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Vault
Vault

Manage Kubernetes native secrets with the Vault Secrets Operator

  • 20min
  • |
  • Vault
  • Interactive

Challenge

Vault offers a complete solution for secrets lifecycle management, but that requires developers and operators to learn a new tool. Instead, developers want a cloud native way to access the secrets through Kubernetes and have no need to understand Vault in great depth. Vault Secrets Operator (VSO) updates Kubernetes native secrets. The user accesses Kubernetes native secrets managed on the backend by HashiCorp Vault.

Solution

A Kubernetes operator is a software extension that uses custom resources to manage applications hosted on Kubernetes.

The Vault Secrets Operator is a Kubernetes operator that syncs secrets between Vault and Kubernetes natively without requiring the users to learn details of Vault use.

The Vault secrets operator supports kv-v1 and kv-v2, TLS certificates in PKI and full range of static and dynamic secrets.

Secrets Operator Diagram

The Vault Secrets Operator syncs the secrets between Vault and the Kubernetes secrets in a specified namespace. Within that namespace, applications have access to the secrets. The secrets are still managed by Vault, but accessed through the standard way on Kubernetes.

Launch Terminal

This tutorial includes a free interactive command-line lab that lets you follow along on actual cloud infrastructure.

Prerequisites

Install supporting tools

This tutorial was last tested 27 June 2023 on a macOS 13.3.1 using the following software versions.

$ docker version
Client:
Cloud integration: v1.0.25
Version:           20.10.16
## ...

$ helm version
version.BuildInfo{Version:"v3.12.0", GitCommit:"c9f554d75773799f72ceef38c51210f1842a1dea", GitTreeState:"clean", GoVersion:"go1.20.4"}

$ k9s version
____  __.________
|    |/ _/   __   \______
|      < \____    /  ___/
|    |  \   /    /\___ \
|____|__ \ /____//____  >
      \/            \/

Version:    0.27.3
Commit:     7c76691c389e4e7de29516932a304f7029307c6d
Date:       n/a

$ kubectl version --short
Client Version: v1.27.1
Kustomize Version: v5.0.1
Server Version: v1.26.3

$ minikube version
minikube version: v1.30.1
commit: 08896fd1dc362c097c925146c4a0d0dac715ace0

Clone the GitHub repository

  1. Clone the repository at learn-vault-secrets-operator.

    $ git clone https://github.com/hashicorp-education/learn-vault-secrets-operator
Cloning into 'learn-vault-secrets-operator'...
remote: Enumerating objects: 15, done.
remote: Counting objects: 100% (15/15), done.
remote: Compressing objects: 100% (11/11), done.
remote: Total 15 (delta 0), reused 15 (delta 0), pack-reused 0
Receiving objects: 100% (15/15), done.

  2. Move into that folder.

    $ cd learn-vault-secrets-operator

Start minikube

Minikube allows you to run a miniature Kubernetes cluster on your local machine.

  1. Create a minikube cluster.

    $ minikube start

    The output should resemble the following:

    😄  minikube v1.30.1 on Darwin 13.4 (arm64)
✨  Automatically selected the docker driver
📌  Using Docker Desktop driver with root privileges
👍  Starting control plane node minikube in cluster minikube
🚜  Pulling base image ...
🔥  Creating docker container (CPUs=2, Memory=4000MB) ...
🐳  Preparing Kubernetes v1.26.3 on Docker 23.0.2 ...
   ▪ Generating certificates and keys ...
   ▪ Booting up control plane ...
   ▪ Configuring RBAC rules ...
🔗  Configuring bridge CNI (Container Networking Interface) ...
   ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎  Verifying Kubernetes components...
🌟  Enabled addons: storage-provisioner, default-storageclass
🏄  Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default

    You have created a Kubernetes cluster running on Docker.

Install Vault cluster

Diagram for Kubernetes cluster

Using Helm install Vault on a local instance of minikube. In Kubernetes, install Vault on it's own virtual cluster called a namespace.

  1. If you have not already, add the HashiCorp Repo.

    $ helm repo add hashicorp https://helm.releases.hashicorp.com

  2. Update to the latest version of the HashiCorp Helm charts, update the repository.

    $ helm repo update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "hashicorp" chart repository
...Successfully got an update from the "open" chart repository
...Successfully got an update from the "bitnami" chart repository
Update Complete. ⎈Happy Helming!⎈

    Details of the output might differ, the important thing is the Update Complete message.

