Private docker registry
Learn how to setup your own docker registry and push images for running algorithms in a C2D environment.
The document is intended for a production setup. The tutorial provides the steps to setup a private docker registry on the server for the following scenarios:
  • Allow registry access only to the C2D environment.
  • Anyone can pull the image from the registry but, only authenticated users will push images to the registry.

Setup 1: Allow registry access only to the C2D environment

To implement this use case, 1 domain will be required:
  • example.com: This domain will allow only image pull operations
Note: Please change the domain names to your application-specific domain names.

1.1 Prerequisites

  • Running docker environment on the linux server.
  • Docker compose is installed.
  • C2D environment is running.
  • The domain names is mapped to the server hosting the registry.

1.2 Generate certificates

# install certbot: https://certbot.eff.org/
sudo certbot certonly --standalone --cert-name example.com -d example.com
Note: Do check the access right of the files/directories where certificates are stored. Usually, they are at /etc/letsencrypt/.

1.3 Generate password file

Replace content in <> with appropriate content.
docker run \
--entrypoint htpasswd \
httpd:2 -Bbn <username> <password> > <path>/auth/htpasswd

1.4 Docker compose template file for registry

Copy the below yml content to docker-compose.yml file and replace content in <>.
version: '3'
services:
registry:
restart: always
container_name: my-docker-registry
image: registry:2
ports:
- 5050:5000
environment:
REGISTRY_AUTH: htpasswd
REGISTRY_AUTH_HTPASSWD_PATH: /auth/htpasswd
REGISTRY_AUTH_HTPASSWD_REALM: Registry Realm
REGISTRY_HTTP_SECRET: <secret>
volumes:
- <path>/data:/var/lib/registry
- <path>/auth:/auth
nginx:
image: nginx:latest
container_name: nginx
volumes:
- <path>/nginx/logs:/app/logs/
- nginx.conf:/etc/nginx/nginx.conf
- /etc/letsencrypt/:/etc/letsencrypt/
ports:
- 80:80
- 443:443
depends_on:
- registry

1.5 Nginx configuration

Copy the below nginx configuration to a nginx.conf file.
events {}
http {
access_log /app/logs/access.log;
error_log /app/logs/error.log;
server {
client_max_body_size 4096M;
listen 80 default_server;
server_name _;
return 301 https://$host$request_uri;
}
server {
# Allowed request size should be large enough to allow pull operations
client_max_body_size 4096M;
listen 443 ssl;
server_name example.com;
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
location / {
proxy_connect_timeout 75s;
proxy_pass http://registry-read-only:5000;
}
}
}

1.6 Create kubernetes secret in C2D server

Login into Compute-to-data enviroment and run the following command with appropriate credentials:
kubectl create secret docker-registry regcred --docker-server=example.com --docker-username=<username> --docker-password=<password> --docker-email=<email_id> -n ocean-compute

1.7 Update operator-engine configuration

Add PULL_SECRET property with value regcred in the operator.yml file of operator-engine configuration. For more detials on operator-engine properties refer this link
Apply updated operator-engine configuration.
kubectl config set-context --current --namespace ocean-compute
kubectl apply -f operator-engine/kubernetes/operator.yml

Steup 2: Allow anyonymous pull operations

To implement this use case, 2 domains will be required:
  • example.com: This domain will allow image push/pull operations only to the authenticated users.
  • readonly.example.com: This domain will allow only image pull operations
Note: Please change the domain names to your application-specific domain names.

2.1 Prerequisites

  • Running docker environment on the linux server.
  • Docker compose is installed.
  • 2 domain names is mapped to the same server IP address.

2.2 Generate certificates

# install certbot: https://certbot.eff.org/
sudo certbot certonly --standalone --cert-name example.com -d example.com
sudo certbot certonly --standalone --cert-name readonly.example.com -d readonly.example.com
Note: Do check the access right of the files/directories where certificates are stored. Usually, they are at /etc/letsencrypt/.

2.3 Generate password file

Replace content in <> with appropriate content.
docker run \
--entrypoint htpasswd \
httpd:2 -Bbn <username> <password> > <path>/auth/htpasswd

2.4 Docker compose template file for registry

Copy the below yml content to docker-compose.yml file and replace content in <>. Here, we will be creating two services of the docker registry so that anyone can pull the images from the registry but, only authenticated users can push the images.
version: '3'
services:
registry:
restart: always
container_name: my-docker-registry
image: registry:2
ports:
- 5050:5000
environment:
REGISTRY_AUTH: htpasswd
REGISTRY_AUTH_HTPASSWD_PATH: /auth/htpasswd
REGISTRY_AUTH_HTPASSWD_REALM: Registry Realm
REGISTRY_HTTP_SECRET: <secret>
volumes:
- <path>/data:/var/lib/registry
- <path>/auth:/auth
registry-read-only:
restart: always
container_name: my-registry-read-only
image: registry:2
read_only: true
ports:
- 5051:5000
environment:
REGISTRY_HTTP_SECRET: ${REGISTRY_HTTP_SECRET}
volumes:
- <path>/docker-registry/data:/var/lib/registry:ro
depends_on:
- registry
nginx:
image: nginx:latest
container_name: nginx
volumes:
- <path>/nginx/logs:/app/logs/
- nginx.conf:/etc/nginx/nginx.conf
- /etc/letsencrypt/:/etc/letsencrypt/
ports:
- 80:80
- 443:443
depends_on:
- registry-read-only

2.5 Nginx configuration

Copy the below nginx configuration to a nginx.conf file.
events {}
http {
access_log /app/logs/access.log;
error_log /app/logs/error.log;
server {
client_max_body_size 4096M;
listen 80 default_server;
server_name _;
return 301 https://$host$request_uri;
}
server {
# Allowed request size should be large enough to allow push operations
client_max_body_size 4096M;
listen 443 ssl;
server_name readonly.example.com;
ssl_certificate /etc/letsencrypt/live/readonly.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/readonly.example.com/privkey.pem;
location / {
proxy_connect_timeout 75s;
proxy_pass http://registry:5000;
}
}
server {
# Allowed request size should be large enough to allow pull operations
client_max_body_size 4096M;
listen 443 ssl;
server_name example.com;
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
location / {
proxy_connect_timeout 75s;
proxy_pass http://registry-read-only:5000;
}
}
}

Start the registry

docker-compose -f docker-compose.yml up

Working with registry

Login to registry

docker login example.com -u <username> -p <password>

Build and push an image to the registry

Use the commands below to build an image from a Dockerfile and push it to your private registry.
docker build . -t example.com/my-algo:latest
docker image push example.com/my-algo:latest

List images in the registry

curl -X GET -u <username>:<password> https://example.com/v2/_catalog

Pull an image from the registry

Use the commands below to build an image from a Dockerfile and push it to your private registry.
# requires login
docker image pull example.com/my-algo:latest
# allows anonymous pull if 2nd setup scenario is implemented
docker image pull readonly.example.com/my-algo:latest

Next step

You can publish an algorithm asset with the metadata containing registry URL, image, and tag information to enable users to run C2D jobs.

Further references