How To Set Up a Private Docker Registry using Docker

Setting up a private Docker registry is an essential step for managing and securing your container images within your organization. A private registry allows you to host, store, and distribute Docker images without relying on public repositories, providing greater control over access, versioning, and deployment workflows. In this guide, we’ll walk you through the process of setting up a private Docker registry using Docker, ensuring your images remain secure and easily accessible for your team.

Pre-requisite

• Install Docker

Create a directory to permanently store images.

$ mkdir -p /registry/data

Authenticate with DockerHub

$docker login

Start the registry container.

$ docker run -d \
  -p 5000:5000 \
  --name registry \
  -v /registry/data:/var/lib/registry \
  --restart always \
  registry:2
b1a641f8d710eee34405ad575050179f5a1262f1c845806cc3c2b435dea1648c

Display running containers.

$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS
                    NAMES
3a056bf96c6d        registry:2          "/entrypoint.sh /etc…"   About an hour ago   Up About an hour    0.0.0
.0:5000->5000/tcp   registry

Pull Alpine 3.6 image from official repository.

$ docker pull alpine:3.6

stretch: Pulling from library/alpine
723254a2c089: Pull complete
Digest: sha256:0a5fcee6f52d5170f557ee2447d7a10a5bdcf715dd7f0250be0b678c556a501b
Status: Downloaded newer image for alpine:3.6
Tag local alpine 3.6 image with an additional tag - local repository address.

$ docker tag alpine:3.6 localhost:5000/alpine:3.6
Push image to the local repository.
[node1] (local) root@192.168.0.23 ~

$ docker push localhost:5000/alpine:3.6
The push refers to repository [localhost:5000/alpine:3.6]
90d1009ce6fe: Pushed
stretch: digest: sha256:38236c068c393272ad02db100e09cac36a5465149e2924a035ee60d6c60c38fe size: 529
[node1] (local) root@192.168.0.23 ~
Remove local images.
[node1] (local) root@192.168.0.23 ~

$ docker image remove alpine:3.6
Untagged: alpine:3.6
Untagged: alpine@sha256:df6ebd5e9c87d0d7381360209f3a05c62981b5c2a3ec94228da4082ba07c4f05

[node1] (local) root@192.168.0.23 ~
$ docker image remove localhost:5000/alpine:3.6
Untagged: localhost:5000/alpine:3.6
Untagged: localhost:5000/debian@sha256:38236c068c393272ad02db100e09cac36a5465149e2924a035ee60d6c60c38fe
Deleted: sha256:4879790bd60d439cfe39c063660eef7af525d5f6f1cbb701a14c7cfc11cbfcf7
Pull Alpine 3.6 image from local repository.

[node1] (local) root@192.168.0.23 ~
$ docker pull localhost:5000/alpine:3.6
stretch: Pulling from alpine
54f7e8ac135a: Pull complete
Digest: sha256:38236c068c393272ad02db100e09cac36a5465149e2924a035ee60d6c60c38fe
Status: Downloaded newer image for localhost:5000/alpine:3.6

List stored images.

[node1] (local) root@192.168.0.23 ~
$ docker image ls
REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
localhost:5000/alpine   3.6                 4879790bd60d        12 days ago         101MB
registry                2                   2e2f252f3c88        2 months ago        33.3MB

Shared local registry

Create a directory to permanently store images.

$ mkdir -p /srv/registry/data

Create a directory to permanently store certificates and authentication data.

$ mkdir -p /srv/registry/security

Store domain and intermediate certificates using /srv/registry/security/registry.crt file, private key using /srv/registry/security/registry.key file. Use valid certificate and do not waste time with self-signed one. This step is required do use basic authentication.

Install apache2-utils to use htpasswd utility.

[node1] (local) root@192.168.0.23 ~
$ apk add apache2-utils
OK: 302 MiB in 110 packages
Create initial username and password. The only supported password format is bcrypt.

