auth: expose backend storage layout version when relevant

.github/actions/spell-check/expect.txt

@@ -1339,6 +1339,7 @@ stickysidebar
 Stillaway
 Stirnimann
 Stolte
+storageversion
 Storbeck
 Storesund
 stou

docs/http-api/swagger/authoritative-api-swagger.yaml

@@ -1,6 +1,6 @@
 swagger: '2.0'
 info:
-  version: "0.0.17"
+  version: "0.0.18"
   title: PowerDNS Authoritative HTTP API
   license:
     name: MIT
@@ -79,6 +79,30 @@ paths:
             $ref: '#/definitions/Server'
         <<: *commonErrors
 
+  '/servers/{server_id}/backends/{backend_id}/storageversion':
+    get:
+      summary: 'Return the backend storage version used to store zone data.'
+      description: 'This returns a backend-dependent version information. Currently only supported by the LMDB backend.'
+      tags:
+        - zones
+      parameters:
+        - name: server_id
+          in: path
+          required: true
+          description: The id of the server to retrieve
+          type: string
+        - name: backend_id
+          type: string
+          in: path
+          required: true
+          description: The name of the backend to query
+      responses:
+        '200':
+          description: Storage version number
+          schema:
+              $ref: '#/definitions/StorageVersion'
+        <<: *commonErrors
+
   '/servers/{server_id}/cache/flush':
     put:
       summary: Flush a cache-entry by name
@@ -1611,3 +1635,10 @@ definitions:
         items:
           $ref: '#/definitions/Network'
 
+  StorageVersion:
+    title: StorageVersion
+    description: 'The version number of the backend storage for a zone'
+    properties:
+      storageversion:
+        type: number
+

modules/lmdbbackend/lmdbbackend.cc

@@ -356,12 +356,8 @@ void copyIndexDBI(MDB_txn* txn, MDB_dbi sdbi, MDB_dbi tdbi)
 
 }
 
-bool LMDBBackend::upgradeToSchemav5(std::string& filename)
+bool LMDBBackend::upgradeToSchemav5(std::string& filename, uint32_t currentSchemaVersion, uint32_t shardCount)
 {
-  auto currentSchemaVersionAndShards = getSchemaVersionAndShards(filename);
-  uint32_t currentSchemaVersion = currentSchemaVersionAndShards.first;
-  uint32_t shards = currentSchemaVersionAndShards.second;
-
   if (currentSchemaVersion != 3 && currentSchemaVersion != 4) {
     throw std::runtime_error("upgrade to v5 requested but current schema is not v3 or v4, stopping");
   }
@@ -397,7 +393,7 @@ bool LMDBBackend::upgradeToSchemav5(std::string& filename)
 #endif
 
   std::cerr << "migrating shards" << std::endl;
-  for (uint32_t i = 0; i < shards; i++) {
+  for (uint32_t i = 0; i < shardCount; i++) {
     string shardfile = filename + "-" + std::to_string(i);
     if (access(shardfile.c_str(), F_OK) < 0) {
       if (errno == ENOENT) {
@@ -659,7 +655,7 @@ bool LMDBBackend::upgradeToSchemav5(std::string& filename)
   return true;
 }
 
-bool LMDBBackend::upgradeToSchemav6(std::string& /* filename */)
+bool LMDBBackend::upgradeToSchemav6(std::string& /* filename */, uint32_t /* currentSchemaVersion */, uint32_t /* shardCount */)
 {
   // a v6 reader can read v5 databases just fine
   // so this function currently does nothing
@@ -766,16 +762,19 @@ LMDBBackend::LMDBBackend(const std::string& suffix)
     LMDBLS::s_flag_deleted = mustDo("flag-deleted");
   }
 
+  // The current state of this code only supports one schema version and
+  // requires users to update their schema if outdated.
+  d_currentschema = SCHEMAVERSION;
+
   bool opened = false;
 
   if (s_first) {
     auto lock = std::scoped_lock(s_lmdbStartupLock);
     if (s_first) {
       auto filename = getArg("filename");
 
