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    Manage Apache Solr credentials using the KubeVault operator

    OpenBao’s solr-database-plugin is a dynamic-credentials database plugin for Apache Solr. The plugin provisions credentials by talking to Solr’s Security Plugin API: each issued credential becomes a Basic Auth Plugin user and is bound to one or more pre-existing roles on the configured Rule-Based Authorization Plugin via Solr’s set-user-role API. The plugin does not create roles; it only manages users and their role bindings, so every role referenced from creationStatements must already exist on the authorizer.

    The same CRD shape is used both for the in-process solr-database-plugin and for the hub-spoke remote-solr-plugin; the difference is whether the Vault AppBinding referenced by SecretEngine.spec.vaultRef is marked deploymentMode: RemoteAgent (then the SecretEngine controller rewrites plugin_name to remote-solr-plugin and attaches spoke_name).

    You need to be familiar with the following CRDs:

    Before you begin

    • Install KubeVault operator in your cluster from here.
    • Run an Apache Solr cluster with the Basic Auth Plugin and Rule-Based Authorization Plugin enabled (security.json in ZooKeeper / SolrCloud, or server/solr/security.json for standalone). The configured admin principal must have permission to add users and assign roles.
    • Pre-create the Solr roles you want to bind credentials to (e.g. admin, read). The plugin only binds — it does not create roles.
    $ kubectl create ns demo
namespace/demo created

    Vault Server

    Deploy a Vault Server using the KubeVault operator: Deploy Vault Server. The KubeVault operator will create an AppBinding wiring up Kubernetes auth.

    $ kubectl get appbinding -n demo vault -o yaml

    AppBinding for Apache Solr

    Create an AppBinding pointing at the Solr HTTP endpoint. Unlike most database engines, the URL here is not a JDBC/connection URI — it is the HTTP(S) base URL of a Solr node (the Security Plugin REST API lives under /solr/admin/authentication and /solr/admin/authorization). The referenced Secret carries the username and password of a Solr Basic Auth principal that has permission to manage users and assign roles.

    apiVersion: appcatalog.appscode.com/v1alpha1
kind: AppBinding
metadata:
  name: solr
  namespace: demo
spec:
  clientConfig:
    url: http://solr.demo.svc:8983
  secret:
    kind: Secret
    name: solr-cred
---
apiVersion: v1
kind: Secret
metadata:
  name: solr-cred
  namespace: demo
type: kubernetes.io/basic-auth
stringData:
  username: solr
  password: change-me

    If you front the Solr endpoint with a self-signed TLS cert, set SecretEngine.spec.solr.insecure: true below. Drop the knob once you front Solr with a real CA-issued certificate.

    Enable and Configure Solr Secret Engine

    When a SecretEngine crd object is created, the KubeVault operator will enable a secret engine on a specified path and configure the secret engine with the given configuration.

    A sample SecretEngine for Solr:

    apiVersion: engine.kubevault.com/v1alpha1
kind: SecretEngine
metadata:
  name: solr-engine
  namespace: demo
spec:
  vaultRef:
    name: vault
  solr:
    databaseRef:
      name: solr
      namespace: demo
    pluginName: solr-database-plugin   # optional; this is the default
    allowedRoles:
      - "*"
    insecure: false                    # set true only for self-signed dev clusters

    Apply it and wait for STATUS=Success:

    $ kubectl apply -f solr-engine.yaml
secretengine.engine.kubevault.com/solr-engine created

$ kubectl get secretengines -n demo
NAME          STATUS    AGE
solr-engine   Success   10s

    Use kubectl describe secretengine -n demo solr-engine to inspect error events, if any.

    Create a SolrRole

    A SolrRole describes how the plugin should mint a dynamic credential. creationStatements is a single-element string slice holding a JSON role document of the form '{"roles":["admin","read"]}'. The listed roles must already exist on the Rule-Based Authorization Plugin — the plugin only binds via set-user-role, it does not create roles.

    apiVersion: engine.kubevault.com/v1alpha1
kind: SolrRole
metadata:
  name: solr-readonly
  namespace: demo
spec:
  secretEngineRef:
    name: solr-engine
  creationStatements:
    - '{"roles":["admin","read"]}'
  defaultTTL: 1h
  maxTTL: 24h

    Apply and verify:

    $ kubectl apply -f solr-role.yaml
solrrole.engine.kubevault.com/solr-readonly created

$ kubectl get solrrole -n demo
NAME            STATUS    AGE
solr-readonly   Success   12s

    The role name in Vault follows the format k8s.{clusterName}.{metadata.namespace}.{metadata.name}, so you can verify directly with the Vault CLI:

    $ vault read your-database-path/roles/k8s.-.demo.solr-readonly
Key                      Value
---                      -----
creation_statements      [{"roles":["admin","read"]}]
db_name                  k8s.-.demo.solr
default_ttl              1h
max_ttl                  24h

    Deleting the SolrRole removes the role from Vault.

    Issue Solr credentials

    Request a dynamic credential by creating a SecretAccessRequest:

    apiVersion: engine.kubevault.com/v1alpha1
kind: SecretAccessRequest
metadata:
  name: solr-cred-rqst
  namespace: demo
spec:
  roleRef:
    kind: SolrRole
    name: solr-readonly
  subjects:
    - kind: ServiceAccount
      name: demo-sa
      namespace: demo

    Approve it through the KubeVault CLI:

    $ kubectl vault approve secretaccessrequest solr-cred-rqst -n demo
approved

    Once approved, the operator issues the credential, stores it in a Secret, and binds the listed subjects via a Role/RoleBinding. The plugin creates a new Basic Auth Plugin user on Solr and binds it to admin and read on the configured Rule-Based Authorization Plugin. The credential lives on the lease until you delete the SecretAccessRequest or it expires; on lease revocation the plugin removes the Basic Auth user (Solr’s delete-user is idempotent, so no separate revocation statements are required).

    $ kubectl get secretaccessrequest solr-cred-rqst -n demo -o json | jq '.status'
{
  "lease": {
    "duration": "1h0m0s",
    "id": "your-database-path/creds/k8s.-.demo.solr-readonly/abc...",
    "renewable": true
  },
  "secret": {
    "name": "solr-cred-rqst-xxxxxx"
  }
}

$ kubectl get secret -n demo solr-cred-rqst-xxxxxx -o jsonpath='{.data.username}' | base64 -d
v-kubernetes-demo-XXXXXXXX

$ kubectl get secret -n demo solr-cred-rqst-xxxxxx -o jsonpath='{.data.password}' | base64 -d
xxxxxxxxxxxxxxxxxx

    Use the issued username / password as HTTP Basic-Auth credentials when querying Solr; the credential is revoked when the SecretAccessRequest is deleted.

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