How-to: Enable Keystone Database TLS/mTLS

This guide walks an operator through opting a control plane's Keystone into encrypted, mutually-authenticated connections to MariaDB/MaxScale. On a ControlPlane deployment the knob lives on the ControlPlane CR (spec.infrastructure.database.tls); the c5c3-operator projects the whole database block — including tls — onto the projected controlplane-keystone child. When enabled, the keystone-operator provisions a cert-manager Certificate from the shared OpenStack DB CA, mounts the resulting keypair into every Keystone workload that opens a database connection, and appends the ssl_* parameters to the database DSN so the live transport is TLS-protected.

For the authoritative field reference, see DatabaseTLSSpec in the Keystone CRD reference and InfrastructureSpec in the ControlPlane CRD reference. For the underlying MariaDB and CA issuer manifests, see OpenStack DB CA Issuer and MariaDB Galera Cluster.

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Prerequisites

Devstack

This guide is written against the Quick Start (ControlPlane) devstack. Stand it up first:

KIND_HOST_PORT=8443 WITH_CONTROLPLANE=true make deploy-infra

Follow that tutorial through to its final Verify step, so a ControlPlane CR named controlplane is Ready in the openstack namespace and its projected controlplane-keystone Keystone child is running. Every resource name in the examples below is one that devstack produces.

1. cert-manager installed. The chart from deploy/flux-system/releases/cert-manager.yaml provides the cert-manager.io/v1 CRDs (Certificate, Issuer, ClusterIssuer). Confirm the controller is healthy:

   kubectl -n cert-manager get pods

2. openstack-db-ca-issuer ClusterIssuer Ready. The dedicated DB CA is declared in deploy/flux-system/infrastructure/db-ca-issuer.yaml. hack/deploy-infra.sh applies it in Phase 2. Verify:

   kubectl get clusterissuer openstack-db-ca-issuer \
     -o jsonpath='{.status.conditions[?(@.type=="Ready")].status}'

   Expected: True.

3. A MariaDB that offers server-side TLS. Client-side DB TLS only works against a server that speaks it. On the managed ControlPlane devstack the c5c3-operator provisions the openstack-db MariaDB from a minimal spec and leaves server-side TLS/issuerRefs unset — DB-server hardening is a platform-team concern outside the aggregate's knowledge (see the DECISION on reconcileInfrastructure in operators/c5c3/internal/controller/reconcile_infrastructure.go). So before enabling client DB TLS on a ControlPlane, run a MariaDB with spec.tls.enabled=true (and, for the plaintext-rejection check below, required=true) — either harden the managed MariaDB out-of-band or point spec.infrastructure.database at a brownfield MariaDB that already enables TLS via the same openstack-db-ca-issuer. Confirm the cluster is healthy:

   kubectl -n openstack get mariadb openstack-db

   Expected: STATUS=Ready.

   Do not enable verify-full against a plaintext MariaDB

   Enabling verify-full client TLS against a MariaDB that offers no server TLS breaks the connection — the child Keystone reports DatabaseReady=False. The standalone Quick Start devstack ships its openstack-db with spec.tls.required=true, so the standalone flow at the end of this guide is fully runnable end-to-end without extra MariaDB hardening.

4. keystone-operator running. Either via the Helm release in deploy/flux-system/releases/keystone-operator.yaml or a locally built image deployed with hack/ci-deploy-operator.sh. The operator's RBAC must include the cert-manager.io/certificates rule; the chart's ClusterRole carries it by default.

5. The controlplane ControlPlane CR you own. The tls block is an optional pointer on spec.infrastructure.database (a nil value preserves the previous plaintext behavior), and it is not frozen by the ControlPlane immutability webhook, so flipping it on is a no-mutation patch on a live control plane.

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Steps

1. Patch the ControlPlane CR with a spec.infrastructure.database.tls block

Set the tls block on the ControlPlane CR's shared database, not on the projected Keystone child. The reconciler deep-copies the whole spec.infrastructure.database block — tls included — onto controlplane-keystone on every reconcile. The minimal TLS-enabled block uses mode: verify-full (the strongest mode — verifies the server certificate chain AND that the server hostname matches the certificate identity). In managed mode, the keystone-operator provisions the Secret controlplane-keystone-db-client carrying ca.crt, tls.crt, and tls.key, so a single reference satisfies both caBundleSecretRef and clientCertSecretRef:

spec:
  infrastructure:
    database:
      clusterRef:
        name: openstack-db
      database: keystone
      secretRef:
        name: keystone-db
      tls:
        mode: verify-full
        caBundleSecretRef:
          name: controlplane-keystone-db-client
        clientCertSecretRef:
          name: controlplane-keystone-db-client

