In every tutorial I've found regarding Docker registry there is a command like this:
docker run -d -p 5000:5000 --name registry registry:2
Tag 2 is used here. Why? I've tried registry without the tag and it also worked.
I think it has something to do with different API (?) of Docker registry but I am not sure.
Yes, you are correct! the tag 2 represents Docker Registry v2 Implementation which is also Docker Registry HTTP API V2. which solves several problems that were in V1 and introduce new features as described in the following links:
Docker Registry HTTP API V2
More about Registry 2.0
By removing 2 then docker goes to a default tag called latest which currently points to the following tags 2.7.1, 2.7, 2.
So when Docker Inc. releases Registry V3, the latest tag will point to V3 and in case you need V2 in specific you have to add it to your command explicitly. You can check the available tags for the registry image
You are right about the API. From github.com/docker/distribution:
Distribution
The Docker toolset to pack, ship, store, and deliver content.
This repository's main product is the Docker Registry 2.0 implementation for storing and distributing Docker images. It supersedes the docker/docker-registry project with a new API design, focused around security and performance.
and:
registry
An implementation of the Docker Registry HTTP API V2 for use with docker 1.6+.
Why both work?
When you docker pull registry you actually pull registry:latest and it has the same digest as registry:2. Demo:
$ docker pull registry
Using default tag: latest
latest: Pulling from library/registry
169185f82c45: Already exists
046e2d030894: Pull complete
188836fddeeb: Pull complete
832744537747: Pull complete
7ceea07e80be: Pull complete
Digest: sha256:870474507964d8e7d8c3b53bcfa738e3356d2747a42adad26d0d81ef4479eb1b
Status: Downloaded newer image for registry:latest
$ docker pull registry:2
2: Pulling from library/registry
Digest: sha256:870474507964d8e7d8c3b53bcfa738e3356d2747a42adad26d0d81ef4479eb1b
Status: Downloaded newer image for registry:2
Related
Can docker be connected to more than one registry at a time and how to figure out which registries it is currently connected too?
$ docker help | fgrep registr
login Log in to a Docker registry
logout Log out from a Docker registry
pull Pull an image or a repository from a registry
push Push an image or a repository to a registry
As you can see, there is no option to list the registries. I did find
a way by running:
$ docker system info | fgrep -i registr
Registry: https://index.docker.io/v1/
So... one regsitry at a time only? It is not like apt where one can point to more than one source? Anybody can point me to some good documentation about docker and registries?
Oddly, I search the web to no vail.
Aside from docker login, Docker isn't "connected to a registry" per se. Registry names are part of the image name, and Docker will connect to a registry server if it needs to pull an image.
As a specific example, the official Docker image for Elasticsearch is on a non-default registry run by Elastic. The example in that documentation is
docker pull docker.elastic.co/elasticsearch/elasticsearch:7.17.0
# ^^^^^^^^^^^^^^^^^
# registry host name
You don't need to otherwise configure your system to connect to that registry, download an index, or anything else. In fact, you don't even need this docker pull command; if you directly docker run the image, Docker will download it if it doesn't have a copy locally.
The default registry is Docker Hub, docker.io, and this cannot be changed.
There are several alternate registries out there. The various public-cloud providers each have their own, and there are also several free-standing image registries. Each has its own instructions on how to set it up. You always need to include the registry name as part of the image name. The Google Container Registry has a simple name syntax, for example, so if you use GCR then you can
# build an image locally, labeled to be stored in GCR
# (this step does not contact or use GCR at all)
docker build gcr.io/my-name/my-image:tag
# authenticate to the registry
# (normally GCR has a Google-specific login sequence)
docker login https://gcr.io
# push the image
docker push gcr.io/my-name/my-image:tag
# run the image, pulling it if not present
docker run ... gcr.io/my-name/my-image:tag
I am trying to pull docker image from Nexus repo without using the registry mirror in the command line and it is throwing an error. If I use the registry mirror in the pull it is succeeding but the image name is not I would like.
