Problem with Ansible EC2 dynamic inventory - ansible

Question

I am trying to use ansible dynamic inventory.
I am getting the results when I run,
$ ./ec2.py --list
...
...
"ec2": [
"xx.xx.xx.xx"
]
}
But when I try to run it with ansible command, it does not run successfully.
$ ansible -i ec2.py -e "ansible_ssh_port=3003" -m ping
Usage: ansible <host-pattern> [options]
Define and run a single task 'playbook' against a set of hosts
Options:
-a MODULE_ARGS, --args=MODULE_ARGS
module arguments
--ask-vault-pass ask for vault password
-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
-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
--list-hosts outputs a list of matching hosts; does not execute
anything else
-m MODULE_NAME, --module-name=MODULE_NAME
module name to execute (default=command)
-M MODULE_PATH, --module-path=MODULE_PATH
prepend colon-separated path(s) to module library (def
ault=['/Users/luvpreetsingh/.ansible/plugins/modules',
'/usr/share/ansible/plugins/modules'])
-o, --one-line condense output
--playbook-dir=BASEDIR
Since this tool does not use playbooks, use this as a
subsitute playbook directory.This sets the relative
path for many features including roles/ group_vars/
etc.
-P POLL_INTERVAL, --poll=POLL_INTERVAL
set the poll interval if using -B (default=15)
--syntax-check perform a syntax check on the playbook, but do not
execute it
-t TREE, --tree=TREE log output to this directory
--vault-id=VAULT_IDS the vault identity to use
--vault-password-file=VAULT_PASSWORD_FILES
vault password file
-v, --verbose verbose mode (-vvv for more, -vvvv to enable
connection debugging)
--version show program's version number and exit
Connection Options:
control as whom and how to connect to hosts
-k, --ask-pass ask for connection password
--private-key=PRIVATE_KEY_FILE, --key-file=PRIVATE_KEY_FILE
use this file to authenticate the connection
-u REMOTE_USER, --user=REMOTE_USER
connect as this user (default=None)
-c CONNECTION, --connection=CONNECTION
connection type to use (default=smart)
-T TIMEOUT, --timeout=TIMEOUT
override the connection timeout in seconds
(default=10)
--ssh-common-args=SSH_COMMON_ARGS
specify common arguments to pass to sftp/scp/ssh (e.g.
ProxyCommand)
--sftp-extra-args=SFTP_EXTRA_ARGS
specify extra arguments to pass to sftp only (e.g. -f,
-l)
--scp-extra-args=SCP_EXTRA_ARGS
specify extra arguments to pass to scp only (e.g. -l)
--ssh-extra-args=SSH_EXTRA_ARGS
specify extra arguments to pass to ssh only (e.g. -R)
Privilege Escalation Options:
control how and which user you become as on target hosts
-s, --sudo run operations with sudo (nopasswd) (deprecated, use
become)
-U SUDO_USER, --sudo-user=SUDO_USER
desired sudo user (default=root) (deprecated, use
become)
-S, --su run operations with su (deprecated, use become)
-R SU_USER, --su-user=SU_USER
run operations with su as this user (default=None)
(deprecated, use become)
-b, --become run operations with become (does not imply password
prompting)
--become-method=BECOME_METHOD
privilege escalation method to use (default=sudo),
valid choices: [ sudo | su | pbrun | pfexec | doas |
dzdo | ksu | runas | pmrun | enable ]
--become-user=BECOME_USER
run operations as this user (default=root)
--ask-sudo-pass ask for sudo password (deprecated, use become)
--ask-su-pass ask for su password (deprecated, use become)
-K, --ask-become-pass
ask for privilege escalation password
Some modules do not make sense in Ad-Hoc (include, meta, etc)
ERROR! Missing target hosts
I get this long statement with the error of missing target hosts.
Then, when I run by specifying the region, it does not give any error but does not return any instances.
$ ansible -i ec2.py us-west-2 -e "ansible_ssh_port=3003" -m ping
[WARNING]: Could not match supplied host pattern, ignoring: us-west-2
[WARNING]: No hosts matched, nothing to do
Firstly, why is it not running? what am I doing wrong?
Secondly, why do the error changes when I specify the region? Is specifying region mandatory? shouldn't it pick the region from ec2.ini?

Answer 1

You do not have any hosts listed. Try adding all at the end of your ansible command:
ansible -i ec2.py -e "ansible_ssh_port=3003" -m ping all

Answer 2

The above command is partly right. The inventory has been specified with the -i argument but the target host group has not been specified. The command should be
ansible all -i ec2.py -e "ansible_ssh_port=3003" -m ping
# The command syntax could be written as below
ansible <target_host_group> -i <inventory> -e "extra_vars" -m "module_name" -a "module_arguments"
Please refer to the documentation on Working with patterns and Ad-Hoc Commands from the ansible documentation.