Phase 3 Basics
Time: July 14, 2023
Participants: the whole class
Contents:
playbook configuration file
Table of contents
1. The concept of playbook configuration file
Create a playbook configuration file
2. The core elements of Playbook
6. Conduct the test (the test can be carried out after the pre-test is successful)
The experimental example of the handlers trigger is as follows:
playbook configuration file
1. The concept of playbook configuration file
The Playbook configuration file uses YAML syntax, which is concise and clear, and has a clear structure .
The Playbook configuration file is similar to a shell script and is a YAML format file used to save a task list for specific requirements;
Although the ansible commands introduced above can complete various tasks, when configuring a series of tasks, it is very inefficient to enter commands one by one. A more effective way is to configure all task codes in the playbook configuration;
Use the ansible-playbook command to execute the file, which can realize automatic operation and maintenance;
YAML files usually have the extension .yaml or .yml.
YAML syntax is similar to other high-level languages. Its structure is displayed by indentation, options are expressed by "-", and keys and values are separated by colons ":". The entire file starts with "---" and ends with "..." as follows:
example:
Modify the hosts file
Modify the configuration as follows:
vim /etc/ansible/hosts
The configuration is as follows:
Create a playbook configuration file
vim /etc/ansible/test1.yml
The configuration is as follows:
Notes on yml script writing:
vim /etc/ansible/test1.yml #Create test, yml file
--- #beginning format (can be ignored)
- hosts: hu1 #Indicates the operation on test01 (192.168.59.138)
remote_user: root #Remote execution user identity root
tasks: #task list
- name: adduser #task name
user: name=user2 state=present #Execute the user module to create a user
tags: #create tag tag
- testa #tag tag is testa
- name: addgroup #task name
group: name=tests system=yes #Execute the group module to create a group account
tags: #create tag tag
- testb #tag tag is testb
- hosts: hu2 #Indicates the operation on test02 (192.168.59.140)
remote_user: root #Remote execution user identity root
tasks: #task list
- name: copy file #task name
copy: src=/etc/passwd dest=/home #Execute the copy module to copy files
tags: #create tag tag
- testc #tag tag is testsc
... #end format (can be ignored)
All "-" and ":" are followed by spaces, and attention should be paid to indentation and alignment
2. The core elements of Playbook
Include:
hosts: the target host of the task, multiple hosts are separated by colons, generally call the group information in /etc/ansible/hosts;
remote_user: On the remote host, the default for running this task is root;
tasks: task, that is, the specific task defined, the list of operations defined by the module;
handlers: triggers, similar to tasks, only trigger tasks under certain conditions. When the status of a task is changed after running, it can be notified to the corresponding handlers through "notify" to trigger execution;
roles: role, which is a specific structural collection composed of tasks, handlers, etc., by stripping hosts.
3. Usage of Playbook
The tasks defined in the Playbook file need to be invoked and executed through the ansible-playbook command. The usage of the ansible-playbook command is as follows:
Usage: ansible-playbook [option] /PATH/PLAYBOOK.yml
The functions of the [option] section include:
1.--syntax-check: Check the syntax of the yaml file;
2.-C (--check): test, will not change any configuration of the host;
3.--list-hosts: List the list of hosts affected by the yaml file;
4.--list-tasks: List the task list of the yaml file;
5.--list-tags: List the tags in the yaml file;
6. -t TAGS (--tags=TAGS): Indicates that only tasks with specified tags are executed;
7. --skip-tags=SKIP_TAGSS: Indicates that in addition to the specified tag task, perform other tasks;
8. --start-at-task=START_AT: Start running from the specified task.
4. Experimental case:
(1) Workflow
1. Grammar check
ansible-playbook --syntax-check
/etc/ansible/test1.yml
2. Pre-test (most important)
ansible-playbook -C /etc/ansible/test1.yml
Error conditions:
Correct situation:
3. List hosts
ansible-playbook --list-hosts /etc/ansible/test1.yml
4. List tasks
ansible-playbook --list-tasks /etc/ansible/test1.yml
5. List tags
ansible-playbook --list-tags /etc/ansible/test1.yml
6. Conduct the test (the test can be carried out after the pre-test is successful)
ansible-playbook /etc/ansible/test1.yml
7. Test view
【huyang2】tail -5 /etc/passwd tail -5 /etc/group
【huyang3】ls /man/
Usually, the ansible-playbook -C/PATH/PLAYBOOK.yml command is executed first for testing, and then the ansible-playbook /PATH/TO/PLAYBOOK.yml command is executed after the test is OK.
(2) Trigger
Tasks that need to be triggered to be executed. When the tasks previously defined in tasks are executed, if you want to trigger other tasks on the basis, you need to define handlers.
For example, after the configuration file of the target host is modified through the ansible module, if the task is executed successfully, a trigger can be triggered, and the service restart operation of the target host can be defined in the trigger so that the configuration file takes effect. The handlers trigger has the following advantages :
Handlers are one of the conditional mechanisms provided by Ansible. Handlers are similar to tasks, but they will only trigger execution when they are notified by the task;
Handlers will only be executed after all tasks are executed, and even if they are notified many times, it will only be executed once, and handlers will be executed in the order defined.
The experimental example of the handlers trigger is as follows:
vim /etc/ansible/httpd.yml
The configuration is as follows:
Script comments:
--- #Fixed beginning format
- hosts: hu1 #Specify the running host as the Rich group
remote_user: root #Specify the identity of the peer running user
tasks: #task list
- name: reset httpd #Define task name
command: sed -i 's/Listen 80/Listen 8080/g' /etc/httpd/conf/httpd.conf #Module is command: use sed command to replace listening port with 8080
notify: #Call the restart httpd server trigger after the task is completed
- reset httpd
handlers: #Configure triggers
- name: reset httpd #Specify the trigger name
service: name=httpd state=restarted #Specify the trigger condition to restart the httpd service
... #end sentence
Experiment:
1. Pre-test:
ansible-playbook -C /etc/ansible/httpd.yml
2. Execute the test:
ansible-playbook /etc/ansible/httpd.yml
3. Result verification
