Day 57: Comprehensive Guide to YAML

YAML is used for configuration files in software applications, enabling easy modification and readability. It's vital for defining complex structures like API documentation or orchestrating multi-container setups in tools like Docker Compose. Additionally, it's valuable in CI/CD pipelines for defining deployment steps.

What is a MarkUp language?

• For example, we have HTML which is a markup language. It has a sequence of things which has to be done in order.

Likewise, we can have steps for the same,

\=> first header will come.

\=> Then we will have a list inside the body.

\=> Inside the list we have bullet points.

\=> In bullet we have paragraphs and other things.

• So this relation of what goes inside what is called MarkUp language, basically it stores "Documents".

Before: YAML => Yet Another MarkUp Language.

• It's not a programming language basically a data format used to exchange data.

After: YAML => YAML Ain't MarkUp language.

So why isn't Markup Language?

• Basically, a simple human-readable language that can be used to represent data.Thus it is called YAML

• In YAML, We can store data and can be used as instruction set for the CLI(Command Line Interface) to perform specific task.

Data Serialization and Deserialization.

• For example, we have data object of student who will be having name,roll.no and standard so we have to put that data in Android-iOS Phones or on Website so for the different apps, we need to change the code and syntax. So we used Serialization and Deserialization.

What is Data Serialization and Deserialization?

• Data Serialization is a process of converting data objects into a complex data structure in a Stream of bytes which are encrypted.

• Data Deserialization is a process opposite to serialization (Object turned into file) here files are decrypted into objects.

• For example, In JSON data when we get an API call where we get JSON data we convert that into JSON Objects.

What is YAML is used for?

• YAML (short for "YAML Ain't Markup Language" or sometimes "Yet Another Markup Language") is a human-readable data serialization format. It's often used for configuration files and data exchange between languages with different data structures. YAML files use indentation to represent nesting and hierarchy, making iteasily readable by both humans and computers.

• Configuration Files: Many software applications use YAML files to store configuration settings. This can include settings for web servers, databases, continuous integration pipelines, and more. The human-readable nature of YAML makes it well-suited for configuration files, as it's easy for developers to understand and modify.

• API Documentation: Some APIs and web services use YAML to define and document their endpoints, request parameters, and responses. This approach, often known as "Swagger" or "OpenAPI Specification" provides a clear and standardized way to describe API functionality.

• Docker Compose: Docker Compose, a tool for defining and running multi-container Docker applications, uses YAML files to define the services, networks, and volumes that make up a containerized application.

• Automation and Orchestration: YAML is often used in configuration management tools like Ansible and SaltStack to define the desired state of systems and automate deployment and management tasks.

• CI/CD Pipelines: Continuous Integration and Continuous Deployment (CI/CD) pipelines are often defined using YAML. Tools like Jenkins, GitLab CI/CD, and GitHub Actions Use YAML to describe the sequence of steps required to build, test, and deploy software.

• Configuration Files for Kubernetes: Kubernetes, a popular container orchestration platform, uses YAML files to define resources like pods, services, deployments, and more.

Benefits of YAML:

• Simple and Easy to read.

• It has strict syntax (Indentation is Important)

• Easily Convertible to JSON and XML.

• Most languages use YAML.

• More Powerful when representing complex data.

• Parsing is easy (reading data).

• The file of YAML will be .yaml or .yml.

---

Key-Value Pair, listform and blockform.

Key-Value Pair in YAML.

• In YAML we can store files in the form of Key : value pairs.

"apple" : "I am Red Fruit."

1 : "This is my roll.no."

list form in YAML

• Here we will store file in form of list and for that we will use '-'.

---
 -apple
 -mango
 -banana
 -cherries
 -watermelon
...

# YAML is case sensitive (Apple and apple are two different things.)

---
 -Apple
 -Mango
...

Blockform in YAML.

• Here we will see how to use list in block form which is a kind of Array in another language.

---
# Listform of collection city name under `cities` in Blockform.
cities :
     -Mumbai
     -New Delhi
     -Chennai
     -Kolkata
     -Bangalore
     -Surat
...

---
#Another way of writing blockform.
cities : [Mumbai,New Delhi,Chennai,Kolkata,Bangalore,Surat]
...

How to write the Blockform file into a JSON file.

{
    "cities" : [
        "Mumbai",
        "New Delhi",
        "Chennai",
        "Kolkata",
        "Bangalore",
        "Surat"
    ],

    "Cities" :["Mumbai","New Delhi","Chennai","Kolkata","Bangalore","surat"]
}

Basic Datatype in YAML.

• In YAML, data types refer to the different types of values that can be represented in a YAML document. YAML supports several basic data types, and these data types are used to represent various kinds of values, such as strings, numbers, booleans, lists, dictionaries, and more. Here are some common data types in YAML:

• Strings: Textual data can be represented as strings. Strings can be enclosed in single or double quotes, or left unquoted.

# string_example is a string.

string_example_0: Hello, World!
string_example_1: 'Hello, Rohit!'
string_example_2: "Hello, VScode!"

• Numbers: YAML supports integer and floating-point numbers, which can be written without quotes.

# integer_example is an integer.
integer_example: 42

# float_example is a floating-point number.
float_example: 3.14

• Booleans: Boolean values are represented as true or false (without quotes).

# boolean_example is a boolean.
boolean_example: true

• Null: The absence of a value is represented as null (without quotes).

# null_example represents a null value.
null_example: null
null_example_1: ~

Advanced Datatype in YAML.

Sequences in YAML

• Sequences: It is used to create a sequence of Array and for that, we use "!!seq"

#Here we will see how to write Sequence in Datatype.
#for that we use "!!seq"

---
Student : !!seq
     -marks
     -name
     -roll_no

...

#If some of the key of the sequence will be empty.

Sparse Seq :
      -how
      -are
      -you
      -
      -Null
      -sup
...

#Here we will see nested mapping : which is map within  map
---
name : Rohit Rajput
roll_no :
     age : 21
     job : student
...

---
#Same as,
Name : Rohit Rajput
role : { age : 21 , job : student}
...

Pair in YAML for Array of Hashtable.

• Pair: In YAML, the !!pair tag is not a widely used construct, and its usage might not be supported in all YAML parsers and applications. However, if you're interested in creating an array of hashtables using this tag, you can follow this approach:

array_of_hashtables:
  !!pair
    key1: value1
    key2: value2
  !!pair
    key1: another_value1
    key2: another_value2

Dictionaries in YAML.

• Dictionaries: In YAML, dictionaries are often referred to as "maps" or "associative arrays" and for that, we use "!!omap".

---
People : !!omap
  -Rohit :
     name : Rohit Rajput
     age : 21
     height : 678
  -Rahul :
    name : Rahul Op
    age : 26
    height : 786

...

#Here we will use reusing properties using anchor.
#we use "&" for function call at that instance.
---
liking : &like
    favfruit : Mango
    dislike : Grapes

Person 1 :
    name : Kunal
    << : *like

Person 2 :
    name : Rahul
    << : *like
    dislike : berries
    # this will overwrite like so my dislike will change from grapes to berries.

---

Happy Learning :)