/docker-schema-registry

mDNS enabled confluentinc/cp-schema-registry image

Primary LanguageShellMIT LicenseMIT

mDNS enabled confluentinc/cp-schema-registry

Continuous Integration Source Code Docker Image

This Docker images provides the confluentinc/cp-schema-registry image as base with the mDNS/ZeroConf stack on top. So you can enjoy the app while it is accessible by default as schema-registry.local. (Port 80)

Requirements

  • Host enabled Avahi daemon
  • Host enabled mDNS NSS lookup

Getting starting

To get a Schema Registry service up and running create a docker-compose.yml and insert the following snippet:

zookeeper:
  image: wurstmeister/zookeeper
  ports:
    - "2181"
kafka:
  image: hausgold/kafka
  environment:
    # Mind the .local suffix
    - MDNS_HOSTNAME=kafka.local
  ports:
    # The ports are just for you to know when configure your
    # container links, on depended containers
    - "9092"
  links:
    # Link to the ZooKeeper instance for advertising
    - zookeeper
schema-registry:
  image: hausgold/schema-registry
  environment:
    # Mind the .local suffix
    MDNS_HOSTNAME: schema-registry.local
    # Defaults to zookeeper:2181
    SCHEMA_REGISTRY_KAFKASTORE_CONNECTION_URL: zookeeper:2181
  links:
    - zookeeper

Afterwards start the service with the following command:

$ docker-compose up

Host configs

Install the nss-mdns package, enable and start the avahi-daemon.service. Then, edit the file /etc/nsswitch.conf and change the hosts line like this:

hosts: ... mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns ...

Configure a different mDNS hostname

The magic environment variable is MDNS_HOSTNAME. Just pass it like that to your docker run command:

$ docker run --rm -e MDNS_HOSTNAME=something.else.local hausgold/schema-registry

This will result in something.else.local.

You can also configure multiple aliases (CNAME's) for your container by passing the MDNS_CNAMES environment variable. It will register all the comma separated domains as aliases for the container, next to the regular mDNS hostname.

$ docker run --rm \
  -e MDNS_HOSTNAME=something.else.local \
  -e MDNS_CNAMES=nothing.else.local,special.local \
  hausgold/schema-registry

This will result in something.else.local, nothing.else.local and special.local.

Other top level domains

By default .local is the default mDNS top level domain. This images does not force you to use it. But if you do not use the default .local top level domain, you need to configure your host avahi to accept it.

Further reading