Chapter 7 and 8 of LSF211

jpalko

Why don't these chapters make more use of the excellent a2* commands available in Debian/Ubuntu? e.g. Lab 8.1:

root@debian:~# a2enmod cgi
Your MPM seems to be threaded. Selecting cgid instead of cgi.
Enabling module cgid.
To activate the new configuration, you need to run:
  systemctl restart apache2

Here for example it decided that the cgid module was preferable to cgi as other configuration directives work better with it.

I would also rather always edit the files under /etc/apache2/{conf,mods,sites}-available than make the files in /etc/apache2/{conf,mods,sites}-enabled directories and then execute the related a2enmod, a2ensite or a2enconf commands to make the configuration changes active.

There was one instance of the a2enmod used in exercise 8.1 which is actually the first instance when I followed the instructions given in these two chapters labs... The greatest advantage is that a2enmod handles also the dependency checking of needed modules so that it enables dependencies of the module requested to be enabledof which I put an example below.

root@debian:~# a2enmod lbmethod_heartbeat
Considering dependency proxy_balancer for lbmethod_heartbeat:
Considering dependency proxy for proxy_balancer:
Module proxy already enabled
Considering dependency alias for proxy_balancer:
Module alias already enabled
Considering dependency slotmem_shm for proxy_balancer:
Enabling module slotmem_shm.
Enabling module proxy_balancer.
Enabling module lbmethod_heartbeat.
To activate the new configuration, you need to run:
  systemctl restart apache2

To be honest, I've long wished that other distributions would make use of this excellent solution in Debian for handling Apache configs.

Also I noticed that the chapter 7 knowledge check starts with this claim:

The default configuration of the Apache web server usually listens only to the loopback interface. True or False?

For which the correct answer required is actually incorrect as Debian 10, CentOS 8, Fedora Server and OpenSUSE Tumbleweed ( at least Tumbleweed, didn't test others) configure by default Apache to listen on *:80 and not on localhost.

lee42x

Hello Jpaliko,
Since we support several distributions, distribution specific commands are generally avoided if there is a generic method of completing the task. No, I'm not starting a flame war, each disrto has some very nice options.

We will review he KC question, I believe that the answer was to be false indicating that there could be an open listening port on your system you may not have expected.

During service package installation there is a difference in distros, some distros install applications and automatically start them and other distros install applications and purposely leave them off.

Thank you for your input. Lee

jpalko

Certainly, I understand the need to keep the course material as distribution agnostic as possible. However since some references to distribution specific needs cannot be avoided, I don't see the harm of suggesting to make use of the tools provided by a specific distribution that could make the life of an administrator easier on said distribution.

Don't want to bring up any distribution flame wars either, just suggesting that if a distribution has some features to explore further, they could be recommended to students to take a look at.

coop

As Lee said, a2enmod etc exist on Debian but do not exist on any RHEL or CentOS system, which are pretty ubiquitous. The courses try to limit themselves to more universal tools if possible. And the exams are given on CentOS and Ubuntu (I don't know if a2enmod has been copied from Debian to Ubuntu). At any rate, there are reasons some folks don't like the way these wrapper scripts are done, but that is beyond both the scope and my expertise to comment on.

jpalko

Ubuntu has it too:

root@ubuntu:~# a2
a2disconf  a2dismod   a2dissite  a2enconf   a2enmod    a2ensite   a2query    

As I said I understand the desire to keep the course material as distribution agnostic as possible but I still see no harm to mention the tools should some admin have those as their main OS choice where they host services.

jpalko

@lee42x said:
We will review he KC question, I believe that the answer was to be false indicating that there could be an open listening port on your system you may not have expected.

lee42x

Thank you , this will be corrected.

lee42x

Just verified that a2emod is indeed in the material.