Assumptions:
- You have some familiarity with Docker and Kubernetes
NOTE : Any yaml file that’s included, please apply it via kubectl apply -f file.yml.
Once you have an application up and running you’ll need to ensure it’s secure. We’ll be explore using letsencrypt to enable SSL. It’s a free certificate authority and makes it very easy to obtain a certificate. Naturally SSL doesn’t mean your app is secure, but it’s a great first step.
LetsEncrypt has two methods to validate the authenticity of the request in order issue a certificate.
- HTTP Validation
- DNS Validation
Since we’re running in K8s, if you do use DNS validation you’ll need to use a DNS provider that integrates with K8s. In order to make this guide more portable and to avoid tying us to any particular DNS provider, I’m going to use HTTP Validation.
Create An Application
Before we get started, we just need to create a simple application to test this with. We’ll install a hello world app running 3 replicas and a service load balancer for port 80. Here’s the yaml I’ve used below.
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: hello-world
name: hello-world
spec:
replicas: 3
selector:
matchLabels:
app: hello-world
strategy: {}
template:
metadata:
labels:
app: hello-world
spec:
containers:
- image: docker.io/lsizani/hello
imagePullPolicy: Always
name: hello-world
ports:
- containerPort: 80
resources: {}
restartPolicy: Always
status: {}
---
apiVersion: v1
kind: Service
metadata:
labels:
app: hello-world
name: hello-docker-svc
namespace: default
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
app: hello-world
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
Now, the IP address of the service is still internal so you won’t be able to connect to it unless you run the following command temporarily.
kubectl port-forward svc/hello-docker-svc 8000:80
After which you can connect to http://127.0.0.1:8000 and you’ll see something along these lines:
Load Balancer
At this point we need to actually expose this to the public. You’ll need to install an nginx-ingress Load balancer.
helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update
helm install nginx ingress-nginx/ingress-nginx --set controller.publishService.enabled=true
Configure nginx to serve traffic on port 80. Please note the lack of SSL. We’ll revisit this configuration and add SSL in a later pass.
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: hello-docker
annotations:
kubernetes.io/ingress.class: nginx
nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
rules:
- host: hello.demo.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: hello-docker-svc
port:
number: 80
I’m using the DNS name hello.demo.com which is just an example, but if your K8s cluster is configured correctly you’ll get provisioned an IP address. Please update the config to use your own DNS value and have it match the IP address.
For example, if hello.demo.com doesn’t resolve to your external IP address this won’t work and it’ll fail to generate an SSL.
At this point if we navigate to http://hello.demo.com we’ll see the nice little hello world screen we’ve seen previously.
Certificate Manager
Now, we need to add a certificate manager. This is where you could choose to use DNS validation. As I mentioned in the intro, I won’t be using DNS validation to make this guide agnostic to the platform. If you do simply specify the correct options you install the helm chart.
Installing the cert-manager:
helm repo add jetstack https://charts.jetstack.io
helm repo update
helm install \
cert-manager jetstack/cert-manager \
--namespace cert-manager \
--create-namespace \
--version v1.3.1 \
--set installCRDs=true
Certificate Issuer
There’s a Prod and Staging environment for LetsEncrypt. I installed both of them for convenience. Staging isn’t rate limited and allows you to debug/validate behavior without risking getting hit by a quota.
Staging
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
name: letsencrypt-staging
spec:
acme:
# You must replace this email address with your own.
# Let's Encrypt will use this to contact you about expiring
# certificates, and issues related to your account.
email: user@email.com
server: https://acme-staging-v02.api.letsencrypt.org/directory
privateKeySecretRef:
# Secret resource that will be used to store the account's private key.
name: letsencrypt-staging-ssl
# Add a single challenge solver, HTTP01 using nginx
solvers:
- http01:
ingress:
class: nginx
Production
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
name: letsencrypt-prod
spec:
acme:
# You must replace this email address with your own.
# Let's Encrypt will use this to contact you about expiring
# certificates, and issues related to your account.
email: samir@es.net
server: https://acme-v02.api.letsencrypt.org/directory
privateKeySecretRef:
# Secret resource that will be used to store the account's private key.
name: letsencrypt-prod
# Add a single challenge solver, HTTP01 using nginx
solvers:
- http01:
ingress:
class: nginx
At this point we have the ability to create a certificate. It will utilize which ever issuer we want. In the example below, I’m using the letsencrypt-prod which matches the definition above.
Certificate
apiVersion: cert-manager.io/v1alpha2
kind: Certificate
metadata:
namespace: default
name: hello-certs
spec:
secretName: hello-certs
issuerRef:
name: letsencrypt-prod
kind: ClusterIssuer
dnsNames:
- hello.demo.com
If everything worked correctly you should be able to see the certificate via
kubectl get secrets hello-certs -o json
Update Nginx To Enable SSL
Finally now that we have a certificate, let’s enable nginx to use it.
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: hello-docker
annotations:
kubernetes.io/ingress.class: nginx
spec:
tls:
- hosts:
- hello.demo.com
secretName: hello-certs
rules:
- host: hello.demo.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: hello-docker-svc
port:
number: 80
At this point you should be able to connect https://hello.demo.com and get a valid response.
You can also check the validity of your certificate by testing it via SSL Labs I received in A+ for the certificate I generated
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