Breaking down PR tektoncd#4759 originally proposed by @pxp928 to addr…

…ess TEP-0089 according @lumjjb suggestions. Plan for breaking down PR is PR 1.1: api PR 1.2: entrypointer (+cmd line + test/entrypointer) Entrypoint takes results and signs the results (termination message). PR 1.3: reconciler + pod + cmd/controller + integration tests Controller will verify the signed result. This commit corresponds to 1.3 above.

cmd/imagedigestexporter/main.go

@@ -17,9 +17,12 @@ limitations under the License.
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"flag"
 
+	"github.com/tektoncd/pipeline/pkg/spire"
+	"github.com/tektoncd/pipeline/pkg/spire/config"
 	"github.com/tektoncd/pipeline/pkg/termination"
 	"knative.dev/pkg/logging"
 
@@ -31,9 +34,12 @@ import (
 var (
 	images                 = flag.String("images", "", "List of images resources built by task in json format")
 	terminationMessagePath = flag.String("terminationMessagePath", "/tekton/termination", "Location of file containing termination message")
+	enableSpire            = flag.Bool("enable_spire", false, "If specified by configmap, this enables spire signing and verification")
+	socketPath             = flag.String("spire_socket_path", "unix:///spiffe-workload-api/spire-agent.sock", "Experimental: The SPIRE agent socket for SPIFFE workload API.")
 )
 
-/* The input of this go program will be a JSON string with all the output PipelineResources of type
+/*
+The input of this go program will be a JSON string with all the output PipelineResources of type
 Image, which will include the path to where the index.json file will be located. The program will
 read the related index.json file(s) and log another JSON string including the name of the image resource
 and the digests.
@@ -76,6 +82,21 @@ func main() {
 
 	}
 
+	if enableSpire != nil && *enableSpire && socketPath != nil && *socketPath != "" {
+		ctx := context.Background()
+		spireConfig := config.SpireConfig{
+			SocketPath: *socketPath,
+		}
+
+		spireWorkloadAPI := spire.NewEntrypointerAPIClient(&spireConfig)
+		signed, err := spireWorkloadAPI.Sign(ctx, output)
+		if err != nil {
+			logger.Fatal(err)
+		}
+
+		output = append(output, signed...)
+	}
+
 	if err := termination.WriteMessage(*terminationMessagePath, output); err != nil {
 		logger.Fatalf("Unexpected error writing message %s to %s", *terminationMessagePath, err)
 	}

config/config-feature-flags.yaml

@@ -97,3 +97,8 @@ data:
   # Acceptable values are "v1beta1" and "v1alpha1".
   # The default is "v1alpha1".
   custom-task-version: "v1alpha1"
+  # Setting this flag will determine how Tekton pipelines will handle non-falsifiable provenance.
+  # If set to "spire", then SPIRE will be used to ensure non-falsifiable provenance.
+  # If set to "none", then Tekton will not have non-falsifiable provenance.
+  # This is an experimental feature and thus should still be considered an alpha feature.
+  enforce-nonfalsifiablity: "none"

config/config-spire.yaml

@@ -0,0 +1,49 @@
+# Copyright 2022 The Tekton Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: config-spire
+  namespace: tekton-pipelines
+  labels:
+    app.kubernetes.io/instance: default
+    app.kubernetes.io/part-of: tekton-pipelines
+data:
+  _example: |
+    ################################
+    #                              #
+    #    EXAMPLE CONFIGURATION     #
+    #                              #
+    ################################
+    # This block is not actually functional configuration,
+    # but serves to illustrate the available configuration
+    # options and document them in a way that is accessible
+    # to users that `kubectl edit` this config map.
+    #
+    # These sample configuration options may be copied out of
+    # this example block and unindented to be in the data block
+    # to actually change the configuration.
+    #
+    # spire-trust-domain specifies the SPIRE trust domain to use.
+    # spire-trust-domain: "example.org"
+    #
+    # spire-socket-path specifies the SPIRE agent socket for SPIFFE workload API.
+    # spire-socket-path: "unix:///spiffe-workload-api/spire-agent.sock"
+    #
+    # spire-server-addr specifies the SPIRE server address for workload/node registration.
+    # spire-server-addr: "spire-server.spire.svc.cluster.local:8081"
+    #
+    # spire-node-alias-prefix specifies the SPIRE node alias prefix to use.
+    # spire-node-alias-prefix: "/tekton-node/"

config/controller.yaml

@@ -117,6 +117,8 @@ spec:
           value: feature-flags
         - name: CONFIG_LEADERELECTION_NAME
           value: config-leader-election
+        - name: CONFIG_SPIRE
+          value: config-spire
         - name: CONFIG_TRUSTED_RESOURCES_NAME
           value: config-trusted-resources
         - name: SSL_CERT_FILE