Ansible/Hosts/AWS - Revision history

Admin: /* How to use Ansible Hosts file with AWS */

2018-11-10T19:06:55Z

How to use Ansible Hosts file with AWS

← Older revision		Revision as of 19:06, 10 November 2018
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	{{Main\|Ansible/Hosts/Dynamic Inventory}}		{{Main\|Ansible/Hosts/Dynamic Inventory}}

	The hosts inventory file is treated as static when managing our own infrastructure.		The hosts inventory file is treated as static when managing our own infrastructure. With AWS or large numbers of Vagrant machines, we do not want to manage machines by hand.

	~~However,~~ with AWS, ~~or with large numbers of Vagrant machines~~, ~~managing~~ machines by ~~hand can become painful~~.		To use Ansible with AWS, we need to use a dynamic hosts file, and use the AWS API to get information about machines. We can do that by using an executable hosts file that runs a program to return the information we need. (Also see [[Ansible/Hosts/Dynamic Inventory]] page.)

	~~Ansible can get information via~~ the ~~AWS API, but has to know to do that.~~		The dynamic inventory script must accept to command line flags, for the two ways Ansible will call this dynamic inventory script:

	Ansible ~~can be put in dynamic inventory mode by........ using an executable~~ dynamic inventory ~~file (not sure how you specify an inventory file, but ok)~~:

	<pre>		<pre>
	~~chmod +x dynamic.py~~		--host=<hostname> show host details
			--list list groups
	</pre>		</pre>

	~~The~~ script ~~must accept two command line flags~~:		For example, Ansible will call the inventory script like so:

	<pre>		<pre>
	--host=~~<hostname> show host details~~		./dynamic.py --host=vagrant2
	~~--list list groups~~
	</pre>		</pre>

	For example, ~~Ansible will call~~ the ~~inventory script like so~~:		We can call the dynamic inventory script ourselves to test, but usually what we're doing is calling Ansible and passing the -i flag, along with the path to the inventory file.

			For example, if we want to use a dynamic inventory file to get information about the vagrant hosts running on a system, and we wanted to ping a vagrant box named myvagrantbox, we could run the command:

	<pre>		<pre>
	~~$ ./~~dynamic.py -~~-host=vagrant2~~		ansible -i dynamic.py myvagrantbox -m ping
	</pre>		</pre>

	===Example ~~executable~~ dynamic inventory ~~script~~===		(where dynamic.py is the dynamic inventory file that interacts with vagrant.)

			===Example dynamic inventory scripts===

	{{Main\|Ansible/Hosts/Dynamic Inventory}}		{{Main\|Ansible/Hosts/Dynamic Inventory}}

			Vagrant dynamic inventory script: https://charlesreid1.com/wiki/Ansible/Hosts/Dynamic_Inventory#Putting_it_all_together

	===Huge list of user-contributed dynamic inventory scripts===		===Huge list of user-contributed dynamic inventory scripts===

Admin: /* Basics */

2018-11-10T18:27:41Z

Basics

← Older revision		Revision as of 18:27, 10 November 2018
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	=Basics=		=Basics=

	==How to use Ansible ~~hosts~~ file with AWS==		==How to use Ansible Hosts file with AWS==

	The hosts inventory file is treated as static when managing our own infrastructure, ~~but~~ with AWS ~~this information will~~ become ~~out of date quickly~~. Ansible can get information via the AWS API, but has to know to do that.		{{Main\|Ansible/Hosts/Dynamic Inventory}}

			The hosts inventory file is treated as static when managing our own infrastructure.

			However, with AWS, or with large numbers of Vagrant machines, managing machines by hand can become painful.

			Ansible can get information via the AWS API, but has to know to do that.