Apply via patch:

kubectl -n openstack patch controlplane controlplane --type merge --patch '
spec:
  infrastructure:
    database:
      tls:
        mode: verify-full
        caBundleSecretRef:
          name: controlplane-keystone-db-client
        clientCertSecretRef:
          name: controlplane-keystone-db-client
'

Do not patch spec.database.tls on the projected child

Setting spec.database.tls on the controlplane-keystone Keystone CR directly is reverted on the next reconcile: the c5c3-operator re-asserts the entirespec.database block from spec.infrastructure.database, so any tls you write on the child that is not present on the ControlPlane CR is deep-copied away. Always set tls on the ControlPlane CR.

The keystone-operator's mutating webhook does not materialize the tls block on the child when it is absent — TLS is strictly opt-in. When tls is present with an empty mode, the webhook materializes mode: "require" as the documented baseline (a present block means "on"). Set mode: disabled to keep the block and its certificate references while turning TLS off.

2. Wait for the operator to issue the client Certificate

reconcileDatabaseTLS on the child creates a cert-manager Certificate named controlplane-keystone-db-client with issuerRef = openstack-db-ca-issuer (ClusterIssuer). cert-manager writes the resulting keypair into a Secret of the same name. The reconciler reports progress via the DatabaseTLSReady status condition on the child:

Condition reason	Meaning
NotRequired	tls is nil, its mode is empty, or its mode is disabled — plaintext connection.
CertificatePending	Managed mode; cert-manager has not yet issued the leaf.
CertificateIssued	Managed mode; client keypair ready and mounted.
ExternallyManaged	Brownfield mode (spec.infrastructure.database.host set) — the client keypair must be supplied out-of-band.

---

Verification

1. DatabaseTLSReady=True with reason=CertificateIssued

kubectl -n openstack get keystone controlplane-keystone \
  -o jsonpath='{range .status.conditions[?(@.type=="DatabaseTLSReady")]}{.status} {.reason} {.message}{"\n"}{end}'

Expected: True CertificateIssued Database client Certificate "controlplane-keystone-db-client" issued into Secret "controlplane-keystone-db-client".

The Secret should carry the three keys cert-manager writes:

kubectl -n openstack get secret controlplane-keystone-db-client \
  -o go-template='{{range $k, $_ := .data}}{{$k}}{{"\n"}}{{end}}'

Expected: ca.crt, tls.crt, tls.key.

2. The live connection is encrypted (Ssl_cipher non-empty)

Exec into a running Keystone Pod and ask MariaDB to report the cipher in use for this very session. The Keystone container has pymysql installed (it is the MySQL driver pinned by openstack/requirements) and the db-tls volume mounted at /etc/keystone/db-tls/, so we can parse the same OS_DATABASE__CONNECTION DSN the API uses and dial directly:

POD=$(kubectl -n openstack get pods \
  -l app.kubernetes.io/instance=controlplane-keystone,app.kubernetes.io/name=keystone \
  -o jsonpath='{.items[0].metadata.name}')

kubectl -n openstack exec "$POD" -c keystone -- python3 -c '
import os, ssl, pymysql
from urllib.parse import urlparse, parse_qs
url = urlparse(os.environ["OS_DATABASE__CONNECTION"])
qs = parse_qs(url.query)
ssl_kwargs = {}
if "ssl_ca" in qs:    ssl_kwargs["ca"] = qs["ssl_ca"][0]
if "ssl_cert" in qs:  ssl_kwargs["cert"] = qs["ssl_cert"][0]
if "ssl_key" in qs:   ssl_kwargs["key"] = qs["ssl_key"][0]
if ssl_kwargs:
    ssl_kwargs["verify_mode"] = ssl.CERT_REQUIRED if qs.get("ssl_verify_cert", ["false"])[0].lower() == "true" else ssl.CERT_NONE
    ssl_kwargs["check_hostname"] = qs.get("ssl_verify_identity", ["false"])[0].lower() == "true"
kw = dict(host=url.hostname, port=url.port or 3306,
          user=url.username, password=url.password,
          database=url.path.lstrip("/"))
if ssl_kwargs: kw["ssl"] = ssl_kwargs
conn = pymysql.connect(**kw)
with conn.cursor() as cur:
    cur.execute("SHOW STATUS LIKE %s", ("Ssl_cipher",))
    row = cur.fetchone()
    print(row[1] if row else "")
conn.close()
'

Expected: a non-empty TLS cipher name (e.g., TLS_AES_256_GCM_SHA384). An empty value means the live connection is not encrypted — re-check DatabaseTLSReady and confirm the MariaDB CR has spec.tls.required=true (see prerequisite 3).