  3. Determine the latest version of Vault.

    $ helm search repo hashicorp/vault
NAME                                    CHART VERSION   APP VERSION     DESCRIPTION                          
hashicorp/vault                         0.28.1          1.17.2          Official HashiCorp Vault Chart       
hashicorp/vault-secrets-operator        0.7.1           0.8.0           Official Vault Secrets Operator Chart

    Vault Secrets Operator supports the latest three versions of Vault. Please see Supported Vault versions for details.

  4. Using the YAML file in the appropriate sub-folder, install Vault on your minikube cluster

    $ helm install vault hashicorp/vault -n vault --create-namespace --values vault/vault-values.yaml

    The output should resemble the following:

    NAME: vault
LAST DEPLOYED: Fri Mar 31 09:37:42 2023
NAMESPACE: vault
STATUS: deployed
REVISION: 1
NOTES:
Thank you for installing HashiCorp Vault!

Now that you have deployed Vault, you should look over the docs on using
Vault with Kubernetes available here:

https://www.vaultproject.io/docs/

Your release is named vault. To learn more about the release, try:
$ helm status vault
$ helm get manifest vault

  5. Wait until the Vault pods are Ready 1/1 and status is Running.

    $ kubectl get pods -n vault
NAME      READY   STATUS    RESTARTS   AGE
vault-0   1/1     Running   0          3m

Configure Vault

setup Vault cluster

Here you connect to the Vault instance on minikube, enable and configure Kubernetes authentication, KV secrets engine, a role and policy for Kubernetes, and create a static secret.

  1. Connect to the Vault instance. Until you exit you will be executing from inside the Vault instance.

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

  2. Move into the tmp directory.

    $ cd tmp

  3. Enable the Kubernetes auth method.

    $ vault auth enable -path demo-auth-mount kubernetes
Success! Enabled kubernetes auth method at: demo-auth-mount/

  4. Configure the auth method.

    $ vault write auth/demo-auth-mount/config \
   kubernetes_host="https://$KUBERNETES_PORT_443_TCP_ADDR:443"

    The output should resemble the following:

    Success! Data written to: auth/demo-auth-mount/config

  5. Enable the kv v2 Secrets Engine.

    $ vault secrets enable -path=kvv2 kv-v2
Success! Enabled the kv-v2 secrets engine at: kvv2/

  6. Create a JSON file with a Vault policy.

    $ tee webapp.json <<EOF
path "kvv2/data/webapp/config" {
   capabilities = ["read", "list"]
}
EOF

    After uploading the Vault policy, it allows reading of the webapp/config secret in the kvv2 secrets engine mount.

    $ vault policy write webapp webapp.json
Success! Uploaded policy: webapp

  7. Create a role in Vault to enable access to secrets within the kv v2 secrets engine.

    $ vault write auth/demo-auth-mount/role/role1 \
   bound_service_account_names=demo-static-app \
   bound_service_account_namespaces=app \
   policies=webapp \
   audience=vault \
   ttl=24h

    The output should resemble the following:

     Success! Data written to: auth/demo-auth-mount/role/role1

    Notice that the bound_service_account_namespaces is app, limiting which namespace the secret is synced to.

  8. Create a secret.

    $ vault kv put kvv2/webapp/config username="static-user" password="static-password"
===== Secret Path =====
kvv2/data/webapp/config

======= Metadata =======
Key                Value
---                -----
created_time       2023-04-03T16:35:56.1103993Z
custom_metadata    <nil>
deletion_time      n/a
destroyed          false
version            1

  9. Exit the Vault instance.

    $ exit

Install the Vault Secrets Operator

Vault Secrets Operator

  1. Use Helm to deploy the Vault Secrets Operator.

    $ helm install vault-secrets-operator hashicorp/vault-secrets-operator -n vault-secrets-operator-system --create-namespace --values vault/vault-operator-values.yaml
NAME: vault-secrets-operator
LAST DEPLOYED: Fri Mar 31 10:00:29 2023
NAMESPACE: vault-secrets-operator-system
STATUS: deployed
REVISION: 1

  2. Examine the file vault-operator-values.yaml for the values that this tutorial uses for VSO:

    $ cat vault/vault-operator-values.yaml
defaultVaultConnection:
   enabled: true
   address: "http://vault.vault.svc.cluster.local:8200"
   skipTLSVerify: false
...

    For more details on these values see the values.yaml file for the Vault Secrets Operator Helm chart.

Deploy and sync a secret

Create secret in App pod

In this section you will set up a namespace with a Kubernetes secret. The Vault Secrets Operator is configured to manage that secret.

