Split pkg/server from pkg/api (#616)

API clients using pkg/api.NewClient , like github.com/sigstore/cosign,
currently end up depending on all the implementation details of the servers,
unnecessarily increasing their binary size and supply-chain attack surface.

Instead, move the server code to a new pkg/server (assuming there are
no external users of that functionality), and leave pkg/api as a package only
providing a client (as it is used in practice, and documented in various
places in this repo).

The move includes pkg/api/version.go, because it is only useful
with a Go build that specifies the various values at build time,
which is unlikely to be the case for any third-party importer
of that package.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

.golangci.yml

@@ -32,7 +32,7 @@ issues:
     - errcheck
     - gosec
   # the following section is due to the legacy API being deprecated
-  - path: pkg/api/legacy_server.go
+  - path: pkg/server/legacy_server.go
     linters:
     - staticcheck
     text: SA1019

Makefile

@@ -46,8 +46,8 @@ ifeq ($(DIFF), 1)
     GIT_TREESTATE = "dirty"
 endif
 
-FULCIO_PKG=github.com/sigstore/fulcio/pkg/api
-LDFLAGS=-X $(FULCIO_PKG).gitVersion=$(GIT_VERSION) -X $(FULCIO_PKG).gitCommit=$(GIT_HASH) -X $(FULCIO_PKG).gitTreeState=$(GIT_TREESTATE) -X $(FULCIO_PKG).buildDate=$(BUILD_DATE)
+FULCIO_VERSION_PKG=github.com/sigstore/fulcio/pkg/server
+LDFLAGS=-X $(FULCIO_VERSION_PKG).gitVersion=$(GIT_VERSION) -X $(FULCIO_VERSION_PKG).gitCommit=$(GIT_HASH) -X $(FULCIO_VERSION_PKG).gitTreeState=$(GIT_TREESTATE) -X $(FULCIO_VERSION_PKG).buildDate=$(BUILD_DATE)
 
 KO_PREFIX ?= gcr.io/projectsigstore
 export KO_DOCKER_REPO=$(KO_PREFIX)

cmd/app/grpc.go

@@ -27,12 +27,12 @@ import (
 	grpc_recovery "github.com/grpc-ecosystem/go-grpc-middleware/recovery"
 	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/sigstore/fulcio/pkg/api"
 	"github.com/sigstore/fulcio/pkg/ca"
 	"github.com/sigstore/fulcio/pkg/config"
 	gw "github.com/sigstore/fulcio/pkg/generated/protobuf"
 	gw_legacy "github.com/sigstore/fulcio/pkg/generated/protobuf/legacy"
 	"github.com/sigstore/fulcio/pkg/log"
+	"github.com/sigstore/fulcio/pkg/server"
 	"github.com/spf13/viper"
 	"google.golang.org/grpc"
 )
@@ -75,7 +75,7 @@ func createGRPCServer(cfg *config.FulcioConfig, ctClient *ctclient.LogClient, ba
 		)),
 		grpc.MaxRecvMsgSize(int(maxMsgSize)))
 
-	grpcCAServer := api.NewGRPCCAServer(ctClient, baseca)
+	grpcCAServer := server.NewGRPCCAServer(ctClient, baseca)
 	// Register your gRPC service implementations.
 	gw.RegisterCAServer(myServer, grpcCAServer)
 
@@ -86,7 +86,7 @@ func createGRPCServer(cfg *config.FulcioConfig, ctClient *ctclient.LogClient, ba
 func (g *grpcServer) setupPrometheus(reg *prometheus.Registry) {
 	grpcMetrics := grpc_prometheus.DefaultServerMetrics
 	grpcMetrics.EnableHandlingTimeHistogram()
-	reg.MustRegister(grpcMetrics, api.MetricLatency, api.RequestsCount)
+	reg.MustRegister(grpcMetrics, server.MetricLatency, server.RequestsCount)
 	grpc_prometheus.Register(g.Server)
 }
 
@@ -137,7 +137,7 @@ func createLegacyGRPCServer(cfg *config.FulcioConfig, v2Server gw.CAServer) (*gr
 		)),
 		grpc.MaxRecvMsgSize(int(maxMsgSize)))
 
-	legacyGRPCCAServer := api.NewLegacyGRPCCAServer(v2Server)
+	legacyGRPCCAServer := server.NewLegacyGRPCCAServer(v2Server)
 
