GHA cache: support and use cache key prefixes

api/cirrus_ci_service.proto

@@ -494,6 +494,7 @@ message HeartbeatResponse {
 message CacheInfoRequest {
   TaskIdentification task_identification = 1;
   string cache_key = 2;
+  repeated string cache_key_prefixes = 3;
 }
 
 message CacheInfo {

internal/agent/http_cache/ghacache/cirruscimock/cirruscimock.go

@@ -17,6 +17,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 	"io"
 	"net"
+	"net/http"
 	"testing"
 	"time"
 )
@@ -138,8 +139,8 @@ func (mock *cirrusCIMock) CacheInfo(ctx context.Context, request *api.CacheInfoR
 		Key:    aws.String(request.CacheKey),
 	})
 	if err != nil {
-		var aerr awserr.Error
-		if errors.As(err, &aerr) && aerr.Code() == s3.ErrCodeNoSuchKey {
+		var requestFailure awserr.RequestFailure
+		if errors.As(err, &requestFailure) && requestFailure.StatusCode() == http.StatusNotFound {
 			return nil, status.Errorf(codes.NotFound, "cache entry for key %s is not found",
 				request.CacheKey)
 		}

internal/agent/http_cache/ghacache/ghacache.go

@@ -8,6 +8,9 @@ import (
 	"github.com/cirruslabs/cirrus-cli/pkg/api"
 	"github.com/go-chi/render"
 	"github.com/puzpuzpuz/xsync/v3"
+	"github.com/samber/lo"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 	"log"
 	"math"
 	"math/rand"
@@ -55,33 +58,42 @@ func (cache *GHACache) get(writer http.ResponseWriter, request *http.Request) {
 	keys := strings.Split(request.URL.Query().Get("keys"), ",")
 	version := request.URL.Query().Get("version")
 
-	for _, key := range keys {
-		httpCacheURL := cache.httpCacheURL(key, version)
+	keysWithVersions := lo.Map(keys, func(key string, _ int) string {
+		return httpCacheKey(key, version)
+	})
+
+	grpcRequest := &api.CacheInfoRequest{
+		TaskIdentification: client.CirrusTaskIdentification,
+		CacheKey:           keysWithVersions[0],
+	}
 
-		resp, err := http.Head(httpCacheURL)
-		if err != nil {
-			fail(writer, request, http.StatusInternalServerError, "GHA cache failed to "+
-				"retrieve %q: %v", httpCacheURL, err)
+	if len(keysWithVersions) > 1 {
+		grpcRequest.CacheKeyPrefixes = keysWithVersions[1:]
+	}
+
+	grpcResponse, err := client.CirrusClient.CacheInfo(request.Context(), grpcRequest)
+	if err != nil {
+		if status, ok := status.FromError(err); ok && status.Code() == codes.NotFound {
+			writer.WriteHeader(http.StatusNoContent)
 
 			return
 		}
 
-		if resp.StatusCode == http.StatusOK {
-			jsonResp := struct {
-				Key string `json:"cacheKey"`
-				URL string `json:"archiveLocation"`
-			}{
-				Key: key,
-				URL: httpCacheURL,
-			}
+		fail(writer, request, http.StatusInternalServerError, "GHA cache failed to "+
+			"retrieve information about cache key %q: %v", keys[0], err)
 
-			render.JSON(writer, request, &jsonResp)
+		return
+	}
 
-			return
-		}
+	jsonResp := struct {
+		Key string `json:"cacheKey"`
+		URL string `json:"archiveLocation"`
+	}{
+		Key: strings.TrimSuffix(grpcResponse.Info.Key, "-"+version),
+		URL: cache.httpCacheURL(grpcResponse.Info.Key),
 	}
 
-	writer.WriteHeader(http.StatusNoContent)
+	render.JSON(writer, request, &jsonResp)
 }
 
 func (cache *GHACache) reserveUploadable(writer http.ResponseWriter, request *http.Request) {
@@ -279,8 +291,8 @@ func httpCacheKey(key string, version string) string {
 	return fmt.Sprintf("%s-%s", url.PathEscape(key), url.PathEscape(version))
 }
 
-func (cache *GHACache) httpCacheURL(key string, version string) string {
-	return fmt.Sprintf("http://%s/%s", cache.cacheHost, httpCacheKey(key, version))
+func (cache *GHACache) httpCacheURL(keyWithVersion string) string {
+	return fmt.Sprintf("http://%s/%s", cache.cacheHost, keyWithVersion)
 }
 
 func getID(request *http.Request) (int64, bool) {