Introduction to Ansible Batch Management Service

Significance of Ansible Batch Management

• Improves work efficiency.
• Enhances accuracy of operations.
• Reduces maintenance costs.
• Minimizes repetitive tasks.

Key Functionalities

• Perform batch system configuration and operations.
• Deploy software and services in bulk.
• Distribute files and data across multiple hosts.
• Collect system information from remote hosts.

Architecture Overview

• Inventory Configuration: Defines the list of managed hosts.
• Module Library: A collection of reusable modules for various tasks.
• SSH Key Authentication: Connects to hosts using SSH keys for secure, passwordless access.
• SELinux Requirement: SELinux must be disabled on managed hosts (or the libselinux-python package installed).
• Playbook System: Allows automation through reusable scripts.

Key Features

1. No Server on Control Node: Ansible does not require a daemon or server process.
2. Minimal Configuration: The control node can work with out a configuration file, but /etc/ansible/ansible.cfg is available.
3. No Agent on Managed Nodes: Managed hosts do not need Ansible installed (though libselinux-python is required if SELinux is not disabled).
4. No Agent Process on Managed Nodes: No background agent runs on the target machines.
5. Rich Module Ecosystem: A vast library of modules covers almost all administrative tasks.
6. Playbook Automation: YAML-based playbooks enable complex, automated workflows.

Official Documentation

• https://docs.ansible.com/

How to Access Help

• ansible-doc -l — List all available modules with brief descriptions.
• ansible-doc -s <module_name> — Show detailed options and parameters for a specific module.
• ansible-doc <module_name> — Display documentation examples for use in playbooks.

Deploying Ansible

Prerequisites (Control Node)

1. Install Ansible

   yum install -y ansible
   rpm -ql ansible
   

2. Configure Inventory File (/etc/ansible/hosts)

   # Add target host IPs or hostnames at the end of the file
   172.16.1.41
   172.16.1.7
   172.16.1.31
   

3. Test Connectivity

   ansible all -a "hostname"
   

Common Ansible Modules

The general syntax for using a module is:

ansible <host_pattern> -m <module_name> -a "<arguments>"

1. Command Module (Default Module)

Executes a simple command on the remote host. It does not process shell variables, redirects, or pipes.

Basic Usage:

ansible 172.16.1.31 -m command -a "ifconfig"

Common Parameters:

• chdir: Change to a directory before executing the command.

  ansible 172.16.1.31 -m command -a "chdir=/tmp touch oldboy.txt"
  

• creates: If the specified file already exists, the command is not executed.

  ansible 172.16.1.31 -m command -a "creates=/tmp/hosts touch oldboy.txt"
  

• removes: If the specified file exists, the command is executed.

  ansible 172.16.1.31 -m command -a "removes=/tmp/hosts chdir=/tmp touch oldboy.txt"
  

• free_form (required): A valid Linux command must be provided.

Important Note: The command module cannot handle shell operators like <, >, |, ;, and &.

2. Ping Module

Tests connectivity to the remote host.

ansible all -m ping

3. Shell Module (Universal Module)

Executes commands using the shell, supporting all shell features (pipes, redirects, variables).

Basic Usage:

ansible 172.16.1.31 -m shell -a "hostname"
ansible 172.16.1.31 -m shell -a "echo 123 > haha.txt"
ansible 172.16.1.31 -m shell -a "netstat -anptu | grep LISTEN"

4. Script Module (Universal Module)

Copies and executes a local script on the remote host.

Example:

1. Create a script on the control node (/root/yum.sh):

   #!/bin/bash
   yum install htop
   

2. Run the script on the target host:

   ansible 172.16.1.31 -m script -a "chdir=/root/yum.sh"
   

3. Verify installation:

   ansible 172.16.1.31 -m shell -a "rpm -qa | grep htop"
   

Note: The script module accepts similar parameters to the command module.

5. Copy Module

Copies files from the control node to the remote host.

Basic Usage:

ansible 172.16.1.31 -m copy -a "src=/etc/hosts dest=/root/"

Example Output:

172.16.1.31 | CHANGED => {
    "changed": true,
    "checksum": "6ed7f68a1d6b4b36c1418338b2001e421eeba270",
    "dest": "/root/hosts",
    "gid": 0,
    "group": "root",
    "md5sum": "7afd7b74854f0aaab646b3e932f427c0",
    "mode": "0644",
    "owner": "root",
    "size": 401,
    "src": "/root/.ansible/tmp/ansible-tmp-1557804498.23-26487341925325/source",
    "state": "file",
    "uid": 0
}

Advanced Usage:

• Change owner and group:

  ansible 172.16.1.31 -m copy -a "src=/etc/ansible/file/rsync/rsync.password dest=/etc/ owner=oldboy group=oldboy"
  

• Set permissions:

  ansible 172.16.1.31 -m copy -a "src=/etc/ansible/file/rsync/rsync.password dest=/etc/ mode=1777"
  

• Backup existing file on destination before copying:

  ansible 172.16.1.31 -m copy -a "src=/etc/ansible/file/rsync/rsync.password dest=/etc/ backup=yes"
  

• Create a file with specific content:

  ansible 172.16.1.31 -m copy -a "content='zhangbiao' dest=/root/zhangbiao.txt"
  

• Copy directories:

  • If src does not end with /, the directory itself and its contents are copied.
  • If src does end with /, only the contents of the directory are copied.

