Is it possible, to pull private images from Docker Hub to a Google Cloud Kubernetes cluster?
Is this recommended, or do I need to push my private images also to Google Cloud?
I read the documentation, but I found nothing that could explain me this clearly. It seems that it is possible, but I don´t know if it's recommended.
There is no restriction to use any registry you want. If you just use the image name, (e.g., image: nginx) in pod specification, the image will be pulled from public docker hub registry with tag assumed as :latest
As mentioned in the Kubernetes documentation:
The image property of a container supports the same syntax as the
docker command does, including private registries and tags. Private
registries may require keys to read images from them.
Using Google Container Registry
Kubernetes has native support for the Google Container Registry (GCR), when running on Google
Compute Engine (GCE). If you are running your cluster on GCE or Google
Kubernetes Engine, simply use the full image name (e.g.
gcr.io/my_project/image:tag). All pods in a cluster will have read
access to images in this registry.
Using AWS EC2 Container Registry
Kubernetes has native support for the AWS EC2 Container Registry, when nodes are AWS EC2 instances.
Simply use the full image name (e.g.
ACCOUNT.dkr.ecr.REGION.amazonaws.com/imagename:tag) in the Pod
definition. All users of the cluster who can create pods will be able
to run pods that use any of the images in the ECR registry.
Using Azure Container Registry (ACR)
When using Azure Container Registry you can authenticate using either an admin user or a
service principal. In either case, authentication is done via standard
Docker authentication. These instructions assume the azure-cli command
line tool.
You first need to create a registry and generate credentials, complete
documentation for this can be found in the Azure container registry
documentation.
Configuring Nodes to Authenticate to a Private Repository
Here are the recommended steps to configuring your nodes to use a private
registry. In this example, run these on your desktop/laptop:
Run docker login [server] for each set of credentials you want to use. This updates $HOME/.docker/config.json.
View $HOME/.docker/config.json in an editor to ensure it contains just the credentials you want to use.
Get a list of your nodes, for example:
if you want the names: nodes=$(kubectl get nodes -o jsonpath='{range.items[*].metadata}{.name} {end}')
if you want to get the IPs: nodes=$(kubectl get nodes -o jsonpath='{range
.items[*].status.addresses[?(#.type=="ExternalIP")]}{.address}
{end}')
Copy your local .docker/config.json to the home directory of root on each node.
for example: for n in $nodes; do scp ~/.docker/config.json root#$n:/root/.docker/config.json; done
Use cases:
There are a number of solutions for configuring private registries.
Here are some common use cases and suggested solutions.
Cluster running only non-proprietary (e.g. open-source) images. No need to hide images.
Use public images on the Docker hub.
No configuration required.
On GCE/Google Kubernetes Engine, a local mirror is automatically used for improved speed and availability.
Cluster running some proprietary images which should be hidden to those outside the company, but visible to all cluster users.
Use a hosted private Docker registry.
It may be hosted on the Docker Hub, or elsewhere.
Manually configure .docker/config.json on each node as described above.
Or, run an internal private registry behind your firewall with open read access.
No Kubernetes configuration is required.
Or, when on GCE/Google Kubernetes Engine, use the project’s Google Container Registry.
It will work better with cluster autoscaling than manual node configuration.
Or, on a cluster where changing the node configuration is inconvenient, use imagePullSecrets.
Cluster with a proprietary images, a few of which require stricter access control.
Ensure AlwaysPullImages admission controller is active. Otherwise, all Pods potentially have access to all images.
Move sensitive data into a “Secret” resource, instead of packaging it in an image.
A multi-tenant cluster where each tenant needs own private registry.
Ensure AlwaysPullImages admission controller is active. Otherwise, all Pods of all tenants potentially have access to all
images.
Run a private registry with authorization required.
Generate registry credential for each tenant, put into secret, and populate secret to each tenant namespace.
The tenant adds that secret to imagePullSecrets of each namespace.
Consider reading the Pull an Image from a Private Registry document if you decide to use a private registry.
There are 3 types of registries:
Public (Docker Hub, Docker Cloud, Quay, etc.)
Private: This would be a registry running on your local network. An example would be to run a docker container with a registry image.
Restricted: That is one registry that needs some credentials to validate. Google Container Registry (GCR) in an example.
As you are well saying, in a public registry, such as Docker Hub, you can have private images.
Private and Restricted registries are more secure obviously, as one of them is not even exposed to internet (ideally), and the other one needs credentials.
I guess you can achieve an acceptable security level with any of them. So, it is matter of choice. If you feel your application is critical, and you don't want to run any risk, you should have it in GCR, or in a private registry.
If you feel like it is important, but not critical, you could have it in any public repository, making it private. This will give a layer of security.
