Master Essential Ansible Modules: Ping, Setup, File, Copy, Service, and More

Ansible is a powerful agentless IT automation platform; this article introduces several commonly used modules.

1. ping module

Tests connectivity of a host; usage is simple and requires no parameters.

# ansible 10.212.52.252 -m ping
10.212.52.252 | success >> {
  "changed": false,
  "ping": "pong"
}

2. setup module

Collects host information; often used via the gather_facts parameter in playbooks. Commonly filtered with the filter argument.

# ansible 10.212.52.252 -m setup -a 'filter=ansible_*_mb'
# ansible 10.212.52.252 -m setup -a 'filter=ansible_eth[0-2]'
# ansible all -m setup --tree /tmp/facts

3. file module

Manages files on remote hosts. Options include force for creating or replacing symbolic links.

ansible test -m file -a "src=/etc/fstab dest=/tmp/fstab state=link"
ansible test -m file -a "path=/tmp/fstab state=absent"
ansible test -m file -a "path=/tmp/test state=touch"

4. copy module

Copies files to remote hosts. Key options:

backup: backup before overwriting (yes|no)

content: replace src with raw content

dest: required destination path

directory_mode: set directory permissions

force: overwrite existing file if yes

src: local source path (file or directory)

validate: command to validate the file before copying

ansible test -m copy -a "src=/srv/myfiles/foo.conf dest=/etc/foo.conf owner=foo group=foo mode=0644"
ansible test -m copy -a "src=/mine/ntp.conf dest=/etc/ntp.conf owner=root group=root mode=644 backup=yes"
ansible test -m copy -a "src=/mine/sudoers dest=/etc/sudoers validate='visudo -cf %s'"

5. service module

Manages system services. Important options include name, state, enabled, pattern, and others.

# Example action to reload service httpd
- service: name=httpd state=reloaded
# Enable service httpd without changing its running state
- service: name=httpd enabled=yes
# Start service foo based on a running process
- service: name=foo pattern=/usr/bin/foo state=started
# Restart network service for interface eth0
- service: name=network state=restarted args=eth0

6. cron module

Manages scheduled jobs.

ansible test -m cron -a 'name="a job for reboot" special_time=reboot job="/some/job.sh"'
ansible test -m cron -a 'name="yum autoupdate" weekday="2" minute=0 hour=12 user="root"'
ansible 10.212.52.252 -m cron -a 'backup="True" name="test" minute="0" hour="2" job="ls -alh > /dev/null"'
ansible test -m cron -a 'cron_file=ansible_yum-autoupdate state=absent'

7. yum module

Manages packages with the yum package manager.

ansible test -m yum -a 'name=httpd state=latest'
ansible test -m yum -a 'name="@Development tools" state=present'
ansible test -m yum -a 'name="http://nginx.org/packages/centos/6/noarch/RPMS/nginx-release-centos-6-0.el6.ngx.noarch.rpm" state=present'

8. user and group modules

Creates, modifies, or removes users and groups.

- user: name=johnd comment="John Doe" uid=1040 group=admin
- user: name=james shell=/bin/bash groups=admins,developers append=yes
- user: name=johnd state=absent remove=yes
- user: name=james18 shell=/bin/zsh groups=developers expires=1422403387
- user: name=test generate_ssh_key=yes ssh_key_bits=2048 ssh_key_file=.ssh/id_rsa

Note: When specifying the password parameter, encrypt the password before placing it in the module.

# openssl passwd -1 -salt $(< /dev/urandom tr -dc '[:alnum:]' | head -c 32)
Password: $1$YngB4z8s$atSVltYKnDxJmWZ3s.4/80
# echo "123456" | openssl passwd -1 -salt $(< /dev/urandom tr -dc '[:alnum:]' | head -c 32) -stdin
$1$4P4PlFuE$ur9ObJiT5iHNrb9QnjaIB0
# ansible all -m user -a 'name=foo password="$1$4P4PlFuE$ur9ObJiT5iHNrb9QnjaIB0"'

- group: name=somegroup state=present

9. synchronize module

Synchronizes files using rsync.

src=some/relative/ path dest=/some/absolute/ path rsync_path="sudo rsync"
src=some/relative/ path dest=/some/absolute/ path archive=no links=yes
src=some/relative/ path dest=/some/absolute/ path checksum=yes times=no
src=/tmp/helloworld dest=/var/www/helloword rsync_opts=--no-motd,--exclude=.git mode=pull

10. mount module

Manages mount points. Important options:

dumpfstype: required filesystem type

name: required mount point name

opts: options passed to the mount command

src: required source device or file

state: present, absent, mounted, unmounted

name=/mnt/dvd src=/dev/sr0 fstype=iso9660 opts=ro state=present
name=/srv/disk src='LABEL=SOME_LABEL' state=present
name=/home src='UUID=b3e48f45-f933-4c8e-a700-22a159ec9077' opts=noatime state=present
ansible test -a 'dd if=/dev/zero of=/disk.img bs=4k count=1024'
ansible test -a 'losetup /dev/loop0 /disk.img'
ansible test -m filesystem 'fstype=ext4 force=yes opts=-F dev=/dev/loop0'
ansible test -m mount 'name=/mnt src=/dev/loop0 fstype=ext4 state=mounted opts=rw'

11. get_url module

Downloads files from HTTP/HTTPS/FTP sources, similar to wget.

sha256sum: verify checksum after download

timeout: download timeout (default 10s)

url: source URL

url_username / url_password: credentials for protected URLs

use_proxy: whether to use a proxy defined in the environment

- name: download foo.conf
  get_url:
    url: http://example.com/path/file.conf
    dest: /etc/foo.conf
    mode: 0440
- name: download file with sha256 check
  get_url:
    url: http://example.com/path/file.conf
    dest: /etc/foo.conf
    sha256sum: b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c

12. command module

Executes commands directly without shell processing, enhancing security.

Other useful modules include git, svn, sysctl, authorized_key, apt, zypper, pip, gem, find, template, mysql_db, redis, and url.