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DevOps Day 87: Ansible Install Package & Troubleshooting

This document outlines the solution for DevOps Day 87. The goal was to use Ansible to install the samba package on all application servers. During the process, a connection error (rc: 137) occurred on stapp01, which required troubleshooting the inventory configuration.

Table of Contents

Task Overview

Objective: The Nautilus DevOps team needs to install the samba package on all App Servers (stapp01, stapp02, stapp03) using Ansible.

Requirements: 1. Inventory: Create /home/thor/playbook/inventory with all app servers. 2. Playbook: Create /home/thor/playbook/playbook.yml to install samba. 3. Module: Use the Ansible yum module. 4. Validation: Run ansible-playbook -i inventory playbook.yml.

Step-by-Step Solution

1. Create the Inventory File

We define a group [app] containing all servers and set the connection variables.

Command: 

mkdir -p ~/playbook
cd ~/playbook
vi inventory

Initial Content: 

[app]
stapp01 ansible_host=stapp01 ansible_user=tony ansible_ssh_pass=Ir0nM@n
stapp02 ansible_host=stapp02 ansible_user=steve ansible_ssh_pass=Am3ric@
stapp03 ansible_host=stapp03 ansible_user=banner ansible_ssh_pass=BigGr33n

[all:vars]
ansible_ssh_common_args='-o StrictHostKeyChecking=no'

2. Create the Playbook

We use the yum module to install the package. become: true is essential because installing packages requires root privileges.

Command: 

vi playbook.yml

Content: 

---
- name: install packages on app servers
  hosts: all
  become: true
  tasks: 
    - name: install samba using yum
      yum:
        name: samba
        state: present

3. Initial Execution & Error

When running the playbook initially, stapp01 failed.

Command: 

ansible-playbook -i inventory playbook.yml

Error: 

fatal: [stapp01]: FAILED! => {"changed": false, "module_stderr": "Shared connection to stapp01 closed.\r\n", ... "rc": 137}
Analysis: Return code 137 often indicates a memory issue or an abrupt termination of the process on the remote host. However, in Ansible contexts, connection failures like "Shared connection closed" usually point to SSH authentication issues or SSH timeout configurations.

4. Troubleshooting & Fix

Upon reviewing the inventory, we switched to using ansible_ssh_password (which is synonymous with ansible_ssh_pass but sometimes handled differently depending on the plugin versions or environment configuration). We also ensured the password for stapp01 (Ir0nM@n) was correct and had no hidden characters.

Corrected Inventory Content: 

[app]
stapp01  ansible_host=stapp01 ansible_user=tony ansible_ssh_password=Ir0nM@n
stapp02  ansible_host=stapp02 ansible_user=steve ansible_ssh_password=Am3ric@
stapp03  ansible_host=stapp03 ansible_user=banner ansible_ssh_password=BigGr33n

[all:vars]
ansible_ssh_common_args='-o StrictHostKeyChecking=no'

5. Final Validation

Re-running the playbook with the corrected inventory resulted in success.

Command: 

ansible-playbook -i inventory playbook.yml

Result: 

TASK [install samba using yum] ******************************************************
ok: [stapp03]
ok: [stapp02]
changed: [stapp01]
* changed: [stapp01] indicates Samba was successfully installed. * ok: [stapp02] and [stapp03] indicates Samba was already installed (from the previous partial run).

Deep Dive: Ansible Concepts Used

The yum Module

The yum module manages packages on RHEL/CentOS systems. * name: The name of the package (e.g., samba, httpd). * state: * present: Ensures it is installed (default). * latest: Updates to the newest version. * absent: Uninstalls the package.

Connection Troubleshooting

When Ansible fails with "Shared connection closed", check: 1. Passwords: Are they correct? Do they contain special characters that need escaping? 2. SSH Keys: If using keys, are they in authorized_keys? 3. Privilege Escalation: Does the user have sudo rights? (The become: true requires sudo access). 4. Resource Limits: On very small VMs, installing heavy packages might OOM (Out of Memory) kill the process, though rare for basic packages like Samba.