Ansible now available as an RPM

Ansible is now available as an RPM from the EPEL repo. It pulls in all the dependencies needed by Ansible (Python libraries, libyaml and sshpass). The RPM provides Ansible version 2.0.2.0 which includes a number of bug fixes including a security one (CVE-2016-3096). This is a lot easier to handle than fiddling with Python’s package manager of the day.

$ sudo yum install ansible
...
=============================================================================================================
Package                         Arch                 Version                       Repository          Size
=============================================================================================================
Installing:
ansible                         noarch               2.0.2.0-1.el6                 epel               2.9 M
Installing for dependencies:
PyYAML                          x86_64               3.10-3.1.el6                  base               157 k
libyaml                         x86_64               0.1.3-4.el6_6                 base                52 k
python-babel                    noarch               0.9.4-5.1.el6                 base               1.4 M
python-crypto                   x86_64               2.0.1-22.el6                  base               159 k
python-crypto2.6                x86_64               2.6.1-2.el6                   epel               513 k
python-httplib2                 noarch               0.7.7-1.el6                   epel                70 k
python-jinja2-26                noarch               2.6-3.el6                     epel               527 k
python-keyczar                  noarch               0.71c-1.el6                   epel               219 k
python-paramiko                 noarch               1.7.5-2.1.el6                 base               728 k
python-pyasn1                   noarch               0.0.12a-1.el6                 base                70 k
python-simplejson               x86_64               2.0.9-3.1.el6                 base               126 k
python-six                      noarch               1.9.0-2.el6                   base                28 k
sshpass                         x86_64               1.05-1.el6                    epel                19 k

Transaction Summary
=============================================================================================================
Install      14 Package(s)

Total download size: 6.9 M
Installed size: 33 M
Is this ok [y/N]:

Key references for various tools

The following post was contributed by Mike Weilgart who has recently joined the ranks of Linux system administrators.

For `bash` and POSIX shell scripting:

Variable quoting

Miscellaneous

For `vi` and Vim:

The article “Why, oh WHY, do those #?@! nutheads use vi?”
Stack Overflow answer encapsulating basics of vi command language
Stack Overflow answer encapsulating buffers vs. windows vs. tabs
Quick tips for using buffers effectively

For git:

What exactly do we mean by “branch”?
The Think Like a Git website, including all of the links on the “Resources” page.

`cgroups`:

Stack Exchange answer serving as an Introduction to cgroups

Training program to make a Novice System Administrator

I’ve put together a program to make entry-level Linux system administrators because we need more to maintain the IT fabric of modern civilization.

The program is self-paced, using online resources. This is not training I deliver personally, rather I will guide you to quality training resources, in the correct sequence, and work with you to debug any stops. There is no fee to me for this program. The training takes 2-3 months full-time and costs about USD 1,000 for the online training courses and books. You’ll need a practice computer you can install Linux on.

Pre-requisites: Aspirants need to know how to use a computer for basic tasks (e.g., Web, email, word processing).

Part I – Linux Essentials

Read “Linux Essentials” [2015]

342 pages

$25.80

Do the “Introduction to Linux” (LFS101x) [2014]

Online course

40-60 hours
Free

Part II – The Linux Command Line

Read “The Linux Command Line” [2013]

537 pages

Free

Part III – Linux System Administration

Do the “Essentials of System Administration” (LFS201)

Online course
40-50 hours
$499 (includes certification exam)

Do Cricket Liu’s DNS course from the Linux Sysadmin Basics

Video training from oreilly.com

Free with a 10 day Safari trial

Part IV – Certification (optional)

– Linux Professional Institute Linux Server Professional (LPIC-1) $42.49 at Pearson VUE

– Linux Foundation Certified System Administrator (LFCS) included with LFS201

Part V – Introduction to Computer Science (can be done after starting work)

Introduction to Computer Science (CS50x) online training from edX.org
100 – 200 hours

Free

Professional Library

In addition, I recommend the following professional library (you can build it up as you start earning in your new profession):

UNIX and Linux System Administration Handbook 4th Edition [2010] $50.28

The Practice of System and Network Administration, 2nd Edition [2007] $46.87

The Practice of Cloud System Administration [2014] $46.23

Principles of Network and System Administration 2nd Edition [2004] $61.10

Time Management for System Administrators [2005] $24.95

Total: $229.43

Summary of All Costs

Total cost: $1029.72

Time investment needed: 2-4 months full-time or 6-12 months part-time

Code of Ethics

As a professional system administrator, study and commit yourself to our Code of Ethics.

