Setting up private registry in Docker - Visual Walkthrough

Process Flow - Setting up private registry

Start Docker Registry Container

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Docker Registry Runs Locally

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Tag Local Image with Registry Address

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Push Image to Private Registry

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Pull Image from Private Registry

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Use Image in Docker Environment

This flow shows starting a private Docker registry, tagging images, pushing them to the registry, and pulling them back for use.

Execution Sample

Docker

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

docker tag myapp localhost:5000/myapp

docker push localhost:5000/myapp

docker pull localhost:5000/myapp

Commands to start a private registry, tag an image, push it to the registry, and pull it back.

Process Table

Step	Command	Action	Result
1	docker run -d -p 5000:5000 --name registry registry:2	Start registry container	Registry container running on port 5000
2	docker tag myapp localhost:5000/myapp	Tag local image	Image 'myapp' tagged as 'localhost:5000/myapp'
3	docker push localhost:5000/myapp	Push image to registry	Image pushed to private registry at localhost:5000
4	docker pull localhost:5000/myapp	Pull image from registry	Image pulled from private registry
5	-	End	Private registry setup and image transfer complete

💡 All steps completed successfully; private registry is running and images are stored locally.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
registry_container	not running	running	running	running	running	running
image_tag	myapp	myapp	localhost:5000/myapp	localhost:5000/myapp	localhost:5000/myapp	localhost:5000/myapp
image_location	local only	local only	local and tagged for registry	pushed to registry	available locally	available locally

Key Moments - 3 Insights

Why do we tag the image with 'localhost:5000/myapp' before pushing?

Tagging with 'localhost:5000/myapp' tells Docker to push the image to the private registry running on localhost port 5000, as shown in step 2 of the execution table.

What happens if the registry container is not running before pushing?

If the registry container is not running (step 1), the push command in step 3 will fail because there is no registry to receive the image.

Does pulling the image from the private registry overwrite the local image?

Yes, pulling the image from the private registry (step 4) updates or adds the image locally tagged as 'localhost:5000/myapp', as tracked in the variable_tracker.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of the registry container after step 1?

A Not running

B Running on port 5000

C Stopped

D Crashed

💡 Hint

Check the 'Result' column in row for step 1 in the execution_table.

At which step is the image tagged for the private registry?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Action' column in the execution_table for tagging.

If the registry container was not running, what would happen at step 3?

A Push would fail

B Image would push successfully

C Image would be deleted

D Image would be pulled instead

💡 Hint

Refer to key_moments about registry container state and push command.

Concept Snapshot

Setting up a private Docker registry:
1. Run registry container: docker run -d -p 5000:5000 --name registry registry:2
2. Tag image: docker tag myapp localhost:5000/myapp
3. Push image: docker push localhost:5000/myapp
4. Pull image: docker pull localhost:5000/myapp
This allows storing and sharing images locally without Docker Hub.

Full Transcript

To set up a private Docker registry, first run the registry container on your machine using 'docker run -d -p 5000:5000 --name registry registry:2'. This starts a registry listening on port 5000. Next, tag your local image with the registry address using 'docker tag myapp localhost:5000/myapp'. This tells Docker where to push the image. Then push the image to your private registry with 'docker push localhost:5000/myapp'. Finally, you can pull the image back from the registry using 'docker pull localhost:5000/myapp'. This process keeps your images stored locally and accessible without using public Docker Hub.