  1. Create a namespace called app on your Kubernetes cluster.

    $ kubectl create ns app
namespace/app created

  2. Set up Kubernetes authentication for the secret.

    $ kubectl apply -f vault/vault-auth-static.yaml
vaultauth.secrets.hashicorp.com/static-auth created

    HCP Vault Dedicated

    If you are using HCP Vault Dedicated, similar to Vault enterprise you will need to add the namespace parameter to the spec field in the vault-auth-static.yaml file.

  3. Create the secret names secretkv in the app namespace.

    $ kubectl apply -f vault/static-secret.yaml
vaultstaticsecret.secrets.hashicorp.com/vault-kv-app created

    If you examine the static-secret.yaml just used, look near the bottom.

    Either version you will find a field called refreshAfter. That fields determines how often to check the secret for updates. In the Vault community edition example, it set up to refresh after 30 seconds.

    In the Vault enterprise example the refreshAfter field is a fallback option, set to 1 hour. Since the instantUpdates is enabled, so the refreshAfter field is ignored.

   ...
   syncConfig:
    instantUpdates: true
   ..

Rotate the static secret

In this section you use the k9s tool to display the secret. Then you use Vault to manually rotate the secret, and k9s to verify rotation of the Kubernetes secret.

  1. Open a new terminal and start up k9s.

    $ k9s

  2. If not already displayed, list the namespaces by typing :ns.

    List namespaces

  3. Use the up and down arrows to choose the app namespace and press enter.

    Take a gander at the app namespace

  4. This area is blank, so type in :secrets and press enter.

    typing :secrets

  5. Now the secrets named secretkv is displayed, highlight it.

    highlight the secret

  6. Display the secret by pressing the x key.

    Press the "x" key

  7. In the original terminal, connect to the Vault instance.

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

  8. Rotate the secret.

    $ vault kv put kvv2/webapp/config username="static-user2" password="static-password2"
===== Secret Path =====
kvv2/data/webapp/config

======= Metadata =======
Key                Value
---                -----
created_time       2023-04-03T16:40:31.274411719Z
custom_metadata    <nil>
deletion_time      n/a
destroyed          false
version            2

    Wait about 30 seconds before continuing to the next step, to allow for the secret to refresh.

  9. Return to k9s, and escape back to the secret page and press x again to display the updated secret.

    Rotated secret

    The secret has changed, and now will be different than noted earlier.

  10. At the first window, exit Vault.

    $ exit

Dynamic secrets

Manually rotating secrets is cumbersome and prone to human error. Vault dynamic secrets provides a solution for this.

Now you will create a dynamic secret with the database secrets engine. Dynamic secrets lifecycle is managed by Vault and will be automatically rotated. The lifecycle management includes deleting and recreating the secrets. In this section we will use the Vault Secrets Operator to rotate the Kubernetes secrets every 1 minute.

Install Postgres pod

install PostgreSQL

You will create a pod and install PostGreSQL. PostGreSQL will later generate credentials for the database secrets engine.

  1. Create a namespace for the PostGreSQL pod.

    $ kubectl create ns postgres

  2. Add the Bitnami repository to your local Helm.

    $ helm repo add bitnami https://charts.bitnami.com/bitnami

  3. Install PostgreSQL.

    $ helm upgrade --install postgres bitnami/postgresql --namespace postgres --set auth.audit.logConnections=true  --set auth.postgresPassword=secret-pass

    The output should resemble the following:

    Release "postgres" does not exist. Installing it now.
NAME: postgres
LAST DEPLOYED: Wed Jun  7 05:56:05 2023
NAMESPACE: postgres
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
CHART NAME: postgresql
CHART VERSION: 12.5.6
APP VERSION: 15.3.0

...

Setup PostGreSQL

Setup PostGreSQL

Connect to the Vault instance, and set up a database secrets engine in Vault with a corresponding role and policy.

