=====================
Get Certbot
=====================

.. contents:: Table of Contents
   :local:


About Certbot
=============

*Certbot is meant to be run directly on a web server*, normally by a system administrator. In most cases, running Certbot on your personal computer is not a useful option. The instructions below relate to installing and running Certbot on a server.

System administrators can use Certbot directly to request certificates; they should *not* allow unprivileged users to run arbitrary Certbot commands as ``root``, because Certbot allows its user to specify arbitrary file locations and run arbitrary scripts.

Certbot is packaged for many common operating systems and web servers. Check whether
``certbot`` (or ``letsencrypt``) is packaged for your web server's OS by visiting
certbot.eff.org_, where you will also find the correct installation instructions for
your system.

.. Note:: Unless you have very specific requirements, we kindly suggest that you use the Certbot packages provided by your package manager (see certbot.eff.org_). If such packages are not available, we recommend using ``certbot-auto``, which automates the process of installing Certbot on your system.

.. _certbot.eff.org: https://certbot.eff.org


.. _system_requirements:

System Requirements
===================

Certbot currently requires Python 2.7 or 3.4+ running on a UNIX-like operating
system. By default, it requires root access in order to write to
``/etc/letsencrypt``, ``/var/log/letsencrypt``, ``/var/lib/letsencrypt``; to
bind to port 80 (if you use the ``standalone`` plugin) and to read and
modify webserver configurations (if you use the ``apache`` or ``nginx``
plugins).  If none of these apply to you, it is theoretically possible to run
without root privileges, but for most users who want to avoid running an ACME
client as root, either `letsencrypt-nosudo
<https://github.com/diafygi/letsencrypt-nosudo>`_ or `simp_le
<https://github.com/zenhack/simp_le>`_ are more appropriate choices.

The Apache plugin currently requires an OS with augeas version 1.0; currently `it
supports
<https://github.com/certbot/certbot/blob/master/certbot-apache/certbot_apache/constants.py>`_
modern OSes based on Debian, Fedora, SUSE, Gentoo and Darwin.


Additional integrity verification of certbot-auto script can be done by verifying its digital signature.
This requires a local installation of gpg2, which comes packaged in many Linux distributions under name gnupg or gnupg2.


Installing with ``certbot-auto`` requires 512MB of RAM in order to build some
of the dependencies. Installing from pre-built OS packages avoids this
requirement. You can also temporarily set a swap file. See "Problems with
Python virtual environment" below for details.


Alternate installation methods
================================

If you are offline or your operating system doesn't provide a package, you can use
an alternate method for installing ``certbot``.

.. _certbot-auto:

Certbot-Auto
------------

The ``certbot-auto`` wrapper script installs Certbot, obtaining some dependencies
from your web server OS and putting others in a python virtual environment. You can
download and run it as follows::

  user@webserver:~$ wget https://dl.eff.org/certbot-auto
  user@webserver:~$ sudo mv certbot-auto /usr/local/bin/certbot-auto
  user@webserver:~$ sudo chown root /usr/local/bin/certbot-auto
  user@webserver:~$ chmod 0755 /usr/local/bin/certbot-auto
  user@webserver:~$ /usr/local/bin/certbot-auto --help

To check the integrity of the ``certbot-auto`` script,
you can use these steps::


	    user@webserver:~$ wget -N https://dl.eff.org/certbot-auto.asc
	    user@webserver:~$ gpg2 --keyserver pool.sks-keyservers.net --recv-key A2CFB51FA275A7286234E7B24D17C995CD9775F2
	    user@webserver:~$ gpg2 --trusted-key 4D17C995CD9775F2 --verify certbot-auto.asc /usr/local/bin/certbot-auto



The output of the last command should look something like::


	    gpg: Signature made Wed 02 May 2018 05:29:12 AM IST
	    gpg:                using RSA key A2CFB51FA275A7286234E7B24D17C995CD9775F2
	    gpg: key 4D17C995CD9775F2 marked as ultimately trusted
	    gpg: checking the trustdb
	    gpg: marginals needed: 3  completes needed: 1  trust model: pgp
	    gpg: depth: 0  valid:   2  signed:   2  trust: 0-, 0q, 0n, 0m, 0f, 2u
	    gpg: depth: 1  valid:   2  signed:   0  trust: 2-, 0q, 0n, 0m, 0f, 0u
	    gpg: next trustdb check due at 2027-11-22
	    gpg: Good signature from "Let's Encrypt Client Team <letsencrypt-client@eff.org>" [ultimate]



The ``certbot-auto`` command updates to the latest client release automatically.
Since ``certbot-auto`` is a wrapper to ``certbot``, it accepts exactly
the same command line flags and arguments. For more information, see
`Certbot command-line options <https://certbot.eff.org/docs/using.html#command-line-options>`_.

For full command line help, you can type::

  /usr/local/bin/certbot-auto --help all

Problems with Python virtual environment
----------------------------------------

On a low memory system such as VPS with less than 512MB of RAM, the required dependencies of Certbot will fail to build.
This can be identified if the pip outputs contains something like ``internal compiler error: Killed (program cc1)``.
You can workaround this restriction by creating a temporary swapfile::

  user@webserver:~$ sudo fallocate -l 1G /tmp/swapfile
  user@webserver:~$ sudo chmod 600 /tmp/swapfile
  user@webserver:~$ sudo mkswap /tmp/swapfile
  user@webserver:~$ sudo swapon /tmp/swapfile

Disable and remove the swapfile once the virtual environment is constructed::

  user@webserver:~$ sudo swapoff /tmp/swapfile
  user@webserver:~$ sudo rm /tmp/swapfile

.. _docker-user:

Running with Docker
-------------------

Docker_ is an amazingly simple and quick way to obtain a
certificate. However, this mode of operation is unable to install
certificates or configure your webserver, because our installer
plugins cannot reach your webserver from inside the Docker container.

