Httpd – How to start Apache on CentOS7 for the first time

Apache2centos7httpd

I have updated yum using sudo yum update and installed sudo yum install httpd

I edited httpd.conf so the ServerName is the IP address of the web server I remote into.

when I try to restart httpd using sudo service httpd restart I get the following error messages:

Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details.

systemctl -l status httpd.service returns the following:

 httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2017-07-11 14:20:39 EDT; 1min 22s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 3275 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=1/FAILURE)
  Process: 3273 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=0/SUCCESS)
 Main PID: 3273 (code=exited, status=0/SUCCESS)

Jul 11 14:20:39 blondie systemd[1]: Starting The Apache HTTP Server...
Jul 11 14:20:39 blondie httpd[3273]: httpd (pid 2260) already running
Jul 11 14:20:39 blondie kill[3275]: kill: cannot find process ""
Jul 11 14:20:39 blondie systemd[1]: httpd.service: control process exited, code=exited status=1
Jul 11 14:20:39 blondie systemd[1]: Failed to start The Apache HTTP Server.
Jul 11 14:20:39 blondie systemd[1]: Unit httpd.service entered failed state.
Jul 11 14:20:39 blondie systemd[1]: httpd.service failed.

running journalctl -xe returns:

Unit user-0.slice has begun starting up.
Jul 11 14:10:01 blondie systemd[1]: Started Session 7 of user root.
-- Subject: Unit session-7.scope has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit session-7.scope has finished starting up.
-- 
-- The start-up result is done.
Jul 11 14:10:01 blondie systemd[1]: Starting Session 7 of user root.
-- Subject: Unit session-7.scope has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit session-7.scope has begun starting up.
Jul 11 14:10:01 blondie CROND[3154]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Jul 11 14:10:01 blondie systemd[1]: Removed slice user-0.slice.
-- Subject: Unit user-0.slice has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has finished shutting down.
Jul 11 14:10:01 blondie systemd[1]: Stopping user-0.slice.
-- Subject: Unit user-0.slice has begun shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has begun shutting down.
Jul 11 14:10:40 blondie sudo[3162]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/systemctl status
Jul 11 14:13:09 blondie sudo[3164]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/sbin/service httpd -
Jul 11 14:16:19 blondie sudo[3195]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/nano /etc/httpd/
Jul 11 14:16:40 blondie sudo[3212]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/nano /etc/httpd/
Jul 11 14:18:19 blondie sudo[3215]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/sbin/apachectl confi
Jul 11 14:19:14 blondie sudo[3221]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/nano /etc/httpd/
Jul 11 14:20:01 blondie systemd[1]: Created slice user-0.slice.
-- Subject: Unit user-0.slice has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has finished starting up.
-- 
-- The start-up result is done.
Jul 11 14:20:01 blondie systemd[1]: Starting user-0.slice.
-- Subject: Unit user-0.slice has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has begun starting up.
Jul 11 14:20:01 blondie systemd[1]: Started Session 8 of user root.
-- Subject: Unit session-8.scope has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit session-8.scope has finished starting up.
-- 
-- The start-up result is done.
Jul 11 14:20:01 blondie systemd[1]: Starting Session 8 of user root.
-- Subject: Unit session-8.scope has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit session-8.scope has begun starting up.
Jul 11 14:20:01 blondie CROND[3225]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Jul 11 14:20:01 blondie systemd[1]: Removed slice user-0.slice.
-- Subject: Unit user-0.slice has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has finished shutting down.
Jul 11 14:20:01 blondie systemd[1]: Stopping user-0.slice.
-- Subject: Unit user-0.slice has begun shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit user-0.slice has begun shutting down.
Jul 11 14:20:14 blondie sudo[3251]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/nano /etc/httpd/
Jul 11 14:20:39 blondie sudo[3255]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/sbin/service httpd r
Jul 11 14:20:39 blondie polkitd[637]: Registered Authentication Agent for unix-process:3256:362038 (system bus name :1.63 [/usr
Jul 11 14:20:39 blondie systemd[1]: Starting The Apache HTTP Server...
-- Subject: Unit httpd.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit httpd.service has begun starting up.
Jul 11 14:20:39 blondie httpd[3273]: httpd (pid 2260) already running
Jul 11 14:20:39 blondie kill[3275]: kill: cannot find process ""
Jul 11 14:20:39 blondie systemd[1]: httpd.service: control process exited, code=exited status=1
Jul 11 14:20:39 blondie systemd[1]: Failed to start The Apache HTTP Server.
-- Subject: Unit httpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit httpd.service has failed.
-- 
-- The result is failed.
Jul 11 14:20:39 blondie systemd[1]: Unit httpd.service entered failed state.
Jul 11 14:20:39 blondie systemd[1]: httpd.service failed.
Jul 11 14:20:39 blondie polkitd[637]: Unregistered Authentication Agent for unix-process:3256:362038 (system bus name :1.63, ob
Jul 11 14:22:01 blondie sudo[3280]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/systemctl -l sta
Jul 11 14:23:13 blondie sudo[3283]: admin1 : TTY=pts/0 ; PWD=/home/admin1 ; USER=root ; COMMAND=/bin/journalctl -xe

