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In this knowledge base article, we set up Hashicorp Vault and injector service with the Hashicorp Vault Helm chart and store a HiveMQ License as a secret. Then we will deploy the HiveMQ broker cluster with the hivemq-operator Helm chart to demonstrate how the Hashicorp Vault injector service retrieves, decodes and writes the secret to /opt/hivemq/license/hivmq.lic file on the pod for the HiveMQ application to use.

Prerequisites

These instructions require the following tools on the local machine:

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The kubectl context should be set to the Kubernetes cluster where the HiveMQ broker will be installed.

\uD83D\uDCD8 Instructions

Install the Hashicorp Vault Helm Chart

1. Add the HashiCorp Helm repository.

   Code Block
   language bash
   helm repo add hashicorp https://helm.releases.hashicorp.com

2. Update all the repositories to ensure helm is aware of the latest versions.

   Code Block
   language bash
   helm repo update hashicorp

3. Install the latest version of the Hashicorp Vault server running in development mode.
   Development mode: Running a Hashicorp Vault server in development is automatically initialized and unsealed. This is ideal in a learning environment but NOT recommended for a production environment.

   Code Block
   language bash
   helm install vault hashicorp/vault --set "server.dev.enabled=true"

   The vault pod and vault Agent Injector pod are deployed in the default namespace.

4. Display all the pods in the default namespace.

   Code Block
   language bash
   kubectl get pods

   Code Block
   language text
   NAME READY STATUS RESTARTS AGE vault-0 1/1 Running 0 80s vault-agent-injector-5945fb98b5-tpglz 1/1 Running 0 80s

   The vault-0 pod runs a vault server in development mode. The vault-agent-injector pod performs the injection based on the annotations present or patched on a deployment.
   

5. Wait until the vault-0 pod and vault-agent-injector pod are running and ready (1/1).

Set a secret in Hashicorp Vault

1. Copy the hivemq-license file to the vault-0 pod.

   Code Block
   language bash
   kubectl cp hivemq.lic vault-0:/tmp/

2. Verify that the file is copied.

   Code Block
   language bash
   kubectl exec -it vault-0 -- ls /tmp

   Code Block
   language text
   hivemq.lic

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

   Code Block
   language bash
   kubectl exec -it vault-0 -- /bin/sh

   

   Your system prompt is replaced with a new prompt / $. Commands issued at this prompt are executed on the vault-0 container.

4. Enable kv-v2 secrets at the path hivemq.

   Code Block
   language bash
   vault secrets enable -path=hivemq kv-v2

   Code Block
   language text
   Success! Enabled the kv-v2 secrets engine at: hivemq/

5. Create a secret at path hivemq/myenv/license with a hivemq_license_b64 key and base64-encoded /tmp/hivemq.lic file.

   Code Block
   language bash
   cd /tmp vault kv put hivemq/myenv/license hivemq_license_b64="$(base64 -w 0 hivemq.lic)"

   Code Block
   language text
   ====== Secret Path ====== hivemq/data/myenv/license ======= Metadata ======= Key Value --- ----- created_time 2024-02-21T17:34:39.261249639Z custom_metadata <nil> deletion_time n/a destroyed false version 1

6. Verify that the secret is defined at the path hivemq/myenv/license.

   Code Block
   language bash
   vault kv get hivemq/myenv/license

   Code Block
   language text
   ====== Secret Path ====== hivemq/data/myenv/license ======= Metadata ======= Key Value --- ----- created_time 2024-02-21T14:57:01.446984026Z custom_metadata <nil> deletion_time n/a destroyed false version 1 ========= Data ========= Key Value --- ----- hivemq_license_b64 SCFNUSRbM10.......

   The secret is ready for the application.

7. Lastly, exit the vault-0 pod.

   Code Block
   language bash
   exit

Configure Kubernetes authentication

Hashicorp Vault provides a Kubernetes authentication method that enables clients to authenticate with a Kubernetes Service Account Token. This token is provided to each pod when it is created.

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

   Code Block
   language bash
   kubectl exec -it vault-0 -- /bin/sh

   

   Your system prompt is replaced with a new prompt / $. Commands issued at this prompt are executed on the vault-0 container.

2. Enable the Kubernetes authentication method.

   Code Block
   language bash
   vault auth enable kubernetes

   Code Block
   language text
   Success! Enabled kubernetes auth method at: kubernetes/

   Hashicorp Vault accepts a service token from any client in the Kubernetes cluster. During authentication, Hashicorp Vault verifies that the service account token is valid by querying a token review Kubernetes endpoint.

