SPIRE

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SPIRE is a production-ready implementation of the SPIFFE specification that performs node and workload attestation in order to securely issue cryptographic identities to workloads running in heterogeneous environments. SPIRE can be configured as a source of cryptographic identities for Istio workloads through an integration with Envoy’s SDS API. Istio can detect the existence of a UNIX Domain Socket that implements the Envoy SDS API on a defined socket path, allowing Envoy to communicate and fetch identities directly from it.

This integration with SPIRE provides flexible attestation options not available with the default Istio identity management while harnessing Istio’s powerful service management. For example, SPIRE’s plugin architecture enables diverse workload attestation options beyond the Kubernetes namespace and service account attestation offered by Istio. SPIRE’s node attestation extends attestation to the physical or virtual hardware on which workloads run.

For a quick demo of how this SPIRE integration with Istio works, see Integrating SPIRE as a CA through Envoy’s SDS API.

The integration is compatible with Istio upgrades.

Install SPIRE

Option 1: Quick start

Istio provides a basic sample installation to quickly get SPIRE up and running:

$ kubectl apply -f @samples/security/spire/spire-quickstart.yaml@

This will deploy SPIRE into your cluster, along with two additional components: the SPIFFE CSI Driver — used to share the SPIRE Agent’s UNIX Domain Socket with the other pods throughout the node — and the SPIRE Kubernetes Workload Registrar, a facilitator that performs automatic workload registration within Kubernetes. See Install Istio to configure Istio and integrate with the SPIFFE CSI Driver.

Option 2: Configure a custom SPIRE installation

See the SPIRE’s Quick start for Kubernetes guide to get started deploying SPIRE into your Kubernetes environment. See SPIRE CA Integration Prerequisites for more information on configuring SPIRE to integrate with Istio deployments.

SPIRE CA Integration Prerequisites

To integrate your SPIRE deployment with Istio, configure SPIRE:

Access the SPIRE Agent reference and configure the SPIRE Agent socket path to match the Envoy SDS defined socket path.
```
socket_path = "/run/secrets/workload-spiffe-uds/socket"
```
Share the SPIRE Agent socket with the pods within the node by deploying the SPIFFE CSI Driver. The -workload-api-socket-dir argument to the driver should be the mount location of the socket’s directory.

See Install Istio to configure Istio to integrate with the SPIFFE CSI Driver.

Install Istio

Download Istio release 1.14+.

After deploying SPIRE into your environment, and verifying that all deployments are in Ready state, install Istio with custom patches for the Ingress-gateway as well as for istio-proxy.

$ istioctl install --skip-confirmation -f - <<EOF
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
  namespace: istio-system
spec:
  profile: default
  meshConfig:
    trustDomain: example.org
  values:
    global:
    # This is used to customize the sidecar template
    sidecarInjectorWebhook:
      templates:
        spire: |
          spec:
            containers:
            - name: istio-proxy
              volumeMounts:
              - name: workload-socket
                mountPath: /run/secrets/workload-spiffe-uds
                readOnly: true
            volumes:
              - name: workload-socket
                csi:
                  driver: "csi.spiffe.io"
  components:
    ingressGateways:
      - name: istio-ingressgateway
        enabled: true
        label:
          istio: ingressgateway
        k8s:
          overlays:
            - apiVersion: apps/v1
              kind: Deployment
              name: istio-ingressgateway
              patches:
                - path: spec.template.spec.volumes.[name:workload-socket]
                  value:
                    name: workload-socket
                    csi:
                      driver: "csi.spiffe.io"
                - path: spec.template.spec.containers.[name:istio-proxy].volumeMounts.[name:workload-socket]
                  value:
                    name: workload-socket
                    mountPath: "/run/secrets/workload-spiffe-uds"
                    readOnly: true
                - path: spec.template.spec.initContainers
                  value:
                    - name: wait-for-spire-socket
                      image: busybox:1.28
                      volumeMounts:
                        - name: workload-socket
                          mountPath: /run/secrets/workload-spiffe-uds
                          readOnly: true
                      env:
                        - name: CHECK_FILE
                          value: /run/secrets/workload-spiffe-uds/socket
                      command:
                        - sh
                        - "-c"
                        - |-
                          echo `date -Iseconds` Waiting for: ${CHECK_FILE}
                          while [[ ! -e ${CHECK_FILE} ]] ; do
                            echo `date -Iseconds` File does not exist: ${CHECK_FILE}
                            sleep 15
                          done
                          ls -l ${CHECK_FILE}
EOF

