Table of Contents
- Code components and layout
- Writing your own plugin
- Coding style
- Submitting a pull request
- Updating the documentation
- Other methods for running the client
- Notes on OS dependencies
Running the client in developer mode from your local tree is a little
different than running
letsencrypt-auto. To get set up, do these things
git clone https://github.com/letsencrypt/letsencrypt cd letsencrypt ./bootstrap/install-deps.sh ./bootstrap/dev/venv.sh
Then in each shell where you’re working on the client, do:
After that, your shell will be using the virtual environment, and you run the client by typing:
Activating a shell in this way makes it easier to run unit tests
tox and integration tests, as described below. To reverse this, you
deactivate. More information can be found in the virtualenv docs.
You can find the open issues in the github issue tracker. Comparatively easy ones are marked Good Volunteer Task. If you’re starting work on something, post a comment to let others know and seek feedback on your plan where appropriate.
Once you’ve got a working branch, you can open a pull request. All changes in your pull request must have thorough unit test coverage, pass our integration tests, and be compliant with the coding style.
The following tools are there to help you:
toxstarts a full set of tests. Please note that it includes apacheconftest, which uses the system’s Apache install to test config file parsing, so it should only be run on systems that have an experimental, non-production Apache2 install on them.
tox -e apacheconftestcan be used to run those specific Apache conf tests.
tox -e py27,
tox -e py26etc, run unit tests for specific Python versions.
tox -e coverchecks the test coverage only. Calling the
./tox.cover.shscript directly (or even
./tox.cover.sh $pkg1 $pkg2 ...for any subpackages) might be a bit quicker, though.
tox -e lintchecks the style of the whole project, while
pylint --rcfile=.pylintrc pathwill check a single file or specific directory only.
- For debugging, we recommend
pip install ipdband putting
import ipdb; ipdb.set_trace()statement inside the source code. Alternatively, you can use Python’s standard library
pdb, but you won’t get TAB completion...
Generally it is sufficient to open a pull request and let Github and Travis run integration tests for you.
Mac OS X users: Run
/tests/mac-bootstrap.sh instead of
install dependencies, configure the environment, and start boulder.
The script will download, compile and run the executable; please be
patient - it will take some time... Once its ready, you will see
Server running, listening on 127.0.0.1:4000.... Add an
/etc/hosts entry pointing
le.wtf to 127.0.0.1. You may now
run (in a separate terminal):
./tests/boulder-integration.sh && echo OK || echo FAIL
If you would like to test
letsencrypt_nginx plugin (highly
encouraged) make sure to install prerequisites as listed in
letsencrypt-nginx/tests/boulder-integration.sh and rerun
the integration tests suite.
- contains all protocol specific code
- all client code
Let’s Encrypt has a plugin architecture to facilitate support for different webservers, other TLS servers, and operating systems. The interfaces available for plugins to implement are defined in interfaces.py.
There are also
which implement bindings to alternative UI libraries.
Authenticators are plugins designed to prove that this client deserves a
certificate for some domain name by solving challenges received from
the ACME server. From the protocol, there are essentially two
different types of challenges. Challenges that must be solved by
individual plugins in order to satisfy domain validation (subclasses
DNS) and continuity specific
challenges (subclasses of
ProofOfPossession). Continuity challenges are
always handled by the
ContinuityAuthenticator, while plugins are
expected to handle
Right now, we have two authenticator plugins, the
StandaloneAuthenticator. The Standalone and Apache
authenticators only solve the
TLSSNI01 challenge currently.
(You can set which challenges your authenticator can handle through the
(FYI: We also have a partial implementation for a
in a separate branch).
Installers plugins exist to actually setup the certificate in a server,
possibly tweak the security configuration to make it more correct and secure
(Fix some mixed content problems, turn on HSTS, redirect to HTTPS, etc).
Installer plugins tell the main client about their abilities to do the latter
supported_enhancements() call. We currently
have two Installers in the tree, the
ApacheConfigurator. and the
NginxConfigurator. External projects have made some progress toward
support for IIS, Icecast and Plesk.
Installers and Authenticators will oftentimes be the same class/object (because for instance both tasks can be performed by a webserver like nginx) though this is not always the case (the standalone plugin is an authenticator that listens on port 443, but it cannot install certs; a postfix plugin would be an installer but not an authenticator).
Installers and Authenticators are kept separate because
it should be possible to use the
StandaloneAuthenticator (it sets
up its own Python server to perform challenges) with a program that
cannot solve challenges itself (Such as MTA installers).
There are a few existing classes that may be beneficial while
developing a new
Installers aimed to reconfigure UNIX servers may use Augeas for
configuration parsing and can inherit from
to handle much of the interface. Installers that are unable to use
Augeas may still find the
Reverter class helpful in handling
configuration checkpoints and rollback.
Let’s Encrypt client supports dynamic discovery of plugins through the
setuptools entry points. This way you can, for example, create a
custom implementation of
IInstaller without having to merge it
with the core upstream source code. An example is provided in
Please be aware though that as this client is still in a developer-preview stage, the API may undergo a few changes. If you believe the plugin will be beneficial to the community, please consider submitting a pull request to the repo and we will update it with any necessary API changes.
Be consistent with the rest of the code.
def foo(arg): """Short description. :param int arg: Some number. :returns: Argument :rtype: int """ return arg
Remember to use
- Write your code!
- Make sure your environment is set up properly and that you’re in your
virtualenv. You can do this by running
./bootstrap/dev/venv.sh. (this is a very important step)
./pep8.travis.shto do a cursory check of your code style. Fix any errors.
tox -e lintto check for pylint errors. Fix any errors.
toxto run the entire test suite including coverage. Fix any errors.
- If your code touches communication with an ACME server/Boulder, you should run the integration tests, see integration. See Known Issues for some common failures that have nothing to do with your code.
- Submit the PR.
- Did your tests pass on Travis? If they didn’t, it might not be your fault! See Known Issues. If it’s not a known issue, fix any errors.
In order to generate the Sphinx documentation, run the following commands:
make -C docs clean html
This should generate documentation in the
If you are a Vagrant user, Let’s Encrypt comes with a Vagrantfile that
automates setting up a development environment in an Ubuntu 14.04
LTS VM. To set it up, simply run
vagrant up. The repository is
/vagrant, so you can get started with:
vagrant ssh cd /vagrant sudo ./venv/bin/letsencrypt
Support for other Linux distributions coming soon.
Unfortunately, Python distutils and, by extension, setup.py and tox, use hard linking quite extensively. Hard linking is not supported by the default sync filesystem in Vagrant. As a result, all actions with these commands are significantly slower in Vagrant. One potential fix is to use NFS (related issue).
OSX users will probably find it easiest to set up a Docker container for
development. Let’s Encrypt comes with a Dockerfile (
for doing so. To use Docker on OSX, install and setup docker-machine using the
instructions at https://docs.docker.com/installation/mac/.
To build the development Docker image:
docker build -t letsencrypt -f Dockerfile-dev .
Now run tests inside the Docker image:
docker run -it letsencrypt bash cd src tox -e py27
OS level dependencies are managed by scripts in
bootstrap. Some notes
are provided here mainly for the developers reference.
sudois required as a suggested way of running privileged process
- Python 2.6/2.7 is required
- Augeas is required for the Python bindings
pipare used for managing other python library dependencies
For squeeze you will need to:
virtualenv --no-site-packages -p pythoninstead of