// TestInterface performs all interfaces tests for this database driver.
func TestInterface(t *testing.T) {
t.Parallel()
// Create a new database to run tests against.
dbPath := filepath.Join(os.TempDir(), "ffldb-interfacetest")
_ = os.RemoveAll(dbPath)
db, err := database.Create(dbType, dbPath, blockDataNet)
if err != nil {
t.Errorf("Failed to create test database (%s) %v", dbType, err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Ensure the driver type is the expected value.
gotDbType := db.Type()
if gotDbType != dbType {
t.Errorf("Type: unepxected driver type - got %v, want %v",
gotDbType, dbType)
return
}
// Run all of the interface tests against the database.
runtime.GOMAXPROCS(runtime.NumCPU())
// Change the maximum file size to a small value to force multiple flat
// files with the test data set.
ffldb.TstRunWithMaxBlockFileSize(db, 2048, func() {
testInterface(t, db)
})
}
// loadBlockDB opens the block database and returns a handle to it.
func loadBlockDB() (database.DB, error) {
// The database name is based on the database type.
dbName := blockDbNamePrefix + "_" + cfg.DbType
dbPath := filepath.Join(cfg.DataDir, dbName)
log.Infof("Loading block database from '%s'", dbPath)
db, err := database.Open(cfg.DbType, dbPath, activeNetParams.Net)
if err != nil {
// Return the error if it's not because the database doesn't
// exist.
if dbErr, ok := err.(database.Error); !ok || dbErr.ErrorCode !=
database.ErrDbDoesNotExist {
return nil, err
}
// Create the db if it does not exist.
err = os.MkdirAll(cfg.DataDir, 0700)
if err != nil {
return nil, err
}
db, err = database.Create(cfg.DbType, dbPath, activeNetParams.Net)
if err != nil {
return nil, err
}
}
log.Info("Block database loaded")
return db, nil
}
// loadBlockDB loads (or creates when needed) the block database taking into
// account the selected database backend and returns a handle to it. It also
// contains additional logic such warning the user if there are multiple
// databases which consume space on the file system and ensuring the regression
// test database is clean when in regression test mode.
func loadBlockDB() (database.DB, error) {
// The memdb backend does not have a file path associated with it, so
// handle it uniquely. We also don't want to worry about the multiple
// database type warnings when running with the memory database.
if cfg.DbType == "memdb" {
btcdLog.Infof("Creating block database in memory.")
db, err := database.Create(cfg.DbType)
if err != nil {
return nil, err
}
return db, nil
}
warnMultipeDBs()
// The database name is based on the database type.
dbPath := blockDbPath(cfg.DbType)
// The regression test is special in that it needs a clean database for
// each run, so remove it now if it already exists.
removeRegressionDB(dbPath)
btcdLog.Infof("Loading block database from '%s'", dbPath)
db, err := database.Open(cfg.DbType, dbPath, activeNetParams.Net)
if err != nil {
// Return the error if it's not because the database doesn't
// exist.
if dbErr, ok := err.(database.Error); !ok || dbErr.ErrorCode !=
database.ErrDbDoesNotExist {
return nil, err
}
// Create the db if it does not exist.
err = os.MkdirAll(cfg.DataDir, 0700)
if err != nil {
return nil, err
}
db, err = database.Create(cfg.DbType, dbPath, activeNetParams.Net)
if err != nil {
return nil, err
}
}
btcdLog.Info("Block database loaded")
return db, nil
}
// This example demonstrates how to create a new chain instance and use
// ProcessBlock to attempt to attempt add a block to the chain. As the package
// overview documentation describes, this includes all of the Bitcoin consensus
// rules. This example intentionally attempts to insert a duplicate genesis
// block to illustrate how an invalid block is handled.
func ExampleBlockChain_ProcessBlock() {
// Create a new database to store the accepted blocks into. Typically
// this would be opening an existing database and would not be deleting
// and creating a new database like this, but it is done here so this is
// a complete working example and does not leave temporary files laying
// around.