Tips for Success

Mike Weilgart completed the program and adds:

And a crucial ingredient to success (and I’m being entirely serious): Spend plenty of time during your training reading up on what you’re studying on the Unix & Linux Stack Exchange.

Elective – Learn How to Make a Web Site

Exercise: Setup a personal site, e.g., like Mark Burgess has

There is an excellent WordPress tutorial at http://websitesetup.org/

To learn the underlying technology, HTML/CSS, I recommend http://websitesetup.org/html-beginners-guide/

Also, you can write in Markdown and use pandoc to convert to HTML. Try it!

Elective – Learn How to Use strace to Spy on Your Programs

Click to access strace-zine-unfolded.pdf

Elective – Postgres Database Administration

“The Accidental DBA” (or, Administering PostgreSQL When It’s Not Your Job) to those just getting into Postgres database server administration. Josh Berkus, from the PostgreSQL Core Team, presented it in 2015 (https://www.youtube.com/watch?v=qoQRGl_P2aQ (2.5 hour video)) and the original (2012) slides by Christophe Pettus at http://thebuild.com/blog/2012/06/04/postgresql-when-its-not-your-job-at-djangocon-europe/

CFEngine Enterprise: Enabling Postgres Query Logging

Since the CFEngine Postgres database internals aren’t widely documented, you can learn more about them by observing what queries the Mission Portal sends to the DB (e.g., to do things like get the count of hosts with health issues which powers the health indicator you see in the Mission Portal status bar).

Postgres has a configuration parameter log_statement which you can change from none to all to enable query logging (i.e., all queries will get logged to /var/log/postgresql.log) to learn what queries the Mission Portal sends to the database.

Let’s check what the default is:

myhost# grep -i 'log_statement =' /var/cfengine/state/pg/data/postgresql.conf #log_statement = 'none' # none, ddl, mod, all myhost#

The built-in default is none. The Postgres folks have the line commented out; to change it, uncomment the line and set the value to all to enable query logging. Then connect to the Postgres database and reload the configuration:

myhost# /var/cfengine/bin/psql -U cfpostgres cfdb psql (9.3.2) Type "help" for help.


cfdb=# SELECT pg_reload_conf();
 pg_reload_conf
t

(1 row)

cfdb=# q myhost#

Go to the UI and perform an operation (i.e. run a report) and you’ll see in /var/cfengine/postgresql.log the SQL commands that the Mission Portal PHP UI sends to the Postgres database.

CFEngine and Ansible are complementary

CFEngine is designed for ongoing maintenance and verification of desired state; whereas Ansible is designed as a simple tool for making changes quickly.

CFEngine and Ansible complement each other. For example, I have a CFEngine promise to inventory CliQr version by reading in /usr/local/osmosix/MANIFEST.MF. By pulling up a CFEngine Enterprise report, I can tell in 3 seconds how many of my thousands of hosts are on which version of CliQr. To run this report with Ansible would take minutes (the more hosts, the longer it would take).

However to develop, test and deploy this CFEngine promise took its own time (an initial up-front investment).

Another example: I wanted to quickly check, just one time, in preparation for a CliQr upgrade (actual example) if /usr/local/osmosix/MANIFEST.MF is a symlink to /usr/local/osmosix/agent/MANIFEST.MF on ALL hosts, I used Ansible, as that was quicker than (a) writing a CFEngine promise and (b) scheduling a window to deploy it. Ansible is faster for an ad-hoc report like this.

However if I then wanted to ensure that symlink is present on all hosts (current and future), I’d use CFEngine, as doing it with Ansible would only reach the hosts up at that instant.

So these tools are complementary, and I intend to use them together. For example, CFEngine could keep servers up to date on patches but I’d use Ansible to reboot specific groups of servers during scheduled maintenance windows (to load the new patchset).

For bash and POSIX shell scripting:

Variable quoting

Miscellaneous

For vi and Vim:

For git:

cgroups:

pg_reload_conf

For `bash` and POSIX shell scripting:

For `vi` and Vim:

`cgroups`: