In my server, I have deployed a custom docker registry with Docker Registry.
So commands below works (assuming the host is registry.example.com):
docker pull alpine
docker tag alpine registry.example.com/alpine
docker push registry.example.com/alpine
docker system prune -af # just clean up
docker pull registry.example.com/alpine # It works!
But then, when I navigate to registry.example.com on a browser, it shows a completely blank page (HTTP returns empty).
I would like to do something similar to hub.docker.com.
How can I add a custom HTML page, so that when navigating to registry.example.com it will return some HTML instead of an empty body? (I don't need a backend server for registration or database. Just a simple HTML document will suffice.)
Do I need to modify some files or config in /var/lib/registry?
Thanks a lot
on the Docker documentation, https://docs.docker.com/registry/configuration/
i was trying to find a setting to have a custom webpage, i could not find a setting for this. The docker hub probably has a page and retrieves the data from the Docker API
Docker HUB != Docker Registry
because
Docker HUB > Docker Registry
You need to create own RestAPI or WEB service that will call docker via CLI/docker internal API and response JSON data/HTML pages.
If you want to use ready solution, I recommend portainer as docker WebUI
Related
I want to implement CI/CD for my application, so far I have managed to build and upload my image on docker hub with GitHub actions. Now I need a way to pull that image on my VPS and run the docker image. I do not know how to achieve that, I tried multiple youtube videos but none show that.
Could someone point me to the right direction?
What I have done is:
Setup a webhook on vps, this serves as a webhook server, define a endpoint and a script to redeploy (Will be executed when endpoint is called and met)
In your GitHub ctions flow, add new a step, send a request to this webhook server endpoint
Usually flow after image exists in Dockerhub is:
you use the docker login command to log in to the user which has permissions to pull the image
You can either pre pull the image using the docker pull command or you can straight on just use the docker run command and it will pull the image if not existing and run it.
For an example with Nginx, the image resides in Dockerhub and with help of official docs you can see
docker run --name mynginx1 -p 80:80 -d nginx
the command which will pull the Nginx image (latest in this case) and run the container with the name of mynigninx1 and expose the port on host 80 and map it to port 80 inside the container.
There is a docker image you can run on your server to watch your working or selected docker containers and when there is a new push to the docker hub registry then it will update your docker image of your project
Its called watchtower
containrrr/watchtower
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 have created docker hub repo and also created and pushed a docker image of python application to the repo.
However, I cannot find the correct Url of the image that I have to provide to the other services which will use this image. for eg azure service fabric or Kubernetes.
How can I find the exact URL? Through PowerShell or through the browser...
You don't usually download images by url. Instead, you use the docker CLI with the repository and image name.
If it's a private repo, login first, by using docker login
more about login
Use docker pull {reponame/imagename:tag} to download an image to your machine.
more about pull
Replace {reponame} with the repository name.
Replace {imagename} with the name you used with docker push.
Replace {tag} with the tag you put on the image (or latest).
For example, I use this line to get my docker hub image:
docker pull loekd/nanoserver:2.0
I am new to Docker. I know the default registry is 'docker hub'. And there are tutorials on navigating 'Docker Hub', e.g. search image etc. But that kind of operations are performed in Docker Hub UI via web.
I was granted a private Docker registry. After I login using the command like docker login someremotehost:8080, I do not know what command to use to navigate around inside the registry. I do not know what images are available and what their tags are.
Could anyone share some info/link on what command to use to explore private remote registry after user login?
Also, to use images from the private registry, the name I need to use becomes something like 'my.registry.address:port/repositoryname.
Is there a way to change the configuration of my docker application, so that it will make my.registry the default registry, and I can just use repositoryname, without specifying registry name in every docker command?
There are no standard CLI commands to interact with remote registries beyond docker pull and docker push. The registry itself might provide some sort of UI (for example, Amazon ECR can list images through the standard AWS console), or your local development team might have a wiki that lists out what's generally available.
You can't change the default Docker registry. You have a pretty strong expectation that e.g. ubuntu is really docker.io/library/ubuntu and not something else.
For the Docker there are only two commands for communication of registry:
Docker Pull and Docker Push
And about the docker private registry there is no any default setting in docker to get the pull from only from the specific registry. The reason for this is name of docker image.For official docker image there is direct name like Centos . But in the docker registry there is also some images which is created by non-official organisation or person. In that kind of docker images there is always name of user or organisation like pivotaldata/centos. So this naming convention is help to docker find the image in docker registry in public(via login) or public registry.
In the case you want to interact more with private repo you can write your own batch script or bash script. Like I have created a batch script which pull all the tag from the private repo if user give the wrong tag.
#echo off
docker login --username=xxxx --password=xxxx
docker pull %1:%2
IF NOT %ERRORLEVEL%==0 (
echo "Specified Version is Not Found "
echo "Available Version for this image is :"
for /f %%i in (' curl -s -H "Content-Type:application/json" -X POST -d "{\"username\":\"user\",\"password\":\"password\"}" https://hub.docker.com/v2/users/login ^|jq -r .token ') do set TOKEN=%%i
curl -sH "Authorization: JWT %TOKEN%" "https://hub.docker.com/v2/repositories/%1/tags/" | jq .results[].name
)
In our current setup we are do proxy to entire docker hub to pull the images, but what we want is limit this proxy to only official indexes like ubuntu, apache etc.
During configuration of repository there was this option to set custom index for the repository, so my two questions are :
With this custom index option will I be able to achieve what I explained above?
If yes, then from where I should get the URL for custom index. so far I tried using https://hub.docker.com/_/centos/ for centos but it didn't worked.
Please suggest how to go about this.
Yes, you can use a custom index to limit what's available in your repo. To achieve that you have to deploy and maintain your own docker registry index service and use that when configuring your docker proxy repository.
However, an easier solution would be to use a content selector to limit what's allowed to be access via your docker proxy repository while still using Docker Hub with it's original index.
Using the simplified content selector solution is a bit hacky, but might work for you. Essentially you have to provide a whitelist (or a blacklist) in a form of a regex. The implication of this solution is that users of your registry will still be able to search for any available image, because you can keep using the Docker Hub's index for simplicity.
Create a docker proxy repository pointing to the Docker Hub.
Create a content selector with a white/black list of images, eg. path =~ '^/v2/library/(alpine|ubuntu).*$' will only allow alpine and ubuntu to be downloaded.
Create a new privilege of type Repository Content Selector.
Create a role containing the above privilege.
Create a user with an above role.
Now, the user you have created shall log into your registry, eg. $ docker login nexus.local:8085. That user will be authorised to pull both alpine and ubuntu (based on the content selector from step 2), but will fail to download anything else.
A sample succesful pull:
$ docker pull nexus.local:8085/alpine
Using default tag: latest
latest: Pulling from alpine
Digest: sha256:0873c923e00e0fd2ba78041bfb64a105e1ecb7678916d1f7776311e45bf5634b
Status: Image is up to date for nexus.local:8085/alpine:latest
A sample failed pull:
$ docker pull nexus.local:8085/postgres
Using default tag: latest
Error response from daemon: unauthorized: access to the requested resource is not authorized
we are do proxy to entire docker hub to pull the images, but what we want is limit this proxy to only official indexes like ubuntu, apache
What I did was:
Create a routing rule
Mode: ALLOW
I wanted only alpine and centos so I created two matches with:
^/v2/library/centos.*$
^/v2/library/alpine.*$
Go to configuration of the docker proxy repository
Go to Routing Rule
And pick the routing rule you created.
That way all except centos and alpine are available from that docker proxy repo. Pulling anything else results in "manigest unknown" error from docker.