Linux

Linux remains the backbone of modern cloud infrastructure and DevOps/SRE workflows. Mastery of Linux is essential for engineers working with AWS, Azure, GCP, and hybrid environments.

Why DevOps & SREs Need Linux

1. Cloud-Native Operations: Most cloud VMs, containers, and Kubernetes nodes run Linux. Engineers must manage, troubleshoot, and optimize these systems daily.

2. Automation & Scripting: Bash, Python, and other scripting languages on Linux enable automated deployments, monitoring, and remediation. Tools like Ansible, Terraform, and CI/CD runners often execute on Linux hosts.

3. Security & Compliance: Linux offers granular access controls (SELinux, AppArmor), audit logging, and patch automation. SREs use these features to enforce compliance and respond to incidents.

4. Observability: Logging (journald, syslog), metrics (Prometheus node_exporter), and tracing are natively supported on Linux, making it the platform of choice for observability stacks.

5. Open Source Ecosystem: Most DevOps tools (Docker, Kubernetes, Helm, Git, etc.) are built for Linux first.

Real-Life Examples

1. Automated Patch Management (Ansible)

- name: Patch all Linux servers
  hosts: linux_servers
  become: yes
  tasks:
    - name: Update all packages
      apt:
        upgrade: dist
        update_cache: yes

2. Troubleshooting a Failing Pod in Kubernetes

kubectl exec -it mypod -- bash
journalctl -u myservice
cat /var/log/app.log

3. Secure SSH Access with Key Rotation

# Rotate SSH keys for all users
for user in $(cut -f1 -d: /etc/passwd); do
  ssh-keygen -f /home/$user/.ssh/id_rsa -N '' -q
  # Distribute new public keys via Ansible or cloud-init
  # ...
done

4. Monitoring with Prometheus Node Exporter

# Install node_exporter
wget https://github.com/prometheus/node_exporter/releases/download/v*/node_exporter-*.linux-amd64.tar.gz
# ...extract and run as a systemd service...

Best Practices (2025)

• Use Infrastructure as Code (Terraform, Ansible) for all Linux provisioning

• Automate patching and configuration drift detection

• Enforce least privilege with sudoers and SELinux/AppArmor

• Monitor system health and logs centrally (Prometheus, ELK, Grafana)

• Use containers for reproducible environments

• Document all custom scripts and automation

Common Pitfalls

• Not automating user and key management

• Ignoring security updates

• Overlooking log rotation and disk space

• Hardcoding credentials in scripts

• Not monitoring resource usage (CPU, memory, disk)

References

• Linux Foundation Training
• Ansible Docs
• Kubernetes Docs
• Prometheus Docs

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Linux Joke: Why do DevOps engineers love Linux? Because rebooting is always the last resort, not the first step!