Balancers - an interim doc and qmail problem

[NormW]

Greetings All,
Had a couple of goes replying to a thread that asked about a doc for the
Mod_Proxy balancer, and twice qmail sent it back saying the 'subject' was
empty.
Hopefully this works.
Attached (maybe) is something I've pulled together from digging, and look to
some detailed docs in the near future.
HTH,
Norm

Title: Mod_Proxy - Configuration

Dated 31August, 2004
Creating a Balancer
Coding example:
<Proxy balancer://<name>>
   BalancerMember  <method>://<IP/DNS>:<port> [key=value] [key=value ...]
   ....
</Proxy>

where <name> is any practical value.
Use the ProxySet directive to set any of the properties of the Balancer itself.
  ProxySet <balancer name> key=value [key=value ...]

For Balancers, their 'balancer name' comprises the method and <name>, for example:
  balancer://tcbal_1

The "key" can be any of the following:

Key Name
Description
Constraint(s)
nofailover
Disable failover for sticky sessions
Must be 'on' or 'off'
stickysession
Sticky Session identifier
 
timeout
Timeout for waiting on free connection
Must be at least one second


For the Balancer members:

<method> identifies the protocol to use by the BalancerMember (http, ftp, ajp),
<IP/DNS>:<port> identifies the location of the proxy machine.

The "key" can be any of the following:


Key Name
Description
Constraint(s)
loadfactor
Initial load balancing factor
Must be between 1..100 (percent)
retry
Retry interval
Must be at least one second
ttl
Maximum time (seconds) a connection 
may be available while
 exceeding the soft limit
Must be at least one second
min
Desired minimum number of available connections
Must be positive number
max
Hard maximum on the total number of connections
Must be positive number
smax
Soft maximum on the total number of connections
Must be positive number
acquire
Acquire timeout when maximum connections is exceeded
Must be at least one milli-second
timeout
Connection timeout
Must be at least one second
iobuffersize
Input-Output buffer size
Must be >= AP_IOBUFSIZE
receivebuffersize
Receive buffer size
Must be >= 512 bytes, or 0 for system default
keepalive
Enable/Disable Keepalive for this worker
Must be 'on' or 'off'
route
Balancing route
val
redirect
Temporary balancing redirection route
val


Alternatively, use the ProxySet directive to set BalancerMember properties:
  ProxySet <member name> key=value [key=value ...]

For Balancer Members, their 'member name' comprises the method, host and port values, for example:
  ajp://myserver.com:8080

The current configuration of "Balancers" can be seen at the bottom of the /server-status/ page,
if mod_status is loaded in the Apache Web Server.
Assigning a URL to a Balancer
To assign a URL segment to a Balancer, use the ProxyPass directive as follows:

Inside a <Location > block

  <Location /admin/>
    Proxypass <balancer name>
  </Location>


In a single statement

  Proxypass <balancer name> /admin/