 	// Register your gRPC service implementations.
 	gw_legacy.RegisterCAServer(myServer, legacyGRPCCAServer)

cmd/app/http.go

@@ -26,10 +26,10 @@ import (
 
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"github.com/sigstore/fulcio/pkg/api"
 	gw "github.com/sigstore/fulcio/pkg/generated/protobuf"
 	legacy_gw "github.com/sigstore/fulcio/pkg/generated/protobuf/legacy"
 	"github.com/sigstore/fulcio/pkg/log"
+	"github.com/sigstore/fulcio/pkg/server"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/metadata"
@@ -43,7 +43,7 @@ type httpServer struct {
 
 func extractOIDCTokenFromAuthHeader(ctx context.Context, req *http.Request) metadata.MD {
 	token := strings.Replace(req.Header.Get("Authorization"), "Bearer ", "", 1)
-	return metadata.Pairs(api.MetadataOIDCTokenKey, token)
+	return metadata.Pairs(server.MetadataOIDCTokenKey, token)
 }
 
 func createHTTPServer(ctx context.Context, serverEndpoint string, grpcServer, legacyGRPCServer *grpcServer) httpServer {
@@ -63,9 +63,9 @@ func createHTTPServer(ctx context.Context, serverEndpoint string, grpcServer, le
 	}
 
 	// Limit request size
-	handler := api.WithMaxBytes(mux, maxMsgSize)
-	handler = promhttp.InstrumentHandlerDuration(api.MetricLatency, handler)
-	handler = promhttp.InstrumentHandlerCounter(api.RequestsCount, handler)
+	handler := server.WithMaxBytes(mux, maxMsgSize)
+	handler = promhttp.InstrumentHandlerDuration(server.MetricLatency, handler)
+	handler = promhttp.InstrumentHandlerCounter(server.RequestsCount, handler)
 
 	api := http.Server{
 		Addr:    serverEndpoint,
@@ -96,20 +96,20 @@ func setResponseCodeModifier(ctx context.Context, w http.ResponseWriter, _ proto
 	}
 
 	// set SCT if present ahead of modifying response code
-	if vals := md.HeaderMD.Get(api.SCTMetadataKey); len(vals) > 0 {
-		delete(md.HeaderMD, api.SCTMetadataKey)
+	if vals := md.HeaderMD.Get(server.SCTMetadataKey); len(vals) > 0 {
+		delete(md.HeaderMD, server.SCTMetadataKey)
 		delete(w.Header(), "Grpc-Metadata-sct")
 		w.Header().Set("SCT", vals[0])
 	}
 
 	// set http status code
-	if vals := md.HeaderMD.Get(api.HTTPResponseCodeMetadataKey); len(vals) > 0 {
+	if vals := md.HeaderMD.Get(server.HTTPResponseCodeMetadataKey); len(vals) > 0 {
 		code, err := strconv.Atoi(vals[0])
 		if err != nil {
 			return err
 		}
 		// delete the headers to not expose any grpc-metadata in http response
-		delete(md.HeaderMD, api.HTTPResponseCodeMetadataKey)
+		delete(md.HeaderMD, server.HTTPResponseCodeMetadataKey)
 		delete(w.Header(), "Grpc-Metadata-X-Http-Code")
 		w.WriteHeader(code)
 	}

cmd/app/version.go

@@ -18,7 +18,7 @@ package app
 import (
 	"fmt"
 
-	"github.com/sigstore/fulcio/pkg/api"
+	"github.com/sigstore/fulcio/pkg/server"
 	"github.com/spf13/cobra"
 )
 
@@ -43,7 +43,7 @@ func newVersionCmd() *cobra.Command {
 }
 
 func runVersion(opts *versionOptions) error {
-	v := api.VersionInfo()
+	v := server.VersionInfo()
 	res := v.String()
 
 	if opts.json {

pkg/api/error.go → pkg/server/error.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"context"

pkg/api/grpc_server.go → pkg/server/grpc_server.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"context"

pkg/api/grpc_server_test.go → pkg/server/grpc_server_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package api
+package server
 
 import (
 	"context"

pkg/api/legacy_server.go → pkg/server/legacy_server.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"context"

pkg/api/max_bytes.go → pkg/server/max_bytes.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import "net/http"
 

pkg/api/max_bytes_test.go → pkg/server/max_bytes_test.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"io/ioutil"

pkg/api/metrics.go → pkg/server/metrics.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"github.com/prometheus/client_golang/prometheus"

pkg/api/version.go → pkg/server/version.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-package api
+package server
 
 import (
 	"encoding/json"