	Ansible can be put in dynamic inventory mode by........ using an executable dynamic inventory file (not sure how you specify an inventory file, but ok):		Ansible can be put in dynamic inventory mode by........ using an executable dynamic inventory file (not sure how you specify an inventory file, but ok):
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	# ...		# ...
	</pre>		</pre>


	=Advanced=		=Advanced=

Admin at 03:49, 9 November 2018

2018-11-09T03:49:23Z

@@ Line 2: / Line 2: @@
 List of user-contributed Ansible scripts to interface with other machine-managing services (like AWS): https://github.com/ansible/ansible/tree/devel/contrib/inventory
 ==How to use Ansible hosts file with AWS==
@@ Line 146: / Line 148: @@
      # ...
 </pre>
 =Flags=

Admin: /* Example executable dynamic inventory script */

2018-11-09T00:46:36Z

Example executable dynamic inventory script

← Older revision		Revision as of 00:46, 9 November 2018
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	{{Main\|Ansible/Hosts/Dynamic Inventory}}		{{Main\|Ansible/Hosts/Dynamic Inventory}}

			===Huge list of user-contributed dynamic inventory scripts===

			See https://github.com/ansible/ansible/tree/devel/contrib/inventory for a huge list of user-contributed dynamic inventory scripts

	==How to manage static and dynamic inventory==		==How to manage static and dynamic inventory==

Admin: /* Example executable dynamic inventory script */

2018-11-09T00:42:56Z

Example executable dynamic inventory script

@@ Line 28: / Line 28: @@
 ===Example executable dynamic inventory script===
-Let's walk through an example.
+{{Main|Ansible/Hosts/Dynamic Inventory}}
 ==How to manage static and dynamic inventory==

Admin: /* How to use Ansible hosts file with AWS */

2018-11-09T00:39:37Z

How to use Ansible hosts file with AWS

← Older revision		Revision as of 00:39, 9 November 2018
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	The hosts inventory file is treated as static when managing our own infrastructure, but with AWS this information will become out of date quickly. Ansible can get information via the AWS API, but has to know to do that.		The hosts inventory file is treated as static when managing our own infrastructure, but with AWS this information will become out of date quickly. Ansible can get information via the AWS API, but has to know to do that.

	Ansible can be put in dynamic inventory mode by ~~making the~~ inventory file (~~<code>playbooks/hosts</code> executable~~):		Ansible can be put in dynamic inventory mode by........ using an executable dynamic inventory file (not sure how you specify an inventory file, but ok):

	<pre>		<pre>
	chmod +x ~~playbooks/hosts~~		chmod +x dynamic.py
	</pre>		</pre>

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	main()		main()
	</pre>		</pre>


	==How to manage static and dynamic inventory==		==How to manage static and dynamic inventory==

Admin: /* How to group hosts in a playbook */

2018-11-08T21:03:52Z

How to group hosts in a playbook

← Older revision		Revision as of 21:03, 8 November 2018
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	Because on AWS we may be dealing with various types of machines, we can use built-in Ansible variables to determine the Linux distribution or architecture of our target machines, and use those to determine which group to add the machines to.		Because on AWS we may be dealing with various types of machines, we can use built-in Ansible variables to determine the Linux distribution or architecture of our target machines, and use those to determine which group to add the machines to.

	Example: <code>{{ ansible_distribution }}</code> refers to the Linux distribution		Example: <code><nowiki>{{ ansible_distribution }}</nowiki></code> refers to the Linux distribution

	To group by distribution type:		To group by distribution type:

Admin: /* How to add and configure hosts in a playbook */

2018-11-08T21:03:34Z

How to add and configure hosts in a playbook

← Older revision		Revision as of 21:03, 8 November 2018
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	Because we use the <code>creates=Vagrantfile</code>, it tells Ansible to only run the first play once (or, if our Vagrant boxes have been destroyed).		Because we use the <code>creates=Vagrantfile</code>, it tells Ansible to only run the first play once (or, if our Vagrant boxes have been destroyed).


			==How to group hosts in a playbook==

			Another useful task is to be able to group hosts in a playbook.

			Because on AWS we may be dealing with various types of machines, we can use built-in Ansible variables to determine the Linux distribution or architecture of our target machines, and use those to determine which group to add the machines to.

