feat: Kubernetes native integration — Helm chart + K8s/SPIFFE config

Helm chart (charts/bascule/):
  Deployment with shell sidecar container (shared jumphost model)
  Service (LoadBalancer/NodePort/ClusterIP)
  ConfigMap with auto-generated config.toml
  RBAC (Role + RoleBinding for pods/exec)
  NetworkPolicy (restrict shell egress, allow DNS + K8s API)
  ServiceAccount with create flag
  Configurable shell image (k8s-ops, net-ops, dev, minimal)
  Helm lint passes clean

K8s backend config (bascule-core):
  [k8s] section: enabled, namespace, pod_name, shell_container, shell
  Auto-detection via POD_NAME/POD_NAMESPACE env vars (downward API)
  Backend priority: K8s > proxy > container > local PTY
  K8s exec implementation deferred to --features k8s (kube crate)

SPIFFE/SPIRE auth config:
  [auth.spiffe] section: trust_domain, trust_bundle_path, workload_api_socket
  JWT-SVID token-as-password authentication pattern
  Implementation deferred to bascule-auth-spiffe crate

Zero substrate dependencies. Default build unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

charts/bascule/Chart.yaml

@@ -0,0 +1,12 @@
+apiVersion: v2
+name: bascule
+description: Identity-aware SSH proxy for Kubernetes
+version: 0.1.0
+appVersion: "0.1.0"
+type: application
+keywords:
+  - ssh
+  - proxy
+  - identity
+  - jumphost
+  - bastion

charts/bascule/templates/NOTES.txt

@@ -0,0 +1,12 @@
+Bascule SSH proxy deployed!
+
+Connect:
+{{- if eq .Values.service.type "LoadBalancer" }}
+  ssh -p {{ .Values.service.port }} $(kubectl get svc {{ include "bascule.fullname" . }} -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+{{- else }}
+  kubectl port-forward svc/{{ include "bascule.fullname" . }} {{ .Values.service.port }}:{{ .Values.service.port }}
+  ssh -p {{ .Values.service.port }} localhost
+{{- end }}
+
+Shell: {{ .Values.shell.image.repository }}:{{ .Values.shell.image.tag }}
+Auth:  {{ .Values.auth.mode }}

charts/bascule/templates/_helpers.tpl

@@ -0,0 +1,36 @@
+{{- define "bascule.name" -}}
+{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
+{{- end }}
+
+{{- define "bascule.fullname" -}}
+{{- if .Values.fullnameOverride }}
+{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
+{{- else }}
+{{- $name := default .Chart.Name .Values.nameOverride }}
+{{- if contains $name .Release.Name }}
+{{- .Release.Name | trunc 63 | trimSuffix "-" }}
+{{- else }}
+{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
+{{- end }}
+{{- end }}
+{{- end }}
+
+{{- define "bascule.labels" -}}
+helm.sh/chart: {{ include "bascule.name" . }}
+{{ include "bascule.selectorLabels" . }}
+app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
+app.kubernetes.io/managed-by: {{ .Release.Service }}
+{{- end }}
+
+{{- define "bascule.selectorLabels" -}}
+app.kubernetes.io/name: {{ include "bascule.name" . }}
+app.kubernetes.io/instance: {{ .Release.Name }}
+{{- end }}
+
+{{- define "bascule.serviceAccountName" -}}
+{{- if .Values.serviceAccount.create }}
+{{- default (include "bascule.fullname" .) .Values.serviceAccount.name }}
+{{- else }}
+{{- default "default" .Values.serviceAccount.name }}
+{{- end }}
+{{- end }}

charts/bascule/templates/configmap.yaml

@@ -0,0 +1,22 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "bascule.fullname" . }}-config
+data:
+  config.toml: |
+    listen_addr = "0.0.0.0:2222"
+    max_sessions = {{ .Values.maxSessions }}
+    {{- if .Values.hostKey.persistence }}
+    host_key_path = "/var/lib/bascule/host_key"
+    {{- end }}
+
+    [auth]
+    mode = "{{ .Values.auth.mode }}"
+    {{- if eq .Values.auth.mode "authorized-keys" }}
+    authorized_keys_path = "{{ .Values.auth.authorizedKeysPath }}"
+    {{- end }}
+
+    [k8s]
+    enabled = true
+    shell_container = "shell"
+    shell = "/bin/bash"

