https://issues.apache.org/bugzilla/show_bug.cgi?id=48939
Summary: Add ability to force workers into
PROXY_WORKER_IN_ERROR when configured statuses are
found
Product: Apache httpd-2
Version: 2.2.15
Platform: Sun
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: mod_proxy
AssignedTo: [email protected]
ReportedBy: [email protected]
Greetings Apache Dev's;
A bug was filed (47207) mid last year under the expectation that HTTPD
should mark servers in error state on a 500 error status return. While I
disagree that this should be universal, we have found ourselves in situations
where we need the ability to mark members as PROXY_WORKER_IN_ERROR
automatically on certain status code returns. This varies heavily by
application and backend, but is a feature worth adding. I feel that this should
be a separate bug report since this is adding a server administrator
configuration parameter rather than applying the proposed change in 47207.
Problem examples:
Apache HTTPD server as reverse proxy to two WebSphere application servers
Some applications take a significant amount of time to initialize. Until they
are done initializing, WebSphere will rightfully return a 503. Depending on how
long this application may take to initialize (30 minutes in the extreme cases
of in-memory databases), this could inadvertently leave a member in service
during a period of time where it can not service requests.
Apache HTTPD server as reverse proxy to another HTTPD reverse proxy
Sometimes DMZ segments are broken up in a way such that only reverse proxies
with specific proxypass rules are allowed to traverse firewalls. Additionally,
sometimes the data carried within those proxies is too sensitive to do in
cleartext, so SSL may be needed. In some situations (server cert expired,
client cert expired, misconfiguration), the target (second) HTTPD reverse proxy
will throw a 502 that gets bubbled up to the first reverse proxy. Marking that
proxy as unusable would be beneficial.
Apache HTTPD server as reverse proxy to any WebSphere application server
In WebSphere, it is possible to have an application deployed but not running.
In the event an application is deployed but not started, the context root is
not bound in the web container. When a request comes in for that context root,
a 404 is returned. While it would be insane to mark a member out of service on
every 404, this is just an example of a use case.
Apache HTTPD server to any backend
Some folks are brazen enough to say their application has handled all possible
error conditions and that a 500 being returned to the user means the
application server must be at fault and taken out of service. Again, this is
madness, but there are other use cases (testing scripts) where taking instances
out of service because of a 500 may be desirable.
The proposed solution:
Add a configuration directive for balancers called "ErrorOnStatus" with usage
like:
ErrorOnStatus=501,502,503,504
Construct a apr_array_header_t that is checked during the currently unused
proxy_balancer_post_request method.
My thoughts:
I chose to use apr_array_header_t because it does not suggest a data type. My
preference would be to use apr_hash_t since it seems it would be faster, but I
am concerned that there is an expectation for character array datatypes for key
and value.
I am tidying up the patch now and will attach it soon.
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