# Stateless multi-replica Deployment (task 46).
#
# - 3 replicas sharing one Postgres + one Redis: no replica holds state
#   another needs (tokens live in Redis under `{state}`-tagged keys).
# - `serve` NEVER migrates; the separate `migrate-job.yaml` owns the schema.
#   Readiness (`/health/ready`) compares `_sqlx_migrations` against the
#   binary's embedded migrations, so new replicas stay out of traffic until
#   the Job has applied the schema (expand/contract keeps N-1 serving).
# - Probes hit the PLAINTEXT pod-IP health listener (`health_addr`,
#   default `0.0.0.0:8081`); the public listener stays TLS-only.
# - `terminationGracePeriodSeconds: 45` covers the server's 1s propagation
#   grace + 30s drain budget (`src/serve.rs`: PROPAGATION_GRACE, DRAIN_DEADLINE).
# - Host hardening: non-root 65532, read-only rootfs, ALL capabilities
#   dropped, `allowPrivilegeEscalation: false`, `RuntimeDefault` seccomp, and
#   `automountServiceAccountToken: false` (the server never calls the
#   Kubernetes API). `networkpolicy.yaml` default-denies pod egress except DNS
#   + Postgres + Redis.
# - Secret material is file-mounted, never env-injected: the token pepper,
#   TOTP key, mandatory PII key, and the Postgres/Redis passwords are projected
#   from `d-oauth-secrets` into a tmpfs volume at `/run/secrets` (`defaultMode:
#   0400`, group 65532 via `fsGroup`) and read through their `*_FILE`
#   variables. The passwordless DSNs come from the ConfigMap. The inline
#   `D_OAUTH_TOKEN_PEPPER` / `D_OAUTH_TOTP_ENCRYPTION_KEY` forms remain
#   supported and take precedence when both are set (`src/config/build.rs`),
#   but this deployment never sets them, so no secret enters the process
#   environment (`/proc/self/environ`, children, crash dumps, `docker
#   inspect`) — a `kubectl exec` reads nothing from the environment.
# - The image reference is the mutable `:latest` tag. Nodes pull it on first
#   use (`imagePullPolicy: IfNotPresent`); pin a digest instead when
#   reproducible production rollouts are required.
apiVersion: apps/v1
kind: Deployment
metadata:
  name: d-oauth-server
  namespace: d-oauth
  labels:
    app.kubernetes.io/name: d-oauth-server
    app.kubernetes.io/part-of: d-oauth
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      # Keep every old replica serving while the migration Job + new
      # replicas converge (expand/contract upgrades).
      maxUnavailable: 0
      maxSurge: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: d-oauth-server
  template:
    metadata:
      labels:
        app.kubernetes.io/name: d-oauth-server
        app.kubernetes.io/part-of: d-oauth
    spec:
      terminationGracePeriodSeconds: 45
      # The app never talks to the Kubernetes API; the auto-mounted service
      # account token is pure attack surface, so it stays disabled.
      automountServiceAccountToken: false
      securityContext:
        runAsNonRoot: true
        runAsUser: 65532
        runAsGroup: 65532
        # Secret volumes are tmpfs; fsGroup makes the 0400 files readable by
        # the runtime group so the pepper/TOTP keys can be mounted as files.
        fsGroup: 65532
        fsGroupChangePolicy: OnRootMismatch
        seccompProfile:
          type: RuntimeDefault
      containers:
        - name: server
          # Mutable `:latest` reference: the newest published image is what
          # pods run once the node pulls it.
          image: ghcr.io/syavne/d-oauth-server:latest
          imagePullPolicy: IfNotPresent
          ports:
            - name: public-tls
              containerPort: 8080
              protocol: TCP
            - name: health
              containerPort: 8081
              protocol: TCP
          envFrom:
            - configMapRef:
                name: d-oauth-config
          env:
            # Every secret is a file, never an env value: code execution in
            # the container cannot read the DB/Redis credentials or key
            # material from the environment. The DSNs (non-secret) come from
            # the ConfigMap above.
            - name: D_OAUTH_DATABASE__PASSWORD_FILE
              value: /run/secrets/database-password
            - name: D_OAUTH_REDIS__PASSWORD_FILE
              value: /run/secrets/redis-password
            - name: D_OAUTH_TOKEN_PEPPER_FILE
              value: /run/secrets/token-pepper
            - name: D_OAUTH_TOTP_ENCRYPTION_KEY_FILE
              value: /run/secrets/totp-encryption-key
            - name: D_OAUTH_PII_ENCRYPTION_KEY_FILE
              value: /run/secrets/pii-encryption-key
          # Liveness is dependency-free by construction (`/health/live`
          # touches no Postgres/Redis), so a dependency outage never
          # triggers a restart storm — readiness absorbs it instead.
          startupProbe:
            httpGet:
              path: /health/live
              port: 8081
            failureThreshold: 30
            periodSeconds: 2
          livenessProbe:
            httpGet:
              path: /health/live
              port: 8081
            periodSeconds: 10
            timeoutSeconds: 2
            failureThreshold: 3
          # Fail-closed: 503 while Postgres/Redis are unreachable OR the
          # `_sqlx_migrations` version does not match the binary (i.e. the
          # migrate Job has not run yet on a fresh/rolling deploy).
          readinessProbe:
            httpGet:
              path: /health/ready
              port: 8081
            periodSeconds: 5
            timeoutSeconds: 2
            failureThreshold: 3
            successThreshold: 1
          resources:
            requests:
              cpu: 100m
              memory: 128Mi
            limits:
              cpu: "1"
              memory: 512Mi
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop:
                - ALL
          volumeMounts:
            - name: certs
              mountPath: /certs
              readOnly: true
            - name: secrets
              mountPath: /run/secrets
              readOnly: true
      volumes:
        - name: certs
          secret:
            secretName: d-oauth-tls
            defaultMode: 0o400
        # tmpfs-backed secret volume. `defaultMode: 0400` plus `fsGroup:
        # 65532` leaves the projected files readable only by the runtime
        # user/group. Every secret is projected here; nothing is injected
        # through a `secretKeyRef` env.
        - name: secrets
          secret:
            secretName: d-oauth-secrets
            defaultMode: 0o400
            items:
              - key: database-password
                path: database-password
              - key: redis-password
                path: redis-password
              - key: token-pepper
                path: token-pepper
              - key: totp-encryption-key
                path: totp-encryption-key
              - key: pii-encryption-key
                path: pii-encryption-key
      topologySpreadConstraints:
        - maxSkew: 1
          topologyKey: topology.kubernetes.io/zone
          whenUnsatisfiable: ScheduleAnyway
          labelSelector:
            matchLabels:
              app.kubernetes.io/name: d-oauth-server
        - maxSkew: 1
          topologyKey: kubernetes.io/hostname
          whenUnsatisfiable: ScheduleAnyway
          labelSelector:
            matchLabels:
              app.kubernetes.io/name: d-oauth-server