Is it possible to login to the docker registry on the RedHat OpenShift Interacting Learning Portal (Playground)

I’m working on the Red Hat OpenShift Interactive Learning Portal – Playground (https://learn.openshift.com/) and would like to push my own image to the Playground’s openshift docker internal registry.

I checked the URL of the registry using the following command.

$ oc get route -n default --as=system:admin

Then, I tried to login to the registry as follows. but I got error messages.

$ docker login -u developer -p xxxxxxx docker-registry-default.2886795284-80-cykoria05.environments.katacoda.com

Error message

WARNING! Using --password via the CLI is insecure. Use --password-stdin.
INFO[0000] Error logging in to v2 endpoint, trying next endpoint: Get https://docker-registry-default.2886795284-80-cykoria05.environments.katacoda.com/v2/: x509: certificate is valid for *.asia.katacoda.com, *.connections.katacoda.com, *.environments.katacoda.com, *.europe.katacoda.com, *.katacoda.com, *.katacoda.community, *.katacoda.dev, *.us.katacoda.com, katacoda.com, katacoda.community, katacoda.dev, not docker-registry-default.2886795284-80-cykoria05.environments.katacoda.com 
Get https://docker-registry-default.2886795284-80-cykoria05.environments.katacoda.com/v2/: x509: certificate is valid for *.asia.katacoda.com, *.connections.katacoda.com, *.environments.katacoda.com, *.europe.katacoda.com, *.katacoda.com, *.katacoda.community, *.katacoda.dev, *.us.katacoda.com, katacoda.com, katacoda.community, katacoda.dev, not docker-registry-default.2886795284-80-cykoria05.environments.katacoda.com

Does this mean the registry is not accessible from the outer world?

Source: StackOverflow