dbPath := filepath.Join(os.TempDir(), "exampleprocessblock")
_ = os.RemoveAll(dbPath)
db, err := database.Create("ffldb", dbPath, chaincfg.MainNetParams.Net)
if err != nil {
fmt.Printf("Failed to create database: %v\n", err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Create a new BlockChain instance using the underlying database for
// the main bitcoin network. This example does not demonstrate some
// of the other available configuration options such as specifying a
// notification callback and signature cache.
chain, err := blockchain.New(&blockchain.Config{
DB: db,
ChainParams: &chaincfg.MainNetParams,
})
if err != nil {
fmt.Printf("Failed to create chain instance: %v\n", err)
return
}
// Create a new median time source that is required by the upcoming
// call to ProcessBlock. Ordinarily this would also add time values
// obtained from other peers on the network so the local time is
// adjusted to be in agreement with other peers.
timeSource := blockchain.NewMedianTime()
// Process a block. For this example, we are going to intentionally
// cause an error by trying to process the genesis block which already
// exists.
genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
isOrphan, err := chain.ProcessBlock(genesisBlock, timeSource, blockchain.BFNone)
if err != nil {
fmt.Printf("Failed to process block: %v\n", err)
return
}
fmt.Printf("Block accepted. Is it an orphan?: %v", isOrphan)
// Output:
// Failed to process block: already have block 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
}
// TestCreateOpenUnsupported ensures that attempting to create or open an
// unsupported database type is handled properly.
func TestCreateOpenUnsupported(t *testing.T) {
// Ensure creating a database with an unsupported type fails with the
// expected error.
testName := "create with unsupported database type"
dbType := "unsupported"
_, err := database.Create(dbType)
if !checkDbError(t, testName, err, database.ErrDbUnknownType) {
return
}
// Ensure opening a database with the an unsupported type fails with the
// expected error.
testName = "open with unsupported database type"
_, err = database.Open(dbType)
if !checkDbError(t, testName, err, database.ErrDbUnknownType) {
return
}
}
// BenchmarkBlockHeader benchmarks how long it takes to load the mainnet genesis
// block.
func BenchmarkBlock(b *testing.B) {
// Start by creating a new database and populating it with the mainnet
// genesis block.
dbPath := filepath.Join(os.TempDir(), "ffldb-benchblk")
_ = os.RemoveAll(dbPath)
db, err := database.Create("ffldb", dbPath, blockDataNet)
if err != nil {
b.Fatal(err)
}
defer os.RemoveAll(dbPath)
defer db.Close()
err = db.Update(func(tx database.Tx) error {
block := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
if err := tx.StoreBlock(block); err != nil {
return err
}
return nil
})
if err != nil {
b.Fatal(err)
}
b.ReportAllocs()
b.ResetTimer()
err = db.View(func(tx database.Tx) error {
blockHash := chaincfg.MainNetParams.GenesisHash
for i := 0; i < b.N; i++ {
_, err := tx.FetchBlock(blockHash)
if err != nil {
return err
}
}
return nil
})
if err != nil {
b.Fatal(err)
}
// Don't benchmark teardown.
b.StopTimer()
}
// TestCreateOpenFail ensures that errors which occur while opening or closing
// a database are handled properly.
func TestCreateOpenFail(t *testing.T) {
// bogusCreateDB is a function which acts as a bogus create and open
// driver function that intentionally returns a failure which can be
// detected.
dbType := "createopenfail"
openError := fmt.Errorf("failed to create or open database for "+
"database type [%v]", dbType)
bogusCreateDB := func(args ...interface{}) (database.DB, error) {
return nil, openError
}
// Create and add driver that intentionally fails when created or opened
// to ensure errors on database open and create are handled properly.
driver := database.Driver{
DbType: dbType,
Create: bogusCreateDB,
Open: bogusCreateDB,
}
database.RegisterDriver(driver)
// Ensure creating a database with the new type fails with the expected
// error.
_, err := database.Create(dbType)
if err != openError {
t.Errorf("expected error not received - got: %v, want %v", err,
openError)
return
}
// Ensure opening a database with the new type fails with the expected
// error.