My docker version is:
Docker version 20.10.8, build 3967b7d
My nexus version is
Sonatype Nexus Repository ManagerOSS 3.31.1-01
docker system info:
Insecure Registries:
xxx.xxx.x.xxx:8083
127.0.0.0/8
Registry Mirrors:
http://xxx.xxx.x.xxx:8083/
When I run: sudo docker pull xxx.xxx.x.xxx:8083/mongo:4.2.3, it succeeds and the debug info is:
DEBU[2021-08-17T10:37:19.364681226-04:00] Calling HEAD /_ping
DEBU[2021-08-17T10:37:19.365301100-04:00] Calling POST /v1.41/images/create?fromImage=192.168.9.175%3A8083%2Fmongo&tag=4.2.3
DEBU[2021-08-17T10:37:19.367151579-04:00] Trying to pull xxx.xxx.x.xxx:8083/mongo from https://xxx.xxx.x.xxx:8083 v2
WARN[2021-08-17T10:37:19.374915464-04:00] Error getting v2 registry: Get https://xxx.xxx.x.xxx:8083/v2/: http: server gave HTTP response to HTTPS client
INFO[2021-08-17T10:37:19.374944418-04:00] Attempting next endpoint for pull after error: Get https://xxx.xxx.x.xxx:8083/v2/: http: server gave HTTP response to HTTPS client
DEBU[2021-08-17T10:37:19.374964188-04:00] Trying to pull xxx.xxx.x.xxx:8083/mongo from http://xxx.xxx.x.xxx:8083 v2
DEBU[2021-08-17T10:37:19.398630498-04:00] Fetching manifest from remote digest="sha256:92814bb60dc673bb68b6aca0b24bcb8738d7b2c267b97ce62fa92adc3746a0ea" error="<nil>" remote="192.168.9.175:8083/mongo:4.2.3"
DEBU[2021-08-17T10:37:19.429454057-04:00] Pulling ref from V2 registry: xxx.xxx.x.xxx:8083/mongo:4.2.3
When I run: sudo docker pull mongo:4.2.3 it fails to pull the image from Nexus with an error and pulls from docker.io on the next try. Debug info as below:
DEBU[2021-08-17T10:26:25.078886904-04:00] Calling HEAD /_ping
DEBU[2021-08-17T10:26:25.079306196-04:00] Calling GET /v1.41/info
DEBU[2021-08-17T10:26:25.097994642-04:00] Calling POST /v1.41/images/create?fromImage=mongo&tag=4.2.3
DEBU[2021-08-17T10:26:25.099642151-04:00] Trying to pull mongo from http://xxx.xxx.x.xxx:8083/ v2
INFO[2021-08-17T10:26:25.116000813-04:00] **Attempting next endpoint for pull after error: manifest unknown: manifest unknown**
DEBU[2021-08-17T10:26:25.116039299-04:00] Trying to pull mongo from https://registry-1.docker.io v2
DEBU[2021-08-17T10:26:25.305043063-04:00] Fetching manifest from remote digest="sha256:58b25d51baa11a85b6aedf7c4e05710d12a27ddc2883e2692e7d58527d98bd73" error="<nil>" remote="docker.io/library/mongo:4.2.3"
DEBU[2021-08-17T10:26:25.360955030-04:00] Pulling ref from V2 registry: mongo:4.2.3
DEBU[2021-08-17T10:26:25.361036645-04:00] docker.io/library/mongo:4.2.3 resolved to a manifestList object with 5 entries; looking for a unknown/amd64 match
Issue with Image name:
REPOSITORY TAG IMAGE ID CREATED SIZE
xxx.xxx.x.xxx:8083/mongo 4.2.3 97a9a3e85158 17 months ago 386MB
Any guidance on this would help.
Nexus Docker ( xxx.xxx.x.xxx:8083) is pointed to hosted Type on port 8083 and the mongo:4.2.3 is uploaded into this docker type. We ultimately want to use this in a air gapped system where there is no internet connection.
There are three things going on here:
I am trying to pull docker image from Nexus repo without using the registry mirror in the command line and it is throwing an error. If I use the registry mirror in the pull it is succeeding but the image name is not I would like.
I'm going to recommend changing your likes. :)
If you want to pull from a specific registry, then use that registry in the image name. Trying to refer to your local registry with short names is merging two different image registry namespaces, which means it's trivial to run an image from the wrong namespace and result in a security breach. This was a large issue for other package repositories (see "dependency confusion" attacks) that docker was not susceptible to because they require the registry name as part of the image name (the only exception being Docker Hub). Even RedHat who tried to get options like add-registry and block-registry into the upstream docker engine (and failed, these options only ever appeared in a RedHat specific fork) is now telling users that it was a very bad idea and now their users are exposed to security vulnerabilities they can't easily fix because removing the feature will break lots of user environments.
Next, why doesn't the pull go to your registry? Because your image name doesn't match that of Docker Hub. Official images without a username are actually under the library repository. This is typically hidden from view, but you can do things like docker pull library/alpine or even docker pull docker.io/library/alpine instead of docker pull alpine, and all 3 will be pulling from the same place.
