ACR image building and pushing in Azure - Step-by-Step Execution

Process Flow - ACR image building and pushing

Write Dockerfile

↓

Build Docker Image

↓

Login to ACR

↓

Tag Image with ACR Repo

↓

Push Image to ACR

↓

Image Stored in ACR

This flow shows the steps to build a Docker image locally, log in to Azure Container Registry (ACR), tag the image for ACR, and push it to store in the registry.

Execution Sample

Azure

az acr login --name myRegistry
docker build -t myapp:v1 .
docker tag myapp:v1 myRegistry.azurecr.io/myapp:v1
docker push myRegistry.azurecr.io/myapp:v1

This code logs into ACR, builds the Docker image locally from the current folder, tags it for ACR, and pushes it to ACR with the tag 'myapp:v1'.

Process Table

Step	Action	Command/Process	Result/Output
1	Login to ACR	az acr login --name myRegistry	Authenticated to myRegistry
2	Build and push image	docker build -t myapp:v1 . docker tag myapp:v1 myRegistry.azurecr.io/myapp:v1 docker push myRegistry.azurecr.io/myapp:v1	Image built locally and pushed to myRegistry/myapp:v1
3	Verify image	az acr repository show-tags --name myRegistry --repository myapp	Tags: v1
4	Exit	No further commands	Image available in ACR for deployments

💡

Status Tracker

Variable	Start	After Login	After Build & Push	Final
Authentication Status	Not logged in	Logged in	Logged in	Logged in
Local Image	Not built	Not built	Built	Built
ACR Image Tags	None	None	v1	v1

Key Moments - 3 Insights

Why do we need to login to ACR before pushing the image?

Logging in authenticates your local machine with ACR, allowing secure push access. See execution_table step 1 where login happens before build and push.

What happens if the image is not tagged correctly with the ACR repository?

The push will fail or go to the wrong place. Tagging with the ACR repo name ensures the image is pushed to the right registry, as shown in step 2.

How do we confirm the image is in ACR after pushing?

By listing tags in the repository using 'az acr repository show-tags', as shown in step 3, confirming the image tag exists.

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after step 1?

A Image pushed to ACR

B Image built locally

C Authenticated to myRegistry

D No authentication

💡 Hint

Check the 'Result/Output' column for step 1 in execution_table.

At which step is the image actually pushed to ACR?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the 'Action' and 'Result/Output' columns in execution_table for when push happens.

If you skip the login step, what variable in variable_tracker would remain unchanged?

A Local Image

B Authentication Status

C ACR Image Tags

D Final

💡 Hint

Check 'Authentication Status' changes in variable_tracker after login.

Concept Snapshot

ACR Image Build & Push:
1. Login to ACR with 'az acr login'.
2. Build image locally, tag with ACR repo name, and push using Docker CLI.
3. Verify image with 'az acr repository show-tags'.
This process stores your container image securely in Azure.

Full Transcript

To build and push a container image to Azure Container Registry (ACR), first write your Dockerfile. Then login to your ACR using 'az acr login --name yourRegistry'. Next, build the image locally with 'docker build -t yourImage:tag .', tag it with 'docker tag yourImage:tag yourRegistry.azurecr.io/yourImage:tag', and push it with 'docker push yourRegistry.azurecr.io/yourImage:tag'. These commands build the image locally and push it to your ACR. Finally, verify the image is stored by listing tags with 'az acr repository show-tags'. This sequence ensures your image is ready for deployment from ACR.

Practice

1. What is the primary purpose of the az acr build command in Azure Container Registry (ACR)?

easy

A. To run a container instance in Azure

B. To delete an image from ACR

C. To create a new Azure Container Registry

D. To build a container image and push it directly to ACR

Solution

1. Step 1: Understand the command purpose

   The az acr build command is designed to build container images from a Dockerfile and push them to an Azure Container Registry.

2. Step 2: Compare options with command function

   Options A, B, and C describe other unrelated actions like deleting images, creating registries, or running containers, which are not the purpose of az acr build.

3. Final Answer:

   To build a container image and push it directly to ACR -> Option D

4. Quick Check:

   az acr build = build and push image [OK]

Hint: Remember: az acr build builds and pushes images [OK]

Common Mistakes:

• Confusing build with delete or create registry commands
• Thinking az acr build runs containers
• Assuming it only builds locally without pushing

2. Which of the following is the correct syntax to build and push an image named myapp:v1 to an Azure Container Registry named myregistry using az acr build?

easy

A. az acr build --registry myregistry --image myapp:v1 .

B. az acr build --image myapp:v1 --registry myregistry

C. az acr build --name myregistry --tag myapp:v1 .

D. az acr build --push --image myapp:v1 --registry myregistry

Solution

1. Step 1: Identify correct parameter order and names

   The correct syntax uses --registry to specify the registry, --image for image name and tag, followed by the build context path (here . for current directory).

