SA: Use read-only connector for GetAuthorizations2 (letsencrypt#5815)

aarongable · web-flow · commit 8eb7272adfa7 · 2021-11-24T16:57:42.000-08:00
Add a feature flag which causes the SA to switch between using the
traditional read-write database connector (pointed at the primary db)
or the newer read-only database connector (usually pointed at a
replica) when executing the `GetAuthorizations2` query.
diff --git a/features/featureflag_string.go b/features/featureflag_string.go
diff --git a/features/features.go b/features/features.go
@@ -52,6 +52,10 @@ const (
 	// ServeRenewalInfo exposes the renewalInfo endpoint in the directory and for
 	// GET requests. WARNING: This feature is a draft and highly unstable.
 	ServeRenewalInfo
+	// GetAuthzReadOnly causes the SA to use its read-only database connection
+	// (which is generally pointed at a replica rather than the primary db) when
+	// querying the authz2 table.
+	GetAuthzReadOnly
 )
 
 // List of features and their default value, protected by fMu
@@ -74,6 +78,7 @@ var features = map[FeatureFlag]bool{
 	ECDSAForAll:              false,
 	StreamlineOrderAndAuthzs: false,
 	ServeRenewalInfo:         false,
+	GetAuthzReadOnly:         false,
 }
 
 var fMu = new(sync.RWMutex)
diff --git a/sa/sa.go b/sa/sa.go
@@ -1597,7 +1597,13 @@ func (ssa *SQLStorageAuthority) GetAuthorizations2(ctx context.Context, req *sap
 		authzFields,
 		strings.Join(qmarks, ","),
 	)
-	_, err := ssa.dbMap.Select(
+	var dbMap *db.WrappedMap
+	if features.Enabled(features.GetAuthzReadOnly) {
+		dbMap = ssa.dbReadOnlyMap
+	} else {
+		dbMap = ssa.dbMap
+	}
+	_, err := dbMap.Select(
 		&authzModels,
 		query,
 		params...,
diff --git a/test/config-next/sa.json b/test/config-next/sa.json
@@ -31,7 +31,8 @@
     },
     "features": {
       "FasterNewOrdersRateLimit": true,
-      "StoreRevokerInfo": true
+      "StoreRevokerInfo": true,
+      "GetAuthzReadOnly": true
     }
   },
 

Original file line number	Diff line number	Diff line change
`@@ -31,7 +31,8 @@`
`31`	`31`	`},`
`32`	`32`	`"features": {`
`33`	`33`	`"FasterNewOrdersRateLimit": true,`
`34`		`- "StoreRevokerInfo": true`
	`34`	`+ "StoreRevokerInfo": true,`
	`35`	`+ "GetAuthzReadOnly": true`
`35`	`36`	`}`
`36`	`37`	`},`
`37`	`38`