Ignore variant when looking up command for platform in entrypoint

cmd/entrypoint/main.go

@@ -19,6 +19,7 @@ package main
 import (
 	"encoding/json"
 	"flag"
+	"fmt"
 	"log"
 	"os"
 	"os/exec"
@@ -110,11 +111,10 @@ func main() {
 			log.Fatal(err)
 		}
 		plat := platforms.DefaultString()
-
-		var found bool
-		cmd, found = cmds[plat]
-		if !found {
-			log.Fatalf("could not find command for platform %q", plat)
+		var err error
+		cmd, err = selectCommandForPlatform(cmds, plat)
+		if err != nil {
+			log.Fatal(err)
 		}
 	}
 
@@ -173,3 +173,20 @@ func main() {
 		}
 	}
 }
+
+func selectCommandForPlatform(cmds map[string][]string, plat string) ([]string, error) {
+	cmd, found := cmds[plat]
+	if found {
+		return cmd, nil
+	}
+
+	// If the command wasn't found, check if there's a
+	// command defined for the same platform without a CPU
+	// variant specified.
+	platWithoutVariant := plat[:strings.LastIndex(plat, "/")]
+	cmd, found = cmds[platWithoutVariant]
+	if found {
+		return cmd, nil
+	}
+	return nil, fmt.Errorf("could not find command for platform %q", plat)
+}

cmd/entrypoint/namespaces.go

@@ -1,3 +1,4 @@
+//go:build !linux
 // +build !linux
 
 package main

cmd/entrypoint/namespaces_test.go

@@ -1,5 +1,22 @@
+//go:build linux
 // +build linux
 
+/*
+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
+
+    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 main
 
 import (

cmd/entrypoint/platform_test.go

@@ -0,0 +1,78 @@
+/*
+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
+
+    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 main
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestSelectCommandForPlatform(t *testing.T) {
+	for _, c := range []struct {
+		desc    string
+		m       map[string][]string
+		plat    string
+		want    []string
+		wantErr bool
+	}{{
+		desc: "platform exists",
+		m: map[string][]string{
+			"linux/amd64": {"my", "command"},
+			"linux/s390x": {"other", "one"},
+		},
+		plat: "linux/amd64",
+		want: []string{"my", "command"},
+	}, {
+		desc: "platform not found",
+		m: map[string][]string{
+			"linux/amd64": {"my", "command"},
+			"linux/s390x": {"other", "one"},
+		},
+		plat:    "linux/ppc64le",
+		wantErr: true,
+	}, {
+		desc: "platform fallback",
+		m: map[string][]string{
+			"linux/amd64": {"my", "command"},
+			"linux/s390x": {"other", "one"},
+		},
+		plat: "linux/amd64/v8",
+		want: []string{"my", "command"},
+	}, {
+		desc: "platform fallback not needed",
+		m: map[string][]string{
+			"linux/amd64":    {"other", "one"},
+			"linux/amd64/v8": {"my", "command"},
+		},
+		plat: "linux/amd64/v8",
+		want: []string{"my", "command"},
+	}} {
+		t.Run(c.desc, func(t *testing.T) {
+			got, err := selectCommandForPlatform(c.m, c.plat)
+			if err != nil {
+				if c.wantErr {
+					return
+				}
+				t.Fatalf("Unexpected error: %v", err)
+			}
+			if d := cmp.Diff(c.want, got); d != "" {
+				t.Fatalf("Diff(-want,+got):\n%s", d)
+			}
+		})
+	}
+}

cmd/entrypoint/runner.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 /*

cmd/entrypoint/runner_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 /*