Ansible: Ad-Hoc Commands

An ansible ad-hoc command is a single command sent to an ansible client. For example:

ansible servers -m ping

This ad-hoc command ping all clients from the servers group in the configured inventory.

Run Shell Commands on Ansible Clients

ansible servers -m shell -a "ip addr show"

ansible servers -m shell -a "uptime"

This commands sends a shell command to all nodes in the group. -a is used to specify the argument for the ad-hoc command which is the command we want to run on each ansible client.

Copy Files from Ansible Controle Node to Clients

ansible servers -m copy -a "src=/home/me/my-file.txt dest=/etc/ansible/data/my-file.txt"

ansible servers -m copy -a "content='My Text file content' dest=/etc/ansible/data/my-text-file.txt"

This command copy a file from ansible control node to all clients. We can choose whether we want to copy the content of the file or file itself by using the content or src params. Note that the destination folder in which the file is going must exist in the clients. When uploading a file content, we must specify the complete destination file name (dest=/data/upload/my-file.conf).

If the file exist in the destination, ansible will use the md5 checksum of the file to determine if that task was previously done. If the file was not modified ansible will not re-upload the file. Otherwise, whether the file was updated in the control node or in the clients, ansible with upload the file again in the selected clients.

Create and Delete File and Folders in Ansible Clients

To create a new file in ansible clients:

ansible servers -m file -a "dest=FILE OR DIRECTORY DESTINATION state=touch"

To delete a file in ansible clients:

ansible servers -m file -a "dest=FILE OR DIRECTORY DESTINATION state=absent"

To create a directory, change the state to directory:

ansible servers -m file -a "dest=/my/directory/data state=directory"

A directory deletion is performed like a file deletion. Just specify the diirectory name in the dest and state=absent then ansible will delete the directory.

Install and Uninstall Packages on Ansible Clients

We can use use the shell or dnf/apt ansible module.

ansible servers -m shell -a "sudo dnf install nginx"

ansible servers -m dnf -a "name=nginx state=present" -b

If the operation requires root user priviledge, we can pass sudo to the shell command. But if we are using dnf/apt module, the ansible user must have root priviledge and we also need to add -b option to the command.

Use the latest state to update already installed package.

ansible servers -m dnf -a "name=nginx state=latest" -b

The state can be one of absent, installed, present, removed, and latest.

Understanding ansible ad-hoc commands is important for understanding ansible playbook. From here, we are going to move slowly towards efficient ways to automate tasks using ansible.