Simplifying rewrite rules

Hi,

I'm implementing two reverse proxies reverse proxy in front of two application
server farms in different data centers, where each customer has one specific
target server. The rewrite rules below are working, but might do several external
redirects, which I'd like to reduce if possible.

It basically works like that:
* the first path component in the request uri is the customer name
* look up this customer name in a RewriteMap
* if found, proxy to the target server
* otherwise look if it is found in the map of the other data center and
redirect there

Both proxies are reached with the same DNS name, but have their own canonical name.
There are web service clients that don't support redirects for individual calls.
Therefore these are redirected once to the canonical hostname when they request their
customer name directly. Some accounts may be used with HTTPS only.

Below are the rules. Do you see a way to simplify them without changing the logic, to
avoid repeated redirects to the same server?

Thanks
Rainer


# canonical name
ServerName login1.portal.example.com
# public common name
ServerAlias login.portal.example.com
UseCanonicalName On

# map of customer instances that are proxied here
RewriteMap c2back dbm:/etc/apache2/portal/customer2backend.db
# map of customer instances in the other datacenter
RewriteMap c2other dbm:/etc/apache2/portal/customer2other.db
# map of local HTTPS-only accounts
RewriteMap c2https dbm:/etc/apache2/portal/customer2https.db

# if account is set to HTTPS only, redirect to same HTTPS URL
RewriteCond %{HTTPS} =off
RewriteCond ${c2https:$1} =s
RewriteRule ^/([^/]+)(/.*)? https://%{SERVER_NAME}$1$2 [R,L]

# redirect requests for a customer name to canonical name
RewriteCond %{HTTP_HOST} !=login1.portal.example.com
RewriteRule ^/([^/]+)/?$ /$1/ [R,L]

# the main proxy rule: lookup backend server for customer, setup ENV
# and send proxy request
# map contains customername=>backendhost/applicationname
RewriteCond ${c2back:$1} ^(.+)$
RewriteRule ^/([^/]+) - [E=CUST:$1,E=TARGET:%1,C]
RewriteRule ^/([^/]+)(/.*)? http://%{ENV:TARGET}$2 [P,L]

ProxyPassInterpolateEnv on
ProxyPassReverse /${CUST}/ http://${TARGET}/ interpolate

# redirect others to the other proxy if found in map
# map contains customername=>otherproxyhostname
RewriteCond %{HTTPS} =on
RewriteRule .* - [E=SSL:s]
RewriteCond ${c2other:$1} ^(.+)$
RewriteRule ^/([^/]+)(/.*)? http%{ENV:SSL}://%1/$1$2 [R,L]

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