This will share the spiffe-csi-driver with the Ingress Gateway and the sidecars that are going to be injected on workload pods, granting them access to the SPIRE Agent’s UNIX Domain Socket.

This will also add an initContainer to the gateway that will wait for SPIRE to create the UNIX Domain Socket before starting the istio-proxy. If the SPIRE agent is not ready or has not been properly configured with the same socket path, the Ingress Gateway initContainer will wait forever.

Use sidecar injection to inject the istio-proxy container into the pods within your mesh. See custom templates for information on how to apply the custom defined spire template into istio-proxy. This allows for the CSI driver to mount the UDS on the sidecars.
Check Ingress-gateway pod state:
```
$ kubectl get pods -n istio-system
NAME                                    READY   STATUS    RESTARTS   AGE
istio-ingressgateway-5b45864fd4-lgrxs   0/1     Running   0          17s
istiod-989f54d9c-sg7sn                  1/1     Running   0          23s
```

Data plane containers will only reach Ready if a corresponding registration entry is created for them on the SPIRE Server. Then, Envoy will be able to fetch cryptographic identities from SPIRE. See Register workloads to register entries for services in your mesh.

Register workloads

This section describes the options available for registering workloads in a SPIRE Server.

Option 1: Automatic registration using the SPIRE workload registrar

By deploying SPIRE Kubernetes Workload Registrar along with a SPIRE Server, new entries are automatically registered for each new pod that is created.

See Verifying that identities were created for workloads to check issued identities.

Note that SPIRE workload registrar is used in the quick start section.

Option 2: Manual Registration

To improve workload attestation security robustness, SPIRE is able to verify against a group of selector values based on different parameters. Skip these steps if you installed SPIRE by following the quick start since it uses automatic registration.

Generate an entry for an Ingress Gateway with a set of selectors such as the pod name and pod UID:

$ INGRESS_POD=$(kubectl get pod -l istio=ingressgateway -n istio-system -o jsonpath="{.items[0].metadata.name}")
$ INGRESS_POD_UID=$(kubectl get pods -n istio-system $INGRESS_POD -o jsonpath='{.metadata.uid}')

Get the spire-server pod:

$ SPIRE_SERVER_POD=$(kubectl get pod -l app=spire-server -n spire -o jsonpath="{.items[0].metadata.name}")

$ kubectl exec -n spire $SPIRE_SERVER_POD -- \
/opt/spire/bin/spire-server entry create \
    -spiffeID spiffe://example.org/ns/spire/sa/spire-agent \
    -selector k8s_psat:cluster:demo-cluster \
    -selector k8s_psat:agent_ns:spire \
    -selector k8s_psat:agent_sa:spire-agent \
    -node -socketPath /run/spire/sockets/server.sock

Entry ID         : d38c88d0-7d7a-4957-933c-361a0a3b039c
SPIFFE ID        : spiffe://example.org/ns/spire/sa/spire-agent
Parent ID        : spiffe://example.org/spire/server
Revision         : 0
TTL              : default
Selector         : k8s_psat:agent_ns:spire
Selector         : k8s_psat:agent_sa:spire-agent
Selector         : k8s_psat:cluster:demo-cluster

