使用Apache 2.4和Mono的Fedora 22服务器上的503错误

Question

I am currently attempting to setup a home webserver. I have a lot of experience programming in C# and have been using Visual Studio and IIS for years. I recently decided to make the move to Linux and have been rebuilding my code bases using MonoDevelop. I have them compiling on my development machine, so I am setting up a home server with Fedora 22 Server, and Apache 2.4.

Using nothing but the default configuration the server is able to serve html pages without a problem, but when I installed Mono, and its dependencies, I have been getting various errors, and they are not detailed enough for someone with my limited experience to resolve. I have spent the entire week working on the issue, and here is where I am stuck.

When browsing to http://71.41.214.194/LDC-Demo/index.aspx , I get a "503 Service Unavailable" error in the browser. When looking at the Apache Error log I get the following:

[Fri Oct 09 15:22:41.809588 2015] [:error] [pid 7577] Failed to connect to mod-mono-server after several attempts to spawn the process.

Since that is not enough to discern the issue, I restarted Apache and tried to reload the page (I was hoping for a related error that could help me chase down the problem)

[Fri Oct 09 15:38:22.000257 2015] [mpm_prefork:notice] [pid 7564] AH00170: caught SIGWINCH, shutting down gracefully
[Fri Oct 09 15:38:23.011225 2015] [:alert] [pid 7564] (13)Permission denied: Failed to acquire dashboard lock before destroying the dashboard
[Fri Oct 09 15:38:23.011668 2015] [:alert] [pid 7564] (13)Permission denied: Failed to acquire dashboard lock before destroying the dashboard
[Fri Oct 09 15:38:23.011770 2015] [:alert] [pid 7564] (13)Permission denied: Failed to acquire dashboard lock before destroying the dashboard
[Fri Oct 09 15:38:24.068911 2015] [core:notice] [pid 7641] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Fri Oct 09 15:38:24.069933 2015] [suexec:notice] [pid 7641] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.localdomain. Set the 'ServerName' directive globa$
[Fri Oct 09 15:38:24.079961 2015] [auth_digest:notice] [pid 7641] AH01757: generating secret for digest authentication ...
[Fri Oct 09 15:38:24.080817 2015] [lbmethod_heartbeat:notice] [pid 7641] AH02282: No slotmem from mod_heartmonitor
[Fri Oct 09 15:38:24.088966 2015] [mpm_prefork:notice] [pid 7641] AH00163: Apache/2.4.16 (Fedora) mod_mono/3.12 configured -- resuming normal operations
[Fri Oct 09 15:38:24.088993 2015] [core:notice] [pid 7641] AH00094: Command line: '/usr/sbin/httpd -D FOREGROUND'
[Fri Oct 09 15:38:36.414478 2015] [:error] [pid 7651] Failed to connect to mod-mono-server after several attempts to spawn the process.

After researching each of these messages to the best of my ability, I could not find anything that was related to the issue. I did find that I could see some more details if I ran the command "journalctl -xe -cat".

Started The Apache HTTP Server.
mono[7646]: segfault at 5 ip 0000000000512710 sp 00007fffa85f01b0 error 6 in mono-sgen[400000+34d000]
<audit-1130> pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=httpd comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Unregistered Authentication Agent for unix-process:7633:25881589 (system bus name :1.83, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
<audit-1400> avc:  denied  { execmem } for  pid=7649 comm="mono" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=process permissive=0
<audit-1400> avc:  denied  { execmem } for  pid=7649 comm="mono" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=process permissive=0
<audit-1701> auid=4294967295 uid=48 gid=48 ses=4294967295 subj=system_u:system_r:httpd_t:s0 pid=7649 comm="mono" exe="/usr/bin/mono-sgen" sig=11
mono[7649]: segfault at 5 ip 0000000000512710 sp 00007ffe5ca30440 error 6 in mono-sgen[400000+34d000]
Not saving repeating crash in '/usr/bin/mono-sgen'
Not saving repeating crash in '/usr/bin/mono-sgen'
<audit-1400> avc:  denied  { sigchld } for  pid=7647 comm="abrt-hook-ccpp" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=0
Failed to create core_backtrace: waitpid failed: Permission denied
Blacklisted package 'mono-core'
'post-create' on '/var/spool/abrt/ccpp-2015-10-09-15:38:24-7644' exited with 1
Deleting problem directory '/var/spool/abrt/ccpp-2015-10-09-15:38:24-7644'
<audit-1400> avc:  denied  { execmem } for  pid=7661 comm="mono" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=process permissive=0
<audit-1400> avc:  denied  { execmem } for  pid=7661 comm="mono" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=process permissive=0
<audit-1701> auid=4294967295 uid=48 gid=48 ses=4294967295 subj=system_u:system_r:httpd_t:s0 pid=7661 comm="mono" exe="/usr/bin/mono-sgen" sig=11
mono[7661]: segfault at 5 ip 0000000000512710 sp 00007ffed5a32ee0 error 6 in mono-sgen[400000+34d000]
Not saving repeating crash in '/usr/bin/mono-sgen'

There is a lot more information in these messages, but I am still having a problem finding the cause. The last 5 lines are repeated three times.

I have tried making modifications to the apache config file (httpd.conf) as well as to the mod_mono.conf file, but nothing seems to get me past the problem.

In my current configuration the mod_mono.conf file is unmodified from the default configuration, and the only change that I have made to httpd.conf is to add a virtual host section as follows:

<VirtualHost *:80>
  ServerName LDC-Demo
  ServerAdmin root@localhost
  ServerAlias LDC-Demo
  DocumentRoot /var/www/html/LDC-Demo/
  MonoServerPath LDC-Demo "/usr/bin/mod-mono-server4"
  MonoDebug LDC-Demo true
  MonoSetEnv LDC-Demo MONO_IOMAP=all
  MonoApplications LDC-Demo "/:/var/www/html/LDC-Demo"
  <Location "/LDC-Demo">
    Allow from all
    Order allow,deny
    MonoSetServerAlias LDC-Demo
    SetHandler mono
    SetOutputFilter DEFLATE
    SetEnvIfNoCase Request_URI "\.(?:gif|jpe?g|png)$" no-gzip dont-vary
  </Location>
</VirtualHost>

Any ideas would be appreciated, as I stated above, I have been working on this all week, and am not making much progress.

Answer 1

I entered this above as a comment, but I intended to answer the question.

I figuered it out. Fedora runs SELinux, and it was interfering with the permissions needed for mod_mono to run. To see these settings I ran the command: getenforce Then to temporarily change the setting I used the following command: setenforce 0 Finally, restart Apache: apachectl restart I refreshed the web browser and the page loaded correctly. To make the setting permanant, edit the selinux file: nano /etc/sysconfig/selinux I rebooted the server, and tried to load the webpage again. Eureka! everything is working.