Description of problem:

This is a continuation of https://bz.apache.org/bugzilla/show_bug.cgi?id=60757.

mod_proxy_hcheck is configured in VirtualHost. I expect a watchdog works for VirtualHost and shows a notification like:

[Thu Jul 12 13:32:10.325851 2018] [proxy_hcheck:debug] [pid 2867] mod_proxy_hcheck.c(1033): AH03265: watchdog callback registered (_proxy_hcheck_ for 127.0.0.1)

However, in fact it shows the failure message:

[Thu Jul 12 13:39:13.729415 2018] [proxy_hcheck:trace4] [pid 2939] mod_proxy_hcheck.c(1018): AH10019: Missing unique per-server context: 127.0.0.1 (5563982bee48:556398236400) (no hchecks)

The configuration is as follows:

<VirtualHost 127.0.0.1:80>
  ProxyRequests off
  ProxyPreserveHost On
  ServerName  127.0.0.1
  #ProxyHCExpr ok23 {%{REQUEST_STATUS} =~ /^[23]/}
  #ProxyHCTemplate hcinterval=5
  <Proxy balancer://jbosscluster>
    BalancerMember http://redhat.com:80/ route=p01 hcmethod=TCP hcinterval=5
    BalancerMember http://jboss.org:80/ route=p02 hcmethod=TCP hcinterval=5
    ProxySet lbmethod=byrequests
    Require all granted
  </Proxy>
  ProxyPass / balancer://jbosscluster/
  ProxyPassReverse / balancer://jbosscluster/
  <Proxy *>
    Require all denied
  </Proxy>
  <Location ~ "/*">
    Require all granted
  </Location>
  LogLevel proxy_hcheck:TRACE8 proxy:TRACE2 watchdog:TRACE2
</VirtualHost>

Uncommenting ProxyHCExpr or ProxyHCTemplate, it works as expected.


Version-Release number of selected component (if applicable):

httpd24-httpd-2.4.27-8.el7.1.x86_64

How reproducible:

Steps to Reproduce:
1. Add the above config in /opt/rh/httpd24/root/etc/httpd/conf.d/
2. Restart the server
3. See error_log

Actual results:

[Thu Jul 12 13:32:10.325851 2018] [proxy_hcheck:debug] [pid 2867] mod_proxy_hcheck.c(1033): AH03265: watchdog callback registered (_proxy_hcheck_ for 127.0.0.1)

Expected results:

[Thu Jul 12 13:39:13.729415 2018] [proxy_hcheck:trace4] [pid 2939] mod_proxy_hcheck.c(1018): AH10019: Missing unique per-server context: 127.0.0.1 (5563982bee48:556398236400) (no hchecks)


Additional info:

If neither of the above 2 directive is defined in VirtualHost, hc_create_config is not invoked. As a result, the root sctx_t instance is reused for each VirtualHost:

Breakpoint 1, hc_post_config (p=<optimized out>, plog=<optimized out>, ptemp=<optimized out>, main_s=<optimized out>) at mod_proxy_hcheck.c:1015
1015            if (s != ctx->s) {
(gdb) print s.server_hostname 
$1 = 0x5555558a00b0 "172.17.0.2"
(gdb) print s                 
$2 = (server_rec *) 0x55555580b400
(gdb) print ctx.s
$3 = (server_rec *) 0x55555580b400
(gdb) c
Continuing.

Breakpoint 1, hc_post_config (p=<optimized out>, plog=<optimized out>, ptemp=<optimized out>, main_s=<optimized out>) at mod_proxy_hcheck.c:1015
1015            if (s != ctx->s) {
(gdb) print s.server_hostname 
$4 = 0x555555899ed0 "127.0.0.1"
(gdb) print s
$5 = (server_rec *) 0x555555893e48
(gdb) print ctx.s
$6 = (server_rec *) 0x55555580b400    <<<<====reused
(gdb)