Ansible principle and installation and deployment

Today, we started learning Ansible, an operation and maintenance automation tool.

1. Ansible principle

1.1 What is Ansible

Ansible is an open source platform / framework that integrates IT system configuration management, application deployment, and specific tasks. Based on the Python language, the core modules include: jinja2, PyYAML and paramiko. Ansible allows repeated execution without errors, no agent on the client, and no deamon process on the server. Ansible features:

Ansible supports API interface calls, such as CMDB calls or public cloud interface calls
Ansible is a framework that works based on modules and plugins
Work based on SSH, that is, the managed end must support SSH management
Write powerful configuration and state management through playbooks to achieve automation

1.2 Ansible important components

Module: Ansible is composed of multiple functional modules
playbook: Ansible playbook, use yml syntax to call different function modules to complete specific functions
roles: Ansbiel roles. You can use the ansible-galaxy command to download the role roles of the third party.
ansible-vault: file encryption tool
ansilbe-console: interact with users based on console
ansible-doc: help documentation, -l all modules, -s brief help

1.3 Ansible execution process and principle description

Load the configuration file, the default is /etc/ansible/ansible.cfg
Load the corresponding module
Produce temporary py files and transfer them to the target machine's ~ / .ansible / tmp directory
Add + x permission to the py file, execute and return the result
Delete py file and sleep 0 to exit

1.4 Ansible execution status description

Green: successful execution, no need to make changes
Yellow: successful execution, change the target host
Red: execution failed

2. Ansible installation and configuration

2.1 Install Ansible

Install Ansible, taking CentOS 7.6 as an example:

  [root@ansible ~]# cat /etc/redhat-release 
    CentOS Linux release 7.6.1810 (Core) 
    [root@ansible ~]# uname -a
    Linux ansible 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
#配置epel源
    [root@ansible ~]# cat /etc/yum.repos.d/epel-7.repo 
    [epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
    baseurl=http://mirrors.aliyun.com/epel/7/$basearch
    failovermethod=priority
    enabled=1
    gpgcheck=0
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
    [epel-debuginfo]
name=Extra Packages for Enterprise Linux 7 - $basearch - Debug
    baseurl=http://mirrors.aliyun.com/epel/7/$basearch/debug
    failovermethod=priority
    enabled=0
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
    gpgcheck=0
    [epel-source]
name=Extra Packages for Enterprise Linux 7 - $basearch - Source
    baseurl=http://mirrors.aliyun.com/epel/7/SRPMS
    failovermethod=priority
    enabled=0
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
    gpgcheck=0
#安装Ansible
    [root@ansible ~]# yum install ansible -y
#查看已安装Ansible版本
    [root@ansible ~]# ansible --version
    ansible 2.8.2
      config file = /etc/ansible/ansible.cfg
      configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
      ansible python module location = /usr/lib/python2.7/site-packages/ansible
      executable location = /usr/bin/ansible
      python version = 2.7.5 (default, Oct 30 2018, 23:45:53) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
    [root@ansible yum.repos.d]# 
    ansible-2.8.2-1.el7.noarch

　　View Ansible related documents

yum info ansible
rpm -qa ansible
rpm -ql ansibel | less

2.2 Ansible configuration file

The main configuration files and functions of Ansible are as follows:

/ etc / ansible / 
    ├── ansible.cfg # Ansible main configuration file 
    ├── hosts #Used to define the list of managed machines 
    └── roles #This directory is used to define roles

/etc/ansible/ansible.cfgDescription of main parameters of 　　Ansible configuration file


#Close the outdated parameter alarm deprecation_warnings = False #Close the 
    command alarm 
command_warnings = False 
    #Do not check for the first connection, cooperate with the following playbook to achieve password-free ssh login 
host_key_checking = False #Set the 
    number of parallels 
forks = 40 
#Open the 
    log log_path = / var / log / ansible.log 
    #ssh timeout time 
timeout = 30

2.3 hosts list

The default hosts file /etc/ansible/hosts, the operated host must be in the hosts list.

CD / etc / ansible 
Vim the hosts 
    # packet 
[Mons] 
    # Set host alias 
Ceph-Node-ansible_ssh_host. 1 = 172.16.93.1 
[Client] 
172.16.93.1:2222 
    # also supported domain and host names, final interpretation to the IP 
    # regular support Expression 
[kvm_node_all] 
172.16.93. [6: 9] 
#Set 
    grouping host variable [kvm_node_all: vars] 
ansible_ssh_user = root 
ansible_ssh_pass = Efly1234 
ansible_ssh_port = 22 
#Automatic 
    meaning variable my_name = zhangsan #Host 
    inheritance relationship, will inherit the parent ’s inheritance All variables 
[kvm_node_all: children] 
client

2.4 Ansible supervisor and managed machine do keys authentication (optional)

# Generate secret key 
    ssh-keygen 
# After generation, you will get the following 2 files 
    [root @ ansible ~] # tree /root/.ssh/ 
    /root/.ssh/ 
    ├── id_rsa 
    └── id_rsa.pub 
# The public key Write to the managed machine 
    ssh-copy-id 192.168.199.52 
# or 
    ssh-copy-id -i /root/.ssh/id_rsa.pub -p 22 [email protected]