Redirect Request to SSL on Apache

NameVirtualHost *:80
<VirtualHost *:80>
   ServerName mysite.example.com
   DocumentRoot /usr/local/apache2/htdocs
   Redirect /secure https://mysite.example.com/secure
</VirtualHost>

<VirtualHost _default_:443>
   ServerName mysite.example.com
   DocumentRoot /usr/local/apache2/htdocs
   SSLEngine On
# etc...
</VirtualHost>

When redirecting everything you don’t even need a DocumentRoot:

NameVirtualHost *:80
<VirtualHost *:80>
   ServerName www.example.com
   Redirect / https://secure.example.com/
</VirtualHost>

<VirtualHost _default_:443>
   ServerName secure.example.com
   DocumentRoot /usr/local/apache2/htdocs
   SSLEngine On
# etc...
</VirtualHost>

Note: Once the configuration is working as intended, a permanent redirection can be considered. This avoids caching issues by most browsers while testing. The directive would then become:

Redirect permanent / https://secure.example.com/

—————

<Directory /topsecret>
  SSLRequireSSL
</Directory>

References
https://wiki.apache.org/httpd/RedirectSSL
https://serverfault.com/questions/429634/restrict-apache-to-only-allow-access-using-ssl-for-some-directories
https://www.tecmint.com/redirect-http-to-https-on-apache/

Configure Let’s Encrypt for Apache on Ubuntu

sudo apt-get install python-letsencrypt-apache 
letsencrypt --apache
nano /etc/apache2/apache2.conf
<VirtualHost *:443>
	SSLEngine on
	SSLCertificateKeyFile /etc/letsencrypt/live/dl.mhdr.ir/privkey.pem
	SSLCertificateFile /etc/letsencrypt/live/dl.mhdr.ir/cert.pem
	SSLCertificateChainFile /etc/letsencrypt/live/dl.mhdr.ir/chain.pem
    DocumentRoot "/var/www/html/dl"
    ServerName dl.mhdr.ir
</VirtualHost>
service apache2 restart

PPA

$ sudo add-apt-repository ppa:certbot/certbot
$ sudo apt-get update
$ sudo apt-get install python-certbot-apache

note : only the last VitualHost will be detected by letsencrypt
References
https://certbot.eff.org/#ubuntuxenial-apache
https://www.digitalocean.com/community/tutorials/how-to-use-apache-http-server-as-reverse-proxy-using-mod_proxy-extension
https://letsencrypt.org/