The Start(Devops)

Mastering Ansible: Quick and Powerful Ad-Hoc Commands for Efficient Automation

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Jayesh Nalawade
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5 min read

Ansible Ad-hoc commands

An Ansible ad hoc command uses the /usr/bin/ansible command-line tool to automate a single task on one or more managed nodes. ad hoc commands are quick and easy, but they are not reusable.

  • you could execute a quick one-liner in Ansible without writing a playbook. An ad hoc command looks like this:

  • $ ansible [pattern] -m [module] -a "[module options]"

The -a option accepts options either through the key=value syntax or a JSON string starting with { and ending with } for more complex option structure. You can learn more about patterns and modules on other pages.

Ansible ad-hoc commands have a simple syntax that you can use to perform quick tasks across your infrastructure

  • ansible <host-pattern> -i <inventory-file> -m <module-name> -a "<module-arguments>" [options]

Explanation of Parameters:

  • ansible: The Ansible command-line tool.

  • <host-pattern>: Specifies the target hosts (e.g., all, web, db, or an individual host).

  • -i <inventory-file>: Specifies the inventory file that contains the hosts you want to target.

  • -m <module-name>: Specifies the Ansible module you want to use (e.g., apt, yum, file, ping, copy, etc.).

  • -a "<module-arguments>": Arguments passed to the module (e.g., the package name, file path, or other options).

  • [options]: Optional flags like --become for privilege escalation, --check for dry-run, etc.

Common Options for Ad-Hoc Commands:

  • --become: Elevates privileges to execute tasks as a superuser (==useful for package installations or service management==).

  • --check: Performs a ==dry-run== of the playbook or command, showing what changes would be made without actually applying them.

  • --diff: Shows a diff of what changes will be made (e.g., when modifying files).

  • --ask-become-pass: Prompts for the sudo password (if required) when using --become

Host Patterns:

  • all: Targets all hosts in the inventory.

  • web: Targets the web group in the inventory.

  • db[0:5]: Targets a range of hosts, like db0, db1, db2, etc.

  • localhost: Targets the local machine (useful for testing or local actions).

  • <hostname>: Targets a specific host by name or IP address.

Important Ad-hoc commands

1. Basic Commands for System Management

  1. Ping all hosts

    • ansible all -i inventory.ini -m ping
    • for particular host ansible <hostname> -i inventory.ini -m ping

  1. Gather Facts (System Information):

    • ansible all -i inventory.ini -m setup

    • for specific tasks use filter ansible all -i inventory.ini -m setup -a "filter=<fact_name> eg .

  1. Gather only memory-related facts: ansible all -i inventory.ini -m setup -a "filter=ansible_memory_mb"

  2. Gather only network-related facts: ansible all -i inventory.ini -m setup -a "filter=ansible_default_ipv4,ansible_all_interfaces

  3. Gather only disk-related facts: ``ansible all -i inventory.ini -m setup -a "filter=ansible_devices

  1. Check System Uptime

    • ``ansible all -i inventory.ini -m command -a "uptime

2.Package Management (Install/Remove Software)

  1. Install Package

    • ansible all -i inventory.ini -m apt -a "name=nginx state=present" --become (debian based eg. ubuntu) change to apt for Redhat based

      • became uses root permissions

  2. Remove a package

    • ansible all -i inventory.ini -m apt -a "name=nginx state=absent" --become

  3. Upgrade All Packages- Upgrades all packages on all hosts.

    • ansible all -i inventory.ini -m apt -a "upgrade=dist" --become

3.File and Directory Management

  1. Create a Directory

    • ansible all -i inventory.ini -m file -a "path=/tmp/testdir state=directory mode=0755

    • Creates a directory at testdir

  2. Copy a File to Remote Hosts

    • ansible all -i inventory.ini -m copy -a "src=/local/file dest=/remote/file mode=0644

  3. Delete a File or Directory

    • ansible all -i inventory.ini -m file -a "path=/tmp/testfile state=absent

  4. Change File Permissions

    • ansible all -i inventory.ini -m file -a "path=/tmp/testfile mode=0755

4. Service Management

  1. Start a service

    • ansible all -i inventory.ini -m service -a "name=nginx state=started" --become

  2. Stop a Service:

    • ansible all -i inventory.ini -m service -a "name=nginx state=stopped" --become

  3. Restart a service:

    • ansible all -i inventory.ini -m service -a "name=nginx state=restarted" --become

  4. Enable a service from boot:

    • ansible all -i inventory.ini -m service -a "name=nginx enabled=yes" --become

    • enabled=no - Disable a Service from boot

5. User and Group Management

  1. Create a User:

    • ansible all -i inventory.ini -m user -a "name=deploy state=present" --become

    • Creates the deploy user on all hosts.

  2. Delete a User:

    • ansible all -i inventory.ini -m user -a "name=deploy state=absent" --become

  3. Add user to group:

    • ansible all -i inventory.ini -m user -a "name=deploy groups=sudo append=yes" --become

    • Adds the deploy user to the sudo group on all hosts

6. Network Management

  1. Check if a Port is Open:

    • ansible all -i inventory.ini -m shell -a "netstat -tuln | grep :80"

    • Checks if port 80 is open on all remote hosts.

  2. Download a File from the Internet:

    • ansible all -i inventory.ini -m get_url -a "url=https://example.com/file.tar.gz dest=/tmp/file.tar.gz"

    • Downloads a file from a URL to the /tmp directory on all hosts.

7.Process and System Management

  1. Reboot Host

    • ansible all -i inentory.ini -m reboot --become

  2. Kill a process

    • ansible all -i inventory.ini -m shell -a "pkill -f provess_name" --become

  3. Check a disk space

    • ansible web -i inventory.ini -m shell -a "df -h"

    • uses only web tagged machines in inventory file

  4. Show running processes:

    • ansible all -i inventory.ini -m shell -a "ps aux"

8.Docker Management

  1. Start Docker Container:

    • ansible all -i inventory.ini -m docker_container -a "name=my_cont image=nginx state=started"

  2. Stop a docker container

    • ansible all -i inventory.ini -m docker_container -a "name=my_cont state=stopped"

9. Log Management

  1. Tail log file

    • ansible all -i inventory.ini -m shell -a "tail -n 10 /var/log/nginx/access.log" --become

10.Other

  1. Execute a Shell Command:

    • ansible all -i inventory.ini -m shell -a "echo Hello, World!"

    • Executes a simple shell command (echo Hello, World!) on all hosts

  2. Create file with content

    • ansible all -i inventory.ini -m copy -a "content='Hello, World!' dest=/usr/share/nginx/html/hello.html"
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