YAML Introduction

YAML (YAML Ain't Markup Language) is a human-readable data serialization standard that is commonly used for configuration files and data exchange between languages with different data structures. It will be extremely useful in your network automation projects. If you are not familiar with YAML, there are many excellent tutorials and resources available.

• https://yaml.org/

The following exercises provide a basic introduction to YAML. To verify your solution, you can use online converters or CLI tools like yq or Nettowel. When working with YAML keep in mind the difference between version 1.1 and 1.2! yq and nettowel use version 1.2 as default.

Tip

You can install "nettowel" with pipx:

pipx install nettowel[full]

JSON to YAML

• Convert the following JSON to YAML:

json

{
    "host": "Switch01",
    "ip": "10.11.12.13",
    "dns": "8.8.8.8",
    "domain_name": "network.automation.lab",
    "fqdn": "Switch01.network.automation.lab"
}

Solution

---
host: Switch01
ip: 10.11.12.13
dns: 8.8.8.8
domain_name: network.automation.lab
fqdn: Switch01.network.automation.lab
...

• Convert the following JSON to YAML:

json

[
    "interface Gig1/0/1",
    "interface Gig1/0/2",
    "interface gig1/0/3"
]

Solution

---
- interface Gig1/0/1
- interface Gig1/0/2
- interface gig1/0/3
...

• Convert the following JSON to YAML:

json

{
    "OSPF": {
        "area": 10,
        "hello": 5,
        "interface-type": "p2p"
    },
    "bgp": {
        "asn": 65123,
        "rr": true
    }
}

Solution

---
OSPF: 
  area: 10
  hello: 5
  interface-type: p2p
bgp:
  asn: 65123
  rr: True
...

• Convert the following JSON to YAML:

json

[
    [
        11,
        "hr"
    ],
    [
        21,
        "finance"
    ],
    [
        31,
        "printer"
    ]
]

Solution

---
-
  - 11
  - hr
-
  - 21
  - finance
-
  - 31
  - printer
...

• Convert the following JSON to YAML:

json

{
    "ospf": {
        "area": 0,
        "interfaces": [
        {
            "name": "Gig1/0/1",
            "passive": false,
            "type": "p2p"
        },
        {
            "name": "Gig1/0/1",
            "passive": true,
            "type": "broadcast"
        }
        ],
        "redistribute": [
        "bgp",
        "isis"
        ],
        "id": "10.10.10.10"
    }
}

Solution

---
ospf:
  area: 0
  interfaces:
    - name: Gig1/0/1
      passive: False
      type: p2p
    - name: Gig1/0/1
      passive: True
      type: broadcast
  redistribute:
    - bgp
    - isis
  id: '10.10.10.10'
...

Craft YAML

• Create a sequence of mappings for vlan definitions with id and name as keys.

Solution

---
- name: hr
  id: 11
- name: finance
  id: 22
- name: printer
  id: 33
- name: server
  id: 100
...

• Create a mapping for interfaces with tagged and untagged vlan sequences.

Solution

---
Ethernet 1/0/1:
  tagged: [10, 11, 12, 20, 21]
  untagged: [1]
Ethernet 1/0/2:
  tagged: [13, 14, 15, 20]
  untagged: [1]
Ethernet 1/0/3:
  tagged: []
  untagged: [20]
...

• Write a YAML file with hostname, domain-name, a list of dns servers, a list of ntp servers and a list of syslog servers.

Solution

---
hostname: sw01
domain-name: network.automation.lab
dns:
  - 1.1.1.1 # CloudFlare
  - 8.8.8.8 # Google DNS
ntp:
  - 0.ch.pool.ntp.org
  - 1.ch.pool.ntp.org
syslog:
  - 10.0.0.11
...

YAML to JSON

• Convert the following YAML to JSON:

yaml

%YAML 1.1
---
sexagesimal: 123:10:10
port: 80
alt_port: !!str 8080
octal: 02472256
hexadecimal: 0x_0A_74_AE
binary: 0b1010_0111_0100_1010_1110
...

Solution

{
  "sexagesimal": 443410,
  "port": 80,
  "alt_port": "8080",
  "octal": 685230,
  "hexadecimal": 685230,
  "binary": 685230,
}

• Convert the following YAML to JSON:

yaml

%YAML 1.2
---
sexagesimal: 123:10:10
port: 80
alt_port: !!str 8080
octal: 02472256
hexadecimal: 0x_0A_74_AE
binary: 0b1010_0111_0100_1010_1110
...

Solution

{
  "sexagesimal": "123:10:10",
  "port": 80,
  "alt_port": "8080",
  "octal": 2472256,
  "hexadecimal": 685230,
  "binary": 685230
}

• Convert the following YAML to JSON:

yaml

%YAML 1.1
---
'on': on
'off': off
'yes': yes
'no': no
'~': ~ 
'none': none
...

Solution

{
  "no": false,
  "none": "none",
  "off": false,
  "on": true,
  "yes": true,
  "~": null
}

• Convert the following YAML to JSON:

yaml

%YAML 1.2
---
'on': on
'off': off
'yes': yes
'no': no
'~': ~ 
'none': none
...

Solution

{
  "on": "on",
  "off": "off",
  "yes": "yes",
  "no": "no",
  "~": null,
  "none": "none"
}

Tip

Always use True|true or False|false for booleans.

• Convert the following YAML to JSON:

yaml

---
name: &a Network Automation Labs
alias: *a
mgmt_vlan: &mgmt_vlan
  name: mgmt
  id: 4
access_vlan: &access_vlan
  name: access
  id: 123
vlans:
  - *mgmt_vlan
  - *access_vlan
...

Solution

{
  "name": "Network Automation Labs",
  "alias": "Network Automation Labs",
  "mgmt_vlan": {
    "name": "mgmt",
    "id": 4
  },
  "access_vlan": {
    "name": "access",
    "id": 123
  },
  "vlans": [
    {
      "name": "mgmt",
      "id": 4
    },
    {
      "name": "access",
      "id": 123
    }
  ]
}

• Convert the following YAML to JSON:

yaml

---
CustA: &service
  name: CustA
  redistribute: True
  ipv6: True
  ipv4: True
CustB:
  <<: *service
  name: CustB
...

Solution

{
  "CustA": {
    "name": "CustA",
    "redistribute": true,
    "ipv6": true,
    "ipv4": true
  },
  "CustB": {
    "name": "CustB",
    "redistribute": true,
    "ipv6": true,
    "ipv4": true
  }
}