How to setup TLS correctly in Kubernetes via cert-manager?

Question

I'm trying to setup TLS for a service that's available outside a Kubernetes cluster (AWS EKS). With cert-manager, I've successfully issued a certificate and configured ingress, but I'm still getting error NET::ERR_CERT_AUTHORITY_INVALID. Here's what I have:

namespace tests and hello-kubernetes in it (both deployment and service have name hello-kubernetes-first, serivce is ClusterIP with port 80 and targetPort 8080, deployment is based on paulbouwer/hello-kubernetes:1.8, see details in my previous question)

DNS and ingress configured to show the service:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-kubernetes-ingress
  namespace: tests
spec:
  ingressClassName: nginx
  rules:
  - host: test3.projectname.org
    http:
      paths:
      - path: "/"
        pathType: Prefix
        backend:
          service:
            name: hello-kubernetes-first
            port:
              number: 80

Without configuring TLS, I can access test3.projectname.org via http and see the service (well, it tries to redirect me to https, I see NET::ERR_CERT_AUTHORITY_INVALID, I go to insecure anyway and see the hello-kubernetes page).

note: I have nginx-ingress ingress controller; it was installed before me via the following chart:
```
apiVersion: v2
name: nginx
description: A Helm chart for Kubernetes
type: application
version: 4.0.6
appVersion: "1.0.4"
dependencies:
- name: ingress-nginx
  version: 4.0.6
  repository: https://kubernetes.github.io/ingress-nginx
```
and the values overwrites applied with the chart differ from the original ones mostly in extraArgs: default-ssl-certificate: "nginx-ingress/dragon-family-com" is uncommneted

cert-manager installed via kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.5.4/cert-manager.yaml

ClusterIssuer created with the following config:

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-backoffice
spec:
  acme:
    server: https://acme-staging-v02.api.letsencrypt.org/directory
    # use https://acme-v02.api.letsencrypt.org/directory after everything is fixed and works
    privateKeySecretRef: # this secret is created in the namespace of cert-manager
      name: letsencrypt-backoffice-private-key
    # email: <will be used for urgent alerts about expiration etc>

    solvers:
    # TODO: add for each domain/second-level domain/*.projectname.org
    - selector:
        dnsZones:
          - test.projectname.org
          - test2.projectname.org
          - test3.projectname.org
      http01:
        ingress:
          class: nginx

certificate in the tests namespace. It's config is

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: letsencrypt-certificate-31
  namespace: tests
spec:
  secretName: tls-secret-31
  issuerRef:
    kind: ClusterIssuer
    name: letsencrypt-backoffice
  commonName: test3.projectname.org
  dnsNames:
  - test3.projectname.org

Now, certificate is ready (kubectl get certificates -n tests tells that) and to apply it, I add this to ingress's spec:

  tls:
    - hosts:
      - test3.projectname.org
      secretName: tls-secret-31

However, when I try to open test3.projectname.org via https, it still shows me the NET::ERR_CERT_AUTHORITY_INVALID error. What am I doing wrong? How to debug this? I've checked up openssl s_client -connect test3.projectname.org:443 -prexit* and it shows the following chain:

 0 s:CN = test3.projectname.org
   i:C = US, O = (STAGING) Let's Encrypt, CN = (STAGING) Artificial Apricot R3
 1 s:C = US, O = (STAGING) Let's Encrypt, CN = (STAGING) Artificial Apricot R3
   i:C = US, O = (STAGING) Internet Security Research Group, CN = (STAGING) Pretend Pear X1
 2 s:C = US, O = (STAGING) Internet Security Research Group, CN = (STAGING) Pretend Pear X1
   i:C = US, O = (STAGING) Internet Security Research Group, CN = (STAGING) Doctored Durian Root CA X3

and tells, among other output

Verification error: unable to get local issuer certificate

Unfortunately, I haven't found anything useful to try further, so any help is appreciated.

SYN SYN · Accepted Answer · 2021-11-14T17:16:06

Your ClusterIssuer refers to LetsEncrypt staging issuer. Remove that setting / the default should use their production setup.

How to setup TLS correctly in Kubernetes via cert-manager?

1 Answers