# The YAML Files

# YAML

**YAML** is an information transfer language like ***JSON*** or ***XML***. And it is used for its simplicity and consistency.

# File Extention

These YAML files end with `.yml` or `.yaml`, either of them is correct.

# Indentation

The indentation in YAML is essential, to make an indentation valid you need to use ***2 spaces per indentation***. Indentation is used instead of curly brackets `{}`.

# Syntax

You don't end the line with a `;` or any other special character.

## Comments

Use the `#` symbol to ignore whatever it is in front of this symbol until the end of the line.

```yaml
# variable: string commented
valid: "not commented"
```

## Objects

You use indentation to denote that the variables below are methods of the object. YAML is sensitive to indentation so they all need to be at the same level of indentation.

```yaml
nameoftheobject:
  app: some-name
  port: 9000
  version: 1.7
```

## Lists

Use the `-` symbol to make a list, remember to indent the variables that belong to that list. But you can also avoid indentation while using lists, so don't get confused when you see them in different forms of indentation. But all elements need to have the same indentation.

```yaml
microservices:
  - app: some-name
	port: 9000
	version: 1.7
  - app: other-name
	port: 9002
	version: 1.9
```

```yaml
microservices:
  - some-name
  - other-name
  - app: dog
	port: 19
	versions:
	- 1.2
	- 1.5
	- 1.8
```

You can also use brackets as a primitive.

```yaml
microservices:
  - some-name
  - other-name
  - app: dog
	port: 19
	versions: [1.2, 1.5, 1.8]
```

## Boolean

`true` `false` `yes` `no` `on` and `off`, all of them are used as boolean values.

### Multiline strings

Use the `|` symbol to make separate lines, and use the `>` symbol to make a single line of the string.

```yaml
multilineString: |
  This string is separated
  so there is no need to make a buzz
  this is how it will be shown
```

```yaml
multilineString: >
  This line will be shown as
  one line, no matter how long
  or how many breaks do I make
```

## Environment Variables

Use the `$` **before the name of the environment variable** to use it.

```yaml
command: mysql -h 123.000.000 -u root $THIS_IS_A_PASSWORD -e 'SELECT 1'
```

## Placeholders

Use the double curly brackets `{{}}`to use placeholders for templates.

```yaml
app: {{ .Values.service.name }}
```

## Multiple YAML Files

Use three dashes `---` to separate YAML files inside the same file.

```yaml
thisIsAVariable: blah-blah-blah

---
thisIsAnotherFileInside: this-is-another-file
```

---

Well, that's it for now. I hope it was useful for you. Comment if you have any other suggestions or something to add, I'll be reading you.

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