_, err = database.Open(dbType)
if err != openError {
t.Errorf("expected error not received - got: %v, want %v", err,
openError)
return
}
}
// This example demonstrates creating a new database.
func ExampleCreate() {
// This example assumes the ffldb driver is imported.
//
// import (
// "github.com/btcsuite/btcd/database"
// _ "github.com/btcsuite/btcd/database/ffldb"
// )
// Create a database and schedule it to be closed and removed on exit.
// Typically you wouldn't want to remove the database right away like
// this, nor put it in the temp directory, but it's done here to ensure
// the example cleans up after itself.
dbPath := filepath.Join(os.TempDir(), "examplecreate")
db, err := database.Create("ffldb", dbPath, wire.MainNet)
if err != nil {
fmt.Println(err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Output:
}
// This example demonstrates creating a new database and using a managed
// read-write transaction to store and retrieve metadata.
func Example_basicUsage() {
// This example assumes the ffldb driver is imported.
//
// import (
// "github.com/btcsuite/btcd/database"
// _ "github.com/btcsuite/btcd/database/ffldb"
// )
// Create a database and schedule it to be closed and removed on exit.
// Typically you wouldn't want to remove the database right away like
// this, nor put it in the temp directory, but it's done here to ensure
// the example cleans up after itself.
dbPath := filepath.Join(os.TempDir(), "exampleusage")
db, err := database.Create("ffldb", dbPath, wire.MainNet)
if err != nil {
fmt.Println(err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Use the Update function of the database to perform a managed
// read-write transaction. The transaction will automatically be rolled
// back if the supplied inner function returns a non-nil error.
err = db.Update(func(tx database.Tx) error {
// Store a key/value pair directly in the metadata bucket.
// Typically a nested bucket would be used for a given feature,
// but this example is using the metadata bucket directly for
// simplicity.
key := []byte("mykey")
value := []byte("myvalue")
if err := tx.Metadata().Put(key, value); err != nil {
return err
}
// Read the key back and ensure it matches.
if !bytes.Equal(tx.Metadata().Get(key), value) {
return fmt.Errorf("unexpected value for key '%s'", key)
}
// Create a new nested bucket under the metadata bucket.
nestedBucketKey := []byte("mybucket")
nestedBucket, err := tx.Metadata().CreateBucket(nestedBucketKey)
if err != nil {
return err
}
// The key from above that was set in the metadata bucket does
// not exist in this new nested bucket.
if nestedBucket.Get(key) != nil {
return fmt.Errorf("key '%s' is not expected nil", key)
}
return nil
})
if err != nil {
fmt.Println(err)
return
}
// Output:
}
// This example demonstrates creating a new database, using a managed read-write
// transaction to store a block, and using a managed read-only transaction to
// fetch the block.
func Example_blockStorageAndRetrieval() {
// This example assumes the ffldb driver is imported.
//
// import (
// "github.com/btcsuite/btcd/database"
// _ "github.com/btcsuite/btcd/database/ffldb"
// )
// Create a database and schedule it to be closed and removed on exit.
// Typically you wouldn't want to remove the database right away like
// this, nor put it in the temp directory, but it's done here to ensure
// the example cleans up after itself.
dbPath := filepath.Join(os.TempDir(), "exampleblkstorage")
db, err := database.Create("ffldb", dbPath, wire.MainNet)
if err != nil {
fmt.Println(err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Use the Update function of the database to perform a managed
// read-write transaction and store a genesis block in the database as
// and example.
err = db.Update(func(tx database.Tx) error {
genesisBlock := chaincfg.MainNetParams.GenesisBlock
return tx.StoreBlock(btcutil.NewBlock(genesisBlock))
})
if err != nil {
fmt.Println(err)
return
}
// Use the View function of the database to perform a managed read-only
// transaction and fetch the block stored above.
var loadedBlockBytes []byte
err = db.Update(func(tx database.Tx) error {
genesisHash := chaincfg.MainNetParams.GenesisHash
blockBytes, err := tx.FetchBlock(genesisHash)
if err != nil {
return err
}
// As documented, all data fetched from the database is only
// valid during a database transaction in order to support
// zero-copy backends. Thus, make a copy of the data so it
// can be used outside of the transaction.
