This is to demo the generic usage of Ansible.
Install Ansible, boto3 and botocore via pip3. We install boto3 because it's required by Ansible Inventory EC2 plugin.
pip3 install ansible boto3 botocore
Validate by executing ansible --version and check it's using python3.
Alternatively, you can follow https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html
You can play around by checking localhost, so you can control your machine :)
ansible localhost -v -a 'ls'Note -v means verbose mode. You can add more verbose like -vvvv
- Get a ssh public key in your local machine.
cat ~/.ssh/id_rsa.pub
- Import your ssh public key into AWS as a key pair. https://console.aws.amazon.com/ec2/v2/home?region=us-east-1#KeyPairs:sort=keyName
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Create a EC2 machine with default VPC and subnet
Select a Ubuntu image as free-tier.
create a Security Group with ssh and http
select the existing key pair as imported above
- SSH the EC2 machine in AWS EC2 service
Get the ip address
SSH the instance in your local machine
ssh ubuntu@<ip address from aws ec2>
- Go to
ansible-nginxfolder and run the command as below
ansible-playbook -i <ec2 ip address>, nginx_install.yaml
Explanation:
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i inventory: it tells Ansible which hosts to apply. The default location for inventory is a file called /etc/ansible/hosts. You can specify a different inventory file at the command line using the -i option.
see detail https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html
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*.yml playbook
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Inspect the terminal
- check if Nginx is installed correctly
visit the IP address
Some explanation on Playbook:
Playbooks are the files where Ansible code is written. Playbooks are written in YAML format. YAML stands for Yet Another Markup Language.
Playbooks are one of the core features of Ansible and tell Ansible what to execute. They are like a to-do list for Ansible that contains a list of tasks.
Playbook Structure:
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It is a YAML file. Be careful with indention.
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Start with --- (3 hyphens)
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name: This tag specifies the name of the Ansible playbook. As in what this playbook will be doing. Any logical name can be given to the playbook.
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hosts: This tag specifies the lists of hosts or host group against which we want to run the task. The hosts field/tag is mandatory. It tells Ansible on which hosts to run the listed tasks. The tasks can be run on the same machine or on a remote machine. One can run the tasks on multiple machines and hence hosts tag can have a group of hosts’ entry as well.
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tasks: All playbooks should contain tasks or a list of tasks to be executed. Tasks are a list of actions one needs to perform. A tasks field contains the name of the task. This works as the help text for the user. It is not mandatory but proves useful in debugging the playbook. Each task internally links to a piece of code called a module. A module that should be executed, and arguments that are required for the module you want to execute.
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become: Ansible allows you to ‘become’ another user, different from the user that logged into the machine (remote user).
see Some examples
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user: connect as ssh user
- Uninstall: In order to allow us to see the full cycle we would like to check how to uninstall Nginx. This is the playbook we are going to use.
ansible-playbook -i <ec2 ip address>, nginx_uninstall.yaml
- Config Nginx to display a static html file
ansible-playbook -i <ec2 ip address>, nginx_update.yaml
Tip:
- find modules from https://docs.ansible.com/ansible/latest/modules/modules_by_category.html
--checkThe check mode allows you to run in dry-run mode, without making any change.--syntax-checkThe check will check the YAML syntax
It is fine to install on a remote machine, what about more machines?
- Use this cloudformation template to create EC2 instances for our handson: https://console.aws.amazon.com/cloudformation/home?region=us-east-1#/stacks/create/template
We are going to deploy the sample app -https://github.com/JiangRenDevOps/jrcms
We can use the default VPC and its corresponding subnet. Then go head creating the stack.
While it is being created, let us have a walkthrough at both the project and cloud formation before going next.
Inspect what have been created, e.g. checking ec2 service and instance tags.
After the creation is successful, you should be able to ssh the public IP of the instance.
- List the machines in the default inventory
etc/ansible/hosts
sudo vi /etc/ansible/hostsNote: It is the default inventory location. Create a directory if you don't have it
sudo mkdir -p /etc/ansible- Write the IP address into the file, and then save it
[web]
<public ip from aws cloudformation output>
<public ip from aws cloudformation output>
[redis]
<public ip from aws cloudformation output>- Checkout the inventory graph
ansible-inventory --graph- Execute to ping all machines. You should be able to see the success results from it.
ansible all -m ping -u ubuntu
We can also play around by adding a file like
ansible all -u ubuntu -a "touch michael"ansible all -u ubuntu -a "ls -la"It is not efficient to manually config the list when managing more machines. So we can configure the following to automatically detect client machines from AWS. We need to create an IAM user and configuring three environment variables.
Get the value from your AWS console.
export AWS_ACCESS_KEY=YOUR_AWS_ACCESS_KEY
export AWS_SECRET_KEY=YOUR_AWS_SECRET_KEY
export ANSIBLE_HOST_KEY_CHECKING=False
Note: ANSIBLE_HOST_KEY_CHECKING=False is to skip checking host key. see https://docs.ansible.com/ansible/latest/reference_appendices/config.html
cd DevOpsLectureNotes2/WK7_CM_Ansible/ansible-playbooks
ansible all -i inventory.aws_ec2.yaml -u ubuntu -m ping
You should be able to ping three machines from AWS
Also, you can view the inventory by executing the following:
ansible-inventory -i inventory.aws_ec2.yaml --graph
Note: the display list is no longer IPs.
Use ansible-galaxy install -f requirements.yaml
Alternatively, you can install it directly
ansible-galaxy install -c geerlingguy.docker
Read site.yaml under ansible-playbook-plain.
ansible-playbook -i ../inventory.aws_ec2.yaml site.yaml
Note there is a check flag to inspect if there are any errors. If not, run without flag to execute for real.
If you don't see errors, you should be able to view the app from one of the web server.
Read site.yaml under ansible-playbook-roles.
ansible-playbook -i ../inventory.aws_ec2.yaml site.yaml
Some explanation on Roles
In Ansible, the role is the primary mechanism for breaking a playbook into multiple files. This simplifies writing complex playbooks, and it makes them easier to reuse. The breaking of playbook allows you to logically break the playbook into reusable components.
Each role is basically limited to a particular functionality or desired output, with all the necessary steps to provide that result either within that role itself or in other roles listed as dependencies.
Roles are not playbooks. Roles are small functionality which can be independently used but have to be used within playbooks. There is no way to directly execute a role. Roles have no explicit setting for which host the role will apply to.
Top-level playbooks are the bridge holding the hosts from your inventory file to roles that should be applied to those hosts.
Tip: Exam a role file structure - ansible-galaxy init role1
Install sth like Jenkins, Kubernetes, Wordpress etc.