Jayesh Nalawade

Posted on Dec 20 • Originally published at jayeshdevops.hashnode.dev

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

#ansible #automation #devops #aws

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

2) 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"

3) 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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