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This one is basically a HOWTO I’ve been meaning to write up. I may need a whole new template in Hugo for this kind of thing, if I make a habit of it.

There are situations where you may want to use a Let’s Encrypt certificate but you can’t run the client on the target machine. Two that I’ve come across are:

  • Hosting without shell access
  • Very small VMs without enough RAM to run the full Certbot client

Also, because you shouldn’t run anything as root that you don’t need to, let’s make the whole thing work for our regular user account. You’re going to need Python’s virtualenv package (sudo apt-get install python-virtualenv on Debian or Ubuntu), as well as git for the next step. All of the smarts can run on any machine you trust, such as a laptop, local VM or even on a MacBook.

Clone Certbot and pick a release to check out:

git clone https://github.com/certbot/certbot
cd certbot
git checkout v0.8.1

Okay, now we’ll make a virtualenv - this is a private Python installation that we can install packages into without root permissions, and allows us to avoid conflicts that might arise from installing conflicting versions of packages for different applications.

virtualenv venv

And we’ll install our checked out copy of Certbot into our virtualenv:

venv/bin/python setup.py install

Lots of text will scroll by, hopefully it worked for you. Let me know if not.

Now we have Certbot installed locally, we’ll need to set up some directories for it to work with. It defaults to using system directories which require running as root, but we really don’t want to do that. Let’s make our own:

mkdir -p ~/.le/etc ~/.le/var/lib ~/.le/var/log

And let’s register our certificate:

venv/bin/certbot certonly --text -d arko.insm.cf --keep-until-expiring \
--agree-tos --config-dir ~/.le/etc --work-dir ~/.le/var/lib --logs-dir \
~/.le/var/log --manual --register-unsafely-without-email

You need to swap out arko.insm.cf for your own domain name - the one which currently points at your remote hosting. You can specify more than one -d option with more than one domain, but they will all need to be reachable for verification. I just need one.

You’ll get a wall of text, including a warning that your IP will be logged, which I’ve agreed to and you will need to, too.

-------------------------------------------------------------------------------
NOTE: The IP of this machine will be publicly logged as having requested this
certificate. If you're running certbot in manual mode on a machine that is not
your server, please ensure you're okay with that.

Are you OK with your IP being logged?
-------------------------------------------------------------------------------
(Y)es/(N)o: y
Make sure your web server displays the following content at
http://arko.insm.cf/.well-known/acme-challenge/2qruN2PEJL_-7OBFUSCATEDxhrHLazCOr3UFNrCBJbQ before continuing:

2qruN2PEJL_-75R2436OBFUSCATEDzCOr3UFNrCBJbQ.mGoimgyJQKeruGrLgfDglJlhFMDvhcWLYIV2FNBOWhM

Okay, so just create a file called “2qruN2PEJL_-7OBFUSCATEDxhrHLazCOr3UFNrCBJbQ” with the contents “2qruN2PEJL_-75R2436OBFUSCATEDzCOr3UFNrCBJbQ.mGoimgyJQKeruGrLgfDglJlhFMDvhcWLYIV2FNBOWhM,“. Your value for both the filename and the contents will be different so you can’t just copy them from this post.

Upload your file to the .well-known/acme-challenge folder on your web hosting. Once you’ve done that, press enter on the client to let the Let’s Encrypt servers continue with their challenge.

If it’s successful, you’ll get a message like this:

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at
   /home/aaron/.le/etc/live/arko.insm.cf/fullchain.pem. Your cert will
   expire on 2016-09-20. To obtain a new or tweaked version of this
   certificate in the future, simply run certbot again. To
   non-interactively renew *all* of your certificates, run "certbot
   renew"
 - Your account credentials have been saved in your Certbot
   configuration directory at /home/aaron/.le/etc. You should make a
   secure backup of this folder now. This configuration directory will
   also contain certificates and private keys obtained by Certbot so
   making regular backups of this folder is ideal.
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

The private key will be in your ~/.le/etc/live/<domain>/ directory, along with the certificate, CA chain, and CA chain with certificate in one bundle (fullchain.pem).

You should refer to your webserver or web hosting’s instructions on how to install the certificates, but that’s the process of obtaining them done.

The way that I’ve run the command will not result in you getting notified about your certificate expiring, so you should place a reminder for yourself around 80 days in the future to repeat this process.