loadedBlockBytes = make([]byte, len(blockBytes))
copy(loadedBlockBytes, blockBytes)
return nil
})
if err != nil {
fmt.Println(err)
return
}
// Typically at this point, the block could be deserialized via the
// wire.MsgBlock.Deserialize function or used in its serialized form
// depending on need. However, for this example, just display the
// number of serialized bytes to show it was loaded as expected.
fmt.Printf("Serialized block size: %d bytes\n", len(loadedBlockBytes))
// Output:
// Serialized block size: 285 bytes
}
// TestCreateOpenFail ensures that errors related to creating and opening a
// database are handled properly.
func TestCreateOpenFail(t *testing.T) {
t.Parallel()
// Ensure that attempting to open a database that doesn't exist returns
// the expected error.
wantErrCode := database.ErrDbDoesNotExist
_, err := database.Open(dbType, "noexist", blockDataNet)
if !checkDbError(t, "Open", err, wantErrCode) {
return
}
// Ensure that attempting to open a database with the wrong number of
// parameters returns the expected error.
wantErr := fmt.Errorf("invalid arguments to %s.Open -- expected "+
"database path and block network", dbType)
_, err = database.Open(dbType, 1, 2, 3)
if err.Error() != wantErr.Error() {
t.Errorf("Open: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure that attempting to open a database with an invalid type for
// the first parameter returns the expected error.
wantErr = fmt.Errorf("first argument to %s.Open is invalid -- "+
"expected database path string", dbType)
_, err = database.Open(dbType, 1, blockDataNet)
if err.Error() != wantErr.Error() {
t.Errorf("Open: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure that attempting to open a database with an invalid type for
// the second parameter returns the expected error.
wantErr = fmt.Errorf("second argument to %s.Open is invalid -- "+
"expected block network", dbType)
_, err = database.Open(dbType, "noexist", "invalid")
if err.Error() != wantErr.Error() {
t.Errorf("Open: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure that attempting to create a database with the wrong number of
// parameters returns the expected error.
wantErr = fmt.Errorf("invalid arguments to %s.Create -- expected "+
"database path and block network", dbType)
_, err = database.Create(dbType, 1, 2, 3)
if err.Error() != wantErr.Error() {
t.Errorf("Create: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure that attempting to create a database with an invalid type for
// the first parameter returns the expected error.
wantErr = fmt.Errorf("first argument to %s.Create is invalid -- "+
"expected database path string", dbType)
_, err = database.Create(dbType, 1, blockDataNet)
if err.Error() != wantErr.Error() {
t.Errorf("Create: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure that attempting to create a database with an invalid type for
// the second parameter returns the expected error.
wantErr = fmt.Errorf("second argument to %s.Create is invalid -- "+
"expected block network", dbType)
_, err = database.Create(dbType, "noexist", "invalid")
if err.Error() != wantErr.Error() {
t.Errorf("Create: did not receive expected error - got %v, "+
"want %v", err, wantErr)
return
}
// Ensure operations against a closed database return the expected
// error.
dbPath := filepath.Join(os.TempDir(), "ffldb-createfail")
_ = os.RemoveAll(dbPath)
db, err := database.Create(dbType, dbPath, blockDataNet)
if err != nil {
t.Errorf("Create: unexpected error: %v", err)
return
}
defer os.RemoveAll(dbPath)
db.Close()
wantErrCode = database.ErrDbNotOpen
err = db.View(func(tx database.Tx) error {
return nil
})
if !checkDbError(t, "View", err, wantErrCode) {
return
}
wantErrCode = database.ErrDbNotOpen
err = db.Update(func(tx database.Tx) error {
return nil
})
if !checkDbError(t, "Update", err, wantErrCode) {
return
}
wantErrCode = database.ErrDbNotOpen
_, err = db.Begin(false)
if !checkDbError(t, "Begin(false)", err, wantErrCode) {
return
}
wantErrCode = database.ErrDbNotOpen
_, err = db.Begin(true)
if !checkDbError(t, "Begin(true)", err, wantErrCode) {
return
}
wantErrCode = database.ErrDbNotOpen
err = db.Close()
if !checkDbError(t, "Close", err, wantErrCode) {
return
}
}
// TestPersistence ensures that values stored are still valid after closing and
// reopening the database.