The fix is to run
docker pull xxx.xxx.x.xxx:8083/mongo:4.2.3
docker tag xxx.xxx.x.xxx:8083/mongo:4.2.3 xxx.xxx.x.xxx:8083/library/mongo:4.2.3
docker push xxx.xxx.x.xxx:8083/library/mongo:4.2.3
The last issue I actually can't help you with, it comes from the error message you're seeing when pulling from Hub, which should work:
docker.io/library/mongo:4.2.3 resolved to a manifestList object with 5 entries; looking for a unknown/amd64 match
The unknown/amd64 is unexpected to me, typically that would be linux/amd64 so there is something unexpected with the platform you're running your commands on. If you want to get into debugging that, update your question with docker info. You can try working around that with:
docker pull --platform linux/amd64 mongo:4.2.3
to force the platform, but that still doesn't explain why it doesn't know your current platform.
I guess you are trying to set your nexus docker repository to be the default one for the machine in the sealed network.
that needs changing because of the following from docker documentation:
Tag an image for a private repository
To push an image to a private registry and not the central Docker registry you must tag it with the registry hostname and port (if needed).
$ docker tag 0e5574283393 myregistryhost:5000/fedora/httpd:version1.0
with more upfront configuration and upkeep but no changes requiered for the client machines
Is if you have a DNS server in your network you could point docker.io to your nexus host ip address and put a proxy to intercept the communication and redirect and adapt the requests as they were to the nexus docker registry
Hopes this solves your pickle :)
Update 1:
It could be that you need to also change /etc/containers/registries.conf like specified here to only or also specify your nexus docker registry.
Update 2:
Before letting Gopi give up entirely, I would suggest using Podman as an alternative to Docker. Podman is a daemon-less container engine that works by forking processes to handle each running container. It seamlessly works with docker images thanks to the OCI standard, and on top of that, the only change when using it is replacing the docker command prefix with podman since all the commands are exactly the same. Podman was created by RedHat so by default it searches RedHat repos and you can add your own too as shown in this article that I mentioned before.
Installed Docker version 19.03.12 on ubuntu . using the command docker info
it is showing registry as like below
Registry:https://index.docker.io/v1
Can anyone suggest a method to change the registry to v2 (https://index.docker.io/v2)
There is an issue to pull the image from the docker artifactory repository v2
Vasanthan, if you have just installed docker and all the docker images will be resolved through docker hub, you can set up the same environment in Artifactory by using the default docker remote repository as below,
As you can observe that it is by default v2 and hitting the "https://registry-1.docker.io/" which hits the docker hub. There is no need to use the "https://index.docker.io/v2 " instead use the "https://registry-1.docker.io/". I hope this helps.
I have a docker registry server for my team and I want to do the following when a user pulls image from the registry:
Check if the image exists in my registry.
If yes, return the image from my registry and end here.
If no, try to pull the image from the official docker hub registry. cache the image in my registry for further use and then return it to the user and end here.
In my case, I want my docker register as a bridge. Not only it could store private images, but also cache the images to save the bandwidth.
Do you have any idea to do that?
I have recently implemented such a use case, below is the configuration you have to use to make that happen.
proxy:
remoteurl: https://registry-1.docker.io
username: [username]
password: [password]
Add this configuration in your config.yml file, which you will be using with your registry.
Update the above config with your docker hub credentials.
This use case in particular is known as Registry as a pull through cache.
Official Docker documentation link : https://docs.docker.com/registry/recipes/mirror/
Short answer - There is no out of the box option provided by Docker. You have to run the docker pull command twice.
Pull it from your local repo using the below syntax.
$ docker pull myregistry.local:5000/testing/test-image
If the above fails, pull it from docker repo.
$ docker pull test-image
Refer official docs here.
When I run in docker 1.2 docker pull ubuntu a lot of tags are downloaded. (In the version 1.3 this was changed — to download all the tags I need to run docker pull ubuntu --all-tags
I know that I can see the tags what are going to be downloaded on the Docker Hub — https://registry.hub.docker.com/_/ubuntu/tags/manage/
Is there a way to find out the list of tags that are to be downloaded from docker console utilities?
Docker pull without an explicit tag will pull the "latest" tag. If you call pull with "--all-tags" flag it should then pull all the tags for that image.
Documentation for docker pull is here:
https://docs.docker.com/reference/commandline/cli/#pull