3. Plaintext connections are rejected by MariaDB

This check requires the MariaDB from prerequisite 3 to set spec.tls.required=true, so any connection that does not negotiate TLS is rejected at the transport layer before authentication. The probe/probe credentials below are bogus — they are never checked, because the server rejects the plaintext handshake before it reaches authentication. Probe from inside the Keystone Pod by omitting the ssl= kwarg:

kubectl -n openstack exec "$POD" -c keystone -- python3 -c '
import pymysql
try:
    pymysql.connect(host="openstack-db.openstack.svc", port=3306,
                    user="probe", password="probe",
                    database="keystone", connect_timeout=10)
    print("PLAINTEXT_ACCEPTED")
except Exception as exc:
    print("PLAINTEXT_REJECTED:", type(exc).__name__, exc)
'

Expected: PLAINTEXT_REJECTED: … from the server's TLS-required enforcement.

---

Disabling

WARNING — data-plane outage if you skip the MariaDB step. If the MariaDB serving the control plane ships with spec.tls.required=true, disabling TLS on the Keystone side only will brick the deployment: MariaDB rejects every plaintext handshake at the transport layer, so Keystone cannot connect to the database. Before applying the ControlPlane patch below, set spec.tls.required=false (or fully disable TLS) on the MariaDB CR — updating MariaDB is out of scope of this guide but is a prerequisite for a working plaintext deployment.

To revert to plaintext without uninstalling the operator, drop the tls block from the ControlPlane CR. The reconciler then deep-copies a nil tls onto the child and the keystone-operator's mutating webhook never re-materializes it, so the absence is persistent:

kubectl -n openstack patch controlplane controlplane --type json --patch '[
  {"op": "remove", "path": "/spec/infrastructure/database/tls"}
]'

The child's DatabaseTLSReady condition transitions to True with reason=NotRequired, the operator deletes the managed controlplane-keystone-db-client Certificate (so cert-manager stops renewing it), cert-manager then garbage-collects the issued Secret via the Certificate owner-reference cascade, and subsequent connections fall back to plaintext TCP — but only succeed if MariaDB's spec.tls.required is also turned off (see warning above).

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Standalone Keystone, without a ControlPlane

On the Quick Start / Quick Start (Extended) devstacks a standalone Keystone CR named keystone runs with no ControlPlane projecting it, and the shared openstack-db MariaDB ships with spec.tls.enabled=true, required=true — so this flow is fully runnable end-to-end without extra MariaDB hardening. Set the tls block on the Keystone CR's own spec.database:

kubectl -n openstack patch keystone keystone --type merge --patch '
spec:
  database:
    tls:
      mode: verify-full
      caBundleSecretRef:
        name: keystone-db-client
      clientCertSecretRef:
        name: keystone-db-client
'

The names map as follows; substitute them in every command above:

ControlPlane devstack	Standalone devstack
CR controlplane (patch spec.infrastructure.database.tls)	CR keystone (patch spec.database.tls)
child controlplane-keystone	CR keystone
Certificate / Secret controlplane-keystone-db-client	keystone-db-client
pod selector app.kubernetes.io/instance=controlplane-keystone	app.kubernetes.io/instance=keystone

To disable, drop the tls block from the Keystone CR:

kubectl -n openstack patch keystone keystone --type json --patch '[
  {"op": "remove", "path": "/spec/database/tls"}
]'

The tests/e2e/keystone/database-tls/ chainsaw suite pins the keystone-operator mechanics through this standalone flow.

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See also

• Keystone CRD — DatabaseTLSSpec — authoritative field reference.
• Keystone CRD — Mode → connect-args mapping — DSN parameters per mode.
• ControlPlane CRD — InfrastructureSpec — the spec.infrastructure.database block the reconciler projects.
• Infrastructure Manifests — OpenStack DB CA Issuer — CA keypair and ClusterIssuer.
• Infrastructure Manifests — MariaDB Galera Cluster — server-side TLS configuration.
• tests/e2e/keystone/database-tls/ — chainsaw E2E suite.

Tested by

The canonical check pins all three verifications above — DatabaseTLSReady=True, the encrypted live connection, and the plaintext rejection — against a standalone Keystone CR whose openstack-db ships tls.required=true. Run it on the CI e2e kind cluster:

chainsaw test --test-dir tests/e2e/keystone/database-tls

The suite is also listed in the E2E inventory of the Keystone CRD reference.