Setup a private Docker registry with TLS on Kubernetes
This tutorial will show you how to deploy your own registry on Kubernetes for storing Docker images. You will also learn how to setup TLS certificates which will be issued for free from LetsEncrypt.com.
You will learn how each part works together by following the tutorial.
Do I need my own container registry?
The primary purpose of a container registry is to store and host artifacts packaged in the Docker or OCI-image format.
At present there are managed registries for container images offered by almost every cloud provider. Even companies who do not offer compute are starting to offer registries such as jFrog, GitLab.com, Docker Inc, and GitHub.com.
So why would you want to set up your own?
Hosting a registry inside your Kubernetes cluster is the fastest possible way to push and pull images. This matters for use-case such as auto-scaling and affects the overall speed to deploy from a CI/CD pipeline.
Bandwidth in and out of a datacentre is rarely free, let alone across regions. By hosting Docker images where they are produced and consumed keeps costs to the absolute minimum.
Some regulations and legal restrictions such as GDPR may mean that storing artifacts with a SaaS provider is just not tenable.
Although we don't explore it in the scope of this tutorial, additional security can be added to self-hosted registries using Open Source software like the CNCF's Harbor. Harbor scans Docker images for CVEs and other vulnerabilities.
- automation & portability
You may be able to automate a hosted registry on AWS, but completely different code is required to automate a registry on GCP. By using an Open Source registry that we can self-host, we regain the portability aspect.
- ease of use
It is relatively easy to integrate one or more registries into an existing Kubernetes cluster, in any availability region that you choose.
A domain name, or sub-domain which you own. You need to be able to update DNS A records for your domain. I bought mine at domains.google.
Docker - we'll use a Docker container to generate some of our configuration
Kubernetes - this tutorial is written with k3s in mind, but also works on Kubernetes with a few tweaks.
If you're a Civo user, then we'll be hosting our registry on Civo Cloud. You can use k3sup (ketchup) to deploy Kubernetes on your own Instances within a few minutes. If you have access to the #Kube100 program, then you can use the managed k3s service.
helm - a packaging tool used to install cert-manager and docker-registry Some developers have concerns about using helm's server-side component called
tiller. Rest assured, you can use the
helm templatecommand to avoid installing
tillerif it bothers you.
docker-registry - This is a helm chart for Docker's own open source registry
Note: If you are using k3s, you can skip installing Nginx IngressController
We'll first install helm, then tiller, then Kubernetes users can add Nginx in Host mode and k3s users can skip this because they will be using Traefik. After that we'll add cert-manager and an Issuer to obtain certificates, followed by the registry. After everything is installed, we can then make use of our registry using the password created during the tutorial. You'll finish off by testing everything end-to-end, and if you get stuck, there are some helpful tips on how to troubleshoot.
Some components are installed in their own namespaces such as cert-manager, all others will be installed into the
default namespace. You can control the namespace with
kubectl get --namespace/-n NAME or
kubectl get --all-namespaces/-A.
There will also be some ways to take the tutorial further in the appendix.
Install the helm CLI/client
Instructions for latest Helm install
On MacOS and Linux:
curl https://raw.githubusercontent.com/kubernetes/helm/master/scripts/get | bash
Or via Homebrew on Mac:
brew install kubernetes-helm
For Windows users, go to helm.sh.
- Create RBAC permissions for tiller
kubectl -n kube-system create sa tiller \ && kubectl create clusterrolebinding tiller \ --clusterrole cluster-admin \ --serviceaccount=kube-system:tiller
- Install the server-side Tiller component on your cluster
helm init --skip-refresh --upgrade --service-account tiller
Note: this step installs a server component in your cluster. It can take anywhere between a few seconds to a few minutes to be installed properly. You should see tiller appear on:
kubectl get pods -n kube-system.
- Now wait for tiller to become ready:
kubectl rollout status -n kube-system deploy/tiller-deploy deployment "tiller-deploy" successfully rolled out
Your built-in IngressController with k3s
Given that neither Civo's k3s service nor k3sup offer a cloud LoadBalancer, we need to use an IngressController. Fortunately k3s comes with one called Traefik.
For k3s, don't install an IngressController, you already have one, skip ahead.
