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Ansible can be thought of as a for-loop over SSH scripts, but it's also much more than that.
https://charlesreid1-docker.github.io/charlesreid1-ansible/
 
Ansible is all about taking care of the heavy lifting involved in infrastructure automation.
 
Related:
 
* [[Ansible/Playbooks]] - this is where Ansible becomes really powerful
* [[Ansible/Hosts]] - configuring machines to work with Ansible


Ansible can be thought of as a for-loop over SSH scripts, but it's also much more than that. Ansible is all about taking care of the heavy lifting involved in infrastructure automation.


==Basic Features==
==Basic Features==
Line 28: Line 22:
<pre>
<pre>
playbooks/
playbooks/
    hosts      <-- ansible inventory file
     .vagrant/  <-- directory used by vagrant for keys/machines (if using vagrant)
     .vagrant/  <-- directory used by vagrant for keys/machines (if using vagrant)
     hosts      <-- ansible inventory file
     playbook.yml
</pre>
 
==Using Ansible Locally with Vagrant==
 
[[Vagrant]] allows you to set up virtual machine(s) using VirtualBox, which can give you a way of testing Ansible scripts locally (without using the AWS or Google Cloud platforms). You can then connect Ansible with vagrant to manage and set up compute nodes using Ansible.
 
===Before you begin: set up vagrant box===
 
See the [https://charlesreid1.com/wiki/Vagrant#Basic_Startup_Shutdown_Procedure Basic Startup and Shutdown Procedure] section of the [[Vagrant]] page for steps to set up a Vagrant box, and connect to it via SSH.
 
Briefly:
 
To initialize a vagrant box:
 
<pre>
vagrant init ubuntu/xenial64
</pre>
 
To bring it up:
 
<pre>
vagrant up
</pre>
 
For info about the ssh configuration of the box:
 
<pre>
vagrant ssh-config
</pre>
 
To ssh into the box:
 
<pre>
vagrant ssh
</pre>
 
To halt the machine:
 
<pre>
vagrant halt
</pre>
 
Note: for multiple vagrant boxes, see the guide on the [https://charlesreid1.com/wiki/Ansible/Full_Stack_Playbook#Vagrant_multi-machine_setup Ansible/Full Stack Playbook] page.
 
===Connect Ansible to Vagrant===
 
Use the hosts file to tell Ansible how to connect to the (Vagrant) hosts.
 
Edit <code>playbooks/hosts</code> and include details about each vagrant host.
 
Use the command <code>vagrant ssh-config</code> to get these details.
 
Example:
 
<pre>
$ cat playbooks/hosts
 
myvagrantbox ansible_host=127.0.0.1 ansible_port=2222 ansible_user=vagrant ansible_private_key_file=.vagrant/machines/default/virtualbox/private_key
</pre>
 
'''Side note:''' once you are ready to run with an AWS EC2 node, you would specify the hostname of the EC2 node and the AWS .pem private key, like so:
 
<pre>
$ cat playbooks/hosts
 
myamazonbox ansible_host=ec2-203-0-113-120.compute-1.amazonaws.com ansible_user=ubuntu ansible_private_key_file=/path/to/keyfile.pem
</pre>
 
Your vagrant boxes should be up and running with the <code>vagrant up</code> command.
 
===Ping Vagrant box===
 
To ping the Vagrant machine (that Ansible is managing), use Ansible's ping module.
 
Call Ansible and the name of the machine (must be listed in the hosts file).
 
Pass it the inventory file name with the -i flag, and the ping module with the -m flag:
 
<pre>
ansible myvagrantbox -i hosts -m ping
</pre>
 
You should see some output like this:
 
<pre>
myvagrantbox | success >> {
    "changed": false,
    "ping": "pong"
}
</pre>
 
If it did not succeed, re-run with the <code>-vvvv</code> flag for max verbosity to help debug the issue.
 
This is a basic module that runs a ping test; the server should respond with a pong on the other end.
 
The "'changed': false" indicates that Ansible is not changing the state of the machine.
 
===Use a config file===
 
The inventory file (hosts) required lots of details, and if we have many nodes to deal with that is not going to scale well.
 
To make it easier to deal with, we can use the <code>ansible.cfg</code> file to set some defaults and variables.
 
Where to put ansible.cfg? Here is where Ansible looks:
 
* <code>ANSIBLE_CONFIG</code> env var (specifies the config file)
* <code>/ansible.cfg</code> (current directory)
* <code>~/.ansible.cfg</code> (.ansible.cfg in your home directory
* <code>/etc/ansible/ansible.cfg</code>
 
A good place for it is alongside the playbooks, in the current directory.
 
This dir structure allows you to place the config file, plus the playbooks, under version control in a single repo.
 
