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
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://<YOUR-DOMAIN>:8080
Then running:
docker pull <YOUR-DOMAIN>:8080/test-image
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 "registry-mirrors": [] 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:
{
"registry-mirrors": ["https://my-docker-repo-mirror.my.company.com"]
}
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
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.
The short answer to this is you don't, or at least you really shouldn't.
Yes, there are some container runtimes that allow you to change the default namespace, specifically those from RedHat. However, RedHat now regrets this functionality and discourages customers from using it. Docker has also refused to support this.
The reason this is so problematic is because is results in an ambiguous namespace of images. The same command run on two different machines could pull different images depending on what registry they are configured to use. Since compose files, helm templates, and other ways of running containers are shared between machines, this actually introduces a security vulnerability.
An attacker could squat on well known image names in registries other than Docker Hub with the hopes that a user may change their default configuration and accidentally run their image instead of the one from Hub. It would be trivial to create a fork of a tool like Jenkins, push the image to other registries, but with some code that sends all the credentials loaded into Jenkins out to an attacker server. We've even seen this causing security vulnerability reports this year for other package managers like PyPI, NPM, and RubyGems.
Instead, the direction of container runtimes like containerd is to make all image names fully qualified, removing the Docker Hub automatic expansion (tooling on top of containerd like Docker still apply the default expansion, so I doubt this is going away any time soon, if ever).
Docker does allow you to define registry mirrors for Docker Hub that it will query first before querying Hub, however this assumes everything is still within the same namespace and the mirror is just a copy of upstream images, not a different namespace of images. The TL;DR on how to set that up is the following in the /etc/docker/daemon.json and then systemctl reload docker:
{
"registry-mirrors": ["https://<my-docker-mirror-host>"]
}
For most, this is a non-issue (this issue to me is the docker engine doesn't have an option to mirror non-Hub registries). The image name is defined in a configuration file, or a script, and so typing it once in that file is easy enough. And with tooling like compose files and Helm templates, the registry can be turned into a variable to allow organizations to explicitly pull images for their deploy from a configurable registry name.
if you are using the fedora distro, you can change the file
/etc/containers/registries.conf
Adding domain docker.io
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
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.)
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.
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 <priv registry hostname/ip>:<port>"
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.
Didn't see the answer for MacOS, so want to add here:
2 Method as below:
Option 1 (Through Docker Desktop GUI):
Preference -> Docker Engine -> Edit file -> Apply and Restart
Option 2:
Directly edit the file ~/.docker/daemon.json
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?
Related
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
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://<YOUR-DOMAIN>:8080
Then running:
docker pull <YOUR-DOMAIN>:8080/test-image
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 "registry-mirrors": [] 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:
{
"registry-mirrors": ["https://my-docker-repo-mirror.my.company.com"]
}
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
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.
The short answer to this is you don't, or at least you really shouldn't.
Yes, there are some container runtimes that allow you to change the default namespace, specifically those from RedHat. However, RedHat now regrets this functionality and discourages customers from using it. Docker has also refused to support this.
The reason this is so problematic is because is results in an ambiguous namespace of images. The same command run on two different machines could pull different images depending on what registry they are configured to use. Since compose files, helm templates, and other ways of running containers are shared between machines, this actually introduces a security vulnerability.
An attacker could squat on well known image names in registries other than Docker Hub with the hopes that a user may change their default configuration and accidentally run their image instead of the one from Hub. It would be trivial to create a fork of a tool like Jenkins, push the image to other registries, but with some code that sends all the credentials loaded into Jenkins out to an attacker server. We've even seen this causing security vulnerability reports this year for other package managers like PyPI, NPM, and RubyGems.
Instead, the direction of container runtimes like containerd is to make all image names fully qualified, removing the Docker Hub automatic expansion (tooling on top of containerd like Docker still apply the default expansion, so I doubt this is going away any time soon, if ever).
