Hapistrano
Description
Hapistrano is a deployment library for Haskell applications similar to
Ruby's Capistrano.
Purpose
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.
Usage
Hapistrano 0.4.0.0 looks for a configuration file called hap.yaml
that
typically looks like this:
deploy_path: '/var/projects/my-project'
host: myserver.com
port: 2222
# To perform version control operations
repo: 'https://github.com/stackbuilders/hapistrano.git'
revision: origin/master
# To copy the contents of the directory
local_directory: '/tmp/my-project'
build_script:
- stack setup
- stack build
restart_command: systemd restart my-app-service
The following parameters are required:
deploy_path
— the root of the deploy target on the remote host.
- Related to the
source
of the repository, you have the following options:
- Git repository default — consists of two parameters. When these are set,
hapistrano will perform version control related operations.
Note: Only GitHub is supported.
repo
— 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.
local_directory
— when this parameter is set, hapistrano will copy the
contents of the directory.
The following parameters are optional:
host
— the target host, if missing, localhost
will be assumed (which
is useful for testing and playing with hap
locally).
port
— SSH port number to use. If missing, 22 will be used.
shell
— Shell to use. Currently supported: zsh
ans bash
. If missing, Bash
will be used.
ssh_args
— Optional ssh arguments. Only -p
is passed via the port
variable.
build_script
— instructions how to build the application in the form of
shell commands.
restart_command
— if you need to restart a remote web server after a
successful rollback, specify the command that you use in this variable. It
will be run after both deploy and rollback.
vc_action
- Controls if version control related activity should
take place. It defaults to true. When you don't want activity like
cloning, fetching etc. to take place, set this to false
.
linux
- Specify, whether or not, the target system where Hapistrano will
deploy to is a GNU/Linux or other UNIX (g.e. BSD, Mac). This is set to true
by default so unless the target system is not GNU/Linux, this should not be
necessary. The platform where Hapistrano is running won't affect the
available options for commands (g.e. A Mac deploying to an Ubuntu machine,
doesn't need this flag)
release_format
- The release timestamp format, the
'--release-format' argument passed via the CLI takes precedence over this
value. If neither CLI nor configuration file value is specified, it defaults
to 'short'
keep_releases
- The number of releases to keep, the
'--keep-releases' argument passed via the CLI takes precedence over this
value. If neither CLI nor configuration file value is specified, it defaults
to '5'
keep_one_failed
- A boolean specifying whether to keep all failed releases
or just one (the latest failed release), the '--keep-one-failed' flag passed via
the CLI takes precedence over this value. If neither CLI nor configuration file value is specified,
it defaults to false (i.e. keep all failed releases).
linked_files:
- Listed files that will be symlinked from the {deploy_path}/shared
folder
into each release directory during deployment. Can be used for configuration files
that need to be persisted (e.g. dotenv files). NOTE: The directory structure must
be similar in your release directories in case you need to link a file inside a
nested directory (e.g. shared/foo/file.txt
).
linked_dirs:
- Listed directories that will be symlinked from the {deploy_path}/shared
folder
into each release directory during deployment. Can be used for data directories
that need to be persisted (e.g. upload directories). NOTE: Do not add a slash /
at the end of the directory (e.g. foo/
) because we use parseRelFile
to create
the symlink.
run_locally:
- Instructions to run locally on your machine in the
form of shell commands. Example:
run_locally:
- pwd
- bash deploy.sh
Note how we are even able to execute a bash script named deploy.sh
above. Be sure to use set -e
in your bash script to avoid
headaches. Hapistrano will stop the execution on non-zero exit
codes. Without the usage of set -e
, there is a possibility that your
bash script may return a zero exit code even if your intermediate
command resulted in an error.
After creating a configuration file as above, deploying is as simple as:
$ hap deploy
Rollback is also trivial:
$ hap rollback # to rollback to previous successful deploy
$ hap rollback -n 2 # go two deploys back in time, etc.
Environment Variables
Configuration files are parsed using
loadYamlSettings,
therefore, variable substitution is supported. Considering the following configuration file:
revision: "_env:HAPISTRANO_REVISION:origin/master
...
The revision
value could be overwritten as follows:
HAPISTRANO_REVISION=origin/feature_branch hap deploy
What to do when compiling on server is not viable
Sometimes the target machine (server) is not capable of compiling your
application because e.g. it has not enough memory and GHC exhausts it all.
You can copy pre-compiled files from local machine or CI server using
copy_files
and copy_dirs
parameters:
copy_files:
- src: '/home/stackbuilders/my-file.txt'
dest: 'my-file.txt'
copy_dirs:
- src: .stack-work
dest: .stack-work
src
maybe absolute or relative, it's path to file or directory on local
machine, dest
may only be relative (it's expanded relatively to cloned
repo) and specifies where to put the files/directories on target machine.
Directories and files with clashing names will be overwritten. Directories
are copied recursively.
Deploying to multiple machines concurrently
Beginning with Hapistrano 0.3.1.0 it's possible to deploy to several
machines concurrently. The only things you need to do is to adjust your
configuration file and use targets
parameter instead of host
and port
,
like this:
targets:
- host: myserver-a.com
port: 2222
- host: myserver-b.com
# the rest is the same…
A few things to note here:
-
host
item is required for every target, but port
may be omitted and
then it defaults to 22
.
-
The deployment will run concurrently and finish when interactions with all
targets have finished either successfully or not. If at least one
interaction was unsuccessful, the hap
tool will exit with non-zero exit
code.
-
The log is printed in such a way that messages from several machines get
intermixed, but it's guaranteed that they won't overlap (printing itself
is sequential) and the headers will tell you exactly which machine was
executing which command.
If you don't specify host
and targets
, hap
will assume localhost
as
usually, which is mainly useful for testing.
Docker
Docker images hosted on Docker
Hub are no longer up to
date, newer versions are published to GitHub's Docker
Registry.
Nix
If you want to use Nix for building Hapistrano, the required release.nix and default.nix are available.
For installing the hap binary in your local path:
nix-env -i hapistrano -f release.nix
For developing Hapistrano with Nix, you can create a development environment using:
nix-shell --attr env release.nix
For just building Hapistrano, you just:
nix-build release.nix
Notes
- Hapistrano is not supported on Windows. Please check: Issue #96.
License
MIT, see the LICENSE file.
Contributing
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.