===Example config file===
 
To specify default values for SSH key, username, and inventory filename, use this config file:
 
'''<code>ansible.cfg</code>:'''
 
<pre>
[defaults]
inventory = hosts
remote_user = vagrant
private_key_file = .vagrant/machines/default/virtualbox/private_key
host_key_checking = False
</pre>
 
Now we can also simplify the hosts file:
 
'''<code>playbooks/hosts</code>:'''
 
<pre>
myvagrantbox ansible_host=127.0.0.1 ansible_port=2222
</pre>
</pre>


Because the hosts file is already specified as the inventory file, we don't have to use the -i flag:
See [[Ansible/Directory Layout]] for a much more detailed discussion.


<pre>
==Using Ansible==
$ ansible myvagrantbox -m ping
</pre>


===Executing arbitrary commands===
===Using Ansible Locally with Vagrant===


We have already seen the <code>-m</code> flag used with ansible to specify an ansible module.
{{Main|Ansible/Vagrant}}


We can use the <code>command</code> module to run arbitrary commands on the vagrant machines that ansible is managing.
[[Vagrant]] allows you to set up virtual machine(s) using VirtualBox, which can give you a way of testing Ansible scripts locally (without using the AWS or Google Cloud platforms).  


To run a command on the remote machine via ansible:
Ansible uses the hosts file to connect to Vagrant. You can either manage the hosts file by hand (for a small number of machines), or you can use a dynamic inventory script (for an arbitrary number of machines).


<pre>
See [[Ansible/Vagrant]] for coverage of both methods when using Vagrant.
ansible myvagrantbox -m command -a <the command to run>
</pre>


For example, to run the uptime command:
See [[Ansible/Vagrant/Dynamic_Inventory]] for a dynamic inventory script with Vagrant.


<pre>
===Using Ansible with EC2===
ansible myvagrantbox -m command -a uptime
</pre>


Results in:
{{Main|Ansible/EC2}}


<pre>
When using Ansible with Amazon AWS EC2, AWS manages the compute nodes.
testserver | success | rc=0 >>
17:14:07 up  1:16, 1 user,  load average: 0.16, 0.05, 0.04
</pre>


====Important Note====
Like with Vagrant, Ansible uses the hosts file to connect to the EC2 nodes. The hosts file can either be maintained by hand using the information from AWS, or a dynamic inventory script can be used to call the AWS API and get information about computational resources to give to Ansible.


The command module '''is actually the default module'''!!! So we don't need to specify <code>-m command</code>, that is the default value:
See [[Ansible/EC2]] for coverage of both methods (the static inventory script and the dynamic inventory script) when using Amazon EC2.


<pre>
See [[Ansible/EC2/Dynamic Inventory]] for an example EC2 dynamic inventory script.
ansible myvagrantbox -a <the command to run>
</pre>


For example:
==Ansible Features==


<pre>
===Playbooks===
ansible myvagrantbox -a uptime
</pre>
 
If the command has spaces in it, use quotes:


<pre>
Playbooks are the central feature of Ansible, and are where you tell Ansible what to do on what machines.
ansible myvagrantbox -a "tail /var/log/dmesg"
</pre>


===Executing root commands===
[[Ansible/Playbooks]] - this is where Ansible becomes really powerful


To run commands that require root access, pass the <code>-b</code> flag to BECOME the root user:
[[Ansible/Variables]] - defining and using variables to remove complexity


<pre>
===Hosts===
$ ansible myvagrantbox -b -a "tail /var/log/syslog"
</pre>


===Installing packages===
Ansible host files tell Ansible how to work with host machines. Ansible can also interact programmatically with hosts.


The apt module is useful for installing packages. Here's how you would install nginx:
[[Ansible/Hosts]] - configuring machines to work with Ansible


<pre>
===Roles===
ansible myvagrantbox -b -m apt -a name=nginx
</pre>


'''IMPORTANT:''' The first apt module command you give should also run the equivalent of <code>apt-get update</code> before the package is installed. To do that, change the name to <code>name="nginx update_cache=yes"</code>:
Roles can provide multiple "routes" through a playbook for different types of machines


<pre>
[[Ansible/Roles]] - defining and using roles to make playbooks more powerful
ansible myvagrantbox -b -m apt -a name="nginx update_cache=yes"
</pre>


===Starting services===
===Vaults and Secrets===


Once nginx is installed, the service can be started using the service module:
Ansible uses vaults to encrypt and store keys and secrets. You can include a vault in <code>playbooks/group_vars</code> and have ansible ask for a password on the command line:


<pre>
<pre>
ansible myvagrantbox -b -m service -a "name=nginx state=restarted"
ansible-playbook site.yml --ask-vault-pass
</pre>
</pre>


equivalent of running <code>sudo service nginx restart</code>
[[Ansible/Vaults]] - mechanism for encrypting and decrypting secrets


=Flags=
=Flags=


 
{{AnsibleFlag}}
[[Category:Web Server]]
[[Category:Nginx]]
[[Category:Ansible]]
[[Category:Infrastructure]]
[[Category:Python]]
[[Category:HTTPS]]
[[Category:SSL]]

Latest revision as of 02:25, 29 March 2019

https://charlesreid1-docker.github.io/charlesreid1-ansible/

Ansible can be thought of as a for-loop over SSH scripts, but it's also much more than that. Ansible is all about taking care of the heavy lifting involved in infrastructure automation.

