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什么是 Ansible pre_tasks？ 如何在远程主机 [Linux] 上更新操作系统、安装 Python 和安装 JRE？

已发表: 2019-05-10

什么是 Ansible pre_tasks？如何在远程主机上更新操作系统、安装 Python 和安装 JDK

Ansible 中的 pre_tasks 是什么？

pre_tasks是 Ansible 在执行.yml文件中提到的任何tasks之前执行的任务。

考虑这种情况。 您在Amazon EC2云或Google Cloud上预置了一个新实例。 您需要做的第一件事是安装操作系统更新。 然后安装最新的 Python，安装 Java 等等。

完成上述所有前置任务后，您需要复制您的应用程序并启动这些应用程序。 在复制应用程序依赖项之前，必须安装所有基本二进制文件。

在本教程中，我们将详细介绍如何使用 Ansible pre_task标签执行预任务。

什么是 Ansible pre_tasks？在远程主机上更新操作系统、安装 Python 和安装 JRE？

我们将在本教程中遵循以下场景：

  1. 创建文件crunchify-hosts文件并添加我们将在其上执行 pre_task 的 IP。
  2. 创建文件crunchify-install-python-java.yml这是 ansible playbook。
    • pre_task：安装 python-simplejson
    • pre_task: 安装 python-minimal
    • pre_task：安装系统更新
    • pre_task：安装最新的 JRE
  3. 获取 Python 版本
  4. 获取 Java 版本
  5. 打印所有调试结果
  6. 运行命令 ansible-playbook -i ./crunchify-hosts crunchify-install-python-java.yml 这将执行我们所有的任务

crunchify-hosts 文件

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[ local ]
localhost ansible_connection = local ansible_python_interpreter = python
 
[ crunchify ]
13.58.187.197
 
[ crunchify : vars ]
ansible_ssh_user = ubuntu
ansible_ssh_private_key_file =/ Users / crunchify / Documents / ansible / crunchify . pem
ansible_python_interpreter =/ usr / bin / python3

如您所见，我正在使用crunchify.pem文件进行无密码身份验证。 我可以简单地连接到我的主机而无需任何密码提示。

crunchify-install-python-java.yml 文件

我们在 Ansible 中使用register关键字来注册变量。 它存储raw任务的返回值。

在debug和stdout_lines的帮助下，您可以在命令行上打印结果。

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---
- hosts : crunchify
   become : yes
 
   pre_tasks :
     - raw : sudo apt - get - y install python - simplejson
       register : py_simple_output
     - raw : sudo apt - get - y install python - minimal
       register : py_minimal_output
     - raw : sudo apt - get update
       register : system_output
     - raw : sudo apt - get install - y default - jre
       register : java_output
 
   tasks :
  
    - debug :
         var = py_simple_output . stdout_lines
 
    - debug :
         var = py_minimal_output . stdout_lines
 
    - debug :
         var = system_output . stdout_lines
 
    - debug :
         var = java_output . stdout_lines
 
    - name : get Python version
       shell : python -- version 2 > &1
       register : py_output
    
    - debug :
         var = py_output . stdout_lines
      
    - name : get Java version
       shell : java -- version 2 > &1
       register : java_output
    
    - debug :
         var = java_output . stdout_lines

运行命令：

ansible-playbook -i ./crunchify-hosts crunchify-install-python-java.yml

Ansible 输出：

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bash1 . 2 $ ansible - playbook - i . / crunchify - hosts crunchify - install - python - java . yml
 
PLAY [ crunchify ] ***************************************************************************************************************************************************
 
TASK [ Gathering Facts ] *********************************************************************************************************************************************
ok : [ 13.58.187.197 ]
 
