add v2 / previous version support

main.go

@@ -52,8 +52,12 @@ import (
 
 // convenient global values
 const (
-	DefaultKeyID             = "current"
-	applicationName, apiBase = "tr1d1um", "api/v3"
+	DefaultKeyID       = "current"
+	apiVersion         = "v3"
+	prevAPIVersion     = "v2"
+	applicationName    = "tr1d1um"
+	apiBase            = "api/" + apiVersion
+	apiBaseDualVersion = "api/{version:" + apiVersion + "|" + prevAPIVersion + "}"
 )
 
 const (
@@ -141,7 +145,13 @@ func tr1d1um(arguments []string) (exitCode int) {
 	}
 	rootRouter.Use(otelmux.Middleware("mainSpan", otelMuxOptions...), candlelight.EchoFirstTraceNodeInfo(tracing.Propagator()))
 
-	APIRouter := rootRouter.PathPrefix(fmt.Sprintf("/%s/", apiBase)).Subrouter()
+	// if we want to support the previous API version, then include it in the
+	// api base.
+	urlPrefix := fmt.Sprintf("/%s/", apiBase)
+	if v.GetBool("previousVersionSupport") {
+		urlPrefix = fmt.Sprintf("/%s/", apiBaseDualVersion)
+	}
+	APIRouter := rootRouter.PathPrefix(urlPrefix).Subrouter()
 
 	//
 	// Webhooks (if not configured, handlers are not set up)

primaryHandler.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/go-kit/kit/log"
 	"github.com/goph/emperror"
+	"github.com/gorilla/mux"
 	"github.com/justinas/alice"
 	"github.com/spf13/viper"
 	"github.com/xmidt-org/bascule"
@@ -168,6 +169,9 @@ func authenticationHandler(v *viper.Viper, logger log.Logger, registry xmetrics.
 	}
 
 	authConstructor := basculehttp.NewConstructor(options...)
+	authConstructorLegacy := basculehttp.NewConstructor(append([]basculehttp.COption{
+		basculehttp.WithCErrorHTTPResponseFunc(basculehttp.LegacyOnErrorHTTPResponse),
+	}, options...)...)
 
 	bearerRules := bascule.Validators{
 		bchecks.NonEmptyPrincipal(),
@@ -208,8 +212,21 @@ func authenticationHandler(v *viper.Viper, logger log.Logger, registry xmetrics.
 		basculehttp.WithRules("Bearer", bearerRules),
 		basculehttp.WithEErrorResponseFunc(listener.OnErrorResponse),
 	)
-	constructors := []alice.Constructor{setLogger(logger), authConstructor, authEnforcer, basculehttp.NewListenerDecorator(listener)}
 
-	chain := alice.New(constructors...)
-	return &chain, nil
+	authChain := alice.New(setLogger(logger), authConstructor, authEnforcer, basculehttp.NewListenerDecorator(listener))
+	authChainLegacy := alice.New(setLogger(logger), authConstructorLegacy, authEnforcer, basculehttp.NewListenerDecorator(listener))
+
+	versionCompatibleAuth := alice.New(func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(r http.ResponseWriter, req *http.Request) {
+			vars := mux.Vars(req)
+			if vars != nil {
+				if vars["version"] == prevAPIVersion {
+					authChainLegacy.Then(next).ServeHTTP(r, req)
+					return
+				}
+			}
+			authChain.Then(next).ServeHTTP(r, req)
+		})
+	})
+	return &versionCompatibleAuth, nil
 }

tr1d1um.yaml

@@ -376,4 +376,10 @@ tracing:
   # skipTraceExport: true
 
   # endpoint is where trace information should be routed. Applies to zipkin and jaegar.
-  # endpoint: "http://localhost:9411/api/v2/spans"
+  # endpoint: "http://localhost:9411/api/v2/spans"
+
+# previousVersionSupport allows us to support two different major versions of
+# the API at the same time from the same application.  When this is true,
+# tr1d1um will support both "/v2" and "/v3" endpoints.  When false, only "/v3"
+# endpoints will be supported.
+previousVersionSupport: true