Create Kubernetes native secrets from HCP Vault Dedicated with VSO

10min
|
HCP
Vault

The Vault Secrets Operator allows you to create native Kubernetes Secrets from static and dynamic secrets managed by Vault.

Challenge

Kubernetes secrets can are a static configuration object containing confidential information. They are typically created during the deployment of an application, and remain unchanged throughout the lifecycle of the application’s container. Kubernetes does not support secret rotation, leaving that responsibility to the development or operations team.

Solution

The Vault Secrets Operator takes a static or dynamic secret from Vault and creates a Kubernetes secret. With VSO, using Vault is transparent, which lets you avoid updating your applications or processes.

In this tutorial, you will set up:

Your local environment to support Vault Dedicated.
Start a Kubernetes cluster using minikube.
Configure networking between Vault Dedicated and Kubernetes.
Deploy the Vault Secrets Operator
Create and read Kubernetes secrets managed by Vault Dedicated.

Vault Secrets Operator for self-hosted Vault in Kubernetes

Using the Vault Secrets Operator with self-hosted Vault running in a Kubernetes cluster is explored in the Vault Secrets Operator tutorial.

Prerequisites

HCP Vault Dedicated dev tier or higher cluster available
Vault
kubectl
Helm
minikube installed and configured
ngrok installed and configured with an auth token

This tutorial was tested against the following specific versions:

HCP Vault Dedicated 1.15.4
Vault CLI 1.15
Kubectl 1.27.2
Helm 3.11.2
minikube 1.31
Kubernetes 1.27.3

Lab setup

Vault setup

Note

If you do not have access to an HCP Vault Dedicated cluster, visit the Create a Vault Cluster on HCP tutorial.

Launch the HCP Portal and login.
Click Vault in the left navigation pane.
In the Vault clusters pane, click vault-cluster.
Under Cluster URLs, click Public Cluster URL.
Security consideration
When an HCP Vault Dedicated cluster has public access enabled, you can connect to Vault from any internet connected device. If your use case requires public access to be enabled, we recommend configuring the IP allow list to limit which IPv4 public IP addresses or CIDR ranges can connect to Vault to limit the attack surface.
When the Vault Dedicated cluster has private access enabled you will need to access the cluster from a connected cloud provider such as AWS with a VPC peering connection, a AWS transit gateway connection, or Azure with a Azure Virtual Network peering connection. For the purposes of this tutorial, your cluster should have public access enabled.
Open a new terminal and set the VAULT_ADDR environment variable to the copied address.
```
$ export VAULT_ADDR=<Public_Cluster_URL>
```
Return to the Overview page and click Generate token.
Within a few moments, a new token will be generated.
Copy the Admin Token.
Return to the terminal and set the VAULT_TOKEN environment variable.
```
$ export VAULT_TOKEN=<token>
```
Set the VAULT_NAMESPACE environment variable to admin.
```
$ export VAULT_NAMESPACE=admin
```
The admin namespace is the top-level namespace automatically created by HCP Vault. All CLI operations default to use the namespace defined in this environment variable.
Note
For these tasks, you can use HCP Vault Dedicated's admin token. However, it is recommended that admin tokens are only used for enough initial setup or in emergencies. As a best practice, use an authentication method or token that meets the policy requirements.

Enable the KV secret engine.

$ vault secrets enable -version=2 -path=secret kv

Success! Enabled the kv secrets engine at: secret/

Create a secret at path secret/exampleapp/config with a username and password.

$ vault kv put secret/exampleapp/config username='jalbertson' password='bestpasswordever'

======== Secret Path ========
secret/data/exampleapp/config

======= Metadata =======
Key                Value
---                -----
created_time       2022-06-06T18:26:14.070155Z
custom_metadata    <nil>
deletion_time      n/a
destroyed          false
version            1

The Vault Dedicated server is ready.

Kubernetes setup

You will use minikube, a CLI tool that provisions and manages the lifecycle of single-node Kubernetes cluster, to set up a Kubernetes cluster on your system.

Start a Kubernetes cluster.

$ minikube start

😄  minikube v1.25.2 on Darwin 12.3
✨  Automatically selected the docker driver. Other choices: hyperkit, virtualbox, ssh
👍  Starting control plane node minikube in cluster minikube
🚜  Pulling base image ...
🔥  Creating docker container (CPUs=2, Memory=8100MB) ...
🐳  Preparing Kubernetes v1.23.3 on Docker 20.10.12 ...
    ▪ kubelet.housekeeping-interval=5m
    ▪ Generating certificates and keys ...
    ▪ Booting up control plane ...
    ▪ Configuring RBAC rules ...
🔎  Verifying Kubernetes components...
    ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🌟  Enabled addons: storage-provisioner
🏄  Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default

The initialization process takes several minutes as it retrieves any necessary dependencies and executes various container images.

Verify the status of the Kubernetes cluster.

