Moodle 3.7 & Apache & reverse proxy results ERR_TOO_MANY_REDIRECTS

Question

Moodle 3.7 Apache with reverse proxy results ERR_TOO_MANY_REDIRECTS.

I have an SSL site with following vhosts file:

<VirtualHost *:80>
    RewriteCond %{HTTPS} off
    RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
</VirtualHost>     


<IfModule mod_ssl.c>
<VirtualHost *:443>
ServerName moodle.site.com:443

SSLEngine on
SecAuditEngine On
RewriteEngine On

    ProxyPreserveHost On
    ProxyPass / http://101.102.103.104:80/
    ProxyPassReverse / http://101.102.103.104:80/

</VirtualHost>                                  
</IfModule>

I also redirect all 80 port requests to SSL port.

The command

curl -I https://moodle.site.com/

results:

HTTP/1.1 303 See Other
Date: Fri, 09 Aug 2019 19:13:33 GMT
Server: Apache/2.4.38 (Debian)
Strict-Transport-Security: max-age=15768000; includeSubDomains
Location: https://moodle.site.com
Content-Language: en
Content-Type: text/html; charset=UTF-8

In Moodle config.php I have:

$CFG->wwwroot   = 'https://moodle.site.com';
$CFG->reverseproxy = true;
$CFG->sslproxy  = 1;

Any idea why I get "ERR_TOO_MANY_REDIRECTS" error in Google Chrome, when I try to open https://moodle.site.com URL?

Answer 1

I had 4 problems, so I had to fix them (command line commands should be executed as root or use sudo):

1) mod_ssl Apache module was not activated. Test in the command line, if mod_ssl is active:

apache2ctl -M | grep ssl

Should display this (if active):

ssl_module (shared)

FIX (enable mod_ssl in the command line):

a2enmod ssl
# Considering dependency setenvif for ssl:
# Module setenvif already enabled
# Considering dependency mime for ssl:
# Module mime already enabled
# Considering dependency socache_shmcb for ssl:
# Enabling module socache_shmcb.
# Enabling module ssl.
# See /usr/share/doc/apache2/README.Debian.gz on how to configure SSL and create self-signed certificates.
# To activate the new configuration, you need to run:
# systemctl restart apache2

2) I use the Header directive in Apache SSL conf file, like this:

# Guarantee HTTPS for 180 days including sub domains 
Header always set Strict-Transport-Security "max-age=15768000; includeSubDomains"

Because of this mod_headers Apache module is required, it was not activated. Test in the command line, if mod_headers is active:

apache2ctl -M | grep headers

Should display this (if active):

headers_module (shared)

FIX (enable mod_headers in the command line):

a2enmod headers

3) I had to use https ProxyPass URL instead of http in Apache vhost conf file :

Wrong:

ProxyPass / http://101.102.103.104:80/
ProxyPassReverse / http://101.102.103.104:80/

GOOD:

ProxyPass / https://101.102.103.104/
ProxyPassReverse / https://101.102.103.104/

4) Had to turn on SSLProxyEngine directive to use SSL in ProxyPass in Apache vhost conf file.

FIX: Added SSLProxyEngine on in /etc/apache2/sites-available/myvhost.conf

SSLProxyEngine on