Lab 5.1 suggested corrections

KevinCSmallwood

While this was handled in another discussion ("Lab 5.1"), I would like to suggest that you add that some of the commands in Lab 5.1 are an example only and should not actually be executed as part of the Lab. This includes:

student@ubuntu:~$ sudo docker image pull myregistry.com:5000/alpine:latest

and

student@ubuntu:~$ sudo docker image push myregistry.com:5000/alpine:training

and, finally,

student@ubuntu:~$ sudo docker image rm -f alpine:latest nginx:latest

You might want to separate the example "alpine:latest" from the real "nginx:latest" since the later will really work as part of the Lab. However, because it does work, you should switch the order of the image removal with the last command (inspect) in the Lab:

student@ubuntu:~$ sudo docker image inspect nginx

as inspecting the just removed nginx:latest image will fail. By switching the order of the commands (inspect followed by rm), the Lab will work as expected.

Thanks!

chrispokorni

Thank you for your detailed feedback, Kevin!
I will revise the exercise and make the necessary corrections to improve readability and flow.

Regards,
-Chris

Jenad1kr

@chrispokorni , when I execute the command, sudo docker image pull myregistry.com:5000/alpine:latest
i get
Error response from daemon: Get https://myregistry.com:5000/v2/: net/http: request canceled wh
ile waiting for connection (Client.Timeout exceeded while awaiting headers)

Do I need to open a firewall port or something?
thx.

chrispokorni

Hi @Jenad1kr,

That command is used for illustration purposes only. Typically where you see domains similar toexample.com, myexample.com, or myresource.com these domains are not real, unless they are registered by you

Regards,
-Chris

go2vijay

@Chris,it still fails .can you suggest.

Digest: sha256:c628b67d21744fce822d22fdcc0389f6bd763daac23a6b77147d0712ea7102d0
Status: Image is up to date for nginx:latest
docker.io/library/nginx:latest
vijaykumar_palaniswamy@ubuntu:~$ sudo docker image pull myregistry.com:5000/alphine:training
Error response from daemon: Get https://myregistry.com:5000/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)

toastboy

Adding my 2 cents here: if a step is expected to fail in a teaching lab such as this without the students taking steps which are themselves more complicated than what's being taught in the course (in this case, hosting their own secure private registry) then it really ought to be identified as such. "For example, if you had access to a private registry called 'myregistry.com'"

chrispokorni

Hi @go2vijay,

In an earlier comment you may find the reason it still fails:

That command is used for illustration purposes only. Typically where you see domains similar to example.com, myexample.com, or myresource.com these domains are not real, unless they are registered by you

@toastboy, a clarifying note will be added in a future course update release.

Regards,
-Chris

rogerh

Hi @chrispokorni

I had the same problem. Thanks for the clarification. Understanding the syntax makes sense. A question then has to do with the use of Dockerhub. I have an account so I tried the following syntax:

$ sudo docker image pull hub.docker.com/opaekaa/my_ubuntu:my-ubuntu

I thought it would pull the container my_ubuntu to my local repository with my-ubuntu. I instead got what looks like the binary.

So I tried the following syntax:

$ sudo docker pull opaekaa/my_ubuntu:latest

Error response from daemon: manifest for opaekaa/my_ubuntu:latest not found: manifest unknown: manifest unknown

It is apparent I don't understand the syntax after all.

chrispokorni

Hi @rogerh,

The command $ sudo docker pull opaekaa/my_ubuntu:latest assumes that the image exists in your repository on Docker Hub, and it will attempt to pull it into the local image cache of the Docker Host.

Regards,
-Chris