			Example: <code>{{ ansible_distribution }}</code> refers to the Linux distribution

			To group by distribution type:

			<pre>
			- name: create groups based on Linux distribution
			group_by: key={{ ansible_distribution }}
			</pre>

			===Example playbook grouping by host distribution===

			<pre>
			- name: group hosts by distribution
			hosts: myhosts
			gather_facts: True
			tasks:
			- name: create groups based on distro
			group_by: key={{ ansible_distribution }}

			- name: do something to Ubuntu hosts
			hosts: Ubuntu
			tasks:
			- name: install htop
			apt: name=htop
			# ...

			- name: do something else to CentOS hosts
			hosts: CentOS
			tasks:
			- name: install htop
			yum: name=htop
			# ...
			</pre>

	=Flags=		=Flags=

Admin: /* How to manage static and dynamic inventory */

2018-11-08T20:15:05Z

How to manage static and dynamic inventory

← Older revision		Revision as of 20:15, 8 November 2018
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	</pre>		</pre>

			==How to add and configure hosts in a playbook==

			It is important to note that the dynamic inventory script is executed at the ''beginning'' of a playbook.

			If a playbook creates new hosts, the dynamic inventory script will not pick up the new hosts.

			Therefore, need to add tasks using the <code>add_host</code> module.

			<pre>
			add_host name=hostname groups=web,staging myvar=myval
			</pre>


			===Example playbook adding a host===

			Here is an example playbook that uses the add_host command:

			<pre>
			- name: Provision a vagrant machine
			hosts: localhost
			vars:
			box: xenial64
			tasks:
			- name: create a Vagrantfile
			command: vagrant init {{ box }} creates=Vagrantfile

			- name: Bring up a vagrant machine
			command: vagrant up

			- name: add the vagrant machine to the inventory
			add_host: >
			name=vagrant
			ansible_host=127.0.0.1
			ansible_port=2222
			ansible_user=vagrant
			ansible_private_key_file=/home/username/.vagrant.d/
			insecure_private_key

			- name: Do something to the vagrant machine
			hosts: vagrant
			become: yes
			tasks:
			# The list of tasks would go here
			- ...
			</pre>

			'''NOTE: This is a good pattern to use.'''

			Play number 1 runs against localhost - it configures and provisions the hosts.

			Play number 2 configures the hosts.

			Because we use the <code>creates=Vagrantfile</code>, it tells Ansible to only run the first play once (or, if our Vagrant boxes have been destroyed).

	=Flags=		=Flags=

Admin at 19:42, 8 November 2018

2018-11-08T19:42:44Z

← Older revision		Revision as of 19:42, 8 November 2018
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	==How to use Ansible ~~Hosts File~~ with AWS==		{{Main\|Ansible/Hosts}}

			List of user-contributed Ansible scripts to interface with other machine-managing services (like AWS): https://github.com/ansible/ansible/tree/devel/contrib/inventory

			==How to use Ansible hosts file with AWS==

	The hosts inventory file is treated as static when managing our own infrastructure, but with AWS this information will become out of date quickly. Ansible can get information via the AWS API, but has to know to do that.		The hosts inventory file is treated as static when managing our own infrastructure, but with AWS this information will become out of date quickly. Ansible can get information via the AWS API, but has to know to do that.
Line 22:		Line 26:
	</pre>		</pre>

	==Example dynamic inventory script==		===Example executable dynamic inventory script===

	Let's walk through an example.		Let's walk through an example.
Line 94:		Line 98:
	</pre>		</pre>


			==How to manage static and dynamic inventory==

			To have a regular static inventory file and a dynamic inventory script, or any combination of the above, put them all in a directory, and tell Ansible to use this directory for inventory in the Ansible configuration file or on the command line.

			If our directory structure is:

			<pre>
			playbooks/inventory/hosts
			playbooks/inventory/vagrant.py
			</pre>

			we would have an <code>ansible.cfg</code> with the contents:

			<pre>
			[defaults]
			inventory = inventory
			</pre>




			=Flags=

	[[Category:Ansible]]		[[Category:Ansible]]