Setting up private registry in Docker - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to start a private Docker registry container.

Docker

docker run -d -p 5000:5000 --name registry [1] registry:2

Drag options to blanks, or click blank then click option'

A--restart always

B--network host

C-it

D--rm

Attempts:

3 left

💡 Hint

Common Mistakes

Using --rm removes the container after it stops, which is not desired for a registry.

Using -it is for interactive mode, not needed here.

Using --network host changes networking and is not required.

The --restart always option ensures the registry container restarts automatically if it stops.

2fill in blank

medium

Complete the command to tag a local image for pushing to the private registry.

Docker

docker tag myapp:latest localhost[1]5000/myapp:latest

Drag options to blanks, or click blank then click option'

A.

B/

C-

D:

Attempts:

3 left

💡 Hint

Common Mistakes

Using / between host and port creates an invalid registry address.

Using dash or dot is invalid in this context.

The colon : separates the host from the port in the registry address.

3fill in blank

hard

Fix the error in the command to push the image to the private registry.

Docker

docker push localhost:5000[1]myapp:latest

Drag options to blanks, or click blank then click option'

A:

B/

C-

D.

Attempts:

3 left

💡 Hint

Common Mistakes

Using colon before image name causes Docker to look for a tag, not a path.

Using dash or dot is invalid syntax.

The slash / is needed to separate the registry address from the image name when pushing.

4fill in blank

hard

Fill both blanks to create a secure registry with TLS certificates.

Docker

docker run -d -p 5000:5000 --name registry -v [1]:/certs -e REGISTRY_HTTP_TLS_CERTIFICATE=[2]/cert.pem -e REGISTRY_HTTP_TLS_KEY=[2]/key.pem registry:2

Drag options to blanks, or click blank then click option'

A/home/user/certs

B/etc/ssl

C/certs

D/var/lib/registry

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong container path causes registry to not find certificates.

Mounting wrong local directory means certificates won't be available.

The local directory /home/user/certs is mounted to /certs inside the container where the registry expects TLS files.

5fill in blank

hard

Fill all three blanks to configure Docker daemon to trust the private registry.

Docker

{
  "insecure-registries": ["[1]:[2]"],
  "debug": [3]
}

Drag options to blanks, or click blank then click option'

Alocalhost

B5000

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong host or port prevents Docker from trusting the registry.

Setting debug to false disables helpful logs during setup.

Docker daemon needs the registry address and port in insecure-registries to allow pushing to insecure or self-signed registries. Debug mode is set to true for detailed logs.

Practice

1. What is the main purpose of setting up a private Docker registry?

easy

A. To automatically update Docker images from Docker Hub

B. To speed up Docker container execution

C. To store Docker images securely within your own network

D. To monitor running Docker containers

Solution

1. Step 1: Understand what a Docker registry does

   A Docker registry stores Docker images so they can be shared and reused.

2. Step 2: Identify the benefit of a private registry

   A private registry keeps images secure and accessible only within your network.

3. Final Answer:

   To store Docker images securely within your own network -> Option C

4. Quick Check:

   Private registry = secure image storage [OK]

Hint: Private registry means secure image storage inside your network [OK]

Common Mistakes:

• Confusing registry with container runtime
• Thinking it speeds up container execution
• Assuming it automatically updates images

2. Which command correctly starts a private Docker registry on port 5000?

easy

A. docker start registry -p 5000:5000

B. docker build -t registry:5000 .

C. docker create registry -p 5000:5000

D. docker run -d -p 5000:5000 --name registry registry:2

Solution

1. Step 1: Identify the correct Docker command to run a container

   The command to start a container is 'docker run' with port mapping.

2. Step 2: Check the syntax for running the registry image

   docker run -d -p 5000:5000 --name registry registry:2 uses 'docker run -d -p 5000:5000 --name registry registry:2' which is correct.

3. Final Answer:

   docker run -d -p 5000:5000 --name registry registry:2 -> Option D

4. Quick Check:

   Run container with port 5000 mapped = docker run -d -p 5000:5000 --name registry registry:2 [OK]

Hint: Use 'docker run -d -p 5000:5000' to start registry container [OK]

Common Mistakes:

• Using 'docker start' instead of 'docker run'
• Confusing 'docker create' with 'docker run'
• Trying to build instead of run the registry image

3. After running a private registry on localhost:5000, what is the correct command to tag an image named myapp for pushing to this registry?

medium

A. docker tag myapp localhost:5000/myapp

B. docker push myapp localhost:5000/myapp

C. docker tag localhost:5000/myapp myapp

D. docker run myapp localhost:5000/myapp

Solution

1. Step 1: Understand tagging for private registry

   To push an image to a private registry, you must tag it with the registry address first.

2. Step 2: Identify the correct tag command

   docker tag myapp localhost:5000/myapp uses 'docker tag myapp localhost:5000/myapp' which correctly tags the image.

3. Final Answer:

   docker tag myapp localhost:5000/myapp -> Option A

4. Quick Check:

   Tag image with registry address before push = docker tag myapp localhost:5000/myapp [OK]

Hint: Tag image as 'localhost:5000/name' before pushing [OK]

Common Mistakes:

• Trying to push without tagging first
• Reversing tag source and target
• Using 'docker run' instead of 'docker tag'

4. You tried to push an image to your private registry but got an error: denied: requested access to the resource is denied. What is the most likely cause?

medium

A. The registry container is not running

B. The image was not tagged with the private registry address

C. Docker daemon is not installed

D. The image name contains invalid characters

Solution

1. Step 1: Understand the error meaning

   The error means Docker cannot find the image at the specified registry path.

2. Step 2: Check tagging before pushing

   If the image is not tagged with the private registry address, push will fail with this error.

3. Final Answer:

   The image was not tagged with the private registry address -> Option B

4. Quick Check:

   Push denied = missing correct tag [OK]

Hint: Check if image is tagged with registry address before push [OK]

Common Mistakes:

• Assuming registry container is stopped without checking
• Thinking Docker daemon is missing
• Blaming image name format without evidence

5. You want to secure your private Docker registry with TLS. Which of these steps is necessary to enable HTTPS access?

hard

A. Mount your TLS certificate and key into the registry container and configure the registry to use them

B. Run the registry container with the --tls flag without any certificates

C. Tag images with https:// prefix before pushing

D. Use Docker Hub instead of a private registry

Solution

1. Step 1: Understand TLS setup for private registry

   To enable HTTPS, the registry needs valid TLS certificates mounted and configured.

2. Step 2: Identify correct method to provide TLS certs

   Mounting the certificate and key files into the container and configuring the registry is required.

3. Final Answer:

   Mount your TLS certificate and key into the registry container and configure the registry to use them -> Option A

4. Quick Check:

   TLS requires certs mounted and configured [OK]

Hint: Mount TLS certs into registry container for HTTPS [OK]

Common Mistakes:

• Expecting a --tls flag to work without certs
• Tagging images with https:// prefix
• Using Docker Hub instead of securing private registry