-      auto currentSchemaVersionAndShards = getSchemaVersionAndShards(filename);
-      uint32_t currentSchemaVersion = currentSchemaVersionAndShards.first;
-      // std::cerr<<"current schema version: "<<currentSchemaVersion<<", shards="<<currentSchemaVersionAndShards.second<<std::endl;
+      auto [currentSchemaVersion, shardCount] = getSchemaVersionAndShards(filename);
+      // std::cerr<<"current schema version: "<<currentSchemaVersion<<", shards="<<shardCount<<std::endl;
 
       if (getArgAsNum("schema-version") != SCHEMAVERSION) {
         throw std::runtime_error("This version of the lmdbbackend only supports schema version 6. Configuration demands a lower version. Not starting up.");
@@ -791,14 +790,14 @@ LMDBBackend::LMDBBackend(const std::string& suffix)
       }
 
       if (currentSchemaVersion == 3 || currentSchemaVersion == 4) {
-        if (!upgradeToSchemav5(filename)) {
+        if (!upgradeToSchemav5(filename, currentSchemaVersion, shardCount)) {
           throw std::runtime_error("Failed to perform LMDB schema version upgrade from v4 to v5");
         }
         currentSchemaVersion = 5;
       }
 
       if (currentSchemaVersion == 5) {
-        if (!upgradeToSchemav6(filename)) {
+        if (!upgradeToSchemav6(filename, currentSchemaVersion, shardCount)) {
           throw std::runtime_error("Failed to perform LMDB schema version upgrade from v5 to v6");
         }
         currentSchemaVersion = 6;
@@ -3485,6 +3484,11 @@ void LMDBBackend::flush()
   }
 }
 
+int LMDBBackend::getStorageLayoutVersion()
+{
+  return static_cast<int>(d_currentschema);
+}
+
 class LMDBFactory : public BackendFactory
 {
 public:

modules/lmdbbackend/lmdbbackend.hh

@@ -168,6 +168,8 @@ public:
 
   void flush() override;
 
+  int getStorageLayoutVersion() override;
+
   // other
   string directBackendCmd(const string& query) override;
 
@@ -177,8 +179,8 @@ public:
 
   // functions to use without constructing a backend object
   static std::pair<uint32_t, uint32_t> getSchemaVersionAndShards(std::string& filename);
-  static bool upgradeToSchemav5(std::string& filename);
-  static bool upgradeToSchemav6(std::string& filename);
+  static bool upgradeToSchemav5(std::string& filename, uint32_t currentSchemaVersion, uint32_t shardCount);
+  static bool upgradeToSchemav6(std::string& filename, uint32_t currentSchemaVersion, uint32_t shardCount);
 
 private:
   struct compoundOrdername
@@ -423,6 +425,7 @@ private:
   bool d_handle_dups;
   bool d_views;
   bool d_write_notification_update;
+  uint32_t d_currentschema;
   DTime d_dtime; // used only for logging
   uint64_t d_mapsize_main;
   uint64_t d_mapsize_shards;

pdns/dnsbackend.hh

@@ -535,6 +535,10 @@ public:
   {
   }
 
+  // Return the level/version of the storage layout used by this backend
+  // (values being obviously backend-specific).
+  virtual int getStorageLayoutVersion() { return -1; };
+
 protected:
   bool mustDo(const string& key);
   const string& getArg(const string& key);

pdns/pdnsutil.cc

@@ -3629,11 +3629,27 @@ static int addOrSetMeta(const ZoneName& zone, const string& kind, const vector<s
   return 0;
 }
 
+static std::unique_ptr<DNSBackend> getBackendByName(const std::string& name)
+{
+  for (auto& backend : BackendMakers().all()) {
+    if (backend->getPrefix() == name) {
+      return std::move(backend);
+    }
+  }
+
+  return nullptr;
+}
+
 // Command handlers
 
 static int lmdbGetBackendVersion([[maybe_unused]] vector<string>& cmds, [[maybe_unused]] const std::string_view synopsis)
 {
-  cout << "6" << endl; // FIXME this should reuse the constant from lmdbbackend but that is currently a #define in a .cc
+  if (auto lmdbBackend = getBackendByName("lmdb"); lmdbBackend) {
+    cout << std::to_string(lmdbBackend->getStorageLayoutVersion()) << endl;
+  }
+  else {
+    cout << "LMDB backend not configured." << endl;
+  }
   return 0;
 }
 
@@ -5375,17 +5391,8 @@ static int B2BMigrate(vector<string>& cmds, const std::string_view synopsis)
     return 1;
   }
 
-  unique_ptr<DNSBackend> src{nullptr};
-  unique_ptr<DNSBackend> tgt{nullptr};
-
-  for (auto& backend : BackendMakers().all()) {
-    if (backend->getPrefix() == cmds.at(0)) {
-       src = std::move(backend);
-    }
-    else if (backend->getPrefix() == cmds.at(1)) {
-       tgt = std::move(backend);
-    }
-  }
+  unique_ptr<DNSBackend> src = getBackendByName(cmds.at(0));
+  unique_ptr<DNSBackend> tgt = getBackendByName(cmds.at(1));
 
   if (src == nullptr) {
     cerr << "Unknown source backend '" << cmds.at(0) << "'" << endl;
@@ -5446,13 +5453,7 @@ static int backendCmd(vector<string>& cmds, const std::string_view synopsis)
     return usage(synopsis);
   }
 