i tried removing httpd and re-installing already but i couldn't get httpd to restart

Best Answer

Looks like you might have an orphaned PID file. There is a PID for httpd, but kill doesn't see a process for it.

Check top to see if there are any zombie processes. Also ps aux | grep httpd just to see what is running.

If this is the case, you would have to kill the parent process to clean it up (ps -Hfwe or pstree -paul to find it), or reboot.

Hopefully then you can do a systemctl start.

`prefork`

mpm_prefork is.. well.. it's compatible with everything. It spins off a number of child processes for serving requests, and the child processes only serve one request at a time. Because it's got the server process sitting there, ready for action, and not needing to deal with thread marshaling, it's actually faster than the more modern threaded MPMs when you're only dealing with a single request at a time - but concurrent requests suffer, since they're made to wait in line until a server process is free. Additionally, attempting to scale up in the count of prefork child processes, you'll easily suck down some serious RAM.

It's probably not advisable to use prefork unless you need a module that's not thread safe.

Use if: You need modules that break when threads are used, like mod_php. Even then, consider using FastCGI and php-fpm.

Don't use if: Your modules won't break in threading.

`worker`

mpm_worker uses threading - which is a big help for concurrency. Worker spins off some child processes, which in turn spin off child threads; similar to prefork, some spare threads are kept ready if possible, to service incoming connections. This approach is much kinder on RAM, since the thread count doesn't have a direct bearing on memory use like the server count does in prefork. It also handles concurrency much more easily, since the connections just need to wait for a free thread (which is usually available) instead of a spare server in prefork.

Use if: You're on Apache 2.2, or 2.4 and you're running primarily SSL.

Don't use if: You really can't go wrong, unless you need prefork for compatibility.

However, note that the treads are attached to connections and not requests - which means that a keep-alive connection always keeps a hold of a thread until it's closed (which can be a long time, depending on your configuration). Which is why we have..

`event`

mpm_event is very similar to worker, structurally; it's just been moved from 'experimental' to 'stable' status in Apache 2.4. The big difference is that it uses a dedicated thread to deal with the kept-alive connections, and hands requests down to child threads only when a request has actually been made (allowing those threads to free back up immediately after the request is completed). This is great for concurrency of clients that aren't necessarily all active at a time, but make occasional requests, and when the clients might have a long keep-alive timeout.

The exception here is with SSL connections; in that case, it behaves identically to worker (gluing a given connection to a given thread until the connection closes).

Use if: You're on Apache 2.4 and like threads, but you don't like having threads waiting for idle connections. Everyone likes threads!

Don't use if: You're not on Apache 2.4, or you need prefork for compatibility.

In today's world of slowloris, AJAX, and browsers that like to multiplex 6 TCP connections (with keep-alive, of course) to your server, concurrency is an important factor in making your server scale and scale well. Apache's history has tied it down in this regard, and while it's really still not up to par with the likes of nginx or lighttpd in terms of resource usage or scale, it's clear that the development team is working toward building a web server that's still relevant in today's high-request-concurrency world.

Best Answer

Related Solutions

Command for checking Apache configuration

Httpd – How to select which Apache MPM to use

prefork

worker

event

Related Topic

`prefork`

`worker`

`event`