I am having a private registry (JFrog) which is being used within the company. I would like to set up a registry cache for our project that keeps the heavy load off the private registry.
As the documentation states a registry mirror for private registries is not supported although an answer in Mirroring private docker registry states that now it is supported.
I tried myself with the following setup:
[UBUNTU CLIENT] --- [REGISTRY PROXY] --- [PRIVATE REGISTRY]
Registry Proxy is reachable at 192.168.178.111:30222 (running in k8s)
The private registry contains an image with the name myregistry/mypersonalimg:latest
It is kind of working but not the way I'd like it to. If I want to pull the image from the client I have to use the following command
docker pull 192.168.178.111:30222/mypersonalimg:latest
I would have expected docker pull myregistry/mypersonalimg:latest would work but I guess docker will look then for a registry called myregistry.
Setting /etc/docker/daemon.json with registry-mirrors on the client would work for your case. The dockerd on client will attempting the configured mirrors if the pulled image doesn't give repository address.
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.
I have a private registry at the url registry.lab.example.com where I can push images to from my master node in ocp cluster. When I go about launching a new app referring an image from this private registry, the lookup fails with a error message that the image is not found.
oc new-app --docker-image=registry.lab.example.com/openshift/nginx
My private registry is not even polled to look for the images and that'y why the deployment fails. Is there a way I can add this private registry in the list of to be searched repositories when docker tries to find an image?
There's --add-registry option for docker daemon in RHEL's docker branch (see registry-externally-accessible, check if it's fit to your environment). In addition, you can configure the registry a primary docker source (see pull-through-cache).
I have something on my mind that is bugging me. When running docker images I see a list of my local images I have in my docker environment. When pulling Images I pull it from a registry and more specific pull the specified tag managed by the repository.
so there is the registry as the big hub to store all image
repositories
and the repository is storing commits/tagged versions of a specific image
But what is docker images then? It's a registry as well isn't it? It holds all images that I've built locally or pulled.
If my claim is valid:
How does it comply with running a private registry (mentioned here https://docs.docker.com/registry/deploying/)
Running this docker run -d -p 5000:5000 --restart=always --name registry registry:2
Would deploy this new registry into my docker images...
So now I have a registry within my registry... registception?
What is the difference besides the custom registry is deployable?
Its not a local image registry as other questions have pointed. It is an image cache. The purpose of the image cache is to avoid having every time to download the same image whenever you do a docker run.
docker images simply lists all the cached images on the machine. Whenever there is newer image on the registry, the image(some layers) are downloaded and cached when doing docker pull .... Also, when a layer exists in the local cache, docker tells you that, example:
Step 2/2 : CMD /bin/bash
---> Using cache
On the other hand, a docker registry is a central repository to store images. It provide a remote api to pull and push images. The local image cache does not have this feature. Images in the local cache are read and stored used local docker commands that simply read files under /var/lib/docker/...
To make things clear, think of Docker remote registries (such as Docker Hub) as the remote Git repositories. You pull Docker images (like git repositories) that you need and you play with it.
Like remote Git repositories such as GitHub\BitBucket, Docker registries are also public and private. Public registries are for public usage and open-source projects. Examples include in like Docker Hub. Where as private registries are for organizational use or for your own. Examples for private registries include Azure Container Registry, EC2 Container Registry etc.
The official Docker Registry image is just a Docker registry image for your own system, you can't share them with others unless you have a server or a public Internet IP address. Think of it as Bonobo Private Git Server for Windows.
Your local image registry as you mentioned are all those images that you have build locally or pulled from a registry public or private you can see it like a local cache of images that you can re use without download or rebuild each time.
Running the registry what actually does is to spin up a server that implements the Docker Registry API which allows users to push, pull, delete and handles the storage of this images and their layers. See it like a central repository like npm, nexus
For example if you run the registry in your.registry.com:5000
You can do things like
docker build -t your.registry.com:5000/my-image:tag .
docker push your.registry.com:5000/my-image:tag
So others that have access to your server can pull it
docker pull your.registry.com:5000/my-image:tag
I am using docker-registry to pull my own docker images, but I want to do so without the need to specify the host. meanning:
instead of writing:
docker pull <host>:<port>/<dockerImage>
I want to write:
docker pull <dockerImage>
and first it will try to pull the docker from my private registry, before trying to pull it from the public docker registry.
Is it possible?
I tried to change the DOCKER_INDEX_URL to [my_docker_registry_host]:[port], but it doesn't work.
You can modify or add your /etc/sysconfig/docker
ADD_REGISTRY='--add-registry 192.168.0.169:5000'
INSECURE_REGISTRY='--insecure-registry 192.168.0.169:5000'
then modify /etc/systemd/system/docker.service or /usr/lib/systemd/system/docker.service
ExecStart=/usr/bin/dockerd --registry-mirror=http://192.168.0.169:5000
when you pull a image,docker will pull it from your private registry first,and then docker hub if not found in your private registry.I am working on CentOS 7 Docker 1.12.
No, I think it is not supported yet (1.1.2 as write). I guess main reasons is
The local private registry is not the mirror from the public registry, therefore the logical is not that if it can't be found locally, then it goes to public. They are totally different.
Therefore if we setup own private docker repository but keep the same naming, it will mess up.
When you do docker images, and you see ubuntu, how do you know it is from your local private registry or public.
UPDATE: add one sample case
Also if we have a Dockerfile, put the tomcatit use tomcat7 as base
FROM tomcat7
How do you know this build comes from ?
If we want to have strict process or control on the mapping between the private repo and public repo, it will be complicated.
Technically it is possible, but gain less. It loose the power of docker (community)
It is similar case for other package system which demands the unique name for the package.