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Miłosz Kukuła - dev blog

Contents

Mutual TLS with self-signed certificates in kubernetes

   848 words   4 minutes 
/posts/mutual-tls-with-self-signed-certificates-in-kubernetes/logo.png

Introduction

During my daily work very often I need to set up mutual tls for given service or database. The problem appears during local development, because on local Kubernetes cluster mutual authentication is not provided. In that case, cert manager will help us to solve this problem.

Warning
Self-signed certificates are very useful for local development and testing, but they shouldn’t be used in production environment. In that case, you can use Vault.

0. Prepare necessary configuration files

certconfig.txt

[ req ]
default_md = sha256
prompt = no
string_mask = utf8only
req_extensions = req_ext
distinguished_name = req_distinguished_name
[ req_distinguished_name ]
commonName = kukulam
organizationName = kukulam.dev
[ req_ext ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
keyUsage=critical,digitalSignature,keyEncipherment,keyCertSign
extendedKeyUsage=critical,serverAuth,clientAuth
basicConstraints=critical,CA:true
subjectAltName = @alt_names
[ alt_names ]
DNS.0 = localhost

csrconfig.txt

[ req ]
default_md = sha256
prompt = no
string_mask = utf8only
req_extensions = req_ext
distinguished_name = req_distinguished_name
[ req_distinguished_name ]
commonName = kukulam
organizationName = kukulam.dev
[ req_ext ]
keyUsage=critical,digitalSignature,keyEncipherment,keyCertSign
extendedKeyUsage=critical,serverAuth,clientAuth
basicConstraints=critical,CA:true
subjectAltName = @alt_names
[ alt_names ]
DNS.0 = localhost

generate-cert.sh

Tip
If bash commands are too nerdy for you, there is website which could do the same job. You can generate certificate by using certificatetools.

Script generates tls.crt and tls.key file using configs: csrconfig.txt, certconfig.txt.

# Generate the RSA private key
openssl genpkey -outform PEM -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out tls.key

# Create the CSR
openssl req -new -nodes -key tls.key -config csrconfig.txt -nameopt utf8 -utf8 -out cert.csr

# Self-sign your CSR
openssl req -x509 -nodes -in cert.csr -days 365 -key tls.key -config certconfig.txt -extensions req_ext -nameopt utf8 -utf8 -out tls.crt

# Clean up
rm cert.csr

Result:

» ./generate-cert.sh
.+++
..........................................................................................................................................................................+++
» ls
certconfig.txt   csrconfig.txt    generate-cert.sh tls.crt          tls.key
» cat tls.crt
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
» cat tls.key
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----

1. Encode certificate with base64

Note

To encode you can use the bash command base64

» echo "text" | base64
dGV4dAo=

or you can use base64encode website.

Encoded tls.crt

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

Encoded tls.key

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

2. Setup ClusterIssuer with cert-manager in kubernetes

Note
You can use Issuer instead of ClusterIssuer if you want to isolate resource within single namespace. ClusterIssuer is visible globally in kubernetes cluster.

cluster-issuer-secrets.yml

apiVersion: v1
kind: Secret
metadata:
  name: ca-issuer-certs
  namespace: cert-manager
data:
  tls.crt: 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
  tls.key: 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

cluster-issuer.yml

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: ca-issuer
  namespace: cert-manager
spec:
  ca:
    secretName: ca-issuer-certs

Apply manifests

kubectl apply -f cluster-issuer-secrets.yml
kubectl apply -f cluster-issuer.yml

Result

» kubectl apply -f cluster-issuer-secrets.yml
secret/ca-issuer-certs created
» kubectl apply -f cluster-issuer.yml
clusterissuer.cert-manager.io/ca-issuer created
» kubectl get secrets -n cert-manager
NAME                      TYPE     DATA   AGE
ca-issuer-certs           Opaque   2      43s
cert-manager-webhook-ca   Opaque   3      23h
» kubectl get clusterissuers.cert-manager.io -n cert-manager
NAME        READY   AGE
ca-issuer   True    57s