Add an IngressController if not using k3s
If you're not using k3s, then install Nginx Ingress instead:
helm install stable/nginx-ingress --name nginxingress --set rbac.create=true,controller.hostNetwork=true,controller.daemonset.useHostPort=true,dnsPolicy=ClusterFirstWithHostNet,controller.kind=DaemonSet
You can now install cert-manager, the version used is v0.9.1.
# Install the CustomResourceDefinition resources separately kubectl apply -f https://raw.githubusercontent.com/jetstack/cert-manager/release-0.9/deploy/manifests/00-crds.yaml # Create the namespace for cert-manager kubectl create namespace cert-manager # Label the cert-manager namespace to disable resource validation kubectl label namespace cert-manager certmanager.k8s.io/disable-validation=true # Add the Jetstack Helm repository helm repo add jetstack https://charts.jetstack.io # Update your local Helm chart repository cache helm repo update # Install the cert-manager Helm chart helm install \ --name cert-manager \ --namespace cert-manager \ --version v0.9.1 \ jetstack/cert-manager
See also: cert-manager v0.9.0 docs
Create a ClusterIssuer
The way that cert-manager issues certificates is through an Issuer. The
Issuer can issue certificates for the namespace it is created in, but a
ClusterIssuer can create certificates for any namespace, so that's the one we will use today.
apiVersion: certmanager.k8s.io/v1alpha1 kind: ClusterIssuer metadata: name: letsencrypt-prod namespace: default spec: acme: # The ACME server URL server: https://acme-v02.api.letsencrypt.org/directory # Email address used for ACME registration email: email@example.com # Name of a secret used to store the ACME account private key privateKeySecretRef: name: letsencrypt-prod # Enable the HTTP-01 challenge provider solvers: - http01: ingress: class: traefik
- Edit the file:
Edit the line:
If using Nginx instead of k3s and Traefik, then edit the following:
solvers: - http01: ingress: class: nginx
kubectl apply -f issuer.yaml.
Note you may receive an error, if you do then wait 1-2 minutes and try again whilst cert-manager registers itself
You can check the status of your issuer like this:
kubectl describe clusterissuer/letsencrypt-prod
Look for it to become
For this tutorial a domain
on-k3s.dev was purchased from Google Domains to show a full worked example.
Once you have purchased your domain, you need to point the DNS records at the hosts in the k3s cluster where Nginx is going to be listening on port 80 (HTTP) and port 443 (HTTPS/TLS).
You can find your IP addresses with the Civo UI, or by typing in
civo instance ls through the CLI.
Install the registry
At this stage we can install the registry, but we are going to install it without persistence. If you need persistence see the appendix for how to do this.
Save the following as
export SHA=$(head -c 16 /dev/urandom | shasum | cut -d " " -f 1) export USER=admin echo $USER > registry-creds.txt echo $SHA >> registry-creds.txt docker run --entrypoint htpasswd registry:2 -Bbn admin $SHA > ./htpasswd helm install stable/docker-registry \ --name private-registry \ --namespace default \ --set persistence.enabled=false \ --set secrets.htpasswd=$(cat ./htpasswd)
You will need to have
docker installed and ready for this step. If it's not started, then start it up now.
Then run the script:
chmod +x install-registry.sh ./install-registry.sh
It will install the Docker registry from the docker-registry chart.
Later, when you want to use your registry you can find your username and password in the
Get a TLS certificate for the registry
Now let's get a TLS certificate for the registry.
ingress.yaml, then edit it:
--- apiVersion: extensions/v1beta1 kind: Ingress metadata: name: registry namespace: default annotations: certmanager.k8s.io/cluster-issuer: letsencrypt-prod kubernetes.io/ingress.class: "traefik" nginx.ingress.kubernetes.io/proxy-body-size: 50m labels: app: docker-registry spec: tls: - hosts: - registry.example.com secretName: registry.example.com-cert rules: - host: registry.example.com http: paths: - path: / backend: serviceName: private-registry-docker-registry servicePort: 5000
Update the file:
- Everywhere that you see
registry.example.com, replace it for your domain.