$ : | sudo tee /srv/registry/security/htpasswd
[node1] (local) root@192.168.0.23 ~

$ echo "password" | sudo htpasswd -iB /srv/registry/security/htpasswd username
Adding password for user username
Adding password for user username

[node1] (local) root@192.168.0.23 ~
$ cat /srv/registry/security/htpasswd
username:$2y$05$q9R5FSNYpAppB4Vw/AGWb.RqMCGE8DmZ4q5HZC/1wC87oTWyvB9vy
[node1] (local) root@192.168.0.23 ~
$

Stop and Remove all old containers

$ docker stop $(docker ps -a -q)
3a056bf96c6d

$ docker rm -f $(docker ps -a -q)
3a056bf96c6d

Start the registry container.

[node1] (local) root@192.168.0.23 ~
$ docker run -d   -p 443:5000   --name registry   -v /srv/registry/data:/var/lib/registry   -v /srv/registry/security:/etc/security   -e REGISTRY_HTTP_TLS_CERTIFICATE=/etc/security/registry.crt   -e REGISTRY_HTTP_TLS_KEY=/etc/security/registry.key   -e REGISTRY_AUTH=htpasswd   -e REGISTRY_AUTH_HTPASSWD_PATH=/etc/security/htpasswd   -e REGISTRY_AUTH_HTPASSWD_REALM="Registry Realm"   --restart always   registry:2
e7755af8cbd70ea84ab77237a87cb97fd1abb18c7726fbc116c40f081d3b7098
[node1] (local) root@192.168.0.23 ~

Display running containers.

[node1] (local) root@192.168.0.23 ~
$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS        PORTS               NAMES
e7755af8cbd7        registry:2          "/entrypoint.sh /etc…"   About a minute ago   Restarting (1) 22 seconds ago                       registry
[node1] (local) root@192.168.0.23 ~

Pull Alpine image from official repository.

$ docker pull alpine:3.6

stretch: Pulling from library/alpine
723254a2c089: Pull complete
Digest: sha256:0a5fcee6f52d5170f557ee2447d7a10a5bdcf715dd7f0250be0b678c556a501b
Status: Downloaded newer image for alpine:3.6
Tag local Alpine image with an additional tag - local repository address.

$ docker tag alpine:3.6 registry.collabnix.com/alpine:3.6

This time you need to provide login credentials to use local repository.

$ docker push registry.collabnix.com/alpine:3.6

e27a10675c56: Preparing
no basic auth credentials
$ docker pull registry.collabnix.com/alpine:3.6
Error response from daemon: Get https://registry.collabnix.com/v2/alpine/manifests/3.6: no basic auth credentials

Log in to the local registry.

$ docker login --username username registry.collabnix.com
Password: ********

Login Succeeded

Push image to the local repository.

$ docker push registry.collabnix.com/alpine:3.6
The push refers to repository [registry.collabnix.com/alpine]
e27a10675c56: Pushed
stretch: digest: sha256:02741df16aee1b81c4aaff4c48d75cc2c308bade918b22679df570c170feef7c size: 529

Remove local images.

$ docker image remove alpine:3.6

Untagged: alpine:3.6
Untagged: alpine@sha256:0a5fcee6f52d5170f557ee2447d7a10a5bdcf715dd7f0250be0b678c556a501b

$ docker image remove registry.collabnix.com/alpine:3.6

Untagged: registry.collabnix.com/alpine:3.6
Untagged: registry.sl.collabnix.com/alpine@sha256:02741df16aee1b81c4aaff4c48d75cc2c308bade918b22679df570c170feef7c
Deleted: sha256:da653cee0545dfbe3c1864ab3ce782805603356a9cc712acc7b3100d9932fa5e
Deleted: sha256:e27a10675c5656bafb7bfa9e4631e871499af0a5ddfda3cebc0ac401dfe19382

Pull Debian Stretch image from local repository.

$ docker pull registry.collabnix.com/alpine:3.6

stretch: Pulling from alpine
723254a2c089: Pull complete
Digest: sha256:02741df16aee1b81c4aaff4c48d75cc2c308bade918b22679df570c170feef7c
Status: Downloaded newer image for registry.collabnix.com/alpine:3.6

List stored images.

$ docker image ls

REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
registry                             2                   d1fd7d86a825        4 weeks ago         33.3MB
registry.collabnix.com/alpine        3.6             da653cee0545        2 months ago        100MB
hello-world                          latest              f2a91732366c        2 months ago