[prism] Support AnyOf in Prism.

CHANGES.md

@@ -82,6 +82,8 @@
   * Initial support for AllowedLateness added. ([#33542](https://github.com/apache/beam/pull/33542))
   * The Go SDK's inprocess Prism runner (AKA the Go SDK default runner) now supports non-loopback mode environment types. ([#33572](https://github.com/apache/beam/pull/33572))
   * Support the Process Environment for execution in Prism ([#33651](https://github.com/apache/beam/pull/33651))
+  * Support the AnyOf Environment for execution in Prism ([#33705](https://github.com/apache/beam/pull/33705))
+     * This improves support for developing Xlang pipelines, when using a compatible cross language service.
 
 ## Breaking Changes
 

sdks/go/pkg/beam/runners/prism/internal/environments.go

@@ -23,6 +23,7 @@ import (
 	"log/slog"
 	"os"
 	"os/exec"
+	"slices"
 	"time"
 
 	fnpb "github.com/apache/beam/sdks/v2/go/pkg/beam/model/fnexecution_v1"
@@ -46,16 +47,26 @@ import (
 
 func runEnvironment(ctx context.Context, j *jobservices.Job, env string, wk *worker.W) error {
 	logger := j.Logger.With(slog.String("envID", wk.Env))
-	// TODO fix broken abstraction.
-	// We're starting a worker pool here, because that's the loopback environment.
-	// It's sort of a mess, largely because of loopback, which has
-	// a different flow from a provisioned docker container.
 	e := j.Pipeline.GetComponents().GetEnvironments()[env]
+
+	if e.GetUrn() == urns.EnvAnyOf {
+		// We've been given a choice!
+		ap := &pipepb.AnyOfEnvironmentPayload{}
+		if err := (proto.UnmarshalOptions{}).Unmarshal(e.GetPayload(), ap); err != nil {
+			logger.Error("unmarshaling any environment payload", "error", err)
+			return err
+		}
+		e = selectAnyOfEnv(ap)
+		logger.Info("AnyEnv resolved", "selectedUrn", e.GetUrn(), "worker", wk.ID)
+		// Process the environment as normal.
+	}
+
 	switch e.GetUrn() {
 	case urns.EnvExternal:
 		ep := &pipepb.ExternalPayload{}
 		if err := (proto.UnmarshalOptions{}).Unmarshal(e.GetPayload(), ep); err != nil {
-			logger.Error("unmarshing external environment payload", "error", err)
+			logger.Error("unmarshaling external environment payload", "error", err)
+			return err
 		}
 		go func() {
 			externalEnvironment(ctx, ep, wk)
@@ -65,13 +76,15 @@ func runEnvironment(ctx context.Context, j *jobservices.Job, env string, wk *wor
 	case urns.EnvDocker:
 		dp := &pipepb.DockerPayload{}
 		if err := (proto.UnmarshalOptions{}).Unmarshal(e.GetPayload(), dp); err != nil {
-			logger.Error("unmarshing docker environment payload", "error", err)
+			logger.Error("unmarshaling docker environment payload", "error", err)
+			return err
 		}
 		return dockerEnvironment(ctx, logger, dp, wk, j.ArtifactEndpoint())
 	case urns.EnvProcess:
 		pp := &pipepb.ProcessPayload{}
 		if err := (proto.UnmarshalOptions{}).Unmarshal(e.GetPayload(), pp); err != nil {
-			logger.Error("unmarshing docker environment payload", "error", err)
+			logger.Error("unmarshaling process environment payload", "error", err)
+			return err
 		}
 		go func() {
 			processEnvironment(ctx, pp, wk)
@@ -83,6 +96,33 @@ func runEnvironment(ctx context.Context, j *jobservices.Job, env string, wk *wor
 	}
 }
 
