Step 1 — Installing Certbot
Certbot recommends using their snap package for installation. Snap packages work on nearly all Linux distributions, but they require that you’ve installed snapd first in order to manage snap packages.
Make sure your snapd core is up to date:
$ sudo snap install core; sudo snap refresh core
If you’re working on a server that previously had an older version of certbot installed, you should remove it before going any further:
$ sudo apt remove certbot
After that, you can install the certbot package:
$ sudo snap install --classic certbot
Finally, you can link the certbot command from the snap install directory to your path, so you’ll be able to run it by just typing certbot. This isn’t necessary with all packages, but snaps tend to be less intrusive by default, so they don’t conflict with any other system packages by accident:
$ sudo ln -s /snap/bin/certbot /usr/bin/certbot
Step 2 — Confirming Nginx’s Configuration
Certbot needs to be able to find the correct server block in your Nginx configuration for it to be able to automatically configure SSL. Specifically, it does this by looking for a server_name directive that matches the domain you request a certificate for.
To check, open the configuration file for your domain using nano or your favorite text editor:
$ sudo nano /etc/nginx/sites-available/your_website.com
Find the existing server_name line. It should look like this:
/etc/nginx/sites-available/your_website.com
... server_name your_website.com www.your_website.com; ...
If it does, exit your editor and move on to the next step.
If it doesn’t, update it to match. Then save the file, quit your editor, and verify the syntax of your configuration edits:
$ sudo nginx -t
If you get an error, reopen the server block file and check for any typos or missing characters. Once your configuration file’s syntax is correct, reload Nginx to load the new configuration:
$ sudo systemctl reload nginx
Certbot can now find the correct server block and update it automatically.
Step 3 — Allowing HTTPS Through the Firewall
If you have the ufw firewall enabled, as recommended by the prerequisite guides, you’ll need to adjust the settings to allow for HTTPS traffic. Luckily, Nginx registers a few profiles with ufw upon installation.
You can see the current setting by typing:
$ sudo ufw status
It will probably look like this, meaning that only HTTP traffic is allowed to the web server:
OutputStatus: active To Action From -- ------ ---- OpenSSH ALLOW Anywhere Nginx HTTP ALLOW Anywhere OpenSSH (v6) ALLOW Anywhere (v6) Nginx HTTP (v6) ALLOW Anywhere (v6)
To additionally let in HTTPS traffic, allow the Nginx Full profile and delete the redundant Nginx HTTP profile allowance:
$ sudo ufw allow 'Nginx Full' $ sudo ufw delete allow 'Nginx HTTP'
Your status should now look like this:
$ sudo ufw status
OutputStatus: active To Action From -- ------ ---- OpenSSH ALLOW Anywhere Nginx Full ALLOW Anywhere OpenSSH (v6) ALLOW Anywhere (v6) Nginx Full (v6) ALLOW Anywhere (v6)
Step 4 — Obtaining an SSL Certificate
Certbot provides a variety of ways to obtain SSL certificates through plugins. The Nginx plugin will take care of reconfiguring Nginx and reloading the config whenever necessary. To use this plugin, type the following:
$ sudo certbot --nginx -d your_website.com -d www.your_website.com
This runs certbot with the --nginx plugin, using -d to specify the domain names we’d like the certificate to be valid for.
When running the command, you will be prompted to enter an email address and agree to the terms of service. After doing so, you should see a message telling you the process was successful and where your certificates are stored:
OutputIMPORTANT NOTES: Successfully received certificate. Certificate is saved at: /etc/letsencrypt/live/your_domain/fullchain.pem Key is saved at: /etc/letsencrypt/live/your_domain/privkey.pem This certificate expires on 2022-06-01. These files will be updated when the certificate renews. Certbot has set up a scheduled task to automatically renew this certificate in the background. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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
Your certificates are downloaded, installed, and loaded, and your Nginx configuration will now automatically redirect all web requests to https://. Try reloading your website and notice your browser’s security indicator.
Step 5 — Verifying Certbot Auto-Renewal
Let’s Encrypt’s certificates are only valid for ninety days. The certbot package we installed takes care of this for us by adding a systemd timer that will run twice a day and automatically renew any certificate that’s within thirty days of expiration.
You can query the status of the timer with systemctl:
$ sudo systemctl status snap.certbot.renew.service
Output○ snap.certbot.renew.service - Service for snap application certbot.renew Loaded: loaded (/etc/systemd/system/snap.certbot.renew.service; static) Active: inactive (dead) TriggeredBy: ● snap.certbot.renew.timer
To test the renewal process, you can do a dry run with certbot:
$ sudo certbot renew --dry-run
If you see no errors, you’re all set. When necessary, Certbot will renew your certificates and reload Nginx to pick up the changes. If the automated renewal process ever fails, Let’s Encrypt will send a message to the email you specified, warning you when your certificate is about to expire.