charts/bascule/templates/deployment.yaml

@@ -0,0 +1,102 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{ include "bascule.fullname" . }}
+  labels:
+    {{- include "bascule.labels" . | nindent 4 }}
+spec:
+  replicas: {{ .Values.replicaCount }}
+  selector:
+    matchLabels:
+      {{- include "bascule.selectorLabels" . | nindent 6 }}
+  template:
+    metadata:
+      labels:
+        {{- include "bascule.selectorLabels" . | nindent 8 }}
+    spec:
+      serviceAccountName: {{ include "bascule.serviceAccountName" . }}
+      containers:
+        - name: bascule
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          ports:
+            - name: ssh
+              containerPort: 2222
+              protocol: TCP
+          env:
+            - name: BASCULE_CONFIG
+              value: /etc/bascule/config.toml
+            - name: POD_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.name
+            - name: POD_NAMESPACE
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.namespace
+            - name: BASCULE_SHELL_CONTAINER
+              value: shell
+            {{- range .Values.extraEnv }}
+            - name: {{ .name }}
+              value: {{ .value | quote }}
+            {{- end }}
+          volumeMounts:
+            - name: config
+              mountPath: /etc/bascule
+              readOnly: true
+            {{- if .Values.hostKey.persistence }}
+            - name: hostkey
+              mountPath: /var/lib/bascule
+            {{- end }}
+            {{- if .Values.auth.authorizedKeysSecret }}
+            - name: authorized-keys
+              mountPath: /etc/bascule/keys
+              readOnly: true
+            {{- end }}
+          resources:
+            {{- toYaml .Values.resources | nindent 12 }}
+          livenessProbe:
+            tcpSocket:
+              port: ssh
+            initialDelaySeconds: 5
+            periodSeconds: 30
+          readinessProbe:
+            tcpSocket:
+              port: ssh
+            initialDelaySeconds: 3
+            periodSeconds: 10
+        {{- if .Values.shell.enabled }}
+        - name: shell
+          image: "{{ .Values.shell.image.repository }}:{{ .Values.shell.image.tag }}"
+          imagePullPolicy: {{ .Values.shell.image.pullPolicy }}
+          command: ["sleep", "infinity"]
+          resources:
+            {{- toYaml .Values.shell.resources | nindent 12 }}
+          securityContext:
+            allowPrivilegeEscalation: false
+            capabilities:
+              drop: ["ALL"]
+              add: ["SETUID", "SETGID"]
+        {{- end }}
+      volumes:
+        - name: config
+          configMap:
+            name: {{ include "bascule.fullname" . }}-config
+        {{- if .Values.hostKey.persistence }}
+        - name: hostkey
+          emptyDir: {}
+        {{- end }}
+        {{- if .Values.auth.authorizedKeysSecret }}
+        - name: authorized-keys
+          secret:
+            secretName: {{ .Values.auth.authorizedKeysSecret }}
+            defaultMode: 0600
+        {{- end }}
+      {{- with .Values.tolerations }}
+      tolerations:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}
+      {{- with .Values.nodeSelector }}
+      nodeSelector:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}

charts/bascule/templates/networkpolicy.yaml

@@ -0,0 +1,30 @@
+{{- if .Values.networkPolicy.enabled }}
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: {{ include "bascule.fullname" . }}
+spec:
+  podSelector:
+    matchLabels:
+      {{- include "bascule.selectorLabels" . | nindent 6 }}
+  policyTypes:
+    - Ingress
+    - Egress
+  ingress:
+    - ports:
+        - port: 2222
+          protocol: TCP
+  egress:
+    - ports:
+        - port: 53
+          protocol: UDP
+        - port: 53
+          protocol: TCP
+    {{- if .Values.networkPolicy.allowKubeApi }}
+    - ports:
+        - port: 443
+          protocol: TCP
+        - port: 6443
+          protocol: TCP
+    {{- end }}
+{{- end }}

charts/bascule/templates/rbac.yaml

@@ -0,0 +1,25 @@
+{{- if .Values.rbac.create }}
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: {{ include "bascule.fullname" . }}
+rules:
+  - apiGroups: [""]
+    resources: ["pods/exec"]
+    verbs: ["create"]
+  - apiGroups: [""]
+    resources: ["pods"]
+    verbs: ["get", "list"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: {{ include "bascule.fullname" . }}
+subjects:
+  - kind: ServiceAccount
+    name: {{ include "bascule.serviceAccountName" . }}
+roleRef:
+  kind: Role
+  name: {{ include "bascule.fullname" . }}
+  apiGroup: rbac.authorization.k8s.io
+{{- end }}

charts/bascule/templates/service.yaml

@@ -0,0 +1,15 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ include "bascule.fullname" . }}
+  labels:
+    {{- include "bascule.labels" . | nindent 4 }}
+spec:
+  type: {{ .Values.service.type }}
+  ports:
+    - port: {{ .Values.service.port }}
+      targetPort: ssh
+      protocol: TCP
+      name: ssh
+  selector:
+    {{- include "bascule.selectorLabels" . | nindent 4 }}

