integration: add single-cluster integration tests (#2516)

* integration: add single-cluster integration tests

* remove kind load

integration/cmd/pomerium-integration-tests/main.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/google/go-jsonnet"
+	"github.com/peterbourgon/ff/v3/ffcli"
+	"github.com/rs/zerolog/log"
+	"sigs.k8s.io/yaml"
+)
+
+func main() {
+	generateCmd := &ffcli.Command{
+		Name: "generate-configuration",
+		Exec: func(ctx context.Context, args []string) error {
+			return runGenerateConfiguration(ctx)
+		},
+	}
+	rootCmd := &ffcli.Command{
+		Subcommands: []*ffcli.Command{generateCmd},
+		Exec: func(ctx context.Context, args []string) error {
+			return flag.ErrHelp
+		},
+	}
+	err := rootCmd.ParseAndRun(context.Background(), os.Args[1:])
+	if err != nil && !errors.Is(err, flag.ErrHelp) {
+		log.Fatal().Err(err).Send()
+	}
+}
+
+func runGenerateConfiguration(ctx context.Context) error {
+	log.Info().Msg("generating configuration")
+
+	root := filepath.Join(".", "integration")
+	if _, err := os.Stat(root); err != nil {
+		return fmt.Errorf("expected integration subfolder in cwd")
+	}
+	tplRoot := filepath.Join(root, "tpl")
+
+	var allSrcPaths []string
+	err := filepath.WalkDir(tplRoot, func(srcPath string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+
+		allSrcPaths = append(allSrcPaths, srcPath)
+
+		return err
+	})
+	if err != nil {
+		return err
+	}
+	sort.Strings(allSrcPaths)
+
+	vm := jsonnet.MakeVM()
+	vm.Importer(&jsonnet.FileImporter{JPaths: allSrcPaths})
+	for _, srcPath := range allSrcPaths {
+		if filepath.Ext(srcPath) != ".jsonnet" {
+			continue
+		}
+
+		dstPath := filepath.Join(root, srcPath[len(tplRoot)+1:])
+		dstPath = dstPath[:len(dstPath)-len(filepath.Ext(dstPath))]
+
+		contents, err := vm.EvaluateFile(srcPath)
+		if err != nil {
+			return fmt.Errorf("error evaluating jsonnet (path=%s): %w", srcPath, err)
+		}
+		asYAML, _ := yaml.JSONToYAML([]byte(contents))
+
+		err = os.MkdirAll(filepath.Dir(dstPath), 0755)
+		if err != nil {
+			return fmt.Errorf("error creating directory (path=%s): %w", dstPath, err)
+		}
+
+		err = os.WriteFile(dstPath, asYAML, 0600)
+		if err != nil {
+			return fmt.Errorf("error writing file (path=%s): %w", dstPath, err)
+		}
+	}
+
+	return nil
+}