racket packages:

raco pkg install reloadable

The homepage of the reloadable package is https://github.com/tonyg/racket-reloadable.

Local testing

Running src/main.rkt starts a local server. For your convenience,

make run

starts the server with code reloading enabled.

Automatic code reloading

If you would like to enable the automatic code-reloading feature, set the environment variable SITE_RELOADABLE to a non-empty string. (A good place to do that is in a run-prelude script; see below.)

You must also delete any compiled code .zo files. Otherwise, the system will not be able to correctly replace modules while running. You can use make clean to delete any stray .zo files.

Deployment

Supervision

Startable using djb's daemontools; symlink this directory into your services directory and start it as usual. The run script starts the program, and log/run sets up logging of stdout/stderr.

If the file run-prelude exists in the same directory as run, it will be dotted in before racket is invoked. I use this to update my PATH to include my locally-built racket bin directory, necessary because I don't have a system-wide racket. It's also a good place to put a SITE_RELOADABLE definition, if you would like that enabled for a production deployment.

On Debian, daemontools can be installed with apt-get install daemontools daemontools-run, and the services directory is /etc/service/.

Control signals

You can send signals to the running service by creating files in the signals/ directory. For example:

• creating .pull causes the server to shell out to git pull and then exit. Daemontools will restart it.

• creating .restart causes it to exit, to be restarted by daemontools.

• creating .reload forces a reload, for when you don't have SITE_RELOADABLE defined and you want to do a one-off code reload.

In particular, a git post-receive hook can be used to create the .pull signal in order to update the service on git push.

Copyright and License

Copyright © 2014 Tony Garnock-Jones

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.