chore: support-external-cmd-call-in-template (#8296)

pkg/skaffold/util/env_template.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"os/exec"
 	"reflect"
 	"sort"
 	"strings"
@@ -34,6 +35,7 @@ var (
 	OSEnviron = os.Environ
 	funcsMap  = template.FuncMap{
 		"default": defaultFunc,
+		"cmd":     runCmdFunc,
 	}
 )
 
@@ -160,3 +162,9 @@ func defaultFunc(dflt, value interface{}) interface{} {
 	}
 	return value
 }
+
+func runCmdFunc(name string, args ...string) (string, error) {
+	cmd := exec.Command(name, args...)
+	out, err := RunCmdOut(context.TODO(), cmd)
+	return string(out), err
+}

pkg/skaffold/util/env_template_test.go

@@ -199,3 +199,37 @@ func TestDefaultFunc(t *testing.T) {
 		})
 	}
 }
+
+func TestRunCmdFunc(t *testing.T) {
+	tests := []struct {
+		description     string
+		commandName     string
+		args            []string
+		output          string
+		expectedCommand string
+		err             error
+	}{
+		{
+			description:     "test running command succeeds",
+			commandName:     "bash",
+			args:            []string{"-c", "git rev-parse --verify HEAD"},
+			output:          "123",
+			expectedCommand: "bash -c git rev-parse --verify HEAD",
+		},
+		{
+			description:     "test running command fails",
+			commandName:     "bash",
+			args:            []string{"-c", "gib rev-parse --verify HEAD"},
+			output:          "",
+			expectedCommand: "bash -c gib rev-parse --verify HEAD",
+			err:             fmt.Errorf("command not found"),
+		},
+	}
+	for _, test := range tests {
+		testutil.Run(t, test.description, func(t *testutil.T) {
+			t.Override(&DefaultExecCommand, testutil.CmdRunOut(test.expectedCommand, test.output))
+			out, _ := runCmdFunc(test.commandName, test.args...)
+			t.CheckErrorAndDeepEqual(test.err != nil, test.err, test.output, out)
+		})
+	}
+}