- Ansible Playbook Essentials
- Gourav Shah
- 287字
- 2021-07-16 20:47:47
Plays
A playbook consists of one or more plays, which map groups of hosts to well-defined tasks. The preceding example contains three plays, each to configure one layer in the multitiered web application. Plays also define the order in which tasks are configured. This allows us to orchestrate multitier deployments. For example, configure the load balancers only after starting the web servers, or perform two-phase deployment where the first phase only adds this configurations and the second phase starts the services in the desired order.
YAML – the playbook language
As you may have already noticed, the playbook that we wrote previously resembles more of a text configuration than a code snippet. This is because the creators of Ansible chose to use a simple, human-readable, and familiar YAML format to blueprint the infrastructure. This adds to Ansible's appeal, as users of this tool need not learn any special programming language to get started with. Ansible code is self-explanatory and self-documenting in nature. A quick crash course on YAML should suffice to understand the basic syntax. Here is what you need to know about YAML to get started with your first playbook:
- The first line of a playbook should begin with "--- " (three hyphens) which indicates the beginning of the YAML document.
- Lists in YAML are represented with a hyphen followed by a white space. A playbook contains a list of plays; they are represented with "- ". Each play is an associative array, a dictionary, or a map in terms of key-value pairs.
- Indentations are important. All members of a list should be at the same indentation level.
- Each play can contain key-value pairs separated by ":" to denote hosts, variables, roles, tasks, and so on.
- Qt 5 and OpenCV 4 Computer Vision Projects
- Java 開發從入門到精通（第2版）
- 深入淺出Electron：原理、工程與實踐
- Effective C#：改善C#代碼的50個有效方法（原書第3版）
- 面向STEM的Scratch創新課程
- Java加密與解密的藝術
- INSTANT Django 1.5 Application Development Starter
- Java程序設計
- NGINX Cookbook
- 一塊面包板玩轉Arduino編程
- Scratch3.0趣味編程動手玩：比賽訓練營
- Essential C++（中文版）
- Scala編程（第5版）
- SQL Server 2016 從入門到實戰（視頻教學版）
- Java程序設計入門（第2版）