I'm interested in your comments (good and bad) on implementing a new
option to ProxyPass which would make apache perform a redirect when the
proxy server or balancer cluster is not available. This minics the same
functionality of a dedicated hardware load balancer by issuing a HTTP
redirect response to a holding page ("This service is not available", or
"We are updating out website").
Can anyone see any reason why this is a bad idea to implement within
apache, or see any obstacles in my way ?
The last time I looked at the internals of apache it had a sub-request
facility, I would like to be able to redirect to both external and
internal pages. External being a HTTP 3xx response with Location:
header and would be configured with a absolute url "http://...";.
Internal being a fall through to the configured mapping and content
handler for the URL just as-if the ProxyPass directive wasn't there, I
was thinking along the lines of this being configured with a
"fallthrough:" scheme prefix. This means it would be possible to use:
DocumentRoot /opt/apache/htdocs
ProxyPass / balancer://group1/ timeout=5 maxattempts=3
fallback-redirect=fallthrough:/holding.html
Then if the "balancer://group1" cluster fails the document at
/opt/apache/htdocs/holding.html is served instead.
Request for comments,
Darryl
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Darryl L. Miles
