mod_proxy: add a link to the status flag table

        <td>Route of the worker when used inside load balancer.

        The route is a value appended to session id.

    </td></tr>

    <tr><td>status</td>

    <tr><td><a name="status_table">status</a></td>

        <td>-</td>

        <td>Single letter value defining the initial status of

        this worker.

         <tr><td><code>D</code></td><td>Worker is disabled and will not accept any requests; will be

                    automatically retried.</td></tr>

         <tr><td><code>S</code></td><td>Worker is administratively stopped; will not accept requests

                    and will not be automatically retried</td></tr>

                    and will not be automatically retried.</td></tr>

         <tr><td><code>I</code></td><td>Worker is in ignore-errors mode and will always be considered available.</td></tr>

         <tr><td><code>R</code></td><td>Worker is a hot spare. For each worker in a given lbset that is unusable

                    (draining, stopped, in error, etc.), a usable hot spare with the same lbset will be used in

<note><title>Parameters</title>

  <p>The health check mechanism is enabled via the use of additional

  	BalancerMember parameters, which are configured in the standard

  	way via <directive module="mod_proxy">ProxyPass</directive>:</p>

     <directive module="mod_proxy">BalancerMember</directive> parameters, which are configured

     in the standard way via <directive module="mod_proxy">ProxyPass</directive>:</p>

  <p>A new BalancerMember status state (flag) is defined via this module: "<code>C</code>".

  <p>A new BalancerMember <a href="mod_proxy.html#status_table">status</a> state (flag)

     is defined via this module: "<code>C</code>".

     When the worker is taken offline due to failures as determined by the health

     check module, this flag is set, and can be seen (and modified) via the

     <code>balancer-manager</code>.</p>

        <td>Additional URI to be appended to the worker URL for the health check.</td></tr>

    <tr><td>hctemplate</td>

        <td>&nbsp;</td>

        <td>Name of template, created via <directive>ProxyHCTemplate</directive> to use for setting health check parameters for this worker</td></tr>

        <td>Name of template, created via <directive module="mod_proxy_hcheck">ProxyHCTemplate</directive>,

            to use for setting health check parameters for this worker</td></tr>

    <tr><td>hcexpr</td>

        <td>&nbsp;</td>

        <td>Name of expression, created via <directive>ProxyHCExpr</directive>, used to check response headers for health.<br/>

        <td>Name of expression, created via <directive module="mod_proxy_hcheck">ProxyHCExpr</directive>,

            used to check response headers for health.<br/>

            <em>If not used, 2xx thru 3xx status codes imply success</em></td></tr>

    </table>

</note>

<directivesynopsis>

<name>ProxyHCExpr</name>

<description>Creates a named condition expression to use to determine health of the backend based on its response.</description>

<syntax>ProxyHCExpr name {ap_expr expression}</syntax>

<description>Creates a named condition expression to use to determine health of the backend based on its response</description>

<syntax>ProxyHCExpr <em>name</em> {<em>ap_expr expression</em>}</syntax>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<override>FileInfo</override>

       for creating a named condition expression that checks the response

       headers of the backend server to determine its health. This named

       condition can then be assigned to balancer members via the <code>hcexpr</code>

       parameter</p>

       parameter.</p>

    <example><title>ProxyHCExpr: Allow for 2xx/3xx/4xx as passing</title>

    <highlight language="config">

<directivesynopsis>

<name>ProxyHCTemplate</name>

<description>Creates a named template for setting various health check parameters</description>

<syntax>ProxyHCTemplate name parameter=setting &lt;...&gt;</syntax>

<syntax>ProxyHCTemplate <em>name</em> <em>parameter</em>=<em>setting</em> [...]</syntax>

<contextlist><context>server config</context><context>virtual host</context>

</contextlist>

<override>FileInfo</override>

    <p>The <directive>ProxyHCTemplate</directive> directive allows

       for creating a named set (template) of health check parameters

       that can then be assigned to balancer members via the <code>hctemplate</code>

       parameter</p>

       parameter.</p>

    <example><title>ProxyHCTemplate</title>

    <highlight language="config">

<directivesynopsis>

<name>ProxyHCTPsize</name>

<description>Sets the total server-wide size of the threadpool used for the health check workers.</description>

<syntax>ProxyHCTPsize &lt;size&gt;</syntax>

<description>Sets the total server-wide size of the threadpool used for the health check workers</description>

<syntax>ProxyHCTPsize <em>size</em></syntax>

<contextlist><context>server config</context>

</contextlist>