charts/bascule/templates/serviceaccount.yaml

@@ -0,0 +1,8 @@
+{{- if .Values.serviceAccount.create }}
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: {{ include "bascule.serviceAccountName" . }}
+  labels:
+    {{- include "bascule.labels" . | nindent 4 }}
+{{- end }}

charts/bascule/values.yaml

@@ -0,0 +1,65 @@
+replicaCount: 1
+
+image:
+  repository: ghcr.io/guildhouse/bascule-server
+  tag: "latest"
+  pullPolicy: IfNotPresent
+
+shell:
+  enabled: true
+  image:
+    repository: ghcr.io/guildhouse/bascule-shell
+    tag: "k8s-ops"
+    pullPolicy: IfNotPresent
+  resources:
+    requests:
+      cpu: 100m
+      memory: 128Mi
+    limits:
+      cpu: "1"
+      memory: 512Mi
+
+service:
+  type: LoadBalancer
+  port: 2222
+
+auth:
+  mode: authorized-keys
+  authorizedKeysPath: /etc/bascule/keys
+  authorizedKeysSecret: ""
+
+maxSessions: 100
+
+resources:
+  requests:
+    cpu: 50m
+    memory: 64Mi
+  limits:
+    cpu: 500m
+    memory: 256Mi
+
+hostKey:
+  persistence: true
+  size: 1Mi
+
+serviceAccount:
+  create: true
+  name: ""
+
+rbac:
+  create: true
+
+networkPolicy:
+  enabled: true
+  allowKubeApi: true
+  denyAllOtherEgress: true
+
+podDisruptionBudget:
+  enabled: false
+  minAvailable: 1
+
+extraEnv: []
+
+tolerations: []
+affinity: {}
+nodeSelector: {}

crates/bascule-core/src/config.rs

@@ -40,6 +40,10 @@ pub struct BasculeConfig {
     /// Priority: proxy > container > local PTY.
     pub container: Option<ContainerConfig>,
 
+    /// K8s backend configuration.
+    /// When running in-cluster, exec into a shell sidecar instead of local PTY.
+    pub k8s: Option<K8sConfig>,
+
     /// Telemetry (OTel tracing).
     #[serde(default)]
     pub telemetry: TelemetryConfig,
@@ -78,6 +82,9 @@ pub struct AuthConfig {
 
     /// AI agent authentication via Microsoft Entra Agent ID.
     pub agent_id: Option<AgentIdConfig>,
+
+    /// SPIFFE/SPIRE workload identity authentication.
+    pub spiffe: Option<SpiffeConfig>,
 }
 
 impl Default for AuthConfig {
@@ -86,6 +93,7 @@ impl Default for AuthConfig {
             mode: default_auth_mode(),
             authorized_keys_path: None,
             agent_id: None,
+            spiffe: None,
         }
     }
 }
@@ -114,6 +122,7 @@ impl Default for BasculeConfig {
             max_sessions: 0,
             proxy: None,
             container: None,
+            k8s: None,
             telemetry: TelemetryConfig::default(),
             metrics: MetricsConfig::default(),
         }
@@ -189,6 +198,38 @@ pub struct MountConfig {
     pub readonly: bool,
 }
 
+/// SPIFFE/SPIRE authentication configuration.
+#[derive(Debug, Deserialize, Clone)]
+pub struct SpiffeConfig {
+    /// SPIFFE trust domain.
+    pub trust_domain: String,
+    /// Path to trust bundle PEM file.
+    pub trust_bundle_path: Option<String>,
+    /// SPIRE Workload API socket path.
+    pub workload_api_socket: Option<String>,
+}
+
+/// K8s backend configuration.
+#[derive(Debug, Deserialize, Clone)]
+pub struct K8sConfig {
+    /// Enable K8s backend.
+    #[serde(default)]
+    pub enabled: bool,
+    /// Namespace (auto-detected from downward API if not set).
+    pub namespace: Option<String>,
+    /// Pod name (auto-detected from downward API if not set).
+    pub pod_name: Option<String>,
+    /// Shell container name in the Pod.
+    #[serde(default = "default_shell_container")]
+    pub shell_container: String,
+    /// Shell command inside the container.
+    #[serde(default = "default_k8s_shell")]
+    pub shell: String,
+}
+
+fn default_shell_container() -> String { "shell".to_string() }
+fn default_k8s_shell() -> String { "/bin/bash".to_string() }
+
 /// Telemetry configuration (OTel + metrics).
 #[derive(Debug, Deserialize, Clone, Default)]
 pub struct TelemetryConfig {