Your website’s .htaccess file controls how your website’s visitors access your website, and can be configured to handle different visitor scenarios.

Making changes to your .htaccess requires familiarity with Git.

When implementing redirects in your .htaccess file, be aware of the following best practices:

• Place the following code examples immediately after the RewriteEngine On line in your .htaccess file.

• Include the following line in your rewrite code to exclude Acquia default domains:

  copy

  RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
  # exclude Acquia domains

• Too many redirects can cause minor to serious performance issues for your website. Every page request must follow the redirect rules, requiring added load time on a per-request basis. Acquia recommends regular reviews of rules for consolidation and removal as part of your normal maintenance practices.
• Redirects do not preserve Google campaign tracking information. If you rely on this information, ensure your links do not rely on Acquia infrastructure-side redirects. 

For more information about .htaccess rewrite rules, see Introduction to htaccess rewrite rules.

Redirecting bare domain names to the “www” subdomain

You can change your application’s .htaccess file so when visitors request your application’s URL without the www subdomain, the request redirects to the www subdomain. For example, requests to http://example.com will redirect to http://www.example.com.

The following lines in your Drupal application’s .htaccess file can enforce the redirection, but may cause problems in development:

# RewriteCond %{HTTP_HOST} !^www\. [NC]
# RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Since the preceding lines unconditionally redirect visitors to a www subdomain, the redirection can cause problems if you configured the website to work with different domains, for example, with non-production environments. Instead, replace the commented lines with code like the following, changing the example to your own domain name:

RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirecting traffic between HTTP and HTTPS

For Acquia-hosted websites, secure HTTPS connections end at the load balancer level, which can cause common .htaccess recipes for HTTPS redirects to not work as expected. Since the X-Forwarded-Proto Varnish header indicates to the web infrastructure if a request came in through HTTPS, you must confirm the header in your rewrite conditions.

The examples in each of the available redirect methods use rewrite rule flags. For a thorough explanation of the flags you can use, see RewriteRule Flags.

Redirecting all HTTP traffic to HTTPS

The following sample rule sets HTTP_X_FORWARDED_PROTO to https when accessing the website using HTTPS:

RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirecting all HTTPS traffic to HTTP

If your website displays insecure content warnings because Google indexed your documents using the HTTPS protocol, you must redirect traffic from HTTPS to HTTP using the following group of rules:

RewriteCond %{HTTP:X-Forwarded-Proto} =https
RewriteRule ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirecting all traffic to the “www” SSL domain

To force all traffic to use both the www domain and SSL (even if not initially requested), use the following rules:

# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]
# ensure www.
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirecting all traffic to the bare SSL domain

Cloud Platform Enterprise subscribers using the standard certificate model have the option of redirecting all traffic to a bare domain using the HTTPS protocol by using rules like the following:

# Redirecting http://www.domain.com and https://www.domain.com
# to https://domain.com
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ https://%1%{REQUEST_URI} [L,R=301]
# Redirecting http://domain.com to https://domain.com
RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirecting all traffic from two or more domains to a single domain

If you have two or more domains pointing to your website, your search rankings can be demoted for duplicate content. Use the following code to redirect visitors from two or more domains to a single domain:

RewriteCond %{HTTP_HOST} ^www.domain.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^domain.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^domain.net$ [NC]
RewriteRule ^(.*)$ https://www.domain.net/$1 [R=301,L]

Acquia recommends placing these rules after other redirects, such as Redirecting all HTTP traffic to HTTPS or Redirecting all traffic to the bare SSL domain.

Redirecting all traffic for multi-sites with symlinks

For a new language, you don’t need to add separate blocks for redirection rule. You can add more languages by using the pipe separator.

The following snippet shows the redirection rules for English and French.

#only language arguments in URL
RedirectMatch 301 ^/(en|fr)(/en|/fr)+/(en|fr)$ /$1/
#language arguments followed by path
RedirectMatch 301 ^/(en|fr)(/en|/fr)+/(.*)$ /$1/$3

Excluding Acquia domains and non-production environments

To exclude the default Acquia domains from your redirects, or specific environments (such as Dev and Stage), add one or more of the following conditionals to the top of any group of rewrite rules:

RewriteCond %{ENV:AH_SITE_ENVIRONMENT} prod [NC] # only prod
RewriteCond %{ENV:AH_SITE_ENVIRONMENT} !prod [NC] # not prod
# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]

As an example, if you wanted to ensure all the domains redirected to https://www. except for Acquia default domains, you would use rules like the following:

# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]
# ensure www.
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Identifying and blocking nuisance bots

Bot traffic is the non-human traffic generated on your website. Some bot traffic is useful for search engines and digital assistants. However, malicious bots or unauthorized web crawlers can be a nuisance because they disrupt site analytics and create an outsize impact on your infrastructure utilization.

