Add info about our local Docker Hub mirror

semaphoreci / docs

Semaphore 2.0 documentation.

https://docs.semaphoreci.com

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Add info about our local Docker Hub mirror #231

Closed markoa closed 10 months ago

markoa commented 5 years ago

We recently introduced a Docker Hub mirror which runs inside the same DC as all Semaphore jobs. This should be prominently visible on the "Working with Docker" page.

For comparison, Google Cloud's docs about their DH mirror: link.

schliflo commented 4 years ago

Hi @markoa I found this issue when investigating why I'm getting ff3a5c916c92: Retrying in 20 seconds messages when pulling images in CI jobs. I found out about the undocumented internal semaphore mirror by digging into the config...

Some questions:

Why am i getting these "retrying" messages? Is there some sort of rate limiting?
Why would it be better to use the semaphore mirror rather than googles? Latency/Availability/Speed?

bogyo210 commented 4 years ago

Hi @schliflo, Please let me answer Your questions:

These "retrying" messages can manifest when a docker registry proxy doesn't have the image requested and is working on fetching it before serving it or the docker registry for some other reason cannot serve the request at the moment.

If you find that "retrying" message on several occasions please submit a support request.

schliflo commented 4 years ago

I ran into the Retrying message multiple times before. We use custom images (which are pre-built & published to DockerHub) in our CI jobs. The issue seems to be solved by using the google proxy:

sudo sed -i 's@https://dockerhub.semaphoreci.com/@https://mirror.gcr.io@g' /etc/docker/daemon.json
sudo restart docker

I still think that the default configuration using the semaphore proxy should be documented.

markoa commented 10 months ago

Closing as stale.