DevOps Practice Lab Automating Nginx Installation Using Docker and Ansible

1. Project Goal

The goal of this practice was to simulate a real DevOps environment where:

• A control node runs Ansible
• Multiple target nodes are created using Docker containers
• Ansible connects to these nodes using SSH
• Nginx is installed automatically using an Ansible playbook

This setup helps understand how configuration management tools automate infrastructure.

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2. Architecture

            +----------------------+
            |  Ansible Control Node |
            |   (Host Machine)     |
            +----------+-----------+
                       |
                       | SSH
                       |
        -------------------------------------
        |                                   |
+---------------+                 +---------------+
| Docker Target |                 | Docker Target |
|   Container   |                 |   Container   |
|   target1     |                 |   target2     |
|               |                 |               |
|  SSH + Nginx  |                 |  SSH + Nginx  |
+---------------+                 +---------------+

Docker Network: ansible-net

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3. Tools Used

• Docker
• Ansible
• NGINX
• Ubuntu Linux

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4. Project Directory Structure

ansible-docker-lab
│
├── Dockerfile
├── inventory
├── install-nginx.yaml
└── README.md

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5. Target Node Dockerfile

This Dockerfile creates a container that:

• Runs SSH server
• Allows Ansible to connect
• Has Nginx installed
• Exposes required ports

Dockerfile

FROM ubuntu:22.04

RUN apt update && \
    apt install -y openssh-server sudo nginx && \
    mkdir /var/run/sshd

RUN useradd -m ansible && \
    echo "root:admin" | chpasswd && \
    adduser ansible sudo

EXPOSE 22
EXPOSE 80

CMD ["/usr/sbin/sshd", "-D"]

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6. Build the Docker Image

docker build -t ansible-target .

Verify image: docker images

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7. Create Docker Network

Creating a custom network helps containers communicate easily.

docker network create ansible-net

Verify network:

docker network ls

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8. Run Master & Target Containers

Master node

docker run -dit \
--name master \
--network ansible-net \
ubuntu:latest

Create one target nodes.

Target1

docker run -dit \
--name target1 \
--network ansible-net \
-p 2223:22 \
-p 8082:80 \
ansible-target

Verify containers:

docker ps -a

Go into the Master container and install Ansible

docker exec -it master bash
sudo -i
apt update
apt install python-is-python3 vim iputils-ping openssh-client -y   ##  Geographical area 6 city 44
apt install software-properties-common
add-apt-repository --yes --update ppa:ansible/ansible
apt install ansible

To test Ansible is installed or not

ansible --version
```
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generate the ssh key from the ssh-keygen command

ssh-keygen
provide 3 times enter    (1 location verification + 2 time for passwd )

copy the generated ssh keys from ansible_master to target machine and check the connectivity

Copy the generated key from ansible_master to remote target

ssh-copy-id root@target1
yes

9. Test SSH Connectivity

Test SSH connection manually.

ping target1

ssh ansible@localhost -p 2222

Password:

admin

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11. Create Ansible Inventory OR edit host file

edit ansible host file and provide the target IP’s cd /etc/ansible/ ls Go to hosts file
provide the IP of the target machines like target1

Step 14 verify as you are able to ping target machine from ansible_master

ping

Create a file called inventory

[target]

target1 ansible_host=localhost ansible_port=2222 ansible_user=ansible ansible_password=ansible

target2 ansible_host=localhost ansible_port=2223 ansible_user=ansible ansible_password=ansible

Test connectivity:

ansible -i inventory target -m ping

ansible all -m ping  

Expected output:

target1 | SUCCESS
target2 | SUCCESS

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12. Create Ansible Playbook

File name:

install-nginx.yaml

Playbook

---
- hosts: target
  become: yes

  tasks:

  - name: Install nginx
    apt:
      name: nginx
      state: present
      update_cache: yes

  - name: Start nginx
    service:
      name: nginx
      state: started

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13. Run the Playbook

ansible-playbook -i inventory install-nginx.yaml

ansible-playbook  install-nginx.yaml    if we have not created inventory file

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14. Verify Nginx Installation

Open browser:

http://localhost:8081

and

http://localhost:8082

You should see the NGINX welcome page.

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15. Useful Docker Commands Used

Check containers

docker ps

Stop container

docker stop target1

Start container

docker start target1

Remove container

docker rm target1

Enter container

docker exec -it target1 bash

Check logs

docker logs target1

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16. Issues Faced During the Practice

While performing this lab, several issues occurred:

1 IP Address Changes

Containers get new IPs when recreated.

Solution:

Use Docker network + container names

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2 Missing Port Exposure

Initially port 80 was not exposed, so Nginx was not reachable.

Solution:

EXPOSE 80

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3 SSH Connection Problems

SSH failed because:

• Port not mapped
• SSH service not running

Solution:

EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]

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4 Command Syntax Errors

Example mistake while using sed:

sed -e "s/^target/target1"

Correct command:

sed -e "s/^target/target1/"

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17. Best Practices Learned

✔ Use Docker networks instead of static IPs ✔ Always expose required ports in Dockerfile ✔ Use SSH keys instead of passwords ✔ Automate configuration using Ansible playbooks ✔ Maintain infrastructure using version-controlled code (Git)

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18. Learning Outcome

Through this practice I learned:

• How Ansible connects to remote machines
• How Docker containers can simulate infrastructure
• How to automate package installation
• How to troubleshoot configuration issues
• Importance of automation in DevOps workflows

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19. Future Improvements

Next steps for improving this lab:

• Add Ansible control node container
• Use Docker Compose
• Deploy application containers
• Integrate with CI/CD pipeline
• Move setup to Kubernetes cluster

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If you want, I can also give you a much more advanced GitHub project version (the kind that impresses DevOps interviewers) with:

• Docker Compose setup
• 3 Ansible target nodes
• Automatic SSH key setup
• Production-style folder structure
• Architecture diagram

That kind of project can seriously strengthen your DevOps resume.