System requirements¶
Some system requirements are needed to install Alignak:
- python 2.7 or 3.5/3.6
- python pip
The Python pip tool is necessary to install the Python dependencies needed by Alignak. Installing Python pip on different systems is documented here.
Note
for sure, the required Python packages should be made available in the Alignak repositories, but it is quite a lot of work and we do not have enough time for this… any help appreciated for this;)
User account¶
Alignak is an application started from a privileged user account and it needs to use a low privileged user account. We recommend creating a user account identified as (in the default shipped configuration) alignak member of a group alignak.
# Create alignak system user/group for Alignak application sudo addgroup --system alignak sudo adduser --system alignak --ingroup alignak
Note
the post installation Alignak script installed with distro packaging will create a default alignak user account if it does not yet exist on your system.
If you intend to use the Nagios checks plugins and if they are installed on your system, you should invite the user alignak into the nagios group. Most often, the installation of the Nagios checks plugins create a nagios user member of the nagios group…
sudo usermod -a -G nagios alignak
Python version¶
If you intend to use Python 3, follow these recommendations.
Install the pip for Python 3:
# For Debian-like
$ sudo apt install python3-pip
$ pip -V
pip 8.1.1 from /usr/lib/python3/dist-packages (python 3.5)
# For CentOS-like
$ sudo yum install python34-pip
As defined in some PEP, the python command is mapped to Python 2. This may be a little tricky to use Python 3 per default. Thanks to update-alternatives it is easy to choose the default Python interpreter:
# Nothing configured (it is often the case...)
update-alternatives --list python
update-alternatives: error: no alternatives for python
$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
update-alternatives: using /usr/bin/python2.7 to provide /usr/bin/python (python) in auto mode
$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.5 2
update-alternatives: using /usr/bin/python3.5 to provide /usr/bin/python (python) in auto mode
$ update-alternatives --list python
/usr/bin/python2.7
/usr/bin/python3.5
# Python 3.5 is now the default one!
$ python --version
Python 3.5.2
# Change this
$ update-alternatives --config python
There are 2 choices for the alternative python (providing /usr/bin/python).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/bin/python3.5 2 auto mode
1 /usr/bin/python2.7 1 manual mode
2 /usr/bin/python3.5 2 manual mode
Press <enter> to keep the current choice[*], or type selection number:
# Back to Python 2.7 if you choose 1
$ python --version
Python 2.7.12
Note
that you may need to choose Python 2 as the default interpreter for some operations on your system :/
Warning
update-alternatives is not easy to manage with CentOS7. You would rather choose a python version and get stucked with this version!
Python pip¶
If your system does not yet include the Python pip tool, here is an installation reminder.
- For Debian-like Linux
# Python 2 sudo apt install python-pip # Python 3 sudo apt install python3-pip
For RHEL-like Linux
On a RHEL (CentOS, Oracle Linux,…), the Python pip installer tool is not included in the standard RHEL repositories but it is part of the EPEL repository. You must enable EPEL repository to install pip.
sudo yum install epel-release sudo yum -y update # Python 2 sudo yum install python-pip # Python 3 sudo yum install python3-pip # On some older versions, it may be necessary to install extra compiler tools for the python *psutil* package:: sudo yum install gcc python-devel
For FreeBSD:
# Python 2.7
sudo pkg install py27-pip
# Python 3.6
sudo pkg install py36-pip