3. Configure the Kubernetes authentication method to use the location of the Kubernetes API.

   Note: For the best compatibility with recent Kubernetes versions, ensure you are using Hashicorp Vault v1.13.3 or greater.

   Code Block
   language bash
   vault write auth/kubernetes/config kubernetes_host="https://$KUBERNETES_PORT_443_TCP_ADDR:443"

   Successful output from the command resembles this example:

   Code Block
   language text
   Success! Data written to: auth/kubernetes/config

   The environment variable KUBERNETES_PORT_443_TCP_ADDR is defined and references the internal network address of the Kubernetes host.

4. For a client to read the secret data defined at hivemq/myenv/license, requires that the read capability be granted for the path hivemq/data/myenv/license. This is an example of a policy. A policy defines a set of capabilities.

5. Write out the policy named hivemq that enables the read capability for secrets at path hivemq/data/myenv/license.

   Code Block
   language bash
   vault policy write hivemq - <<EOF path "hivemq/data/myenv/license" { capabilities = ["read"] } EOF

6. Create a Kubernetes authentication role named hivemq.

   Code Block
   language bash
   vault write auth/kubernetes/role/hivemq \ bound_service_account_names=hivemq-hivemq-operator-hivemq \ bound_service_account_namespaces=hivemq \ policies=hivemq \ ttl=24h

   Successful output from the command resembles this example:

   Code Block
   language text
   Success! Data written to: auth/kubernetes/role/hivemq

   The role connects the Kubernetes service account, hivemq-hivemq-operator-hivemq, and namespace, hivemq, with the Hashicorp Vault policy, hivemq. The tokens returned after authentication are valid for 24 hours.

7. Lastly, exit the vault-0 pod.

   Code Block
   language bash
   exit

Inject secrets into the pods

1. If you do not have values.yaml file yet, you can get the latest version from the Helm chart repository and store it as a file, for example, values-hivemq.yaml:

   Code Block
   language bash
   helm show values hivemq/hivemq-operator > values-hivemq.yaml

2. Edit the values-hivemq.yaml file. Add annotations to the hivemq pods.

   Code Block
   language yaml
   hivemq: # Annotations to add to the HiveMQ Pods podAnnotations: vault.hashicorp.com/agent-inject: "true" vault.hashicorp.com/role: "hivemq" vault.hashicorp.com/agent-inject-status: 'update' vault.hashicorp.com/agent-inject-secret-hivemq.lic: "hivemq/data/myenv/license" vault.hashicorp.com/secret-volume-path-hivemq.lic: "/opt/hivemq/license/" vault.hashicorp.com/agent-inject-template-hivemq.lic: | {{- with secret \"hivemq/data/myenv/license\" -}} {{- $hivemq_broker_license := base64Decode .Data.data.hivemq_license_b64 -}} {{- $hivemq_broker_license -}} {{- end -}}

3. (Re)install hivemq

   Code Block
   language bash
   helm upgrade hivemq --install hivemq/hivemq-operator -n hivemq -f values-hivemq.yaml

4. Get all the pods in the hivemq namespace.

   Code Block
   language bash
   kubectl get pods --namespace hivemq

   Code Block
   language text
   NAME READY STATUS RESTARTS AGE hivemq-599cb74d9c-s8hhm 0/2 Init:0/1 0 23s hivemq-69697d9598-l878s 1/1 Running 0 20m vault-0 1/1 Running 0 78m vault-agent-injector-5945fb98b5-tpglz 1/1 Running 0 78m

   Wait until the re-deployed hivemq pod reports that it is Running and ready (2/2).

   This new pod now launches two containers. The application container, named hivemq, and the Hashicorp Vault Agent container, named vault-agent.
   

5. Display the logs of the vault-agent container in the new hivemq pod.

   Code Block
   language bash
   kubectl logs \ $(kubectl get pod -l app=hivemq -o jsonpath="{.items[0].metadata.name}") \ --container vault-agent

   Hashicorp Vault Agent manages the token lifecycle and the secret retrieval. The secret is rendered in the hivemq container at the path /opt/hivemq/license/.

6. Display the secret written to the hivemq container.

   Code Block
   language bash
   kubectl exec \ $(kubectl get pod -l app=hivemq -o jsonpath="{.items[0].metadata.name}") \ --container hivemq -- cat /opt/hivemq/license/hivemq.lic

   The base64-decoded secret data is present on the container

\uD83D\uDCCB Related articles

https://developer.hashicorp.com/vault/tutorials/kubernetes/kubernetes-sidecar?ajs_aid=f51d5b2f-f5e5-4e88-8689-d479a67a2ae8&product_intent=vault#inject-secrets-into-the-pod

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