bazel: pseudo version tool freshness check (#1869)

* switch to darwin compatible shasum

* add bazel rule

* update shellscript for in-place updates

* Revert "update shellscript for in-place updates"

This reverts commit 87d39b06f7.

* add version tool freshness check

* remove pseudo-version file

* revert to `sha256sum`

* fix workflow indentation

hack/pseudo-version/check/check.go

@@ -0,0 +1,176 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+package main
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/aws/aws-sdk-go/service/s3/s3manager"
+	"github.com/bazelbuild/rules_go/go/runfiles"
+)
+
+const (
+	darwinArm64Filename = "pseudo_version_darwin_arm64"
+	darwinAmd64Filename = "pseudo_version_darwin_amd64"
+	linuxArm64Filename  = "pseudo_version_linux_arm64"
+	linuxAmd64Filename  = "pseudo_version_linux_amd64"
+	bucket              = "cdn-constellation-backend"
+	keyPrefix           = "constellation/cas/sha256/"
+)
+
+func main() {
+	checker, err := newChecker()
+	if err != nil {
+		log.Fatalf("failed to create checker: %v", err)
+	}
+
+	if err := checker.checkAll(); err != nil {
+		log.Fatalf("failed to check pseudo-version tools: %v", err)
+	}
+
+	log.Println("All pseudo-version tools are up-to-date")
+}
+
+// a checker checks if the pseudo-version tool with the specified hash exists in S3.
+type checker struct {
+	files                      *runfiles.Runfiles
+	downloader                 *s3manager.Downloader
+	uploader                   *s3manager.Uploader
+	pseudoVersionToolFilenames []string
+}
+
+// newChecker creates a new checker.
+func newChecker() (*checker, error) {
+	files, err := runfiles.New()
+	if err != nil {
+		return nil, fmt.Errorf("Failed to create runfiles: %v", err)
+	}
+
+	sess := session.Must(session.NewSession(&aws.Config{
+		Region: aws.String("eu-central-1"),
+	}))
+
+	return &checker{
+		files:      files,
+		downloader: s3manager.NewDownloader(sess),
+		uploader:   s3manager.NewUploader(sess),
+		pseudoVersionToolFilenames: []string{
+			darwinArm64Filename,
+			darwinAmd64Filename,
+			linuxArm64Filename,
+			linuxAmd64Filename,
+		},
+	}, nil
+}
+
+// checkAll checks all embedded pseudo-version tools.
+func (c *checker) checkAll() error {
+	for _, filename := range c.pseudoVersionToolFilenames {
+		if err := c.check(filename); err != nil {
+			return fmt.Errorf("failed to check pseudo-version tool (%s): %v", filename, err)
+		}
+	}
+	return nil
+}
+
+// check checks if the pseudo-version tool with the specified hash exists in S3 and
+// uploads it if it doesn't.
+func (c *checker) check(filename string) error {
+	log.Println("Checking pseudo-version tool:", filename)
+	hash, err := c.hashPseudoVersionTool(filename)
+	if err != nil {
+		return fmt.Errorf("failed to hash pseudo-version tool (%s): %v", filename, err)
+	}
+	log.Printf("Hash: %x\n", hash)
+
+	exists, err := c.matchesS3Hash(filename, hash)
+	if err != nil {
+		return fmt.Errorf("failed to check if pseudo-version tool (%s) exists in S3: %v", filename, err)
+	}
+	log.Println("Exists in S3:", exists)
+
+	if !exists {
+		log.Println("Uploading pseudo-version tool:", filename)
+		if err := c.uploadToS3(filename, hash); err != nil {
+			return fmt.Errorf("failed to upload pseudo-version tool (%s) to S3: %v", filename, err)
+		}
+	}
+
+	return nil
+}
+
+// uploadToS3 uploads the pseudo-version tool with the specified hash to S3.
+func (c *checker) uploadToS3(filename string, hash [32]byte) error {
+	contents, err := c.files.ReadFile(fmt.Sprintf("__main__/hack/pseudo-version/%s", filename))
+	if err != nil {
+		return fmt.Errorf("failed to read pseudo-version tool (%s): %v", filename, err)
+	}
+
+	key := keyPrefix + fmt.Sprintf("%x", hash)
+	_, err = c.uploader.Upload(&s3manager.UploadInput{
+		Bucket: aws.String(bucket),
+		Key:    aws.String(key),
+		Body:   bytes.NewReader(contents),
+	})
+	if err != nil {
+		return fmt.Errorf("failed to upload %x to S3: %v", filename, err)
+	}
+
+	return nil
+}
+
+// matchesS3Hash checks the pseudo-version tool with the specified hash exists in S3.
+func (c *checker) matchesS3Hash(filename string, hash [32]byte) (bool, error) {
+	tmpfileName := filename + "-tmp"
+	tmpfile, err := os.Create(tmpfileName)
+	if err != nil {
+		return false, fmt.Errorf("failed to create temporary file %s: %v", tmpfileName, err)
+	}
+	defer os.Remove(tmpfileName)
+
+	key := keyPrefix + fmt.Sprintf("%x", hash)
+	_, err = c.downloader.Download(tmpfile, &s3.GetObjectInput{
+		Bucket: aws.String(bucket),
+		Key:    aws.String(key),
+	})
+	if err != nil {
+		if isNoSuchKeyErr(err) {
+			return false, nil
+		}
+		return false, fmt.Errorf("failed to download %x from S3: %v", filename, err)
+	}
+
+	// A file with the hash exists in S3
+	tmpfile.Close()
+	return true, nil
+}
+
+// hashPseudoVersionTool hashes the specified embedded pseudo-version tool.
+func (c *checker) hashPseudoVersionTool(filename string) ([32]byte, error) {
+	contents, err := c.files.ReadFile(fmt.Sprintf("__main__/hack/pseudo-version/%s", filename))
+	if err != nil {
+		return [32]byte{}, fmt.Errorf("failed to read pseudo-version tool (%s): %v", filename, err)
+	}
+
+	return sha256.Sum256(contents), nil
+}
+
+func isNoSuchKeyErr(err error) bool {
+	if aerr, ok := err.(awserr.Error); ok {
+		if aerr.Code() == s3.ErrCodeNoSuchKey {
+			return true
+		}
+	}
+	return false
+}