TLS

Bank-Vaults tries to automate as much as possible for handling TLS certificates.

• The vault-operator automates the creation and renewal of TLS certificates for Vault.
• The vault Helm Chart automates only the creation of TLS certificates for Vault via Sprig.

Both the operator and the chart generate a Kubernetes Secret holding the TLS certificates, this is named ${VAULT_CR_NAME}-tls. For most examples in the vault-operator repository, the name of the secret is vault-tls.

The Secret data keys are:

• ca.crt
• ca.key
• server.crt
• server.key

Note: The operator doesn’t overwrite this Secret if it already exists, so you can provide this certificate in any other way, for example using cert-manager or by simply placing it there manually.

Operator custom TLS settings

The following attributes influence the TLS settings of the operator. The ca.crt key is mandatory in existingTlsSecretName, otherwise the Bank-Vaults components can’t verify the Vault server certificate.

CANamespaces

The list of namespaces where the generated CA certificate for Vault should be distributed. Use ["*"] for all namespaces.

Default value: []

ExistingTLSSecretName

The name of the secret that contains a TLS server certificate, key, and the corresponding CA certificate. The secret must be in the kubernetes.io/tls type secret keys + ca.crt key format. If the attribute is set, the operator uses the certificate already set in the secret, otherwise it generates a new one.

The ca.crt key is mandatory, otherwise the Bank-Vaults components can’t verify the Vault server certificate.

Default value: ""

TLSAdditionalHosts

A list hostnames or IP addresses to add to the SAN on the automatically generated TLS certificate.

Default value: []

TLSExpiryThreshold

The expiration threshold of the Vault TLS certificate in Go Duration format.

Default value: 168h

Helm chart custom TLS settings

Starting with version 1.20, the Vault Helm chart allows you to set custom TLS settings. The following attributes influence the TLS settings of the Helm chart. The ca.crt key is mandatory in secretName, otherwise the Bank-Vaults components can’t verify the Vault server certificate.

SecretName

The name of the secret that contains a TLS server certificate, key, and the corresponding CA certificate. The secret must be in the kubernetes.io/tls type secret keys + ca.crt key format. If the attribute is set, the operator uses the certificate already set in the secret, otherwise it generates a new one.

The ca.crt key is mandatory, otherwise the Bank-Vaults components can’t verify the Vault server certificate.

Default value: ""

CANamespaces

The list of namespaces where the generated CA certificate for Vault should be distributed.

Default value: []

Using the generated custom TLS certificate with vault-operator

To use an existing secret which contains the TLS certificate, define existingTlsSecretName in the Vault custom resource.

Generate custom certificates with CFSSL

If you don’t want to use the certificates generated by Helm or the Bank-Vaults operator, the easiest way to create a custom certificate for Bank-Vaults is using CFSSL.

The TLS directory in the documentation holds a set of custom CFSSL configurations which are prepared for the Helm release name vault in the default namespace. Of course, you can put any other certificates into the Secret below, this is just an example.

1. Install CFSSL.

2. Create a CA:

   cfssl genkey -initca csr.json | cfssljson -bare ca
   

3. Create a server certificate:

   cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=config.json -profile=server server.json | cfssljson -bare server
   

4. Put these certificates (and the server key) into a Kubernetes Secret:

   kubectl create secret generic vault-tls --from-file=ca.crt=ca.pem --from-file=server.crt=server.pem --from-file=server.key=server-key.pem
   

5. Install the Vault instance:

   • With the chart which uses this certificate:

   helm upgrade --install vault ../charts/vault --set tls.secretName=vault-tls
   

   • With the operator, create a Vault custom resource, and apply it:

   kubectl apply -f vault-cr.yaml
   

Generate custom certificates with cert-manager

You can use the following cert-manager custom resource to generate a certificate for Bank-Vaults.

kubectl apply -f - <<EOF
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: test-selfsigned
spec:
  selfSigned: {}
---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: selfsigned-cert
spec:
  commonName: vault
  usages:
    - server auth
  dnsNames:
    - vault
    - vault.default
    - vault.default.svc
    - vault.default.svc.cluster.local
  ipAddresses:
    - 127.0.0.1
  secretName: selfsigned-cert-tls
  issuerRef:
    name: test-selfsigned
EOF