To keep such traffic at bay, Acquia recommends adding nuisance bots to .htaccess:

# BLEXBot marketing crawler.
#Mozilla/5.0 (compatible; BLEXBot/1.0; +http://webmeup-crawler.com/)"
RewriteCond %{HTTP_USER_AGENT} ^(.*)BLEXBot(.*)$
RewriteRule .* - [F,L]

# Moz Link Index Crawler.
#Mozilla/5.0 (compatible; DotBot/1.1; http://www.opensiteexplorer.org/
dotbot, [email protected])"
RewriteCond %{HTTP_USER_AGENT} ^(.*)DotBot(.*)$
RewriteRule .* - [F,L]

# Paid SEO bot.
#Curious George - www.analyticsseo.com/crawler"
RewriteCond %{HTTP_USER_AGENT} ^(.*)Curious\ George(.*)$
RewriteRule .* - [F,L]

You can get a list of all nuisance bots by accessing your website from your historical web analytics data.

Example

The preceding examples of how and when you would use a rewrite are complex. Here is a breakdown of the scenarios, which may help you determine what your website needs.

A security warning will occur on a bare domain only if the request specifically includes the HTTPS protocol (such as https://example.com), and the load balancer covering the bare domain contains no SSL certificate. A request for http://example.com using the HTTP protocol will not produce a security warning because a secure connection to the bare domain was not requested.

For Cloud Platform, the CNAME record for www.example.com points to the host name of the elastic load balancer where the self-service UI installs the SSL certificate. Bare domains/ non-FQDNs such as example.com cannot have CNAME records without a service like Route 53. Due to the limitation, the domain must point to the elastic IP address of the balancer pair behind the Elastic Load Balancer (ELB).

If the .htaccess file contains a redirect taking all requests for the bare domain and redirecting them to www, due to how the DNS records are configured, the following process occurs if you request http://example.com:

• The request for http://example.com hits the load balancers behind the ELB.
• The .htaccess rule 301 redirects request to https://www.example.com.
• A new request for https://www.example.com hits the ELB (where the certificate exists), and the procedure completes as expected.

If you send a specific request to https://example.com with the HTTPS protocol, the following occurs:

• A request for https://example.com hits the load balancers behind the ELB.
• Your browser displays the normal security warning.
• You examine the certificate and decide to move ahead.
• The .htaccess rule 301 redirects the request to https://www.example.com.
• A new request for https://www.example.com hits the ELB (where the certificate exists), and the procedure completes as expected.

Depending on your Cloud Platform subscription type, there may be more requirements or steps to remove the security warning:

• Cloud Platform Professional

  Cloud Platform Professional uses shared balancers, so you must use a bare domain service (such as Route 53 or CloudFlare) to remove the security warning. Bare domain services allow you to use a CNAME record for the bare domain, and point the bare domain at the host name of the ELB.

• Cloud Platform Enterprise

  Acquia recommends you upload a SSL certificate covering all needed domains as described in Managing SSL certificates, or use another bare domain service such as Route 53 or Cloudflare.

Redirecting visitor requests with the .htaccess file

# RewriteCond %{HTTP_HOST} !^www\. [NC]
# RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteCond %{HTTP:X-Forwarded-Proto} =https
RewriteRule ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]
# ensure www.
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# Redirecting http://www.domain.com and https://www.domain.com
# to https://domain.com
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ https://%1%{REQUEST_URI} [L,R=301]
# Redirecting http://domain.com to https://domain.com
RewriteCond %{HTTPS} off
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteCond %{HTTP_HOST} ^www.domain.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^domain.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^domain.net$ [NC]
RewriteRule ^(.*)$ https://www.domain.net/$1 [R=301,L]

#only language arguments in URL
RedirectMatch 301 ^/(en|fr)(/en|/fr)+/(en|fr)$ /$1/
#language arguments followed by path
RedirectMatch 301 ^/(en|fr)(/en|/fr)+/(.*)$ /$1/$3

RewriteCond %{ENV:AH_SITE_ENVIRONMENT} prod [NC] # only prod
RewriteCond %{ENV:AH_SITE_ENVIRONMENT} !prod [NC] # not prod
# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]

# exclude Acquia domains
RewriteCond %{HTTP_HOST} !\.acquia-sites\.com [NC]
# exclude Acquia Cloud IDE preview sites
RewriteCond %{HTTP_HOST} !\.web\.ahdev\.cloud [NC]
# ensure www.
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# BLEXBot marketing crawler.
#Mozilla/5.0 (compatible; BLEXBot/1.0; +http://webmeup-crawler.com/)"
RewriteCond %{HTTP_USER_AGENT} ^(.*)BLEXBot(.*)$
RewriteRule .* - [F,L]

# Moz Link Index Crawler.
#Mozilla/5.0 (compatible; DotBot/1.1; http://www.opensiteexplorer.org/
dotbot, [email protected])"
RewriteCond %{HTTP_USER_AGENT} ^(.*)DotBot(.*)$
RewriteRule .* - [F,L]

# Paid SEO bot.
#Curious George - www.analyticsseo.com/crawler"
RewriteCond %{HTTP_USER_AGENT} ^(.*)Curious\ George(.*)$
RewriteRule .* - [F,L]