1. install ansible on Ubuntu18.04

(ansible) hok@server:~$ sudo apt update
(ansible) hok@server:~$ sudo apt install software-properties-common
(ansible) hok@server:~$ sudo apt-add-repository --yes --update ppa:ansible/ansible
(ansible) hok@server:~$ sudo apt install ansible

2. ansible general ad-hoc command format

ansible <target> -m <module name> -a arguments

e.g:
ansible web_servers -m copy -a "src=/home/hok/src dest=/mnt/wwwroot"

➜  ~ ansible
usage: ansible [-h] [--version] [-v] [-b] [--become-method BECOME_METHOD]
               [--become-user BECOME_USER] [-K] [-i INVENTORY] [--list-hosts]
               [-l SUBSET] [-P POLL_INTERVAL] [-B SECONDS] [-o] [-t TREE] [-k]
               [--private-key PRIVATE_KEY_FILE] [-u REMOTE_USER]
               [-c CONNECTION] [-T TIMEOUT]
               [--ssh-common-args SSH_COMMON_ARGS]
               [--sftp-extra-args SFTP_EXTRA_ARGS]
               [--scp-extra-args SCP_EXTRA_ARGS]
               [--ssh-extra-args SSH_EXTRA_ARGS] [-C] [--syntax-check] [-D]
               [-e EXTRA_VARS] [--vault-id VAULT_IDS]
               [--ask-vault-pass | --vault-password-file VAULT_PASSWORD_FILES]
               [-f FORKS] [-M MODULE_PATH] [--playbook-dir BASEDIR]
               [-a MODULE_ARGS] [-m MODULE_NAME]
               pattern

Define and run a single task 'playbook' against a set of hosts

positional arguments:
  pattern               host pattern

optional arguments:
  --ask-vault-pass      ask for vault password
  --list-hosts          outputs a list of matching hosts; does not execute
                        anything else
  --playbook-dir BASEDIR
                        Since this tool does not use playbooks, use this as a
                        substitute playbook directory.This sets the relative
                        path for many features including roles/ group_vars/
                        etc.
  --syntax-check        perform a syntax check on the playbook, but do not
                        execute it
  --vault-id VAULT_IDS  the vault identity to use
  --vault-password-file VAULT_PASSWORD_FILES
                        vault password file
  --version             show program's version number, config file location,
                        configured module search path, module location,
                        executable location and exit
  -B SECONDS, --background SECONDS
                        run asynchronously, failing after X seconds
                        (default=N/A)
  -C, --check           don't make any changes; instead, try to predict some
                        of the changes that may occur
  -D, --diff            when changing (small) files and templates, show the
                        differences in those files; works great with --check
  -M MODULE_PATH, --module-path MODULE_PATH
                        prepend colon-separated path(s) to module library (def
                        ault=~/.ansible/plugins/modules:/usr/share/ansible/plu
                        gins/modules)
  -P POLL_INTERVAL, --poll POLL_INTERVAL
                        set the poll interval if using -B (default=15)
  -a MODULE_ARGS, --args MODULE_ARGS
                        module arguments
  -e EXTRA_VARS, --extra-vars EXTRA_VARS
                        set additional variables as key=value or YAML/JSON, if
                        filename prepend with @
  -f FORKS, --forks FORKS
                        specify number of parallel processes to use
                        (default=5)
  -h, --help            show this help message and exit
  -i INVENTORY, --inventory INVENTORY, --inventory-file INVENTORY
                        specify inventory host path or comma separated host
                        list. --inventory-file is deprecated
  -l SUBSET, --limit SUBSET
                        further limit selected hosts to an additional pattern
  -m MODULE_NAME, --module-name MODULE_NAME
                        module name to execute (default=command)
  -o, --one-line        condense output
  -t TREE, --tree TREE  log output to this directory
  -v, --verbose         verbose mode (-vvv for more, -vvvv to enable
                        connection debugging)

Privilege Escalation Options:
  control how and which user you become as on target hosts

  --become-method BECOME_METHOD
                        privilege escalation method to use (default=sudo), use
                        `ansible-doc -t become -l` to list valid choices.
  --become-user BECOME_USER
                        run operations as this user (default=root)
  -K, --ask-become-pass
                        ask for privilege escalation password
  -b, --become          run operations with become (does not imply password
                        prompting)

Connection Options:
  control as whom and how to connect to hosts

  --private-key PRIVATE_KEY_FILE, --key-file PRIVATE_KEY_FILE
                        use this file to authenticate the connection
  --scp-extra-args SCP_EXTRA_ARGS
                        specify extra arguments to pass to scp only (e.g. -l)
  --sftp-extra-args SFTP_EXTRA_ARGS
                        specify extra arguments to pass to sftp only (e.g. -f,
                        -l)
  --ssh-common-args SSH_COMMON_ARGS
                        specify common arguments to pass to sftp/scp/ssh (e.g.
                        ProxyCommand)
  --ssh-extra-args SSH_EXTRA_ARGS
                        specify extra arguments to pass to ssh only (e.g. -R)
  -T TIMEOUT, --timeout TIMEOUT
                        override the connection timeout in seconds
                        (default=10)
  -c CONNECTION, --connection CONNECTION
                        connection type to use (default=smart)
  -k, --ask-pass        ask for connection password
  -u REMOTE_USER, --user REMOTE_USER
                        connect as this user (default=None)

Some modules do not make sense in Ad-Hoc (include, meta, etc)
ERROR! No argument passed to command module

3. list all ansible modules

➜  ~ ansible-doc -l
➜  ~  ansible-doc xml
➜  ~  ansible-doc copy
> COPY    (/usr/local/Cellar/ansible/2.9.13/libexec/lib/python3.8/site-packages/ansible/modules/files/copy.py)

        The `copy' module copies a file from the local or remote
        machine to a location on the remote machine. Use the [fetch]
        module to copy files from remote locations to the local box.
        If you need variable interpolation in copied files, use the
        [template] module. Using a variable in the `content' field
        will result in unpredictable output. For Windows targets, use
        the [win_copy] module instead.

  * This module is maintained by The Ansible Core Team
  * note: This module has a corresponding action plugin.

OPTIONS (= is mandatory):

- attributes
        The attributes the resulting file or directory should have.
        To get supported flags look at the man page for `chattr' on
        the target system.
        This string should contain the attributes in the same order as
        the one displayed by `lsattr'.
        The `=' operator is assumed as default, otherwise `+' or `-'

4. basic concepts of ansible

/etc/ansible/ansible.cfg

inventory
/etc/ansible/hosts

playbook.yml

ansible parallerism

ansible facts: context or environment variables of targeted remote systems.

5. ansible parallerism

6. ansible facts

$ansible all-m setup
$ansible all-m setup -a "gather_subset=network,virtual"

ansible variables:

7. playbook setctions

. target section
. variable section
. task section
. handler section
. loops
. conditionals
. until
. notify