  # Copies /oldboy directory and its contents
  ansible 172.16.1.31 -m copy -a "src=/oldboy dest=/oldboy"
  # Copies only the contents of /oldboy
  ansible 172.16.1.31 -m copy -a "src=/oldboy/ dest=/oldboy"
  

6. File Module

Manages file attributes (owner, group, permissions) and creates/deletes files, directories, or symlinks.

Basic Usage (Set attributes):

ansible 172.16.1.31 -m file -a "dest=/etc/hosts owner=oldboy group=oldboy mode=666"

state Parameter Values:

• absent: Delete the file or directory.
• directory: Create a directory (recursively if needed).
• file: Check if the file exists. No change if exists, error if not.
• hard: Create a hard link.
• link: Create a symbolic link.
• touch: Create an empty file.

Examples:

• Create a directory:

  ansible 172.16.1.31 -m file -a "dest=/oldboy/ state=directory"
  ansible 172.16.1.31 -m file -a "dest=/oldboy/oldboy01/oldboy02/ state=directory"
  

• Create a file:

  ansible 172.16.1.31 -m file -a "dest=/oldboy/oldboy.txt state=touch"
  

• Create links:

  ansible 172.16.1.31 -m file -a "src=/oldboy/oldboy.txt dest=/oldboy/oldboy_hard.txt state=hard"
  ansible 172.16.1.31 -m file -a "src=/oldboy/oldboy.txt dest=/oldboy/oldboy_link.txt state=link"
  

• Delete files or directories:

  ansible 172.16.1.31 -m file -a "dest=/oldboy/oldboy.txt state=absent"
  ansible 172.16.1.31 -m file -a "dest=/oldboy/  state=absent"
  

7. Fetch Module

Pulls a file from a remote host to the control node. The file is saved in a directory structure matching the hostname.

ansible 172.16.1.31 -m fetch -a "src=/tmp/oldboy.txt dest=/tmp"

8. Yum Module

Manages packages using the yum package manager.

Parameters:

• name: Package name.
• state: Desired state (installed, present, latest to install; absent, removed to remove).

ansible 172.16.1.31 -m yum -a "name=iotop state=installed"

9. Service Module

Controls services on remote hosts (start, stop, restart, enable at boot).

Parameters:

• name: Service name.
• state: started, restarted, stopped.
• enabled: yes to enable at boot, no to disable.

Example: Start NFS service and enable it at boot.

ansible 172.16.1.31 -m service -a "name=nfs state=started enabled=yes"

10. Cron Module

Manages cron jobs on remote hosts.

Parameters: minute, hour, day, month, weekday, job.

Basic Usage:

# Schedule time sync at 2:00 AM daily
ansible 172.16.1.31 -m cron -a "minute=0 hour=2 job='/usr/sbin/ntpdate ntp1.aliyun.com >/dev/null 2>&1'"

Advanced Usage:

• Add a comment/name to the cron job:

  ansible 172.16.1.31 -m cron -a "name='time sync' minute=0 hour=2 job='/usr/sbin/ntpdate ntp1.aliyun.com >/dev/null 2>&1'"
  

• Remove a cron job (only works for jobs created by Ansible):

  ansible 172.16.1.31 -m cron -a "name='time sync01' state=absent"
  

• Disable (comment out) a cron job:

  ansible 172.16.1.31 -m cron -a "name='time sync' job='/usr/sbin/ntpdate ntp1.aliyun.com >/dev/null 2>&1' disabled=yes"
  

11. Mount Module

Manages mount points and fstab entries.

Parameters:

• src: Device or remote filesystem.
• path: Mount point.
• fstype: Filesystem type.
• state: present (add to fstab only), mounted (mount and add to fstab), absent (unmount and remove from fstab), unmounted (unmount only).

Example: Mount an NFS share.

ansible 172.16.1.31 -m mount -a 'fstype=nfs src=172.16.1.31:/nfs path=/mnt state=mounted'

12. User Module

Manages user accounts.

Basic Usage (Create a user):

ansible 172.16.1.31 -m user -a "name=oldboy01"

Advanced Usage:

• Set UID:

  ansible 172.16.1.31 -m user -a "name=oldboy02 uid=6666"
  

• Set primary group or supplementary groups:

  # Primary group
  ansible 172.16.1.31 -m user -a "name=oldboy03 group=oldboy02"
  # Supplementary groups
  ansible 172.16.1.31 -m user -a "name=oldboy04 groups=oldboy02"
  

• Create a system user (no home directory, no login shell):

  ansible 172.16.1.31 -m user -a "name=rsync create_home=no shell=/sbin/nologin"
  

• Set password (password must be a hashed string):

  Generate a hashed password:

  • Method 1:

    ansible all -i localhost, -m debug -a "msg={{ '123456' | password_hash('sha512', 'oldboy') }}"
    

  • Method 2:

    yum install -y python-pip
    pip install passlib
    python -c "from passlib.hash import sha512_crypt; import getpass; print(sha512_crypt.using(rounds=5000).hash(getpass.getpass()))"
    

  Apply the hashed password:

  ansible 172.16.1.31 -m user -a 'name=oldboy08 password=$6$oldboy$MVd3DevkLcimrBLdMICrBY8HF82Wtau5cI8D2w4Zs6P1cCfMTcnnyAmmJc7mQaE9zuHxk8JFTRgYMGv9uKW7j1'
  

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Note: This guide covers the most common used modules for routine system administration tasks. Refer to the official documentation for a complete list and advanced usage.