Docker has a free public registry, Docker Hub, that can host your custom Docker images, but there are situations where you will not want your image to be publicly available. Images typically contain all the code necessary to run an application, so using a private registry is preferable when using proprietary software.

In this post, you will set up and secure your own private Docker Registry.

Run a local registry

Creating a Local Registry is not different to running any other container, so we will follow the usual steps we learn on previous posts. Use a command like the following to start the registry container:

#docker run -d -p 5000:5000 --restart=always --name registry registry:2
Unable to find image 'registry:2' locally
 2: Pulling from library/registry
 c87736221ed0: Pull complete 
 1cc8e0bb44df: Pull complete 
 54d33bcb37f5: Pull complete 
 e8afc091c171: Pull complete 
 b4541f6d3db6: Pull complete 
 Digest: sha256:3b00e5438ebd8835bcfa7bf5246445a6b57b9a50473e89c02ecc8e575be3ebb5
 Status: Downloaded newer image for registry:2
 99d9b2ede2ea389a4b1837afadf89868108dd62f3af585de9c38303ddbd0f6bb

Lets check now that the local registry is running:

#docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
 99d9b2ede2ea        registry:2          "/entrypoint.sh /etc…"   36 seconds ago      Up 35 seconds       0.0.0.0:5000->5000/tcp   registry

We can see the local registry is UP and Running, listening on port 5000/tcp.

The registry is now ready to use.

Pushing an image to our new registry

Now that we have our local registry, we are going to push the image we created in the previous post to the local registry.
Before we can push the image to the registry we need to tell Docker that we want to push it to the local registry instead to Docker Hub.
To do that, we tag the image as follows:

docker tag static_web localhost:5000/static_web

This command will tag the image as localhost:5000/static_web. This creates an additional tag for the existing image. When the first part of the tag is a hostname and port, Docker interprets this as the location of a registry, when pushing.

Now we can try pushing the image to the local registry:

#docker push localhost:5000/static_web
docker push localhost:5000/static_web
 The push refers to repository [localhost:5000/static_web]
 23cc06f319e8: Pushed 
 f7c6590a6a8a: Pushed 
 2d6225362742: Pushed 
 26e16f1d4b32: Pushed 
 297fd071ca2f: Pushed 
 2f0d1e8214b2: Pushed 
 7dd604ffa87f: Pushed 
 aa54c2bc1229: Pushed 
 latest: digest: sha256:5f1ad3f9df94315b1b47542aa178f3a5fbee713d88aeba6cbfcf2696f3f1bed8 size: 1987

Now Lets Remove the locally-cached static_web and localhost:5000/static_web images, so that you can test pulling the image from your registry. This does not remove the localhost:5000/static_web image from your registry.

#docker image remove  static_web
 Untagged: static_web:latest
#docker image remove localhost:5000/static_web -f
Untagged: localhost:5000/static_web:latest
Untagged: localhost:5000/static_web@sha256:5f1ad3f9df94315b1b47542aa178f3a5fbee713d88aeba6cbfcf2696f3f1bed8
Deleted: sha256:85190ea11dca718966e65ce1a5445eb34b7e7fb2a2d0ecbabf275f80088c5468

Now, if we run docker images we shouldn't see the static_web image:
#docker images static_web
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
#

Now, if we run docker images we shouldn’t see the static_web image:

#docker images static_web
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
#

At Last we can Pull the localhost:5000/static_web image from your local registry.

# docker pull localhost:5000/static_web
Using default tag: latest
latest: Pulling from static_web
34667c7e4631: Already exists 
d18d76a881a4: Already exists 
119c7358fbfc: Already exists 
2aaf13f3eff0: Already exists 
644067bf57c7: Already exists 
27c1fcd390b1: Already exists 
29ddb2eff7f5: Already exists 
6dd2bd08049b: Already exists 
Digest: sha256:5f1ad3f9df94315b1b47542aa178f3a5fbee713d88aeba6cbfcf2696f3f1bed8
Status: Downloaded newer image for localhost:5000/static_web:latest
root@ip-172-31-89-180:/home/ubuntu# docker images static_web
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
root@ip-172-31-89-180:/home/ubuntu# docker images
REPOSITORY                  TAG                 IMAGE ID            CREATED             SIZE
localhost:5000/static_web   latest              85190ea11dca        18 hours ago        212MB

Stopping the local registry

To stop the registry, use the same docker container stop command as with any other container.

#docker container stop registry

To remove the container, use docker container rm.

#docker container stop registry && docker container rm -v registry