docker registry log warns about redis

Here is the log from the docker registry that I tried to run through a docker-compose.yml. Not sure if the registry needs to point to a redis instance or not?

time="2016-09-01T02:16:37.36649972Z" level=warning msg="No HTTP secret provided - generated random secret. This may cause problems with uploads if multiple registries are behind a load-balancer. To provide a shared secret, fill in http.secret in the configuration file or set the REGISTRY_HTTP_SECRET environment variable." go.version=go1.6.2 instance.id=da01c358-8b1c-49fc-bc5d-3dc865e7bf66 service=registry version=v2.4.1 time="2016-09-01T02:16:37.366768666Z" level=info msg="redis not configured" go.version=go1.6.2 instance.id=da01c358-8b1c-49fc-bc5d-3dc865e7bf66 service=registry version=v2.4.1 time="2016-09-01T02:16:37.36673635Z" level=info msg="Starting upload purge in 46m0s" go.version=go1.6.2 instance.id=da01c358-8b1c-49fc-bc5d-3dc865e7bf66 service=registry version=v2.4.1 time="2016-09-01T02:16:37.393826839Z" level=info msg="using inmemory blob descriptor cache" go.version=go1.6.2 instance.id=da01c358-8b1c-49fc-bc5d-3dc865e7bf66 service=registry version=v2.4.1 time="2016-09-01T02:16:37.395046322Z" level=info msg="listening on [::]:5000" go.version=go1.6.2 instance.id=da01c358-8b1c-49fc-bc5d-3dc865e7bf66 service=registry version=v2.4.1

Here is the portion of the docker-compose for registry:

registry:
    restart: always
    image: registry:2.4.1
    volumes:
    - /sdata/srv/docker/gitlab/gitlab/shared/registry:/registry
    - /sdata/srv/docker/gitlab/certs:/certs
    environment:
    - REGISTRY_LOG_LEVEL=info
    - REGISTRY_STORAGE_FILESYSTEM_ROOTDIRECTORY=/registry
    - REGISTRY_AUTH_TOKEN_REALM=http://cd3labvdapp001:10080/jwt/auth
    - REGISTRY_AUTH_TOKEN_SERVICE=container_registry
    - REGISTRY_AUTH_TOKEN_ISSUER=gitlab-issuer
    - REGISTRY_AUTH_TOKEN_ROOTCERTBUNDLE=/certs/registry-auth.crt
    - REGISTRY_STORAGE_DELETE_ENABLED=true

Start with the docker-compose.yml registry service and the registry:2.4.1 startup log shown in the issue. Check the registry documentation or configuration code for Redis usage and the meaning of the “redis not configured” message. Done means clarifying whether Redis is required for this setup and identifying any necessary configuration change or documentation update.