HashiCorp Vault setup - Kubernetes and cert-manager

Sign in to DigiCert​​®​​ Trust Lifecycle Manager.

Go to Integrations > Connectors.

In the Vaults section, choose HashiCorp.

Follow the steps to download the plugin binary.

Move the plugin to the plugin_directory defined in the next procedure.

Install Vault using its Helm chart and unseal the vault for use. Refer to the HashiCorp documentation for detailed assistance.

Copy the HashiCorp Vault plugin into the vault-0 pod and configure the plugin_directory path in the Vault configuration file.

Start an interactive shell session on the vault-0 pod.

$ kubectl exec --stdin=true --tty=true vault-0 -- /bin/sh

Register the plugin in Vault.

vault write sys/plugins/catalog/secret/vault-pki-backend-digicert 
sha_256="a2b10f2b8c3e76ec2580651fdb3bd012a11eafc20e2f62020956282df16b9a9e" 
command="vault-pki-backend-digicert"user.name@DC-Q91DVX3PJX hashicorp % export VAULT_ADDR='http://127.0.0.1:8200'

Enable the DigiCert​​®​​ PKI secrets engine.

vault secrets enable -path=digicert-pki -plugin-name=vault-pki-backend-digicert plugin

Create a configuration that allows the plugin to connect with the DigiCert​​®​​ environment.

vault write digicert-pki/configs/stage-dcone url="https://stage.one.digicert.com/" api_key="01aad362f1610f7d9e171f0fa2_80995e78c63a8e7d474c41dbecb2a165f049aa47799ad42f90fc386b1edb680c"

Response:

Success! Data written to: digicert-pki/configs/stage-dcone

Create a role to define the default profile_id.

vault write digicert-pki/roles/stage config_name="stage-dcone" profile_id="017e05b0-fedc-4a9a-88f7-1fd759f20f37"

Response:

Success! Data written to: digicert-pki/roles/stage

Create a policy called digicert-pki that enables read access to the PKI secrets engine paths.

vault policy write digicert-pki - <<EOF
path "digicert-pki*"                        { capabilities = ["read", "list"] }
path "digicert-pki/sign/win-the-customer-com"    { capabilities = ["create", "update"] }
path "digicert-pki/issue/win-the-customer-com"   { capabilities = ["create"] }
EOF

Configure Vault to enable clients to authenticate with a Kubernetes Service Account token. Create an authentication role named issuer in the vault-0 pod and bind it to the digicert-pki policy with the Kubernetes Service Account.

vault write auth/kubernetes/role/issuer \
bound_service_account_names=issuer \
bound_service_account_namespaces=default \
policies=digicert-pki \
ttl=20m

Deploy cert-manager.

Create a Service Account called issuer in the default namespace.

$ kubectl create serviceaccount issuer

To set up a Vault issuer you must first create a Kubernetes Secret resource. The Service Account generates a secret that is required by the Issuer in Kubernetes 1.23. In Kubernetes 1.24+, you need to explicitly create the secret.

$ cat >> issuer-secret.yaml <<EOF
apiVersion: v1
kind: Secret
metadata:
  name: issuer-token-lmzpj
  annotations:
    kubernetes.io/service-account.name: issuer
type: kubernetes.io/service-account-token
EOF

Create an issuer secret.

$ kubectl apply -f issuer-secret.yaml
secret/issuer-token-lmzpj created

Get all the secrets in the default namespace. The issuer secret is shown here prefixed with issuer-token.

$ kubectl get secrets
NAME                          TYPE                                  DATA   AGE
issuer-token-lmzpj            kubernetes.io/service-account-token   3      6s
sh.helm.release.v1.vault.v1   helm.sh/release.v1                    1      33m

Create a variable named ISSUER_SECRET_REF to capture the secret name.

ISSUER_SECRET_REF=$(kubectl get secrets --output=json | jq -r '.items[].metadata | select(.name|startswith("issuer-token-")).name')

Define an Issuer resource called vault-issuer, which sets Vault as a certificate issuer.

$ cat > vault-issuer.yaml <<EOF
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: vault-issuer
  namespace: default
spec:
  vault:
    server: http://vault.default:8200
    path: digicert-pki/sign/win-the-customer-com
    auth:
      kubernetes:
        mountPath: /v1/auth/kubernetes
        role: issuer
        secretRef:
          name: $ISSUER_SECRET_REF
          key: token
EOF

Create the vault-issuer Issuer.

$ kubectl apply --filename vault-issuer.yaml

Define a certificate named win-the-customer-com (for example).

cat > win-the-customer-com-cert.yaml <<EOF
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: win-the-customer-com
  namespace: default
spec:
  secretName: win-the-customer-com-tls
  issuerRef:
    name: vault-issuer
  commonName: test.winthecustomer1.com
  dnsNames:
  - test.winthecustomer1.com
EOF

Request the win-the-customer-com certificate.

kubectl apply --filename win-the-customer-com.yaml

View the details of the certificate.

Common Name:  test29sept.winthecustomer.com
  Dns Names:
    test27septdns.winthecustomer.com
  Issuer Ref:
    Name:       issuer
  Secret Name:  win-the-customer-com-tls
Status:
  Conditions:
    Last Transition Time:  2024-09-29T18:08:37Z
    Message:               Certificate is up to date and has not expired
    Observed Generation:   1
    Reason:                Ready
    Status:                True
    Type:                  Ready
  Not After:               2024-10-29T18:08:37Z
  Not Before:              2024-09-29T18:08:37Z
  Renewal Time:            2024-10-19T18:08:37Z
  Revision:                1
Events:
  Type    Reason     Age   From                                       Message
  ----    ------     ----  ----                                       -------
  Normal  Issuing    28s   cert-manager-certificates-trigger          Issuing certificate as Secret does not exist
  Normal  Generated  28s   cert-manager-certificates-key-manager      Stored new private key in temporary Secret resource "win-the-customer-com-q22vp"
  Normal  Requested  28s   cert-manager-certificates-request-manager  Created new CertificateRequest resource "win-the-customer-com-z9lhx"
  Normal  Issuing    26s   cert-manager-certificates-issuing          The certificate has been successfully issued

The certificate issued from DigiCert is now added to your Kubernetes secrets and a copy will also be stored in the vault-0 directory.

vault list vault-pki/certs
Keys
----
281b93ecc49106db473084f5e41095034f67a0a0
56195e18913c66d277b2e509c8b0e194925f59f9
6937bbf0ba698f270804a954c02139507fc25998
7a8619ed9ae90f04dd7a2180887b35bfb487cc81