How to change the default docker registry from docker io to my private registry

Question

By default  if I issue command    sudo docker pull ruby 2 2 1   it will pull from the docker io offical site by default   Pulling repository docker io library ruby   How do I change it to my private registry  That means if I issue   sudo docker pull ruby 2 2 1   it will pull from my own private registry  the output is something like   Pulling repository my private registry port library ruby

User · Answer

Docker official position is explained in issue #11815 :

Issue 11815: Allow to specify default registries used in pull command

Resolution:

Like pointed out earlier (#11815), this would fragment the namespace, and hurt the community pretty badly, making dockerfiles no longer portable.

[the Maintainer] will close this for this reason.

Red Hat had a specific implementation that allowed it (see anwser, but it was refused by Docker upstream projet). It relied on --add-registry argument, which was set in /etc/containers/registries.conf on RHEL/CentOS 7.

EDIT:

Actually, Docker supports registry mirrors (also known as "Run a Registry as a pull-through cache"). https://docs.docker.com/registry/recipes/mirror/#configure-the-docker-daemon

User · Answer

There is the use case of a mirror of Docker Hub  such as Artifactory or a custom one   which I haven t seen mentioned here  This is one of the most valid cases where changing the default registry is needed  Luckily  Docker  at least version 19 03 3  allows you to set a mirror  tested in Docker CE   I don t know if this will work with additional images pushed to that mirror that aren t on Docker Hub  but I do know it will use the mirror instead  Docker documentation  https   docs docker com registry recipes mirror  configure-the-docker-daemon  Essentially  you need to add  quot registry-mirrors quot      to the  etc docker daemon json configuration file  So if you have a mirror hosted at https   my-docker-repo my company com  your  etc docker daemon json should contain       quot registry-mirrors quot     quot https   my-docker-repo-mirror my company com quot      Afterwards  restart the Docker daemon  Now if you do a docker pull postgres 12  Docker should fetch the image from the mirror instead of directly from Docker Hub  This is much better than prepending all images with my-docker-repo my company com

User · Answer

It seems it won t be supported due to the fragmentation it would create within the community  i e  two users would get different images pulling ubuntu latest   You simply have to add the host in front of the image name  See this github issue to join the discussion    Note  this is not intended as an opinionated comment  just a very short summary of the discussion that can be followed in the mentioned github issue

User · Answer

I tried to add the following options in the  etc docker daemon json   I used CentOS7    add-registry     192 168 100 100 5001     block-registry     docker io      after that  restarted docker daemon  And it s working without docker io  I hope this someone will be helpful

User · Answer

UPDATE  Following your comment  it is not currently possible to change the default registry  see this issue for more info   You should be able to do this  substituting the host and port to your own   docker pull localhost 5000 registry-demo   If the server is remote has auth you may need to log into the server with   docker login https    lt YOUR-DOMAIN gt  8080   Then running   docker pull  lt YOUR-DOMAIN gt  8080 test-image

User · Answer

Earlier this could be achieved using DOCKER OPTS in the  etc default docker config file which worked on Ubuntu 14 04 and had some issues on Ubuntu 15 04  Not sure if this has been fixed   The below line needs to go into the file  etc default docker on the host which runs the docker daemon  The change points to the private registry is installed in your local network  Note  you would require to restart the docker service followed with this change   DOCKER OPTS  --insecure-registry  lt priv registry hostname ip gt   lt port gt

User · Answer

I m adding up to the original answer given by Guy which is still valid today  soon 2020    Overriding the default docker registry  like you would do with maven  is actually not a good practice   When using maven  you pull artifacts from Maven Central Repository through your local repository management system that will act as a proxy  These artifacts are plain  raw libs  jars  and it is quite unlikely that you will push jars with the same name   On the other hand  docker images are fully operational  runnable  environments  and it makes total sens to pull an image from the Docker Hub  modify it and push this image in your local registry management system with the same name  because it is exactly what its name says it is  just in your enterprise context  In this case  the only distinction between the two images would precisely be its path    Therefore the need to set the following rule  the prefix of an image indicates its origin  by default if an image does not have a prefix  it is pulled from Docker Hub

User · Answer

It turns out this is actually possible  but not using the genuine Docker CE or EE version   You can either use Red Hat s fork of docker with the  --add-registry  flag or you can build docker from source yourself with registry config go modified to use your own hard-coded default registry namespace index

User · Answer

Haven t tried  but maybe hijacking the DNS resolution process by adding a line in  etc hosts for hub docker com or something similar  docker io   could work

User · Answer

if you are using the fedora distro  you can change the file    etc containers registries conf   Adding domain docker io

[docker] How to change the default docker registry from docker.io to my private registry?

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