- If using Nginx, then change this line:
Note the special setting:
.ingress.kubernetes.io/proxy-body-size: 50m. This value can be customized and allows large Docker images to be stored in the registry.
kubectl apply -f ingress.yaml
Check the certificate
Now check the certificate with the following:
kubectl get cert -n default NAME READY SECRET AGE registry.on-k3s.dev-cert True registry.on-k3s.dev-cert 47s
For any of the entries listed, you can check the status with
kubectl describe cert/registry.on-k3s.dev-cert Status: Conditions: Last Transition Time: 2019-08-29T13:26:20Z Message: Certificate is up to date and has not expired Reason: Ready Status: True Type: Ready Not After: 2019-11-27T12:26:18Z Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Generated 64s cert-manager Generated new private key Normal GenerateSelfSigned 64s cert-manager Generated temporary self signed certificate Normal OrderCreated 63s cert-manager Created Order resource "registry.on-k3s.dev-cert-3194477141" Normal OrderComplete 31s cert-manager Order "registry.on-k3s.dev-cert-3194477141" completed successfully Normal CertIssued 31s cert-manager Certificate issued successfully
Look for hints in the Status and Events sections.
Now let's test the registry
export DOCKER_PASSWORD="" # Populate this with your password used above export DOCKER_USERNAME="admin" export SERVER="registry.example.com" echo $DOCKER_PASSWORD | docker login $SERVER --username $DOCKER_USERNAME --password-stdin
example.comwith your domain
Sometimes it can take a few minutes for your new domain to become available. If it's an existing domain, then the DNS record should be synchronised already.
Once logged in, you can tag an image from the Docker Hub and push it into your own registry.
export SERVER="registry.example.com" docker pull functions/figlet:latest docker tag functions/figlet:latest $SERVER/functions/figlet:latest docker push $SERVER/functions/figlet:latest
Now that we can log into our registry and push images, we need to enable the same from within our cluster. This is done by attaching an image pull secret to the namespace's service account.
export DOCKER_PASSWORD="" # Populate this with your password used above export DOCKER_USERNAME="admin" kubectl create secret docker-registry my-private-repo \ --docker-username=$DOCKER_USERNAME \ --docker-password=$DOCKER_PASSWORD \ --docker-server=$SERVER \ --namespace default
Now edit the service account and grant it permission to access the secret:
kubectl edit serviceaccount default -n default
Add the following and save:
imagePullSecrets: - name: my-private-repo
To check that it's available in Kubernetes, you can run the following OpenFaaS function, which prints an ASCII logo and then exits.
export SERVER="" kubectl run --rm -t -i figlet --restart Never --image $SERVER/functions/figlet:latest -- figlet Kubernetes _ __ _ _ | |/ / _| |__ ___ _ __ _ __ ___| |_ ___ ___ | ' / | | | '_ \ / _ \ '__| '_ \ / _ \ __/ _ \/ __| | . \ |_| | |_) | __/ | | | | | __/ || __/\__ \ |_|\_\__,_|_.__/ \___|_| |_| |_|\___|\__\___||___/ pod "figlet" deleted
This will print out the Kubernetes logo in ASCII art and then delete the Pod used to run the code.
If it didn't work, find out why with this command:
kubectl get events --sort-by=.metadata.creationTimestamp -n default
Take things further (appendix)
You can take things further and start to explore more advanced use-cases for your registry.
It is desirable, but not essential to enable persistence for a registry. When available, persistence means that if the registry crashes, then the images can be recovered.
There are two routes to enable persistence.
Use S3, or S3-compatible buckets S3 is a protocol and standard for storing objects. You can use an AWS account and S3 as a backing for your registry's storage, or you can install Minio onto your Civo instances and use it as an S3 target instead.
Use PersistentVolumes in Kubernetes Storage in Kubernetes comes in the shape of Volumes. When volumes are not ephemeral, then they are called PersistentVolumes or (PVs). In order to use PVs with k3s, you'll have to install Rancher's Longhorn project.
The helm chart explains the options for using PVs or S3: docker-registry chart.
We have now built a Kubernetes cluster using k3s and have a working registry with TLS, authentication and a public URL.
- helm provided us with charts (packaged software for Kubernetes)
- docker-registry gave us a registry with authentication
- cert-manager provided TLS certificates from LetsEncrypt
- Traefik was built into k3s, or we used Nginx on upstream Kubernetes.
You can now share the registry with your team or use it in your CI/CD pipeline using a tool like Jenkins to build and ship Docker images. You may like to try installing other software to start building applications on Kubernetes such as OpenFaaS.