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Lab 82: Installing, Validating, and Managing Nginx

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Install and bring up Nginx so it can sit in front of an internal app as a reverse proxy. Validate configuration syntax, reload safely, and confirm the service is listening on port 80.

services web networking

Scenario

Nginx will sit in front of an internal application as a reverse proxy. You’ve already planned your configuration changes, and now you need to install Nginx, validate its configuration, reload it safely, and confirm that it’s actually serving traffic on the expected port.

Operator context

This mirrors a safe production workflow: install the service, validate config before applying it, reload (not restart) to avoid unnecessary disruption, then confirm socket-level readiness on the expected port.

Objective

  • Install the Nginx package using your distro’s package manager.
  • Enable and start the nginx service so it persists across reboots.
  • Validate Nginx configuration syntax with nginx -t.
  • Reload Nginx and confirm it is listening on :80 using ss.

Concepts

  • A safe change workflow is: validate config (nginx -t), then reload (systemctl reload), then verify listening sockets (ss) and HTTP response (curl).
  • A reload applies updated config without fully restarting worker processes, reducing disruption compared to a restart.
  • “Listening on port 80” is a socket-level check; “serving traffic” is an HTTP-level check. Do both.

Walkthrough

Step 1 : Install the Nginx package.
Note

Use the native package manager for your distro. On RHEL-family systems, prefer dnf over legacy yum.

Commands 
# RHEL / CentOS / Fedora
sudo dnf install -y nginx

# Debian/Ubuntu
sudo apt update
sudo apt install -y nginx

# Arch
sudo pacman -S nginx

Installing Nginx provides the service unit, default config layout, and binaries needed to validate syntax and run as a front-end proxy. 

# Example result (varies by distro):
# nginx installed successfully.
Step 2 : Enable and start Nginx.
Command 
sudo systemctl enable --now nginx

This starts Nginx immediately and ensures it comes up on reboot. If the unit fails, inspect status output and recent logs. 

# Quick verification:
systemctl status nginx --no-pager
Step 3 : Validate Nginx configuration syntax.
Command 
sudo nginx -t

Always validate config before applying it. A successful test confirms Nginx can parse the active configuration and is safe to reload. 

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
Step 4 : Reload Nginx safely.
Command 
sudo systemctl reload nginx

Reload applies configuration changes without tearing down the entire service like a restart would. If reload fails, re-run nginx -t and check logs for the exact error. 

# Example:
# Reloaded nginx configuration.
Step 5 : Confirm Nginx is listening on port 80.
Command 
sudo ss -lntp | grep -E ':\b80\b' || true

This is your socket-level readiness check. You should see a listener bound to :80. If you don’t, confirm the unit is active and review logs. 

# Example:
LISTEN 0 511 0.0.0.0:80 ... nginx
Step 6 : Prove it serves traffic with a local HTTP request.
Commands 
curl -I http://localhost
curl -s http://localhost | head

This is the HTTP-level validation. Headers confirm status and server response; the body check ensures you actually get a page back. 

# Example:
HTTP/1.1 200 OK

Breakpoints

nginx -t fails

Do not reload. Fix the reported file/line, then re-run nginx -t until it passes.

port 80 is already in use

Identify the owning process with ss -lntp. If Apache is running from Lab 81, stop/disable it before you run Nginx on the same host.

curl connects but returns unexpected content

Confirm which default site config is active for your distro and verify the server block/root path you intended is actually being used.

Cleanup checklist

If you want to revert to a clean state, disable/stop the service. Remove the package only if you’re done practicing.

Commands 
# Stop/disable
sudo systemctl disable --now nginx

# Optional: remove the default web content (paths vary by distro)
# Keep it simple for the lab:
sudo rm -f /usr/share/nginx/html/index.html 2>/dev/null || true
sudo rm -f /var/www/html/index.html 2>/dev/null || true

Reference

  • dnf install nginx: Install Nginx on RHEL-family systems.
  • apt install nginx: Install Nginx on Debian/Ubuntu systems.
  • pacman -S nginx: Install Nginx on Arch.
  • systemctl enable --now nginx: Enable at boot and start immediately.
    • enable: start at boot
    • --now: start immediately
  • nginx -t: Validate configuration syntax and active config tree.
    • -t: test configuration and exit
  • systemctl reload nginx: Reload config without a full restart.
  • ss -lntp: Show listening TCP sockets and owning processes.
    • -l: listening sockets
    • -n: numeric output
    • -t: TCP sockets
    • -p: process info
  • curl http://localhost: Test HTTP response locally.
    • -I: fetch headers only
    • -s: silent mode
  • journalctl -u nginx: View Nginx service logs.
    • -n 50: last 50 lines
    • --no-pager: print directly