  1. Connect to the Vault instance.

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

  2. Enable an instance of the Database Secrets Engine.

    $ vault secrets enable -path=demo-db database
Success! Data written to: demo-db/config/demo-db

  3. Configure the Database Secrets Engine.

    $ vault write demo-db/config/demo-db \
   plugin_name=postgresql-database-plugin \
   allowed_roles="dev-postgres" \
   connection_url="postgresql://{{username}}:{{password}}@postgres-postgresql.postgres.svc.cluster.local:5432/postgres?sslmode=disable" \
   username="postgres" \
   password="secret-pass"

    The output should resemble the following:

    Success! Data written to: demo-db/config/demo-db

  4. Create a role for the PostgreSQL pod.

    $ vault write demo-db/roles/dev-postgres \
   db_name=demo-db \
   creation_statements="CREATE ROLE \"{{name}}\" WITH LOGIN PASSWORD '{{password}}' VALID UNTIL '{{expiration}}'; \
      GRANT ALL PRIVILEGES ON DATABASE postgres TO \"{{name}}\";" \
   revocation_statements="REVOKE ALL ON DATABASE postgres FROM  \"{{name}}\";" \
   backend=demo-db \
   name=dev-postgres \
   default_ttl="1m" \
   max_ttl="1m"

    The output should resemble the following:

    Success! Data written to: demo-db/roles/dev-postgres

    Note

    Important: when you define the role in a production deployment, you must create user creation_statements, revocation_statements, renew_statements, and rotation_statements which are valid for the database you've configured. If you do not specify statements appropriate to creating, revoking, or rotating users, Vault inserts generic statements which can be unsuitable for your deployment.

    Also, you do not want default_ttl="1m" or max_ttl="1m" set in production. This is too short and in production a longer TTL should be used. This tutorial is for demonstration purposes.

  5. Create the demo-auth-policy-db policy.

    $ vault policy write demo-auth-policy-db - <<EOF
path "demo-db/creds/dev-postgres" {
   capabilities = ["read"]
}
EOF

    The output should resemble the following:

    Success! Uploaded policy: demo-auth-policy-db

  6. Disconnect to the Vault instance.

    $ exit

Transit encryption

Vault Secrets Operator can be configured to maintain an internal, encrypted persistent cache of client tokens.

This is helpful for being able to transparently renew leases for dynamic secrets should the operator restart. Without using the client cache, the operator would need to fetch new client tokens on restarts, and re-issue credentials for dynamic secrets, causing downtime for applications. With transit encryption configured and enabled, the client token cache is end-to-end encrypted using Transit Encryption so that the persisted tokens cannot be accessed.

  1. The Helm chart vault-operator-values.yaml already set up the Vault secrets operator for client token cache.

    $ cat vault/vault-operator-values.yaml
...
controller:
   manager:
      ...
      clientCache:
         persistenceModel: direct-encrypted
         storageEncryption:
            enabled: true
            mount: demo-auth-mount
            keyName: vso-client-cache
            transitMount: demo-transit
            kubernetes:
               role: auth-role-operator
               serviceAccount: demo-operator

    Much of the remaining tutorial is setting up Vault to these specifications already present in vault-operator-values.yaml.

    The clientCache section has settings for the cache to use the direct encrypted mode.

    The storageEncryption sub-section specifies details of the transit secrets engine, authentication that is used by the transit secrets engine.

    • transitMount sets the transit secrets engine mount named demo-transit.
    • mount sets the Kubernetes auth method engine named demo-auth-transit used by the demo-transit.
    • keyName specifies a key named vso-client-cache used for encrypt/decrypt operations.
    • kubernetes sub-section configures the Vault Kubernetes auth method, specifying the role and the service account.

    Refer to Vault Secrets Operator Helm chart section on storageEncryption documentation for details.

  2. Connect back to the Vault instance.

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

  3. Enable an instance of the Transit Secrets Engine at the path demo-transit.

    $ vault secrets enable -path=demo-transit transit
Success! Enabled the transit secrets engine at: demo-transit/

  4. Create a encryption key.

    $ vault write -force demo-transit/keys/vso-client-cache
Success! Data written to: demo-transit/keys/vso-client-cache

  5. Create a policy for the operator role to access the encryption key.

    $ vault policy write demo-auth-policy-operator - <<EOF
path "demo-transit/encrypt/vso-client-cache" {
   capabilities = ["create", "update"]
}
path "demo-transit/decrypt/vso-client-cache" {
   capabilities = ["create", "update"]
}
EOF

    The output should resemble the following:

    Success! Uploaded policy: demo-auth-policy-operator

  6. Create Kubernetes auth role for the operator.

    $ vault write auth/demo-auth-mount/role/auth-role-operator \
   bound_service_account_names=vault-secrets-operator-controller-manager \
   bound_service_account_namespaces=vault-secrets-operator-system \
   token_ttl=0 \
   token_period=120 \
   token_policies=demo-auth-policy-operator \
   audience=vault

    The output should resemble the following:

    Success! Data written to: auth/demo-auth-mount/role/auth-role-operator

Setup dynamic secrets

Vault includes a number of dynamic secrets engines capable of generating temporary credentials for various applications. In this tutorial, Vault's dynamic secrets engine for PostgreSQL to generate temporary client credentials to the PostgreSQL database.