Docker does allow you to define registry mirrors for Docker Hub that it will query first before querying Hub, however this assumes everything is still within the same namespace and the mirror is just a copy of upstream images, not a different namespace of images. The TL;DR on how to set that up is the following in the /etc/docker/daemon.json and then systemctl reload docker:
{
"registry-mirrors": ["https://<my-docker-mirror-host>"]
}
For most, this is a non-issue (this issue to me is the docker engine doesn't have an option to mirror non-Hub registries). The image name is defined in a configuration file, or a script, and so typing it once in that file is easy enough. And with tooling like compose files and Helm templates, the registry can be turned into a variable to allow organizations to explicitly pull images for their deploy from a configurable registry name.
if you are using the fedora distro, you can change the file
/etc/containers/registries.conf
Adding domain docker.io
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
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.)
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.
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 <priv registry hostname/ip>:<port>"
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.
Didn't see the answer for MacOS, so want to add here:
2 Method as below:
Option 1 (Through Docker Desktop GUI):
Preference -> Docker Engine -> Edit file -> Apply and Restart
Option 2:
Directly edit the file ~/.docker/daemon.json
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?
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
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://<YOUR-DOMAIN>:8080
Then running:
docker pull <YOUR-DOMAIN>:8080/test-image
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 "registry-mirrors": [] 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:
{
"registry-mirrors": ["https://my-docker-repo-mirror.my.company.com"]
}
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
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.
The short answer to this is you don't, or at least you really shouldn't.
Yes, there are some container runtimes that allow you to change the default namespace, specifically those from RedHat. However, RedHat now regrets this functionality and discourages customers from using it. Docker has also refused to support this.
The reason this is so problematic is because is results in an ambiguous namespace of images. The same command run on two different machines could pull different images depending on what registry they are configured to use. Since compose files, helm templates, and other ways of running containers are shared between machines, this actually introduces a security vulnerability.
An attacker could squat on well known image names in registries other than Docker Hub with the hopes that a user may change their default configuration and accidentally run their image instead of the one from Hub. It would be trivial to create a fork of a tool like Jenkins, push the image to other registries, but with some code that sends all the credentials loaded into Jenkins out to an attacker server. We've even seen this causing security vulnerability reports this year for other package managers like PyPI, NPM, and RubyGems.
Instead, the direction of container runtimes like containerd is to make all image names fully qualified, removing the Docker Hub automatic expansion (tooling on top of containerd like Docker still apply the default expansion, so I doubt this is going away any time soon, if ever).
Docker does allow you to define registry mirrors for Docker Hub that it will query first before querying Hub, however this assumes everything is still within the same namespace and the mirror is just a copy of upstream images, not a different namespace of images. The TL;DR on how to set that up is the following in the /etc/docker/daemon.json and then systemctl reload docker:
{
"registry-mirrors": ["https://<my-docker-mirror-host>"]
}
For most, this is a non-issue (this issue to me is the docker engine doesn't have an option to mirror non-Hub registries). The image name is defined in a configuration file, or a script, and so typing it once in that file is easy enough. And with tooling like compose files and Helm templates, the registry can be turned into a variable to allow organizations to explicitly pull images for their deploy from a configurable registry name.
if you are using the fedora distro, you can change the file
/etc/containers/registries.conf
Adding domain docker.io
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
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.)
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.
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 <priv registry hostname/ip>:<port>"
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.
Didn't see the answer for MacOS, so want to add here:
2 Method as below:
Option 1 (Through Docker Desktop GUI):
Preference -> Docker Engine -> Edit file -> Apply and Restart
Option 2:
Directly edit the file ~/.docker/daemon.json
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?
GitHub offers two options for storing container images as I understand it: Container Registry and Packages, but I think the difference is not clear.
In a blog post, they say "With GitHub Actions, publishing to GitHub Container Registry is easy." but the given example pushes images to Packages, not Container Registry.
So, can those two platforms be used interchangeably and does one have an advantage over the other?