$ kubectl exec -n spire $SPIRE_SERVER_POD -- \
/opt/spire/bin/spire-server entry create \
    -spiffeID spiffe://example.org/ns/istio-system/sa/istio-ingressgateway-service-account \
    -parentID spiffe://example.org/ns/spire/sa/spire-agent \
    -selector k8s:sa:istio-ingressgateway-service-account \
    -selector k8s:ns:istio-system \
    -selector k8s:pod-uid:$INGRESS_POD_UID \
    -dns $INGRESS_POD \
    -dns istio-ingressgateway.istio-system.svc \
    -socketPath /run/spire/sockets/server.sock

Entry ID         : 6f2fe370-5261-4361-ac36-10aae8d91ff7
SPIFFE ID        : spiffe://example.org/ns/istio-system/sa/istio-ingressgateway-service-account
Parent ID        : spiffe://example.org/ns/spire/sa/spire-agent
Revision         : 0
TTL              : default
Selector         : k8s:ns:istio-system
Selector         : k8s:pod-uid:63c2bbf5-a8b1-4b1f-ad64-f62ad2a69807
Selector         : k8s:sa:istio-ingressgateway-service-account
DNS name         : istio-ingressgateway.istio-system.svc
DNS name         : istio-ingressgateway-5b45864fd4-lgrxs

Deploy an example workload:

$ istioctl kube-inject --filename @samples/security/spire/sleep-spire.yaml@ | kubectl apply -f -

Note that the workload will need the SPIFFE CSI Driver volume to access the SPIRE Agent socket. To accomplish this, you can leverage the spire pod annotation template from the Install Istio section or add the CSI volume to the deployment spec of your workload. Both of these alternatives are highlighted on the example snippet below:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: sleep
spec:
  replicas: 1
  selector:
      matchLabels:
        app: sleep
  template:
      metadata:
        labels:
          app: sleep
        # Injects custom sidecar template
        annotations:
            inject.istio.io/templates: "sidecar,spire"
      spec:
        terminationGracePeriodSeconds: 0
        serviceAccountName: sleep
        containers:
        - name: sleep
          image: curlimages/curl
          command: ["/bin/sleep", "3650d"]
          imagePullPolicy: IfNotPresent
          volumeMounts:
            - name: tmp
              mountPath: /tmp
          securityContext:
            runAsUser: 1000
        volumes:
          - name: tmp
            emptyDir: {}
          # CSI volume
          - name: workload-socket
            csi:
              driver: "csi.spiffe.io"
              readOnly: true

Get pod information:

$ SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath="{.items[0].metadata.name}")
$ SLEEP_POD_UID=$(kubectl get pods $SLEEP_POD -o jsonpath='{.metadata.uid}')

$ kubectl exec -n spire spire-server-0 -- \
/opt/spire/bin/spire-server entry create \
    -spiffeID spiffe://example.org/ns/default/sa/sleep \
    -parentID spiffe://example.org/ns/spire/sa/spire-agent \
    -selector k8s:ns:default \
    -selector k8s:pod-uid:$SLEEP_POD_UID \
    -dns $SLEEP_POD \
    -socketPath /run/spire/sockets/server.sock

See the SPIRE help on Registering workloads to learn how to create new entries for workloads and get them attested using multiple selectors to strengthen attestation criteria.

Verifying that identities were created for workloads

Use the following command to confirm that identities were created for the workloads:

$ kubectl exec -i -t $SPIRE_SERVER_POD -n spire -c spire-server -- /bin/sh -c "bin/spire-server entry show -socketPath /run/spire/sockets/server.sock"
Found 3 entries
Entry ID         : c8dfccdc-9762-4762-80d3-5434e5388ae7
SPIFFE ID        : spiffe://example.org/ns/istio-system/sa/istio-ingressgateway-service-account
Parent ID        : spiffe://example.org/ns/spire/sa/spire-agent
Revision         : 0
TTL              : default
Selector         : k8s:ns:istio-system
Selector         : k8s:pod-uid:88b71387-4641-4d9c-9a89-989c88f7509d
Selector         : k8s:sa:istio-ingressgateway-service-account
DNS name         : istio-ingressgateway-5b45864fd4-lgrxs