+func selectAnyOfEnv(ap *pipepb.AnyOfEnvironmentPayload) *pipepb.Environment {
+	// Prefer external, then process, then docker, unknown environments are 0.
+	ranks := map[string]int{
+		urns.EnvDocker:   1,
+		urns.EnvProcess:  5,
+		urns.EnvExternal: 10,
+	}
+
+	envs := ap.GetEnvironments()
+
+	slices.SortStableFunc(envs, func(a, b *pipepb.Environment) int {
+		rankA := ranks[a.GetUrn()]
+		rankB := ranks[b.GetUrn()]
+
+		// Reverse the comparison so our favourite is at the front
+		switch {
+		case rankA > rankB:
+			return -1 // Usually "greater than" would be 1
+		case rankA < rankB:
+			return 1
+		}
+		return 0
+	})
+	// Pick our favourite.
+	return envs[0]
+}
+
 func externalEnvironment(ctx context.Context, ep *pipepb.ExternalPayload, wk *worker.W) {
 	conn, err := grpc.Dial(ep.GetEndpoint().GetUrl(), grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {

sdks/go/pkg/beam/runners/prism/internal/environments_test.go

@@ -0,0 +1,53 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements.  See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You 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
+//
+//    http://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.
+
+package internal
+
+import (
+	"testing"
+
+	pipepb "github.com/apache/beam/sdks/v2/go/pkg/beam/model/pipeline_v1"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/urns"
+)
+
+func TestSelectAnyOf(t *testing.T) {
+	tests := []struct {
+		name, want string
+		wantTag    string
+		envs       []*pipepb.Environment
+	}{
+		{name: "singleDefault", want: urns.EnvDefault, envs: []*pipepb.Environment{{Urn: urns.EnvDefault}}},
+		{name: "singleDocker", want: urns.EnvDocker, envs: []*pipepb.Environment{{Urn: urns.EnvDocker}}},
+		{name: "singleProcess", want: urns.EnvProcess, envs: []*pipepb.Environment{{Urn: urns.EnvProcess}}},
+		{name: "singleExternal", want: urns.EnvExternal, envs: []*pipepb.Environment{{Urn: urns.EnvExternal}}},
+		{name: "multiplePickExternal_1", want: urns.EnvExternal, envs: []*pipepb.Environment{{Urn: urns.EnvExternal}, {Urn: urns.EnvDocker}, {Urn: urns.EnvProcess}}},
+		{name: "multiplePickExternal_2", want: urns.EnvExternal, envs: []*pipepb.Environment{{Urn: urns.EnvDocker}, {Urn: urns.EnvProcess}, {Urn: urns.EnvExternal}}},
+		{name: "multiplePickProcess", want: urns.EnvProcess, envs: []*pipepb.Environment{{Urn: urns.EnvDocker}, {Urn: urns.EnvProcess}}},
+		{name: "multiplePickDocker", want: urns.EnvDocker, envs: []*pipepb.Environment{{Urn: urns.EnvDefault}, {Urn: urns.EnvDocker}}},
+		{name: "multiplePickFirstExternal", want: urns.EnvExternal, wantTag: "first", envs: []*pipepb.Environment{{Urn: urns.EnvExternal, Payload: []byte("first")}, {Urn: urns.EnvExternal, Payload: []byte("second")}}},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			selected := selectAnyOfEnv(&pipepb.AnyOfEnvironmentPayload{Environments: test.envs})
+			if selected.GetUrn() != test.want {
+				t.Errorf("expected %v, got %v", test.want, selected.GetUrn())
+			}
+			if got, want := string(selected.GetPayload()), test.wantTag; got != want {
+				t.Errorf("expected payload with tag %v, got %v", want, got)
+			}
+		})
+	}
+
+}

sdks/go/pkg/beam/runners/prism/internal/urns/urns.go

@@ -147,4 +147,5 @@ var (
 	EnvProcess  = envUrn(pipepb.StandardEnvironments_PROCESS)
 	EnvExternal = envUrn(pipepb.StandardEnvironments_EXTERNAL)
 	EnvDefault  = envUrn(pipepb.StandardEnvironments_DEFAULT)
+	EnvAnyOf    = envUrn(pipepb.StandardEnvironments_ANYOF)
 )