Basic Features

Main article: Ansible/Basics

Summary:

  • Ansible is Python-based
  • Ansible uses playbooks, which are YAMl files, to configure remote machines
  • Ansible is push-based, which means your workflow involves making changes to the playbook and pushing those changes to the server
  • Ansible is idempotent, which means you can run the playbook multiple times and it will only carry out new tasks (it will not repeat tasks)
  • Ansible allows executing arbitrary shell commands
  • Ansible uses Jinja templates, in addition to YAML, to deploy files to machines

Directory Structure

The basic directory structure we'll use with Ansible is to create a playbooks directory to hold everything: 

playbooks/
    hosts       <-- ansible inventory file
    .vagrant/   <-- directory used by vagrant for keys/machines (if using vagrant)
    playbook.yml

See Ansible/Directory Layout for a much more detailed discussion.

Using Ansible

Using Ansible Locally with Vagrant

Main article: Ansible/Vagrant

Vagrant allows you to set up virtual machine(s) using VirtualBox, which can give you a way of testing Ansible scripts locally (without using the AWS or Google Cloud platforms).

Ansible uses the hosts file to connect to Vagrant. You can either manage the hosts file by hand (for a small number of machines), or you can use a dynamic inventory script (for an arbitrary number of machines).

See Ansible/Vagrant for coverage of both methods when using Vagrant.

See Ansible/Vagrant/Dynamic_Inventory for a dynamic inventory script with Vagrant.

Using Ansible with EC2

Main article: Ansible/EC2

When using Ansible with Amazon AWS EC2, AWS manages the compute nodes.

Like with Vagrant, Ansible uses the hosts file to connect to the EC2 nodes. The hosts file can either be maintained by hand using the information from AWS, or a dynamic inventory script can be used to call the AWS API and get information about computational resources to give to Ansible.

See Ansible/EC2 for coverage of both methods (the static inventory script and the dynamic inventory script) when using Amazon EC2.

See Ansible/EC2/Dynamic Inventory for an example EC2 dynamic inventory script.

Ansible Features

Playbooks

Playbooks are the central feature of Ansible, and are where you tell Ansible what to do on what machines.

Ansible/Playbooks - this is where Ansible becomes really powerful

Ansible/Variables - defining and using variables to remove complexity

Hosts

Ansible host files tell Ansible how to work with host machines. Ansible can also interact programmatically with hosts.

Ansible/Hosts - configuring machines to work with Ansible

Roles

Roles can provide multiple "routes" through a playbook for different types of machines

Ansible/Roles - defining and using roles to make playbooks more powerful

Vaults and Secrets

Ansible uses vaults to encrypt and store keys and secrets. You can include a vault in playbooks/group_vars and have ansible ask for a password on the command line: 

ansible-playbook site.yml --ask-vault-pass

Ansible/Vaults - mechanism for encrypting and decrypting secrets

Flags


Defcon.png
Ansible
Ansible is a Python library for managing IT and compute infrastructure.

Ansible  · Category:Ansible


Ansible Configuration

Config file: Ansible/Configuration

Secrets and Sensitive Info: Ansible/Security  · Ansible/Vaults


Ansible Playbooks

Basics: Ansible/Playbooks

Examples: Ansible/Nginx Playbook (simple)  · Ansible/Full Stack Playbook (advanced)


Ansible Hosts and Inventory Control

All topics in Ansible Hosts: Ansible/Hosts

Splitting large host files into subfiles: Ansible/Splitting Hosts File

Automatically naming hosts: Ansible/Host Naming

Grouping Hosts: Ansible/Groups

Assigning Variables to Groups: Ansible/Group Variables

Roles: Ansible/Roles


Ansible and Vagrant (Local)

Ansible/Vagrant  · Ansible/Vagrant/Static Inventory  · Ansible/Vagrant/Dynamic Inventory


Ansible and EC2 (Cloud)

Ansible/EC2  · Ansible/EC2/Static Inventory  · Ansible/EC2/Dynamic Inventory


Best Practices

Ansible/Directory Layout  · Ansible/Directory Layout/Details

Ansible/Separate Playbooks by Role

Ansible/Tag Inventory with Environment

Ansible/Group by Distribution

Ansible/Variables and Vaults


Ansible Galaxy

Ansible/Galaxy


Flags  · Template:AnsibleFlag  · e



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