Entry ID         : af7b53dc-4cc9-40d3-aaeb-08abbddd8e54
SPIFFE ID        : spiffe://example.org/ns/default/sa/sleep
Parent ID        : spiffe://example.org/ns/spire/sa/spire-agent
Revision         : 0
TTL              : default
Selector         : k8s:ns:default
Selector         : k8s:pod-uid:ee490447-e502-46bd-8532-5a746b0871d6
DNS name         : sleep-5f4d47c948-njvpk

Entry ID         : f0544fd7-1945-4bd1-88dc-0a5513fdae1c
SPIFFE ID        : spiffe://example.org/ns/spire/sa/spire-agent
Parent ID        : spiffe://example.org/spire/server
Revision         : 0
TTL              : default
Selector         : k8s_psat:agent_ns:spire
Selector         : k8s_psat:agent_sa:spire-agent
Selector         : k8s_psat:cluster:demo-cluster

Check the Ingress-gateway pod state:

$ kubectl get pods -n istio-system
NAME                                    READY   STATUS    RESTARTS   AGE
istio-ingressgateway-5b45864fd4-lgrxs   1/1     Running   0          60s
istiod-989f54d9c-sg7sn                  1/1     Running   0          45s

After registering an entry for the Ingress-gateway pod, Envoy receives the identity issued by SPIRE and uses it for all TLS and mTLS communications.

Check that the workload identity was issued by SPIRE

Retrieve sleep’s SVID identity document using the istioctl proxy-config secret command:

$ istioctl proxy-config secret $SLEEP_POD -o json | jq -r \
'.dynamicActiveSecrets[0].secret.tlsCertificate.certificateChain.inlineBytes' | base64 --decode > chain.pem

Inspect the certificate and verify that SPIRE was the issuer:

$ openssl x509 -in chain.pem -text | grep SPIRE
    Subject: C = US, O = SPIRE, CN = sleep-5f4d47c948-njvpk

SPIFFE Federation

SPIRE Servers are able to authenticate SPIFFE identities originating from different trust domains. This is known as SPIFFE federation.

SPIRE Agent can be configured to push federated bundles to Envoy through the Envoy SDS API, allowing Envoy to use validation context to verify peer certificates and trust a workload from another trust domain. To enable Istio to federate SPIFFE identities through SPIRE integration, consult SPIRE Agent SDS configuration and set the following SDS configuration values for your SPIRE Agent configuration file.

Configuration	Description	Resource Name
`default_svid_name`	The TLS Certificate resource name to use for the default `X509-SVID` with Envoy SDS	default
`default_bundle_name`	The Validation Context resource name to use for the default X.509 bundle with Envoy SDS	null
`default_all_bundles_name`	The Validation Context resource name to use for all bundles (including federated) with Envoy SDS	ROOTCA

This will allow Envoy to get federated bundles directly from SPIRE.

Create federated registration entries

If using the SPIRE Kubernetes Workload Registrar, create federated entries for workloads by adding the pod annotation spiffe.io/federatesWith to the service deployment spec, specifying the trust domain you want the pod to federate with:
```
podAnnotations:
  spiffe.io/federatesWith: "<trust.domain>"
```
For manual registration see Create Registration Entries for Federation.

Cleanup SPIRE

If you installed SPIRE using the quick start SPIRE deployment provided by Istio, use the following commands to remove those Kubernetes resources:

$ kubectl delete CustomResourceDefinition spiffeids.spiffeid.spiffe.io
$ kubectl delete -n spire serviceaccount spire-agent
$ kubectl delete -n spire configmap spire-agent
$ kubectl delete -n spire deployment spire-agent
$ kubectl delete csidriver csi.spiffe.io
$ kubectl delete -n spire configmap spire-server
$ kubectl delete -n spire service spire-server
$ kubectl delete -n spire serviceaccount spire-server
$ kubectl delete -n spire statefulset spire-server
$ kubectl delete clusterrole spire-server-trust-role spire-agent-cluster-role
$ kubectl delete clusterrolebinding spire-server-trust-role-binding spire-agent-cluster-role-binding
$ kubectl delete namespace spire