3. Setup certificate in kubernetes

certificate.yml

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: example-certificate
  namespace: mtls
  labels:
    app.kubernetes.io/name: mtls
spec:
  isCA: false
  secretName: mtls-certs
  duration: 9000h
  renewBefore: 180h
  usages:
    - digital signature
    - key encipherment
    - client auth
  privateKey:
    algorithm: RSA
    encoding: PKCS1
    size: 2048
  dnsNames:
    - "localhost"
    - "127.0.0.1"
  issuerRef:
    name: ca-issuer
    kind: ClusterIssuer
    group: cert-manager.io

Apply manifest

kubectl apply -f certificate.yml

Result

» kubectl apply -f certificate.yml
certificate.cert-manager.io/example-certificate created
» kubectl get certificates -n mtls
NAME                  READY   SECRET       AGE
example-certificate   True    mtls-certs   34s
» kubectl describe certificate example-certificate -n mtls
Name:         example-certificate
Namespace:    mtls
Labels:       app.kubernetes.io/name=mtls
Annotations:  <none>
API Version:  cert-manager.io/v1
Kind:         Certificate
Metadata:
  Creation Timestamp:  2023-04-07T17:26:54Z
  Generation:          1
  Managed Fields:
    API Version:  cert-manager.io/v1
    Fields Type:  FieldsV1
    fieldsV1:
      f:status:
        .:
        f:conditions:
          .:
          k:{"type":"Ready"}:
            .:
            f:lastTransitionTime:
            f:message:
            f:observedGeneration:
            f:reason:
            f:status:
            f:type:
        f:notAfter:
        f:notBefore:
        f:renewalTime:
    Manager:      cert-manager-certificates-readiness
    Operation:    Update
    Subresource:  status
    Time:         2023-04-07T17:26:54Z
    API Version:  cert-manager.io/v1
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .:
          f:kubectl.kubernetes.io/last-applied-configuration:
        f:labels:
          .:
          f:app.kubernetes.io/name:
      f:spec:
        .:
        f:dnsNames:
        f:duration:
        f:isCA:
        f:issuerRef:
          .:
          f:group:
          f:kind:
          f:name:
        f:privateKey:
          .:
          f:algorithm:
          f:encoding:
          f:size:
        f:renewBefore:
        f:secretName:
        f:usages:
    Manager:         kubectl-client-side-apply
    Operation:       Update
    Time:            2023-04-07T17:26:54Z
  Resource Version:  52466
  UID:               ea79b5b7-6ca3-4277-89a9-717e88352364
Spec:
  Dns Names:
    localhost
    127.0.0.1
  Duration:  9000h0m0s
  Issuer Ref:
    Group:  cert-manager.io
    Kind:   ClusterIssuer
    Name:   ca-issuer
  Private Key:
    Algorithm:   RSA
    Encoding:    PKCS1
    Size:        2048
  Renew Before:  180h0m0s
  Secret Name:   mtls-certs
  Usages:
    digital signature
    key encipherment
    client auth
Status:
  Conditions:
    Last Transition Time:  2023-04-07T17:26:54Z
    Message:               Certificate is up to date and has not expired
    Observed Generation:   1
    Reason:                Ready
    Status:                True
    Type:                  Ready
  Not After:               2024-04-11T22:03:41Z
  Not Before:              2023-04-02T22:03:41Z
  Renewal Time:            2024-04-04T10:03:41Z
Events:                    <none>
» kubectl get secrets -n mtls
NAME         TYPE                DATA   AGE
mtls-certs   kubernetes.io/tls   3      4d19h

4. Generated certificate is stored in kubernetes secrets

» kubectl describe secret mtls-certs -n mtls
Name:         mtls-certs
Namespace:    mtls
Labels:       <none>
Annotations:  cert-manager.io/alt-names: localhost,127.0.0.1
              cert-manager.io/certificate-name: example-certificate
              cert-manager.io/common-name:
              cert-manager.io/ip-sans:
              cert-manager.io/issuer-group: cert-manager.io
              cert-manager.io/issuer-kind: ClusterIssuer
              cert-manager.io/issuer-name: ca-issuer
              cert-manager.io/uri-sans:

Type:  kubernetes.io/tls

Data
====
ca.crt:   1253 bytes
tls.crt:  1159 bytes
tls.key:  1675 bytes

GitHub project

All files which I used to generate certificate are stored in github repository.

References

Photo by Muhammad Zaqy Al Fattah on Unsplash

Updated on 2023-04-03
 kubernetes, security
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