func TestPersistence(t *testing.T) {
t.Parallel()
// Create a new database to run tests against.
dbPath := filepath.Join(os.TempDir(), "ffldb-persistencetest")
_ = os.RemoveAll(dbPath)
db, err := database.Create(dbType, dbPath, blockDataNet)
if err != nil {
t.Errorf("Failed to create test database (%s) %v", dbType, err)
return
}
defer os.RemoveAll(dbPath)
defer db.Close()
// Create a bucket, put some values into it, and store a block so they
// can be tested for existence on re-open.
bucket1Key := []byte("bucket1")
storeValues := map[string]string{
"b1key1": "foo1",
"b1key2": "foo2",
"b1key3": "foo3",
}
genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
genesisHash := chaincfg.MainNetParams.GenesisHash
err = db.Update(func(tx database.Tx) error {
metadataBucket := tx.Metadata()
if metadataBucket == nil {
return fmt.Errorf("Metadata: unexpected nil bucket")
}
bucket1, err := metadataBucket.CreateBucket(bucket1Key)
if err != nil {
return fmt.Errorf("CreateBucket: unexpected error: %v",
err)
}
for k, v := range storeValues {
err := bucket1.Put([]byte(k), []byte(v))
if err != nil {
return fmt.Errorf("Put: unexpected error: %v",
err)
}
}
if err := tx.StoreBlock(genesisBlock); err != nil {
return fmt.Errorf("StoreBlock: unexpected error: %v",
err)
}
return nil
})
if err != nil {
t.Errorf("Update: unexpected error: %v", err)
return
}
// Close and reopen the database to ensure the values persist.
db.Close()
db, err = database.Open(dbType, dbPath, blockDataNet)
if err != nil {
t.Errorf("Failed to open test database (%s) %v", dbType, err)
return
}
defer db.Close()
// Ensure the values previously stored in the 3rd namespace still exist
// and are correct.
err = db.View(func(tx database.Tx) error {
metadataBucket := tx.Metadata()
if metadataBucket == nil {
return fmt.Errorf("Metadata: unexpected nil bucket")
}
bucket1 := metadataBucket.Bucket(bucket1Key)
if bucket1 == nil {
return fmt.Errorf("Bucket1: unexpected nil bucket")
}
for k, v := range storeValues {
gotVal := bucket1.Get([]byte(k))
if !reflect.DeepEqual(gotVal, []byte(v)) {
return fmt.Errorf("Get: key '%s' does not "+
"match expected value - got %s, want %s",
k, gotVal, v)
}
}
genesisBlockBytes, _ := genesisBlock.Bytes()
gotBytes, err := tx.FetchBlock(genesisHash)
if err != nil {
return fmt.Errorf("FetchBlock: unexpected error: %v",
err)
}
if !reflect.DeepEqual(gotBytes, genesisBlockBytes) {
return fmt.Errorf("FetchBlock: stored block mismatch")
}
return nil
})
if err != nil {
t.Errorf("View: unexpected error: %v", err)
return
}
}
// TestFailureScenarios ensures several failure scenarios such as database
// corruption, block file write failures, and rollback failures are handled
// correctly.
func TestFailureScenarios(t *testing.T) {
// Create a new database to run tests against.
dbPath := filepath.Join(os.TempDir(), "ffldb-failurescenarios")
_ = os.RemoveAll(dbPath)
idb, err := database.Create(dbType, dbPath, blockDataNet)
if err != nil {
t.Errorf("Failed to create test database (%s) %v", dbType, err)
return
}
defer os.RemoveAll(dbPath)
defer idb.Close()
// Create a test context to pass around.
tc := &testContext{
t: t,
db: idb,
files: make(map[uint32]*lockableFile),
maxFileSizes: make(map[uint32]int64),
}
// Change the maximum file size to a small value to force multiple flat
// files with the test data set and replace the file-related functions
// to make use of mock files in memory. This allows injection of
// various file-related errors.
