Why containers on Azure matter - Why It Works

Introduction

Containers help you package your app and everything it needs to run in one box. Azure lets you run these containers easily in the cloud, so your app works the same everywhere and can grow when many people use it.

When you want to move your app to the cloud without changing how it works on your computer.

When you need to run many copies of your app to handle lots of users at the same time.

When you want to update your app often without stopping it for a long time.

When you want to save money by using only the cloud resources your app needs at the moment.

When you want to keep your app safe and separate from other apps running on the same cloud.

Commands

This command creates a container registry in Azure where you can store your container images safely.

Terminal

az acr create --resource-group example-group --name exampleRegistry --sku Basic

Expected Output

{

  "adminUserEnabled": false,

  "creationDate": "2024-06-01T12:00:00Z",

  "id": "/subscriptions/xxxx/resourceGroups/example-group/providers/Microsoft.ContainerRegistry/registries/exampleRegistry",

  "location": "eastus",

  "loginServer": "exampleRegistry.azurecr.io",

  "name": "exampleRegistry",

  "resourceGroup": "example-group",

  "sku": {

    "name": "Basic",

    "tier": "Basic"

  },

  "status": "Succeeded",

  "type": "Microsoft.ContainerRegistry/registries"

}

→

--resource-group - Specifies the Azure group where the registry will be created

→

--name - Sets the unique name for your container registry

→

--sku - Chooses the pricing tier for the registry

This command logs you into the Azure container registry so you can push and pull container images.

Terminal

az acr login --name exampleRegistry

Expected Output

Login Succeeded

→

--name - Specifies which container registry to log into

This command builds your container image from your app code and tags it with the registry address and version.

Terminal

docker build -t exampleRegistry.azurecr.io/my-app:v1 .

Expected Output

Sending build context to Docker daemon  10.24kB

Step 1/5 : FROM node:18-alpine

 ---> 123abc456def

Step 2/5 : WORKDIR /app

 ---> Using cache

 ---> 789ghi012jkl

Step 3/5 : COPY package*.json ./

 ---> Using cache

 ---> mno345pqr678

Step 4/5 : RUN npm install

 ---> Running in abc123def456

Removing intermediate container abc123def456

 ---> stu901vwx234

Step 5/5 : COPY . .

 ---> Using cache

 ---> yz567abc890

Successfully built yz567abc890

Successfully tagged exampleRegistry.azurecr.io/my-app:v1

This command uploads your container image to the Azure container registry so it can be used in the cloud.

Terminal

docker push exampleRegistry.azurecr.io/my-app:v1

Expected Output

The push refers to repository [exampleRegistry.azurecr.io/my-app]

123abc456def: Pushed 

789ghi012jkl: Pushed 

mno345pqr678: Pushed 

stu901vwx234: Pushed 

yz567abc890: Pushed 

v1: digest: sha256:abcdef1234567890 size: 1578

This command creates a container instance in Azure to run your app with 1 CPU, 1.5 GB memory, and makes it reachable on the internet with a DNS name.

Terminal

az container create --resource-group example-group --name myAppContainer --image exampleRegistry.azurecr.io/my-app:v1 --cpu 1 --memory 1.5 --dns-name-label myappdnslabel --ports 80

Expected Output

{

  "id": "/subscriptions/xxxx/resourceGroups/example-group/providers/Microsoft.ContainerInstance/containerGroups/myAppContainer",

  "name": "myAppContainer",

  "location": "eastus",

  "properties": {

    "provisioningState": "Succeeded",

    "containers": [

      {

        "name": "myAppContainer",

        "properties": {

          "image": "exampleRegistry.azurecr.io/my-app:v1",

          "resources": {

            "requests": {

              "cpu": 1.0,

              "memoryInGb": 1.5

            }

          },

          "ports": [

            {

              "port": 80

            }

          ]

        }

      }

    ],

    "ipAddress": {

      "dnsNameLabel": "myappdnslabel",

      "ports": [

        {

          "port": 80,

          "protocol": "TCP"

        }

      ],

      "type": "Public"

    }

  },

  "type": "Microsoft.ContainerInstance/containerGroups"

}

→

--cpu - Sets how many CPUs the container can use

→

--memory - Sets how much memory the container can use

→

--dns-name-label - Creates a public DNS name to access the container

Key Concept

If you remember nothing else from this pattern, remember: containers let you package your app once and run it anywhere in Azure with the same behavior and easy scaling.

Common Mistakes

Trying to push a container image without logging into the Azure container registry first

The push will fail because Docker does not have permission to upload the image

Always run 'az acr login --name exampleRegistry' before pushing images

Not tagging the container image with the full registry login server address before pushing

Docker will try to push to Docker Hub or another default registry and fail

Tag images with 'exampleRegistry.azurecr.io/my-app:tag' before pushing

Creating a container instance without specifying ports or DNS name

Your app will run but you won't be able to access it from the internet

Use '--ports' and '--dns-name-label' flags to expose your app publicly

Summary

Create an Azure container registry to store your container images securely.

Build and tag your container image with the registry address.

Log in to the registry and push your container image.

Create a container instance in Azure to run your app with specified resources and public access.