One FQDN to rule them all

Question

Is it possible to use one fully qualified domain name (FQDN) for multiple websites?

Answer

While Jahia supports one FQDN per website, it is possible to workaround that thanks to the use of URL rewrite rules at the front-end and Jahia levels BUT before going on this road, you should consider the following:

This kind of scenario is not supported by Jahia so it's not being tested for new releases or new products
Any new modification to the rewrite rules can have unforeseen side effects so it's strongly advised to have an automatic test suite to prevent any regression

The current scenario:

Two FQDNs: www.company1.com and www.company2.com
For each FQDN, three websites:
- a "global" one, accessible through the URL https://<FQDN>/global/en/
- two sub-sites, accessible through the URL:
  - https://<FQDN>/site1/en/
  - https://<FQDN>/site2/en/
The websites need to be configured this way:
- each website of a company has:
  - a site key starting by the "company key" then with the site key
  - a server name starting by the site key then with the domain name. The server name has to be resolved, at least at the front-end level
HAProxy is being used at the front-end level (version 2.0.13-2)

Steps to follow:

Update your HAProxy configuration with the following configuration:

defaults
 log global
 mode http
 option httplog
 option dontlognull
        option  httpclose
 retries 3
        timeout connect 300
        timeout client  1200s
        timeout server  1200s
        option http-server-close
        option forwardfor


frontend http_front
        bind *:80
        redirect scheme https code 301 if !{ ssl_fc }

frontend https_front
        bind *:443 ssl crt /etc/haproxy/key_and_cert.pem
        reqadd X-Forwarded-Proto:\ https
        default_backend https_back

#Production v1.0.16
#dns list
acl dns_www.company1.com hdr(host) -i www.company1.com
acl dns_www.company2.com hdr(host) -i www.company2.com

acl rootpath path_reg ^/$|^/global/$|^/global/..$

#language
acl language_en req.fhdr(accept-language),language(fr;en) -m str en
acl language_fr req.fhdr(accept-language),language(fr;en) -m str fr

#/modules/forms
acl forms path_reg ^/.*modules/forms/.*$

#redirect back
#redirects to company1 corporate website
http-request redirect code 301 location https://www.company1.com/global/fr/ if dns_www.company1.com rootpath language_fr 
http-request redirect code 301 location https://www.company1.com/global/en/ if dns_www.company1.com rootpath

#http-request replace-uri ^/([a-z]{2})/sites/company1_([^/]+)(/.*)$ /\2/\1\3 if dns_www.company1.com
#http-request replace-uri ^/([a-z]{2})/sites/company1_([^/]+)(/.*)$ /global/en/home/about/ if dns_www.company1.com

#redirects to company2 corporate website
http-request redirect code 301 location https://www.company2.com/global/fr/ if dns_www.company2.com rootpath language_fr 
http-request redirect code 301 location https://www.company2.com/global/en/ if dns_www.company2.com rootpath


#rewrites maybe use http-request set-path
http-request replace-uri ^/(?!cms)(.*?)/([a-z]{2})/(.*) /\2/sites/company1_\1/home/\3 if dns_www.company1.com
http-request replace-uri ^/(?!cms)(.*?)/([a-z]{2})/(.*) /\2/sites/company2_\1/home/\3 if dns_www.company2.com

#set header for using right template
acl site_company1 hdr(host) -i www.company1.com
acl site_company2 hdr(host) -i www.company2.com
http-request set-header shared-site company1 if site_company1
http-request set-header shared-site company2 if site_company2
## Header sub-site
http-request set-header sub-site %[capture.req.uri] if !forms
http-request set-header sub-site %[hdr(referer)] if forms
http-request replace-header sub-site ^https?://[^/]*(/[^/]*/[^/]*/.*)$ \1 if forms
http-request replace-header sub-site ^/([^/]*)/?.*$ \1

## Header language
http-request set-header sub-site-language %[capture.req.uri] if !forms
http-request set-header sub-site-language %[hdr(referer)] if forms
http-request replace-header sub-site-language ^https?://[^/]*(/[^/]*/[^/]*/.*)$ \1 if forms
http-request replace-header sub-site-language ^/[^/]*/?([^/]*)/?.*$ \1

## Set the header host in order to activate the SEO for the correct website
http-request set-header Host %[req.hdr(sub-site)].company1.com if dns_www.company1.com !forms
http-request set-header Host %[req.hdr(sub-site)].company2.com if dns_www.company2.com !forms


backend https_back
        compression algo gzip
        compression type text/plain text/css text/js text/xml text/javascript application/javascript application/json application/xml application/rss image/svg text/html
        server jahia1 127.0.0.1:8080 check fall 1 rise 1 inter 2s 
        balance leastconn
 http-request set-header X-Forwarded-Port %[dst_port]
        http-request add-header X-Forwarded-Proto https if { ssl_fc }
 http-request add-header X-CLIENT-IP %[src]

Install a custom module (in our case multi-sites-rewriting) with two URL rewrite rules files (cf this generic documentation):
- seo-urlrewrite-multi-sites-rewriting.xml
- urlrewrite-multi-sites-rewriting.xml
Set the property urlRewriteUseAbsoluteUrls to false in the file JAHIA_HOME/digital-factory-config/jahia/jahia.properties
Flush completely your Internet browser cache

Known issues:

SEO URLs are not working always as expected
Link to a page on another website does is incorrect