Most users should use the operating system packages (see instructions at
certbot.eff.org_) or, as a fallback, ``certbot-auto``. You should only
use Docker if you are sure you know what you are doing and have a
good reason to do so.

You should definitely read the :ref:`where-certs` section, in order to
know how to manage the certs
manually. `Our ciphersuites page <ciphers.html>`__
provides some information about recommended ciphersuites. If none of
these make much sense to you, you should definitely use the
certbot-auto_ method, which enables you to use installer plugins
that cover both of those hard topics.

If you're still not convinced and have decided to use this method, from
the server that the domain you're requesting a certficate for resolves
to, `install Docker`_, then issue a command like the one found below. If
you are using Certbot with the :ref:`Standalone` plugin, you will need
to make the port it uses accessible from outside of the container by
including something like ``-p 80:80`` or ``-p 443:443`` on the command
line before ``certbot/certbot``.

.. code-block:: shell

   sudo docker run -it --rm --name certbot \
               -v "/etc/letsencrypt:/etc/letsencrypt" \
               -v "/var/lib/letsencrypt:/var/lib/letsencrypt" \
               certbot/certbot certonly

Running Certbot with the ``certonly`` command will obtain a certificate and place it in the directory
``/etc/letsencrypt/live`` on your system. Because Certonly cannot install the certificate from
within Docker, you must install the certificate manually according to the procedure
recommended by the provider of your webserver.

There are also Docker images for each of Certbot's DNS plugins available
at https://hub.docker.com/u/certbot which automate doing domain
validation over DNS for popular providers. To use one, just replace
``certbot/certbot`` in the command above with the name of the image you
want to use. For example, to use Certbot's plugin for Amazon Route 53,
you'd use ``certbot/dns-route53``. You may also need to add flags to
Certbot and/or mount additional directories to provide access to your
DNS API credentials as specified in the :ref:`DNS plugin documentation
<dns_plugins>`. If you would like to obtain a wildcard certificate from
Let's Encrypt's ACMEv2 server, you'll need to include ``--server
https://acme-v02.api.letsencrypt.org/directory`` on the command line as
well.

For more information about the layout
of the ``/etc/letsencrypt`` directory, see :ref:`where-certs`.

.. _Docker: https://docker.com
.. _`install Docker`: https://docs.docker.com/engine/installation/

Operating System Packages
-------------------------

**Arch Linux**

.. code-block:: shell

   sudo pacman -S certbot

**Debian**

If you run Debian Stretch or Debian Sid, you can install certbot packages.

.. code-block:: shell

   sudo apt-get update
   sudo apt-get install certbot python-certbot-apache

If you don't want to use the Apache plugin, you can omit the
``python-certbot-apache`` package. Or you can install ``python-certbot-nginx`` instead.

Packages exist for Debian Jessie via backports. First you'll have to follow the
instructions at http://backports.debian.org/Instructions/ to enable the Jessie backports
repo, if you have not already done so. Then run:

.. code-block:: shell

   sudo apt-get install certbot python-certbot-apache -t jessie-backports

**Fedora**

.. code-block:: shell

    sudo dnf install certbot python2-certbot-apache

**FreeBSD**

  * Port: ``cd /usr/ports/security/py-certbot && make install clean``
  * Package: ``pkg install py27-certbot``

**Gentoo**

The official Certbot client is available in Gentoo Portage. If you
want to use the Apache plugin, it has to be installed separately:

.. code-block:: shell

   emerge -av app-crypt/certbot
   emerge -av app-crypt/certbot-apache

When using the Apache plugin, you will run into a "cannot find an
SSLCertificateFile directive" or "cannot find an SSLCertificateKeyFile
directive for certificate" error if you're sporting the default Gentoo
``httpd.conf``. You can fix this by commenting out two lines in
``/etc/apache2/httpd.conf`` as follows:

Change

.. code-block:: shell

   <IfDefine SSL>
   LoadModule ssl_module modules/mod_ssl.so
   </IfDefine>

to

.. code-block:: shell

   #<IfDefine SSL>
   LoadModule ssl_module modules/mod_ssl.so
   #</IfDefine>

For the time being, this is the only way for the Apache plugin to recognise
the appropriate directives when installing the certificate.
Note: this change is not required for the other plugins.

**NetBSD**

  * Build from source: ``cd /usr/pkgsrc/security/py-certbot && make install clean``
  * Install pre-compiled package: ``pkg_add py27-certbot``

**OpenBSD**

  * Port: ``cd /usr/ports/security/letsencrypt/client && make install clean``
  * Package: ``pkg_add letsencrypt``

**Other Operating Systems**

OS packaging is an ongoing effort. If you'd like to package
Certbot for your distribution of choice please have a
look at the :doc:`packaging`.

Installing from source
----------------------

Installation from source is only supported for developers and the
whole process is described in the :doc:`contributing`.

.. warning:: Please do **not** use ``python setup.py install``, ``python pip
   install .``, or ``easy_install .``. Please do **not** attempt the
   installation commands as superuser/root and/or without virtual environment,
   e.g. ``sudo python setup.py install``, ``sudo pip install``, ``sudo
   ./venv/bin/...``. These modes of operation might corrupt your operating
   system and are **not supported** by the Certbot team!
