Day2 - Ansible class notes

Ansible - class notes - 2/14/2022 by - Ravi 

Recap from last class,

Ansible

-------

Why do they use ansible?

- its a configuration management tool to save time. 

- Remote execution of configuration infomration

- Agentless (ssh communication), push mechanism.

- modules

google

ansible modules

go to - module index.

-----------------

install new instance

apt update

# apt 

# cat nginx.yaml

- hosts: remote

  vars:

  packagename: "nginx"

  tasks:

  - name: add repo nginx

  - name: install package nginx

    apt:

         name: "{{packagename}}"

         state: latest

  - name: create a dir tutorial

  - name: copy index.html file

  ....

handlers:

  - name: restart service nginx

# ansible-playbook -i hosts nginx.yaml

Everything came green, ok, ok..

The reason was - 

it was already done

in this example, we use a variable.

Get the ip and paste on the browser, you will see the page.

ansible roles:

we are going to create multiple roles, and those roles are called through playbook.

tmcat, docker,, IAM are seperate roles,

$ site.yaml

---

- hosts: remote

  roles:

  - nginx

# how do you declare 

# cd /etc/ansible

# mkdir roles;cd roles

# ansible-galaxy init niginx

lets install tree pkg through ansible.

# cd ../hosts

[remote]

192.168.10.100

# ansible -i hosts localhost -m apt -a "name=tree state=latest"

# tree roles/nginx

# vi hosts

[remote]

192.168.10.100

[local]

localhost

# all task section you can define  [00:30]

# vi tasks/main.yaml

---

- name:restart nginx

  service "{{pkgname}}

# vi tasks

# vi vars/main.yml

---

packagename: nginx

# cd /etc/ansible; ls 

tutorial

index.html

nginx.yml

roles

hosts

ansible.cfg

# mv index.html tutorial roles/nginx/files

# cp nginx.yml site.yml

# cat site.yml

---

- hosts: remote

  roles:

  - nginx

# ansible-playbook -i hsots site.yml

roles under stite.yaml will call from roles directory in 

# ansibleplaybook -i hosts site.yml

# cd /etc/ansible; cat site.yml

---

- hosts: remote

  roles:

  - nginx

nginx is going to be under roles directory

cd roles/nginx; ls -ltr

# cd tasks; ls -ltr

main.yml

# cat main.yml

we can use ansible galary to use roles

# vi nginx/vars/main.yml

---

packagename: nginx

# vi nginx/tasks/main.yml

# cd ..

# ansible-loayboot -i hosts site.yml

https://github.com/qf-devops/ansible-jenkins

$ cat jenkins.yml

---

- hosts: "webserver"

  roles:

    - naisble-java8-orale

    - jenkins

    - maven

anisble-galary install -r requirements.yaml

-------------------------------

variables/ different types of variables.

how to execute

ansible tower

-------------------------------

variables - vars

got to roles directory

# cd /etc/ansbile/roles; ls -ltr

# cd nginx; ls -ltr

# cd vars

static -> once allocated, value can not be changed.

dynamic -> default value can be override, mean it can be changed.

local variables - scope is local, you can not use in other yaml file

global variables -> you can use anywhere, available in key-value pair. it can collect the facts on target node.

# cd /etc/ansible

# ansible -i hosts remote -m setup

review the output. you will see key-value pair.

ansible_nodename: "ip"

ansible_os_family: ""

# cd roles/nginx/default

# cat main.yaml

---

version: 1:0.0

# cd ../tasks

# vi main.yaml

# print he value

---

- name: debug # module name is debug

  debug:

     msg: "vars: {{ version }}"

.......... [00:57:00]

# ansible-playbook -i /etc/ansible/hosts /etc/ansible/site.yml

see the output, goto debug section and you will see the version output.

# vi ../default/main.yml

removet eh version line and run the play book

# ap -i hosts site.yml

error: undefind variable..

# cd /etc/ansible

# vi ../defaults/main.yml

---

version: 0.0.0

we have to stie,

webserver1

adn webserver2

Where can you declare? 

vars is local variable and can't be overridden.

on inventory section you can defailne

[remote]

# /etc/ansible

# mkdir group_vars; group_vars/remote

# vi main.yml

---

version: 2.0.0v1

# vi /etc/hosts

[1:05:00]

# ap 

# vi etc/ansible/hosts

[remote]

192.168.10.20 version=1.2.3"

 see the output

# ansible-plabook..

# /etc/ansible

# mkdir host_vars

# mkdir 192.168.10.20

# vi main.yml

---

version: 3.00v1

# cat /etc/ansible 

# ap -o hosts site.yml

view the output, 

you can define -e at the promot too.

# ap -i hosts site.yml -e "version=4.0.0"

look at the output.

order that variable is read from,

extra_vars

host_vars

group_vars

default section

extra_vars - > vars 

Note: we can use all types of variables but only extra_vars value will be read.

cd roles/nginx/vars

#

vi main.yml

---

packagename: gninx

dbname: cassandra

vi ../../task/main.yaml

---

- name: debug

  debug

  msg: "vars: {{ version}} {{dbname }}"

# ap -i hosts site.yml -e "version=4.0.0" -e "dbname=mongod"

it will pick up the value you speacify at the command line.

certificate to deploy for all host, use host_vars

for dev, prod, test

extra_vars -> extra is a high priority so it will pick it up first and executed from the inventory file.

# ap -i hosts /etc/ansible.siteyml -e "version=4.0.0" -e "dbname=mongod"

nested variables

in case of aws,

we have multiple datacenter in a region

we have multiple regions

google for default group

how do you handle multiple group?

group variables for groups of group

----------------------------------

[atlanta]

host1

host2

[releigh]

host2

host3

[southeast: children]

atlanta

releigh

[southeast:vars]

....

[usa:children]

southwest

northeast

southwest

nothewest

all:

  children

    usa:

....