$ minikube status

minikube
type: Control Plane
host: Running
kubelet: Running
apiserver: Running
kubeconfig: Configured

The Kubernetes cluster is ready.

Configure Kubernetes

Create Vault service account

Create a Kubernetes service account named vault-auth with a service account token. This token is used by Vault to authenticate with the Kubernetes API.

$ kubectl create -f - <<EOF
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: vault-auth
---
apiVersion: v1
kind: Secret
metadata:
  name: vault-auth
  annotations:
    kubernetes.io/service-account.name: vault-auth
type: kubernetes.io/service-account-token
---
EOF

Example output:

serviceaccount/vault-auth created
secret/vault-auth created

Create a role for the vault-auth service account to permit access to the Kubernetes API.

$ kubectl create -f - <<EOF
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: role-tokenreview-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
  - kind: ServiceAccount
    name: vault-auth
    namespace: default
EOF

Example output:

clusterrolebinding.rbac.authorization.k8s.io/role-tokenreview-binding created

Retrieve the vault-auth secret and store it as an environment variable.

$ VAULTAUTH_SECRET=$(kubectl get secret vault-auth -o json | jq -r '.data') \
    && echo $VAULTAUTH_SECRET

{
  "ca.crt": "LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSURC..<snip>..lwNGN6cmFpb0E9PQotLS0tLUVORCBDRVJUSUZJQ0FURS0tLS0tCg==",
  "namespace": "ZGVmYXVsdA==",
  "token": "ZXlKaGJHY2lPaUpTVXpJMU5pSXNJbXRwWkNJNkl..<snip>..TWR3T0kwRVlxcE0zZGJ1d3JMUW5vMjNhSnJWaU5SaEp3"
}

The secret includes the Kubernetes public key ca.crt and the token as base64 encoded strings.

Decode the ca.crt certificate and store it as an environment variable.

$ K8S_CA_CRT=$(echo $VAULTAUTH_SECRET | jq -r '."ca.crt"' | base64 -d)

Decode the token and store it as an environment variable.
```
$ VAULTAUTH_TOKEN=$(echo $VAULTAUTH_SECRET | jq -r '.token' | base64 -d)
```
You have collected the necessary information for the vault-auth service account to configure the Kubernetes auth method.

Configure networking

In this tutorial, you will configure ngrok to expose the Kubernetes API to Vault Dedicated. For production workloads, this would typically be set up using a peering connection, transit gateway, or VPN. Refer to the HashiCorp Virtual Network documentation to learn more.

In another terminal, start a proxy to expose the Kubernetes API.

$ kubectl proxy --disable-filter=true

Request filter disabled, your proxy is vulnerable to XSRF attacks, please be cautious
Starting to serve on 127.0.0.1:8001

Leave this tab open with the proxy running.

In another terminal, start ngrok and create a tunnel to the proxy listening on port 8001.

Warning

ngrok is used to expose the Kubernetes API over the internet to HCP Vault Dedicated. Using --scheme=http exposes the API without encryption to avoid TLS certificate errors.

For production workloads, use a private peering or transit gateway connection with trusted certificates.

$ ngrok http --scheme=http 127.0.0.1:8001

Example output:

ngrok                                                                                                                                                              (Ctrl+C to quit)

Session Status                online
Account                       username (Plan: Free)
Update                        update available (version 3.0.5, Ctrl-U to update)
Version                       3.1.1
Region                        United States (us)
Latency                       32.791235ms
Web Interface                 http://127.0.0.1:4040
Forwarding                    http://d12b-34-567-89-10.ngrok.io -> 127.0.0.1:8001

Connections                   ttl     opn     rt1     rt5     p50     p90
                              0       0       0.00    0.00    0.00    0.00

Copy the ngrok forwarding address.
Return to the terminal where you set the VAULT_ADDR environment variable and set an environment variable for the ngrok forwarding address.
```
$ export K8S_URL=<actual-address-from-ngrok>
```
The Kubernetes API is now accessible to Vault Dedicated.

Configure Vault

Enable the Kubernetes auth method.

$ vault auth enable kubernetes

Success! Enabled kubernetes auth method at: kubernetes/

Configure the Kubernetes auth method to connect to the Kubernetes API using the vault-auth service account token.

$ vault write auth/kubernetes/config \
 token_reviewer_jwt=$VAULTAUTH_TOKEN \
 kubernetes_host=$K8S_URL \
 kubernetes_ca_cert=$K8S_CA_CRT

Example output:

Success! Data written to: auth/kubernetes/config

Create a Vault policy that permits read access to secret/exampleapp/config

$ vault policy write exampleapp-read - << EOF
path "secret/data/exampleapp/config" {
  capabilities = ["read"]
}
EOF

Example output:

Success! Uploaded policy: exampleapp-read

Create a role for the Kubernetes auth method and include the exampleapp-read Vault policy.