-  std::unique_ptr<DNSBackend> matchingBackend{nullptr};
-
-  for (auto& backend : BackendMakers().all()) {
-    if (backend->getPrefix() == cmds.at(0)) {
-      matchingBackend = std::move(backend);
-    }
-  }
+  std::unique_ptr<DNSBackend> matchingBackend = getBackendByName(cmds.at(0));
 
   if (matchingBackend == nullptr) {
     cerr << "Unknown backend '" << cmds.at(0) << "'" << endl;
@@ -5480,13 +5481,7 @@ static int backendLookup(vector<string>& cmds, const std::string_view synopsis)
     return usage(synopsis);
   }
 
-  std::unique_ptr<DNSBackend> matchingBackend{nullptr};
-
-  for (auto& backend : BackendMakers().all()) {
-    if (backend->getPrefix() == cmds.at(0)) {
-      matchingBackend = std::move(backend);
-    }
-  }
+  std::unique_ptr<DNSBackend> matchingBackend = getBackendByName(cmds.at(0));
 
   if (matchingBackend == nullptr) {
     cerr << "Unknown backend '" << cmds.at(0) << "'" << endl;

pdns/ws-auth.cc

@@ -1926,6 +1926,30 @@ static void apiServerAutoprimariesPOST(HttpRequest* req, HttpResponse* resp)
   resp->status = 201;
 }
 
+static void apiServerBackendStorageVersion(HttpRequest* req, HttpResponse* resp)
+{
+  const std::string backendName = req->parameters["id"];
+  UeberBackend backend;
+  for (auto& onebackend : backend.backends) {
+    if (onebackend->getPrefix() == backendName) {
+      auto version = onebackend->getStorageLayoutVersion();
+      if (version < 0) {
+        throw ApiException("Storage layout version not available");
+      }
+
+      if (req->accept_json) {
+        resp->setJsonBody(Json::object{{"storageversion", version}});
+      }
+      else {
+        resp->headers["Content-Type"] = "text/plain; charset=us-ascii";
+        resp->body = std::to_string(version);
+      }
+      return;
+    }
+  }
+  throw ApiException("Unknown backend");
+}
+
 // create new zone
 static void apiServerZonesPOST(HttpRequest* req, HttpResponse* resp)
 {
@@ -3020,6 +3044,7 @@ void AuthWebServer::webThread()
       d_ws->registerApiHandler("/api/v1/servers/localhost/autoprimaries/<ip>/<nameserver>", &apiServerAutoprimaryDetailDELETE, "DELETE");
       d_ws->registerApiHandler("/api/v1/servers/localhost/autoprimaries", &apiServerAutoprimariesGET, "GET");
       d_ws->registerApiHandler("/api/v1/servers/localhost/autoprimaries", &apiServerAutoprimariesPOST, "POST");
+      d_ws->registerApiHandler("/api/v1/servers/localhost/backends/<id>/storageversion", apiServerBackendStorageVersion, "GET");
       d_ws->registerApiHandler("/api/v1/servers/localhost/networks", apiServerNetworksGET, "GET");
       d_ws->registerApiHandler("/api/v1/servers/localhost/networks/<ip>/<prefixlen>", apiServerNetworksGET, "GET");
       d_ws->registerApiHandler("/api/v1/servers/localhost/networks/<ip>/<prefixlen>", apiServerNetworksPUT, "PUT");

regression-tests.api/test_Backends.py

@@ -0,0 +1,20 @@
+from __future__ import print_function
+import json
+import operator
+import unittest
+import requests.exceptions
+from test_helper import ApiTestCase, is_auth, is_auth_lmdb, BACKEND
+
+@unittest.skipIf(not is_auth(), "Not applicable")
+class AuthBackends(ApiTestCase):
+
+    def test_storage_version(self):
+        # Require a json answer to GET
+        self.session.headers['Content-Type'] = 'application/json'
+        r = self.session.get(self.url("/api/v1/servers/localhost/backends/" + BACKEND + "/storageversion"))
+        if is_auth_lmdb():
+            self.assertEqual(r.status_code, 200)
+            self.assertGreater(r.json()['storageversion'], 5)
+        else:
+            self.assertEqual(r.status_code, 422)
+