2. Step 2: Validate options

   az acr build --image myapp:v1 --registry myregistry omits the required build context path (.). az acr build --registry myregistry --image myapp:v1 . matches the correct syntax. az acr build --name myregistry --tag myapp:v1 . uses incorrect flags --name and --tag which are invalid. az acr build --push --image myapp:v1 --registry myregistry uses --push which is not a valid flag for az acr build.

3. Final Answer:

   az acr build --registry myregistry --image myapp:v1 . -> Option A

4. Quick Check:

   Correct flags: --registry, --image, context path [OK]

Hint: Use --registry then --image followed by context path [OK]

Common Mistakes:

• Using --name instead of --registry
• Adding unsupported flags like --push
• Omitting the build context path

3. Given the command:

az acr build --registry myregistry --image sampleapp:latest ./app

What will happen after this command runs successfully?

medium

A. The image sampleapp:latest is pulled from myregistry and run locally

B. The Dockerfile in ./app is built into an image tagged sampleapp:latest and pushed to myregistry

C. A new Azure Container Registry named sampleapp is created

D. The local Docker daemon builds the image but does not push it

Solution

1. Step 1: Understand the command behavior

   The az acr build command builds the Dockerfile found in the specified path (./app) and pushes the resulting image to the specified Azure Container Registry (myregistry) with the given tag (sampleapp:latest).

2. Step 2: Eliminate incorrect options

   The image sampleapp:latest is pulled from myregistry and run locally describes pulling and running, which az acr build does not do. A new Azure Container Registry named sampleapp is created talks about creating a registry, which requires a different command. The local Docker daemon builds the image but does not push it suggests local build only, but az acr build builds in Azure and pushes automatically.

3. Final Answer:

   The Dockerfile in ./app is built into an image tagged sampleapp:latest and pushed to myregistry -> Option B

4. Quick Check:

   az acr build builds and pushes image [OK]

Hint: az acr build builds remotely and pushes automatically [OK]

Common Mistakes:

• Thinking image is only built locally
• Confusing build with run or pull
• Assuming registry is created automatically

4. You run the command:

az acr build --registry myregistry --image myapp:v2 ./src

but get an error saying Dockerfile not found. What is the most likely cause?

medium

A. The image tag myapp:v2 is invalid

B. The registry name myregistry is incorrect

C. The ./src directory does not contain a Dockerfile

D. You forgot to login to Azure CLI

Solution

1. Step 1: Analyze the error message

   The error Dockerfile not found means the build context directory (./src) does not have a Dockerfile, which is required to build the image.

2. Step 2: Check other options

   Incorrect registry or image tag would cause different errors. Forgetting to login would cause authentication errors, not missing Dockerfile.

3. Final Answer:

   The ./src directory does not contain a Dockerfile -> Option C

4. Quick Check:

   Missing Dockerfile = Dockerfile not found error [OK]

Hint: Ensure Dockerfile exists in build context folder [OK]

Common Mistakes:

• Assuming registry or tag causes Dockerfile error
• Ignoring the build context path
• Not verifying Dockerfile presence before build

5. You want to build and push multiple images with tags v1 and latest for your app using az acr build. Which approach correctly achieves this in a single command?

hard

A. Use --image myapp:v1 --image myapp:latest with the build context path

B. Run az acr build twice, once for each tag

C. Use --tag v1,latest with the image name

D. Build locally twice and push manually

Solution

1. Step 1: Understand multi-tag build syntax

   The az acr build command supports specifying multiple --image flags to tag the same build with different tags in one command.

2. Step 2: Evaluate options

   Use --image myapp:v1 --image myapp:latest with the build context path correctly uses multiple --image flags. Run az acr build twice, once for each tag works but is two commands, not single. Use --tag v1,latest with the image name uses an invalid --tag flag. Build locally twice and push manually is manual and not a single command.

3. Final Answer:

   Use --image myapp:v1 --image myapp:latest with the build context path -> Option A

4. Quick Check:

   Multiple --image flags tag multiple images [OK]

Hint: Use multiple --image flags to tag in one build [OK]

Common Mistakes:

• Trying to use --tag with multiple tags
• Running separate builds unnecessarily
• Building locally instead of using az acr build