Tag Archives: ansible

Proper Logwatch Configuration using Ansible

On my way setting up a proper monitoring for my server, I just installed Logwatch to receive a daily summary of the what happened recently on the machine. I will have a look into Prometheus, Grafana, Icinga etc. later. However, for now I just wanted a quick summary of the daily “what’s going on on the machine”. Eventually, I had to fix an occur No such file or directory error.

Therefore, I decided to use Logwatch as a lightweight solution to my needs.

Installation Script

The Ansible script to install Logwatch is straight forward:

- name: Install logwatch
apt:
name: logwatch
state: latest
tags:
- logwatch

- name: Create logwatch.conf file for customisations
file:
path: /etc/logwatch/conf/logwatch.conf
state: touch
tags:
- logwatch

- name: E-Mail to
lineinfile:
dest: /etc/logwatch/conf/logwatch.conf
regexp: "^MailTo ="
line: "MailTo = {{ logwatch_email }}"
state: present
tags:
- logwatch

- name: Set detail
lineinfile:
dest: /etc/logwatch/conf/logwatch.conf
regexp: "^Detail ="
line: "Detail = {{ logwatch_detail }}"
state: present
tags:
- logwatch

Configuration & Troubleshooting

I basically set up two parameters, the e-mail as well as the detail level I want for the report. Important to know is the order Logwatch is applying your configuration settings. Following the recommendations, I did not change anything in the configuration file at

/usr/share/logwatch/default.conf/logwatch.conf

rather I decided to copy the file to

/etc/logwatch/conf/

The reason is the order, logwatch is scanning for configuration parameters in the following order. Each step actually overwrites the previous one.

  • /usr/share/logwatch/default.conf/*
  • /etc/logwatch/conf/dist.conf/*
  • /etc/logwatch/conf/*
  • The script command line arguments

Eventually, I ended up in the following error:

/etc/cron.daily/00logwatch:
/var/cache/logwatch No such file or directory at /usr/sbin/logwatch line 634.
run-parts: /etc/cron.daily/00logwatch exited with return code 2

To fix this, avoid copying the original configuration to one of the other places. I did this because I followed some recommendation I received. Instead, I now touch a new configuration file as well as setting the two parameters for MailTo= as well as Detail=. Both are s set using Ansible variables in my scripts. The additional configuration file now looks pretty boring, though:

MailTo = mail@example.org
Detail = Low

You also can provide these parameters when calling the script in the cron job: Using Ansible the modification would look like the following:

lineinfile: 
dest: /etc/cron.daily/00logwatch
regexp: "^/usr/sbin/logwatch"
line: "/usr/sbin/logwatch --output mail --mailto {{ logwatch_email }} --detail {{ logwath_detail }}"
state: present
create: yes

I decided to change the cron job call as one never can be safe from the file changing during package updates. The same should be valid for the configuration file at its origin place.

tl;dr

Setting up Logwatch using Ansible might cause strange “No file or directory”-errors during the cron job call. This can be avoided by applying additional configuration settings at appropriate configuration locations.

Personal DevOps #3

While most of the prerequisites are met for my automated server setup I came across some issues when I started with my very first Ansible playbooks.

First Ansible Playbooks

First of all, I wanted to start with a quite simple ping playbook, to ensure the servers are reachable by Ansible.

# Playbook to ping all hosts 
---
- hosts: all
  gather_facts: false
  tasks:
    - ping:

When I run this script I was immediately confronted with the very first error. I really love when such things happen. Nothing can motivate one more than immediate failures like the following.

FAILED! => {
"changed": false,
"module_stderr": "Shared connection to xxx.xxx.xxx.xxx closed.\r\n",
"module_stdout": "/bin/sh: 1: /usr/bin/python: not found\r\n",
"msg": "MODULE FAILURE\nSee stdout/stderr for the exact error",
"rc": 127
}

As I started with a minimal Ubuntu 18.04 LTS installation, there is simply no Python 2 installed. However, to run the Ansible tasks on the node, Python is required. I made use of the raw task in Ansible to update the package lists as well as install the package python-minimal. In addition, I added the package python2.7-apt in this bootstraper as it is needed later on. Once Python has been installed the ping playbook worked without any problems.

# Bootstrap playbook to install python 2 and python-apt
# It checks first so no unecessary apt updates are performed
---
- hosts: all
  gather_facts: False
  
  tasks:
  - name: install python 2
    raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal)
  - name: install python-apt 
    raw: test -e  /usr/lib/python2.7/dist-packages/apt || (apt install -y python2.7-apt)

For both packages, I test for the corresponding directories on the node to avoid unnecessary updates.

Note: When testing for a directory on the shell the following line became very handy:

> [ -e /usr/lib/python2.7/dist-packages/apt ] && echo "Found" || echo "Not found"

At a second step, I created a maintenance playbook to update and upgrade the packages on my node.

# Playbook to update Ubuntu packages 
---
- hosts: all
  gather_facts: false
  tasks:
  - name: update and upgrade apt packages
    become: true
    apt:
      upgrade: yes
      update_cache: yes
      cache_valid_time: 86400

Before including the pyhton-apt package to the bootstraper, I got the following error when dry running the playbook.

fatal: [xxx.xxx.xxx.xxx]: FAILED! => {"changed": false, "msg": "python-apt must be installed to use check mode. If run normally this module can auto-install it."}

Conclusion

While this is not any rocket science for sure, I now have a few essential scripts to bring my server to a base level I can start working with.