Hapistrano is a deployment library for Haskell applications similar to Ruby’s Capistrano.
We created Hapistrano because:
- Deploys should be simple, but as close to atomic as possible (eg, they shouldn’t require much application downtime).
- Rollback should be trivial to achieve to bring the application back to the last-deployed state.
- Deploys shouldn’t fail because of dependency problems.
How it Works
Hapistrano (like Capistrano for Ruby) deploys applications to a new directory marked with a timestamp on the remote host. It creates this new directory quickly by placing a git repository for caching purposes on the remote server.
When the build process completes, it switches a symlink to the ‘current’ release directory, and optionally restarts the web server.
By default, Hapistrano keeps the last five releases on the target host filesystem and deletes previous releases to avoid filling up the disk.
The deploy requires the following environment variables:
DEPLOY_PATH- The root of the deploy target on the remote host
HOST- The target host
REPOSITORY- The origin repository
REVISION- The SHA1 or branch to deploy. If a branch, you will need to specify it as origin/branch_name due to the way that the cache repo is configured.
The following environment variables are optional and affect the deploy process:
BUILD_SCRIPT- The local path to a file that should be executed on the remote server to build the application. The script isn’t executed verbatim - instead, every line is joined with
&&so that the script aborts if any component fails. See a sample script for a clean build of a Haskell/Cabal application in this project under [script/clean-build.sh].
RESTART_COMMAND- If you need to restart a remote web server after a successful deploy, specify the command that you use in this variable. It will be run after both deploy and rollback.
You may want to save the environment variables that you need for your
deploy in a shell script that you
source before deploy. Make sure
export these variables so that they’re available in the shell
after you run the script. For example, you could use the following to
configure your deploy:
export DEPLOY_PATH="/var/project" export HOST="my-app-staging" export REPOSITORY="firstname.lastname@example.org:yourorg/yourrepo.com.git" export REVISION="origin/staging" export BUILD_SCRIPT="/home/you/Code/hapistrano/script/clean-build.sh" export RESTART_COMMAND="echo Replace me with your restart command"
After creating a configuration script as above, deploying is as simple as:
source your-config-script.sh && hap deploy
MIT, see the LICENSE file.
Pull requests for modifications to this program are welcome. Fork and open a PR. Feel free to email me if you have questions about what may be accepted before working on a PR.
If you’re looking for a place to start, you may want to check the open issue.
- Add change log (#23).
- Fix tests (#31).
- Use Stack (#17).
- Clean up package (#20).
- Fix tests (#25).