*Installing Letsencrypt in Linode*

1. Enable EPEL repository
sudo yum install epel-release

2. Install Certbot
sudo yum install certbot python2-certbot-apache python2-certbot-dns-linode

3. Configure Linode API
+ Create Linode API key @ Linodes Applications & API Tokens page
https://manager.linode.com/profile/api
Example credentials file: '/etc/letsencrypt/linode_api_key.ini'

# Linode API credentials used by Certbot
dns_linode_key = 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ64

4. Setup Wildcard Certificates
sudo certbot -a dns-linode -i apache --dns-linode-credentials /etc/letsencrypt/linode_api_key.ini -d "*.EXAMPLE.COM" -d EXAMPLE.COM --server https://acme-v02.api.letsencrypt.org/directory

5. Renew certificates
+ Verify it will work
sudo certbot renew --dry-run
+ Add it to a cron job
0 0,12 * * * python -c 'import random; import time; time.sleep(random.random() * 3600)' && certbot renew && systemctl reload httpd

6. References
# https://certbot.eff.org/lets-encrypt/centosrhel7-apache
# https://certbot-dns-linode.readthedocs.io/en/stable/