TASK [ raw ] *********************************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ raw ] *********************************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ raw ] *********************************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ raw ] *********************************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "py_simple_output.stdout_lines" : [
         "" ,
         "Reading package lists... 0%" ,
         "" ,
         "Reading package lists... 100%" ,
         "" ,
         "Reading package lists... Done" ,
         "" ,
         "" ,
         "Building dependency tree... 0%" ,
         "" ,
         "Building dependency tree... 50%" ,
         "" ,
         "Building dependency tree       " ,
         "" ,
         "" ,
         "Reading state information... 0%" ,
         "" ,
         "Reading state information... Done" ,
         "" ,
         "python-simplejson is already the newest version (3.13.2-1)." ,
         "0 upgraded, 0 newly installed, 0 to remove and 76 not upgraded."
     ]
}
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "py_minimal_output.stdout_lines" : [
         "" ,
         "Reading package lists... 0%" ,
         "" ,
         "Reading package lists... 100%" ,
         "" ,
         "Reading package lists... Done" ,
         "" ,
         "" ,
         "Building dependency tree... 0%" ,
         "" ,
         "Building dependency tree... 50%" ,
         "" ,
         "Building dependency tree       " ,
         "" ,
         "" ,
         "Reading state information... 0%" ,
         "" ,
         "Reading state information... Done" ,
         "" ,
         "python-minimal is already the newest version (2.7.15~rc1-1)." ,
         "0 upgraded, 0 newly installed, 0 to remove and 76 not upgraded."
     ]
}
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "system_output.stdout_lines" : [
         "" ,
         "0% [Working]" ,
         "            " ,
         "Hit:1 http://us-east-2.ec2.archive.ubuntu.com/ubuntu bionic InRelease" ,
         "" ,
         "0% [Connecting to security.ubuntu.com (91.189.88.162)]" ,
         "                                                      " ,
         "Hit:2 http://us-east-2.ec2.archive.ubuntu.com/ubuntu bionic-updates InRelease" ,
         "" ,
         "                                                      " ,
         "Get:3 http://us-east-2.ec2.archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]" ,
         "" ,
         "0% [Connecting to security.ubuntu.com (91.189.88.162)]" ,
         "0% [1 InRelease gpgv 242 kB] [Connecting to security.ubuntu.com (91.189.88.162)" ,
         "                                                                               " ,
         "0% [Connecting to security.ubuntu.com (91.189.88.162)]" ,
         "0% [2 InRelease gpgv 88.7 kB] [Connecting to security.ubuntu.com (91.189.88.162" ,
         "                                                                               " ,
         "0% [Waiting for headers]" ,
         "0% [3 InRelease gpgv 74.6 kB] [Waiting for headers]" ,
         "                                                   " ,
         "Hit:4 http://security.ubuntu.com/ubuntu bionic-security InRelease" ,
         "" ,
         "                                                   " ,
         "0% [3 InRelease gpgv 74.6 kB]" ,
         "                             " ,
         "0% [Working]" ,
         "0% [4 InRelease gpgv 88.7 kB]" ,
         "                             " ,
         "100% [Working]" ,
         "              " ,
         "Fetched 74.6 kB in 0s (249 kB/s)" ,
         "" ,
         "Reading package lists... 0%" ,
         "" ,
         "Reading package lists... 5%" ,
         "" ,
         "Reading package lists... 8%" ,
         "" ,
         "Reading package lists... 53%" ,
         "" ,
         "Reading package lists... 79%" ,
         "" ,
         "Reading package lists... 99%" ,
         "" ,
         "Reading package lists... Done" ,
         ""
     ]
}
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "java_output.stdout_lines" : [
         "" ,
         "Reading package lists... 0%" ,
         "" ,
         "Reading package lists... 100%" ,
         "" ,
         "Reading package lists... Done" ,
         "" ,
         "" ,
         "Building dependency tree... 0%" ,
         "" ,
         "Building dependency tree... 50%" ,
         "" ,
         "Building dependency tree       " ,
         "" ,
         "" ,
         "Reading state information... 0%" ,
         "" ,
         "Reading state information... Done" ,
         "" ,
         "default-jre is already the newest version (2:1.11-68ubuntu1~18.04.1)." ,
         "0 upgraded, 0 newly installed, 0 to remove and 76 not upgraded."
     ]
}
 
TASK [ get Python version ] ******************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "py_output.stdout_lines" : [
         "Python 2.7.15rc1"
     ]
}
 
TASK [ get Java version ] ********************************************************************************************************************************************
changed : [ 13.58.187.197 ]
 
TASK [ debug ] *******************************************************************************************************************************************************
ok : [ 13.58.187.197 ] = > {
     "java_output.stdout_lines" : [
         "openjdk 11.0.2 2019-01-15" ,
         "OpenJDK Runtime Environment (build 11.0.2+9-Ubuntu-3ubuntu118.04.3)" ,
         "OpenJDK 64-Bit Server VM (build 11.0.2+9-Ubuntu-3ubuntu118.04.3, mixed mode, sharing)"
     ]
}
 
PLAY RECAP * ********************************************************************************************************************************************************
13.58.187.197                : ok = 13    changed = 6      unreachable = 0      failed = 0   

而已。

如您所见，在本教程中，我们在远程主机上安装了 Python、java 和系统更新。 此外，将结果返回到 mac 终端窗口。

下一步是什么？

尝试查看有关如何将文件、目录或脚本从本地主机复制到远程主机的教程。