Related
There is an option to set registry-mirrors in daemon.json of docker to config default registry while pulling images.
Is there another way so I can push docker images to a local registry by default (without specifying local registry URL)?
To describe more, we have 2 nexus repositories, one as proxy of default registry (so we pull images through it), and one hosted one.
We want all developers push their images to our hosted registry, not docker hub.
registry-mirrors is a mirror of Docker Hub, so the design is to push to the authoritative source, and if a pull to one of the Hub mirrors fails, that will also fall back to Hub.
It looks like what you are trying to do is merge a multiple namespaces into one, the namespace for Hub, and the namespace for your local Nexus repositories. Doing that is dangerous because deploying the same image reference on different machines, or when the Nexus instance is unavailable for any reason, will result in a dependency confusion attack.
The design of image references is to always specify the registry when you don't want to use Docker Hub. This avoids the dependency confusion attacks seen by other package repositories.
If you're worried about developers pushing images to Hub that they shouldn't be, then I'd recommend setting up an HTTP proxy that rejects POST and PUT requests to registry-1.docker.io (a pull uses GET and HEAD requests), and make sure all developers use that proxy (typically via a network policy that doesn't allow direct access without the proxy).
I'm doing research on how container services in Azure compare with our on-prem implementation of containers, which includes Docker Trusted Registry.
Is one required to use Azure Container Registry to make use of Azure Containers? Or could we tie into our existing on-prem Docker Trusted Registry?
Thank you!
Yes, you could use a private registry---Docker Trusted Registry for Azure Container Instance.
Containers are built from images that are stored in one or more
repositories. These repositories can belong to a public registry, like
Docker Hub, or to a private registry. An example of a private registry
is the Docker Trusted Registry, which can be installed on-premises or
in a virtual private cloud. You can also use cloud-based private
container registry services, including Azure Container Registry.
A publicly available container image does not guarantee security.
Container images consist of multiple software layers, and each
software layer might have vulnerabilities. To help reduce the threat
of attacks, you should store and retrieve images from a private
registry, such as Azure Container Registry or Docker Trusted Registry.
In addition to providing a managed private registry, Azure Container
Registry supports service principal-based authentication through Azure
Active Directory for basic authentication flows. This authentication
includes role-based access for read-only (pull), write (push), and
other permissions.
When you create the ACI via the Azure portal, you will see the three options.
I have my own docker private registry created in my host machine[localhost] and I intend to make use of localhost private registry to pull images in google Kubernetes engine.
How do I make it happen?
You won't be able to use either your locally built docker images (which can be listed by running docker images on your local machine) or your locally set up docker private registry (unless you make it available under some public IP which doesn't make much sense if it's your home computer). Those images can be used by your local kubernetes cluster but not by GKE.
In GKE we generally use GCR (Google Container Registry) for storing images that are used by our Kubernetes Engine. We can build them directly from code (e.g. pulled from our github account) on a cloudshell vm (simply click Cloud Shell icon in your GCP Console). You can build them directly on this machine and you can push them to your GCR directly from there.
Alternatively, if you build your images locally, but by "locally" I mean this time the nodes where kubernetes is installed (so in case of GKE they need to be present on every worker node), you can also use them without a need of pulling them from any external registry. The only requirement is that they are available on all kubernetes worker nodes. You can force kubernetes to always use your local images, present on your nodes, instead of trying to pull them from a registry by specifying:
imagePullPolicy: Never
in your Pod or Deployment specification. More details on that you can find in this answer.
I am using Azure Kubernetes Service(AKS) and I am no allowed to use Docker Hub repository for pushing and pulling Images, so please tell me, is there a way to create kubernetes deployments or pods by using tar of image or by pulling image using ssh connection from other server in which I am having Docker engine running.
I am assuming that the reason why you are not allowed to use Docker Hub is because of the company policy that wants to keep everything private and contained within Azure.
In that case, I suggest using the Azure's own container registry service named Azure Container Registry which have the following benefit:
It works similar to DockerHub in the sense that you can just sign in with username and password, update the image name and you are good to go.
It is the solution from Azure which should fit nicely in your Infrastructure design. Please refer to this link for details instructions on how to connect your AKS and ACR.
The traffic flow from AKS and ACR is private and not exposed to the Internet.
How can I whitelist containers which are allowed to run inside PCF? We want to have control over the containers which are running in pcf.
As I write this Cloud Foundry doesn't directly offer this functionality, but I suppose you could restrict network access so that you can't get to the public registries and can only get to a private registry that you control which only has approved images.
You can use something like Docker Registry, Harbor or Artifactory to run your own registry.
If your custom registry does not have a trusted TLS certificate, you may need to add it to the list of trusted certs in Ops Manager or configure PAS and add it to the Private Docker insecure registry allow list.
Hope that helps!