$ vault write auth/kubernetes/role/exampleapp \
bound_service_account_names=vault-auth \
bound_service_account_namespaces=default \
policies=default,exampleapp-read \
ttl=1h

Example output:

Success! Data written to: auth/kubernetes/role/exampleapp

Install the Vault Secrets Operator

Install and update the HashiCorp Helm repository.

$ helm repo add hashicorp https://helm.releases.hashicorp.com \
    && helm repo update

"hashicorp" already exists with the same configuration, skipping
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "hashicorp" chart repository
Update Complete. ⎈Happy Helming!⎈

Install the Vault Secrets Operator.

$ helm install vault-secrets-operator hashicorp/vault-secrets-operator \
    --namespace vault-secrets-operator \
    --create-namespace \

Example output:

NAME: vault-secrets-operator
LAST DEPLOYED: Thu Jan 25 11:54:37 2024
NAMESPACE: vault-secrets-operator
STATUS: deployed
REVISION: 1

The Vault Secrets Operator has been installed.

Configure the Vault Secrets Operator

Create a connection to Vault Dedicated.

$ kubectl create -f - <<EOF
---
apiVersion: secrets.hashicorp.com/v1beta1
kind: VaultConnection
metadata:
  namespace: default
  name: vault-connection
spec:
  # address to the Vault server.
  address: $VAULT_ADDR
---
EOF

Verify the configuration.

$ kubectl describe vaultconnection.secrets.hashicorp.com/vault-connection

Name:         vault-connection
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  secrets.hashicorp.com/v1beta1
Kind:         VaultConnection
Metadata:
  Creation Timestamp:  2024-01-25T16:58:47Z
  Finalizers:
    vaultconnection.secrets.hashicorp.com/finalizer
  Generation:        1
  Resource Version:  3720
  UID:               60500026-9195-4e82-bb6b-9d255c1cd8dc
Spec:
  Address:          https://vault-cluster-public-vault-a53c80d0.66e2d051.z1.hashicorp.cloud:8200
  Skip TLS Verify:  false
Status:
  Valid:  true
Events:
  Type    Reason    Age   From             Message
  ----    ------    ----  ----             -------
  Normal  Accepted  107s  VaultConnection  VaultConnection accepted

Configure authentication for the Vault Secrets Operator controller.

$ kubectl create -f - <<EOF
---
apiVersion: secrets.hashicorp.com/v1beta1
kind: VaultAuth
metadata:
  name: vault-auth
spec:
  vaultConnectionRef: vault-connection
  method: kubernetes
  mount: kubernetes
  kubernetes:
    role: exampleapp
    serviceAccount: vault-auth
  namespace: "admin" #Vault Dedicated only
---
EOF

Example output:

vaultauth.secrets.hashicorp.com/vault-auth created

Configure the Vault Secrets Operator to read from the secret KV v2 mount at the exampleapp/config path.

$ kubectl create -f - <<EOF
---
apiVersion: secrets.hashicorp.com/v1beta1
kind: VaultStaticSecret
metadata:
  name: vault-static-secret
spec:
  vaultAuthRef: vault-auth
  namespace: "admin" #Vault Dedicated only
  mount: secret
  type: kv-v2
  path:  exampleapp/config
# version: 2
  refreshAfter: 300s
  destination:
    create: true
    name: vso-handled
---
EOF

Example output:

vaultstaticsecret.secrets.hashicorp.com/vault-static-secret created

Verify the Kubernetes secret was created.

$ kubectl get secrets

NAME          TYPE                                  DATA   AGE
vault-auth    kubernetes.io/service-account-token   3      67m
vso-handled   Opaque                                3      23m

The secret vso-handled was created by the Vault Secrets Operator and named based on the name parameter provided in the VaultStaticSecret config.

Read the Kubernetes secret value and decode the base64 encoded strings.

$ kubectl get secret vso-handled -o json | jq ".data | map_values(@base64d)"

{
  "_raw": "{\"data\":{\"password\":\"bestpasswordever\",\"username\":\"jalbertson\"},\"metadata\":{\"created_time\":\"2024-01-25T15:48:31.871429498Z\",\"custom_metadata\":null,\"deletion_time\":\"\",\"destroyed\":false,\"version\":1}}",
  "password": "bestpasswordever",
  "username": "jalbertson"
}

Applications and users can now read the secret natively in Kubernetes such as mounting a volume or using an environment variable.

Clean up

Delete any Vault Dedicated clusters created that will not be used after completing the tutorial.
Stop minikube.
```
$ minikube stop
```
(Optional) Delete the minikube instance.
```
$ minikube delete
```
Return to the terminal running ngrok and type ctrl-c to stop ngrok.
Return to the terminal running the Kubernetes proxy and type ctrl-c to stop the proxy.

Additional Resources

Vault Secrets Operator with HCP Vault tutorial
Vault Secrets Operator documentation

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