tlwiki/content/misc/archive/thurstylark-vps/letsencrypt.md

title	description	author	date	draft
LetsEncrypt	Usage of certbot, and relevant info for Apache configuration	Thurstylark	2021-9-25	false

Certbot Usage

Create a cert using the interactive menu:

# certbot certonly

Automating Renewal

LetsEncrypt Certs are good for a max of 90 days, so automating renewal is a must.

Do a dry-run renewal with certbot:

# certbot renew --dry-run

This will test, and possibly renew all certs that certbot knows about

Now you can use certbot renew --quiet for scripting this renewal. I do mine with a simple systemd script:

# /etc/systemd/system/certbot.service
[Unit]
Description=Let's Encrypt renewal

[Service]
Type=oneshot
ExecStart=/usr/bin/certbot renew --quiet --agree-tos
ExecStartPost=/bin/systemctl reload httpd.service

Apache Configuration

There's a couple of considerations when using ssl certs with Apache. The first is to enable the appropriate modules in httpd.conf:

LoadModule ssl_module modules/mod_ssl.so
LoadModule socache_shmcb_module modules/mod_socache_shmcb.so

Also, make sure to configure apache to listen on port 443:

Listen 443

That will get the basic framework ready for your virtualhost definition. Here is a very simple virtualhost configuration:

<VirtualHost wiki.thurstylark.com:80>
        ServerName wiki.thurstylark.com
	
	DocumentRoot "/srv/wiki/"
	<Directory "/srv/wiki/">
	   AllowOverride None
	   Options None
	   Require all granted
	</Directory>

	# Redirect all except the '.wellk-known' path to https.
	# This allows automated renewal of ssl certs by certbot
        RedirectMatch permanent ^/(?!\.well-known)(.*) https://wiki.thurstylark.com/$1
</VirtualHost>


<VirtualHost wiki.thurstylark.com:443>
        ServerName wiki.thurstylark.com
        ServerAdmin thurstylark@gmail.com

	DocumentRoot "/srv/wiki/"
	<Directory "/srv/wiki/">
	   AllowOverride None
	   Options None
	   Require all granted
	</Directory>

	SSLEngine on
	SSLCertificateChainFile "/etc/letsencrypt/live/wiki.thurstylark.com/fullchain.pem"
	SSLCertificateKeyFile "/etc/letsencrypt/live/wiki.thurstylark.com/privkey.pem"
</VirtualHost>

A couple things to note here: First, this defines two virtualhosts, one for port 80 and one for port 443. This is in order to redirect all traffic to HTTPS except for a very small exception.

This exception is what you see on line 12 in the code above. Only */.well-known/* is not redirected because this is the dir that certbot uses for domain validation. Certbot will only validate over http, and will fail if given a 301 redirect. This allows validation to complete successfuly without a configuration change, thus aiding our automation efforts. Everything else gets a 301 redirect to HTTPS. Be sure to define DocumentRoot with the correct location for both VirtualHosts, or certbot will fail to renew things correctly. (found this one out the hard way)

Lines 28-29 configure Apache to look for the necessary files in the right places. The locations listed here are actually symlinks to the real files, which are kept in an archive. These links are maintained by certbot automagically.

To obtain new certs for a subdomain, copy this config to /etc/httpd/conf/extra/, update the config with the appropriate subdomain name, comment out lines 5-29 to disable the redirect and ssl configuration, and add an include in the main httpd.conf. Once that is all set up, you can run certbot to obtain new certs. Once certbot is finished, you can remove the comments, restart httpd, and begin testing.