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https://github.com/lmtx/ansible-lab-docker

Ansible Lab environment using Docker
https://github.com/lmtx/ansible-lab-docker

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Ansible Lab environment using Docker

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README 

        
# Introduction



The aim of this guide is setup of [Ansible](https://www.ansible.com/) training environment using [Docker](https://www.docker.com/) containers. After finishing this tutorial you will have Docker master container that can manage three host containers (you can easily extend number of managed hosts to meet your needs).



Why I decided to use Docker instead of conventional virtualization like [VirtualBox](https://www.virtualbox.org/)? Docker containers consume much less resources so you can build bigger test environments on your laptop. Docker container is way faster to start/kill than standard virtual machine which is important when you experiment and bring the whole environment up and down. I used [Docker Compose](https://docs.docker.com/compose/overview/) to automate setup of lab environment (there is no need to maintain each container separately).



This guide **is not** Ansible or Docker tutorial (although I explain some basic concepts). It's purpose is solely setup of lab environment to enable experiments with ansible on local machine.



**IMPORTANT**: In order to follow this tutorial you need to install Docker CE (Community Edition) on your machine. The installation is well documented at https://docs.docker.com/engine/installation/#supported-platforms and I will not cover it here.



A brief description of Ansible and Docker:



## Ansible



Ansible is IT automation system. It handles configuration-management, application deployment, cloud provisioning, ad-hoc task-execution, and multinode orchestration - including trivializing things like zero downtime rolling updates with load balancers.



You can read more at [www.ansible.com](https://www.ansible.com/)



## Docker



Docker is the world’s leading software container platform. Developers use Docker to eliminate "works on my machine" problems when collaborating on code with co-workers. Operators use Docker to run and manage apps side-by-side in isolated containers to get better compute density. Enterprises use Docker to build agile software delivery pipelines to ship new features faster, more securely and with confidence for both Linux, Windows Server, and Linux-on-mainframe apps. 



You can read more at [www.docker.com](https://www.docker.com/)



# Quick start



## Clone repository



Clone this git repository:



`git clone https://github.com/LMtx/ansible-lab-docker.git`



## Build images and run containers



Enter **ansible** directory containing [docker-compose.yml](./ansible/docker-compose.yml) file.



Build docker images and run containers in the background (details defined in [docker-compose.yml](./ansible/docker-compose.yml)):



`docker-compose up -d --build`



Connect to **master node**:



`docker exec -it master01 bash`



Verify if network connection is working between master and managed hosts:



`ping -c 2 host01`



Start an [SSH Agent](https://man.openbsd.org/ssh-agent) on **master node** to handle SSH keys protected by passphrase:



`ssh-agent bash`



Load private key into SSH Agent in order to allow establishing connections without entering key passphrase every time:



`ssh-add master_key`



    Enter passphrase for master_key:



As **passphrase** enter: `12345`



Default key passphrase can be changed in [ansible/master/Dockerfile](./ansible/master/Dockerfile)



## Ansible playbooks



Run a [sample ansible playbook](./ansible/master/ansible/ping_all.yml) that checks connection between master node and managed hosts:



`ansible-playbook -i inventory ping_all.yml`



Confirm _every_ new host for SSH connections:



    ECDSA key fingerprint is SHA256:HwEUUnBtOm9hVAR2PJflNdCVchSCzIlpOpqYlwp+w+w.

    Are you sure you want to continue connecting (yes/no)?



Type: `yes` (three times)



Install PHP on web **inventory group**:



In order to group managed hosts for easier maintenance you can use groups in ansible [inventory file](./ansible/master/ansible/inventory).



Run a [sample ansible playbook](./ansible/master/ansible/install_php.yml):



`ansible-playbook -i inventory install_php.yml`



## Copy data between local file system and containers



### Copy directory from container to local file system



`docker cp master01:/var/ans/ .`



### Copy directory from local file system to container:



`docker cp ./ans master01:/var/`



You can check usage executing:



`docker cp --help`



## Cleanup



After you are done with your experiments or want to destroy lab environment to bring new one execute following commands.



Stop containers:



`docker-compose kill`



Remove containers:



`docker-compose rm`



Remove volume:



`docker volume rm ansible_ansible_vol`



If you want you can remove Docker images (although that is not required to start new lab environment):



`docker rmi ansible_host ansible_master ansible_base`



# Tips



In order to share public SSH key between **master** and **host** containers I used Docker **volume** mounted to all containers:



[docker-compose.yml](./ansible/docker-compose.yml):



    [...]

    volumes:

      - ansible_vol:/var/ans

    [...]



Master container stores SSH key in that volume ([ansible/master/Dockerfile](./ansible/master/Dockerfile)):



    [...]

    WORKDIR /var/ans

    RUN ssh-keygen -t rsa -N 12345 -C "master key" -f master_key

    [...]



And host containers add SSH public key to authorized_keys file ([ansible/host/run.sh](./ansible/host/run.sh)) in order to allow connections from master:



    cat /var/ans/master_key.pub >> /root/.ssh/authorized_keys



**IMPORTANT:** this is valid setup for lab environment but for production deployment you have to distribute the public key other way.



# Troubleshooting



## Host containers stop after creation



Check that [ansible/hosts/run.sh](./ansible/host/run.sh) has proper end of line type - it **should be Linux/Unix (LF)** not Windows (CRLF). You can change end of line type using source code editor (like Notepad++ or Visual Studio Code); under Linux you can use `dos2unix` command.



## Other issue



Please open an [issue](https://github.com/LMtx/ansible-lab-docker/issues/new) and I'll try to help.