Ansible Basics

Ansible

Connections:

# Sample Inventory File

web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

db1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!

Whereas,

• web1 & db1 denotes alias name for your server.
• ansible_host denotes your Server host IP / Name.
• ansible_connection denotes the type of your connection (for Linux: ssh & for windows: winrm)
• ansible_user denotes the user name of your server
• ansible_ssh_pass, ansible_ssh_key (for Linux) / ansible_password (for windows)

Create Groups:

# Sample Inventory File

# Web Servers

web1 ansible_host=server1.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

web2 ansible_host=server2.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

web3 ansible_host=server3.company.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Password123!

# Database Servers

b1 ansible_host=server4.company.com ansible_connection=winrm ansible_user=administrator ansible_password=Password123!

[web_servers]

web1

web2

web3

[db_servers]

db1

Whereas,

• [Group name] denotes the name of the group
• Sub-items denote Group items

Parent Group:

[parent_group:children]

child_group1

child_group2

Whereas,

• parent_group denotes the name of your parent group
• child_group1 indicates the name of the groups you want to merge 

For Eg:

sql_db1 ansible_host=sql01.xyz.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Lin$Pass

sql_db2 ansible_host=sql02.xyz.com ansible_connection=ssh ansible_user=root ansible_ssh_pass=Lin$Pass

web_node1 ansible_host=web01.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass

web_node2 ansible_host=web02.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass

web_node3 ansible_host=web03.xyz.com ansible_connection=winrm ansible_user=administrator ansible_password=Win$Pass

[db_nodes]

sql_db1

sql_db2

[web_nodes]

web_node1

web_node2

web_node3

[boston_nodes]

sql_db1

web_node1

[dallas_nodes]

sql_db2

web_node2

web_node3

[us_nodes:children]

boston_nodes

dallas_nodes

Q: Update the playbook with a play to Execute a script on all web server nodes. The script is located at /tmp/install_script.sh

Ans: Playbook.yml are written in YAML Language as follows:

-

    name: 'Execute a script on all web server nodes'

    hosts: web_nodes

    tasks: 

        -

            name: 'Execute a script on all web server nodes'

            script: /tmp/install_script.sh

        -

            name: 'start httpd services'

            service: 'name=httpd state=started'

Most used Ansible Modules:

1. Package management

- 

    name: how to install any package

    dnf / apt / yum:

        name: <packagename>

        state: latest

2. Service

-

    name: Start service foo, based on running process /usr/bin/foo

    service:

        name: foo

        pattern: /usr/bin/foo

        state: started

3. Copy

- 

    name: Copy file with owner and permission, using symbolic representation

    copy:

        src: /srv/myfiles/foo.conf

        dest: /etc/foo.conf

        owner: foo

        group: foo

        mode: u=rw,g=r,o=r

4. Debug
- 

    name: Write some content in a file /tmp/foo.txt

    copy:

        dest: /tmp/foo.txt

        content: |

            Good Morning!

            Awesome sunshine today.

        register: display_file_content

- 

    name: Debug display_file_content

        debug:

            var: display_file_content

            verbosity: 2

5. File

- 

    name: Create a directory if it does not exist
    file:
        path: /etc/some_directory
        state: directory
        mode: '0755' 

6. Lineinfile

- 

    name: Add a line to a file if the file does not exist, without passing regexp
    lineinfile:
        path: /etc/resolv.conf
        line: 192.168.1.99 foo.lab.net foo
        create: yes 

7. Git

- 

    git:
        repo: https://github.com/ansible/ansible-examples.git
        dest: /src/ansible-examples
        separate_git_dir: /src/ansible-examples.git 

8. Cli_command 

- 

    name: configurable backup path
    cli_config:
        config: "{{ lookup('template', 'basic/config.j2') }}"
        backup: yes
        backup_options:
            filename: backup.cfg
            dir_path: /home/user 

9. Archive 

- 

    name: Create a bz2 archive of multiple files, rooted at /path
    archive:
        path:
            - /path/to/foo
            - /path/wong/foo
            dest: /path/file.tar.bz2
            format: bz2 

10. Command 

- 

    name: Change the working directory to somedir/ and run the command as db_owner if /path/to/database does not exist.
    command: /usr/bin/make_database.sh db_user db_name
        become: yes
        become_user: db_owner
        args:
            chdir: somedir/
            creates: /path/to/database

Ansible Core Components

1. Inventories
2. Modules
3. Variables
4. Facts
5. Plays
6. Playbooks
7. Configuration Files

Basic Commands:

# ansible <group> -m <module> -a <arguments>

• Check Ansible Version
• ansible --version

• Dry Run
• ansibal-palybook playbook.yml --check


• Managing services
• Starting a service
• # ansible <group> -m service -a “name=httpd state=started”
• Stopping a service
• # ansible <group> -m service -a “name=httpd state=stopped”
• Restarting a service
• # ansible <group> -m service -a “name=httpd state=restarted”

• Managing Packages
• Check if the package is installed & update it
• # ansible <group> -m yum -a “name=httpd state=latest”
• Check if the package is installed & don’t update it
• # ansible <group> -m yum -a “name= httpd state=present”
• Check if the package is at a specific version
• # ansible <group> -m yum -a “name= httpd-1.8 state=present”
• Check if the package is not installed
• # ansible <group> -m yum -a “name= httpd state=absent”

• Check the connectivity of hosts
• # ansible <group> -m ping

• Rebooting hosts
• # ansible <group> -a “/sbin/reboot”

• Checking the host’s system information
• # ansible <group> -m setup | less
• # ansible <group> -m setup -a “filter=ansible_distribution”

• Transferring files
• # ansible <group> -m copy -a “src=/home/ansible dest=/tmp/home”

• Managing users
• Creating a new user
• # ansible <group> -m user -a “name=ansible password=<encrypted password>”
• Deleting a user
• # ansible <group> -m user -a “name=ansible state=absent”

• Changing permissions & ownership
• Changing permission for a file
• # ansible <group> -m file -a “dest=/home/ansible/file1.txt mode=777”
• Changing the ownership of a file
• # ansible <group> -m file -a “dest=/home/ansible/file1.txt mode=777 owner=ansible group=ansible”


• Tag Formatting
• ansibal-palybook playbook.yml --tags “install”
• ansibal-palybook playbook.yml --skip-tags “install”




 

Thanks & Regards,
Tapan Patni
Email: tapanpatni58@gmail.com

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