Azure Classroom Series – 15/May/2021

Azure Instance Metadata Service and jq

• The jq Refer Here is a light weight json parser.
• Example queries

curl -H Metadata:true --noproxy "*" "http://169.254.169.254/metadata/instance?api-version=2020-09-01" | jq '.| { os: .compute.osType}'

curl -H Metadata:true --noproxy "*" "http://169.254.169.254/metadata/instance?api-version=2020-09-01" | jq '.| { os: .compute.osType, distribution: .compute.offer}'


curl -H Metadata:true --noproxy "*" "http://169.254.169.254/metadata/instance?api-version=2020-09-01" | jq '.| { os: .compute.osType, distribution: .compute.offer, publicip: .network.interface[0].ipv4.ipAddress[].publicIpAddress}'

• Now lets try to write a script which uses IMDS
• This sample script runs on start up of the Linux VM and updates the packages

#!/bin/bash
offer=$(curl -H Metadata:true --noproxy "*" "http://169.254.169.254/metadata/instance/compute/offer?api-version=2020-09-01&format=text")
echo $offer
if [[ $offer == "UbuntuServer" ]]; then
   sudo apt update
elif [[ $offer == "Centos" ]]; then
   sudo yum update -y
else
   echo "The current distribution $offer is not supported"
fi

Azure CLI

• Ensure Azure CLI is installed on the machine
• Now connect to Azure

az login
# once the login is success
az group list

• Azure CLI is a command line utility which can be used to perform operations on Azure
• Azure CLI commands will be in the following structure

az <service> [<sub section>] <action> --parameter1 <value1> ... --parametern <valuen>

• Finding azure cli commands is very simple
• Exercise:
  • Create a resource group in Azure using portal
  • Now lets see how to do the same stuff using azure cli. Navigate to Refer Here
• Output formats for the cli commands Refer Here
• Lets try to use azure cli to search for VM images
• In Azure Any VM Image has the following relation b/w publisher, offer and sku
• Exercise: Explore different windows servers and centos server images available in Azure