As already stated by tgogos the GitHub docs guide on Key differences between GitHub Container Registry and the Docker package registry tells us:
The GitHub Container Registry supersedes the existing Packages Docker
registry and is optimized to support some of the unique needs of
containers.
TLDR; The GH Container Registry will replace the Packages Docker Registry. It also focusses more on the GitHub organization level then on a single repository. So you find your container images on the account level for example - and have to link them optionally later to a repository if needed.
Additionally it features anonymous access to Docker images (see the GHCR intro post here).
I guess the reason they are migrating is that they want to cut that name 'Docker' from the registry. The reason being 'Docker' is just another technology for creating images however you can use other CRI (Container Runtime Images) like cri-o, rkt, container-D. These are CNCF active projects. And down the line, container-D might replace the Docker completely as its popularity has increased a lot over the years. AWS ECS has started using the agent based on container-D in their ECS Instances, Kubernetes has stopped supporting Docker as default CRI from v1.22.
So GitHub wants their customer to use the term 'container' (which could be anything as it is generic) rather than just 'Docker' in the future.
I used the following command: docker pull balenalib/beaglebone-black:latest
I am now trying to find the page for this image on Docker Hub. I search balenalib/beaglebone-black:latest and thousands of results come up, but seemingly not the one I typed in.
I finally found it here by manipulating the URL directly.
Is there a better way to do this? Can I get to that URL by using a command from terminal?
For Docker's registry's web fronted (https://hub.docker.com), there are two primary 'views':
Users|Organizations:
e.g. https://hub.docker.com/u/balenalib
NB "hub.docker.com/u/"
Users'|Organizations' Images
e.g. https://hub.docker.com/r/balenalib/beaglebone-black
NB "hub.docker.com/r/"
In the case of Docker's registry, the docker pull includes an implicit|optional docker.io/ prefix as it defaults to Docker's registry but there are other registries:
docker pull docker.io/balenalib/beaglebone-black:latest
So there's a form docker pull [registry]/[user]/[image]:[tag]
And, if you're using Linux and Chrome, you could browse to it on DockerHub using:
USER=balenalib # for example
IMAGE=beaglebone-black # for example
google-chrome https://hub.docker.com/r/${USER}/${IMAGE}
NB I find this a confusing use of similar terms, but a registry (such as Docker's) includes many repositories. In your example, using the Docker registry, balenalib/beaglebone-black is one repository in it.
I need to block all registries and allow only one private registry for docker to pull images from , how can that be done natively in docker.
Using the RedHat options will not work on the upstream Docker CE or EE engine, RedHat had forked the docker engine and added their own features that are incompatible. You'll also find that /etc/sysconfig/docker is a RedHat only configuration file, designed to work with their version of the startup scripts. And I don't believe RedHat supports this old fork either, instead preferring their own podman and crio runtimes.
A hard limit on registry servers is not currently supported in the Linux Docker engine. The standard way to implement this for servers is with firewall rules on outbound connections, but that needs to only permit outbound connections to a known allow list. You still need to ensure that users don't import images from a tar file, or rebuild the otherwise blocked images from scratch (for example, all of official images on Docker Hub have the source available to rebuild them).
With Docker Desktop, the ability to restrict what registries a user can pull from has been added in their paid business tier with their image access management.
Previously I might have suggested using Notary and Docker Content Trust to ensure you only run trusted images, but that tooling has a variety of known issue, including the use of TOFU (trust on first use) that allows any image from a repo that hasn't been seen before to be signed by anyone and trusted to run. There are a few attempts to replace this, and the current leader is sigstore/cosign, but that isn't integrated directly into the docker engine. If you run in Kubernetes, this would be configured in your admission controller, like Gatekeeper or Kyverno.
Just found in redhat docs:
This can be done on docker daemon config:
/etc/sysconfig/docker
BLOCK_REGISTRY='--block-registry=all'
ADD_REGISTRY='--add-registry=registry.access.redhat.com'
and then do:
systemctl restart docker