See Dynamic Secrets for another example.

Create a role to allow access to the Kubernetes secrets engine for the demo-ns.

  1. Create a new role for the dynamic secret.

    $ vault write auth/demo-auth-mount/role/auth-role \
   bound_service_account_names=demo-dynamic-app \
   bound_service_account_namespaces=demo-ns \
   token_ttl=0 \
   token_period=120 \
   token_policies=demo-auth-policy-db \
   audience=vault

    The output should resemble the following:

    Success! Data written to: auth/demo-auth-mount/role/auth-role

  2. Exit the shell.

    $ exit

Create the application

Dynamic secrets

In this section you create a namespace demo-ns that has a dynamic secret available, and an application to access it. By using this secret the application has access to PostgreSQL. Later you will use k9s to examine the variable and verify that it automatically rotates.

  1. Create a new namespace.

    $ kubectl create ns demo-ns
namespace/demo-ns created

  2. Create the app, Vault connection, authentication, service account and corresponding secrets.

    $ kubectl apply -f dynamic-secrets/.
deployment.apps/vso-db-demo created
secret/vso-db-demo created
vaultauth.secrets.hashicorp.com/default configured
vaultauth.secrets.hashicorp.com/demo-operator created
vaultconnection.secrets.hashicorp.com/default configured
vaultdynamicsecret.secrets.hashicorp.com/vso-db-demo-create created
vaultdynamicsecret.secrets.hashicorp.com/vso-db-demo created
serviceaccount/demo-operator created

    Note

    If you receive warning messages resembling the following:

    Warning: resource vaultauths/default is missing the kubectl.kubernetes.io/last-applied-configuration annotation. The kubectl apply requires this. The kubectl apply command should be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically.

    No preexisting information for annotation kubectl.kubernetes.io/last-applied-configuration exists, therefore this first configuration and will be used to compare for changes later.

Examine the dynamic secret

Using k9s, examine the dynamic secret and confirm the secrets change every minute.

  1. Go back to the window with k9s and display all the available namespaces with the :ns command.

  2. Find and choose the demo-ns by highlighting it and pressing return.

    select the demo-ns

  3. Display the secrets in the demo-ns pod by typing :secrets and enter.

    Run secrets command

  4. Choose the first secret displayed and press x.

    choose a secret

    The secrets should resemble the following, remember to note down the password displayed

    Note down password

  5. Exit screen with escape key and wait a minimum of 60 seconds, and check the values once again with x. Notice the password has automatically changed.

    command and output results

Clean up

  1. Delete the minikube cluster.

    $ minikube delete
🔥  Deleting "minikube" in docker ...
🔥  Deleting container "vault-secrets-operator" ...
🔥  Removing /Users/mrken/.minikube/machines/vault-secrets-operator ...
💀  Removed all traces of the "vault-secrets-operator" cluster.

Additional discussion

A Kubernetes operator is a software extension that uses custom resources to manage applications hosted on Kubernetes. The Vault Secret Operator leverages HashiCorp Vault as a complete secrets management solution.

Secrets exist within Namespaces, which are virtual clusters with a Kubernetes Cluster. The secrets operator allows you to administer the secrets through Vault, but access them as a native Kubernetes primitive.

Kubernetes cluster administrators interested in using the Vault Secrets Operator to rotate Dynamic secrets are encouraged to look at the demo included with the source for the Vault Secrets Operator.

In this tutorial you began to learn about the Vault Secrets Operator by setting up a minikube cluster with a Vault instance and a Vault Secrets Operator controller, then created a secret in a namespace called app. Then you displayed the secret in k9s, and used Vault to rotate the secret. You then validated the change in the Vault secret value also changed the Kubernetes secret.

In the Dynamic Secrets section you set up a PostgreSQL pod, placeholder application and created a dynamic secret. Then, using k9s you watched the secret rotate automatically.

The Vault Secrets Operator is a Kubernetes operator pattern for use with HashiCorp Vault. It is responsible for syncing Vault secrets to Kubernetes Secrets natively.

Features of the Vault Secrets Operator include support for all secrets engines and Kubernetes, AWS, JWT and AppRole authentication to Vault.

References

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Manage Kubernetes service tokens

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Templated policy for Kubernetes workloads