store := idb.(*db).store
store.maxBlockFileSize = 1024 // 1KiB
store.openWriteFileFunc = func(fileNum uint32) (filer, error) {
if file, ok := tc.files[fileNum]; ok {
// "Reopen" the file.
file.Lock()
mock := file.file.(*mockFile)
mock.Lock()
mock.closed = false
mock.Unlock()
file.Unlock()
return mock, nil
}
// Limit the max size of the mock file as specified in the test
// context.
maxSize := int64(-1)
if maxFileSize, ok := tc.maxFileSizes[fileNum]; ok {
maxSize = int64(maxFileSize)
}
file := &mockFile{maxSize: int64(maxSize)}
tc.files[fileNum] = &lockableFile{file: file}
return file, nil
}
store.openFileFunc = func(fileNum uint32) (*lockableFile, error) {
// Force error when trying to open max file num.
if fileNum == ^uint32(0) {
return nil, makeDbErr(database.ErrDriverSpecific,
"test", nil)
}
if file, ok := tc.files[fileNum]; ok {
// "Reopen" the file.
file.Lock()
mock := file.file.(*mockFile)
mock.Lock()
mock.closed = false
mock.Unlock()
file.Unlock()
return file, nil
}
file := &lockableFile{file: &mockFile{}}
tc.files[fileNum] = file
return file, nil
}
store.deleteFileFunc = func(fileNum uint32) error {
if file, ok := tc.files[fileNum]; ok {
file.Lock()
file.file.Close()
file.Unlock()
delete(tc.files, fileNum)
return nil
}
str := fmt.Sprintf("file %d does not exist", fileNum)
return makeDbErr(database.ErrDriverSpecific, str, nil)
}
// Load the test blocks and save in the test context for use throughout
// the tests.
blocks, err := loadBlocks(t, blockDataFile, blockDataNet)
if err != nil {
t.Errorf("loadBlocks: Unexpected error: %v", err)
return
}
tc.blocks = blocks
// Test various failures paths when writing to the block files.
if !testWriteFailures(tc) {
return
}
// Test various file-related issues such as closed and missing files.
if !testBlockFileErrors(tc) {
return
}
// Test various corruption scenarios.
testCorruption(tc)
}
// chainSetup is used to create a new db and chain instance with the genesis
// block already inserted. In addition to the new chain instnce, it returns
// a teardown function the caller should invoke when done testing to clean up.
func chainSetup(dbName string) (*blockchain.BlockChain, func(), error) {
if !isSupportedDbType(testDbType) {
return nil, nil, fmt.Errorf("unsupported db type %v", testDbType)
}
// Handle memory database specially since it doesn't need the disk
// specific handling.
var db database.DB
var teardown func()
if testDbType == "memdb" {
ndb, err := database.Create(testDbType)
if err != nil {
return nil, nil, fmt.Errorf("error creating db: %v", err)
}
db = ndb
// Setup a teardown function for cleaning up. This function is
// returned to the caller to be invoked when it is done testing.
teardown = func() {
db.Close()
}
} else {
// Create the root directory for test databases.
if !fileExists(testDbRoot) {
if err := os.MkdirAll(testDbRoot, 0700); err != nil {
err := fmt.Errorf("unable to create test db "+
"root: %v", err)
return nil, nil, err
}
}
// Create a new database to store the accepted blocks into.
dbPath := filepath.Join(testDbRoot, dbName)
_ = os.RemoveAll(dbPath)
ndb, err := database.Create(testDbType, dbPath, blockDataNet)
if err != nil {
return nil, nil, fmt.Errorf("error creating db: %v", err)
}
db = ndb
// Setup a teardown function for cleaning up. This function is
// returned to the caller to be invoked when it is done testing.
teardown = func() {
db.Close()
os.RemoveAll(dbPath)
os.RemoveAll(testDbRoot)
}
}
// Create the main chain instance.
chain, err := blockchain.New(&blockchain.Config{
DB: db,
ChainParams: &chaincfg.MainNetParams,
})
if err != nil {
teardown()
err := fmt.Errorf("failed to create chain instance: %v", err)
return nil, nil, err
}
return chain, teardown, nil
}