Add compile tests to verify physical stores satisfy the correct interfaces (#3820)

physical/azure/azure.go

@@ -32,6 +32,9 @@ type AzureBackend struct {
 	permitPool *physical.PermitPool
 }
 
+// Verify AzureBackend satisfies the correct interfaces
+var _ physical.Backend = (*AzureBackend)(nil)
+
 // NewAzureBackend constructs an Azure backend using a pre-existing
 // bucket. Credentials can be provided to the backend, sourced
 // from the environment, AWS credential files or by IAM role.

physical/cache.go

@@ -33,7 +33,11 @@ type TransactionalCache struct {
 	Transactional
 }
 
-var _ Purgable = &Cache{}
+// Verify Cache satisfies the correct interfaces
+var _ Purgable = (*Cache)(nil)
+var _ Backend = (*Cache)(nil)
+var _ Transactional = (*TransactionalCache)(nil)
+var _ Purgable = (*TransactionalCache)(nil)
 
 // NewCache returns a physical cache of the given size.
 // If no size is provided, the default size is used.

physical/cassandra/cassandra.go

@@ -26,6 +26,9 @@ type CassandraBackend struct {
 	logger log.Logger
 }
 
+// Verify CassandraBackend satisfies the correct interfaces
+var _ physical.Backend = (*CassandraBackend)(nil)
+
 // NewCassandraBackend constructs a Cassandra backend using a pre-existing
 // keyspace and table.
 func NewCassandraBackend(conf map[string]string, logger log.Logger) (physical.Backend, error) {

physical/cockroachdb/cockroachdb.go

@@ -20,7 +20,9 @@ import (
 	_ "github.com/lib/pq"
 )
 
-var _ physical.Transactional = &CockroachDBBackend{}
+// Verify CockroachDBBackend satisfies the correct interfaces
+var _ physical.Backend = (*CockroachDBBackend)(nil)
+var _ physical.Transactional = (*CockroachDBBackend)(nil)
 
 // CockroachDBBackend Backend is a physical backend that stores data
 // within a CockroachDB database.

physical/consul/consul.go

@@ -67,11 +67,11 @@ const (
 
 type notifyEvent struct{}
 
-// Verify interfaces are satisfied
+// Verify ConsulBackend satisfies the correct interfaces
-var _ physical.Backend = &ConsulBackend{}
+var _ physical.Backend = (*ConsulBackend)(nil)
-var _ physical.HABackend = &ConsulBackend{}
+var _ physical.HABackend = (*ConsulBackend)(nil)
-var _ physical.Lock = &ConsulLock{}
+var _ physical.Lock = (*ConsulLock)(nil)
-var _ physical.Transactional = &ConsulBackend{}
+var _ physical.Transactional = (*ConsulBackend)(nil)
 
 // ConsulBackend is a physical backend that stores data at specific
 // prefix within Consul. It is used for most production situations as

physical/couchdb/couchdb.go

@@ -27,6 +27,11 @@ type CouchDBBackend struct {
 	permitPool *physical.PermitPool
 }
 
+// Verify CouchDBBackend satisfies the correct interfaces
+var _ physical.Backend = (*CouchDBBackend)(nil)
+var _ physical.PseudoTransactional = (*CouchDBBackend)(nil)
+var _ physical.PseudoTransactional = (*TransactionalCouchDBBackend)(nil)
+
 type couchDBClient struct {
 	endpoint string
 	username string
@@ -254,8 +259,6 @@ func (m *CouchDBBackend) List(ctx context.Context, prefix string) ([]string, err
 	return out, nil
 }
 
-var _ physical.PseudoTransactional = &TransactionalCouchDBBackend{}
-
 // TransactionalCouchDBBackend creates a couchdb backend that forces all operations to happen
 // in serial
 type TransactionalCouchDBBackend struct {

physical/dynamodb/dynamodb.go

@@ -69,6 +69,11 @@ const (
 	DynamoDBWatchRetryInterval = 5 * time.Second
 )
 
+// Verify DynamoDBBackend satisfies the correct interfaces
+var _ physical.Backend = (*DynamoDBBackend)(nil)
+var _ physical.HABackend = (*DynamoDBBackend)(nil)
+var _ physical.Lock = (*DynamoDBLock)(nil)
+
 // DynamoDBBackend is a physical backend that stores data in
 // a DynamoDB table. It can be run in high-availability mode
 // as DynamoDB has locking capabilities.

physical/etcd/etcd2.go

@@ -55,10 +55,10 @@ type Etcd2Backend struct {
 	haEnabled  bool
 }
 
-// Verify interfaces are satisfied
+// Verify Etcd2Backend satisfies the correct interfaces
-var _ physical.Backend = &Etcd2Backend{}
+var _ physical.Backend = (*Etcd2Backend)(nil)
-var _ physical.HABackend = &Etcd2Backend{}
+var _ physical.HABackend = (*Etcd2Backend)(nil)
-var _ physical.Lock = &Etcd2Lock{}
+var _ physical.Lock = (*Etcd2Lock)(nil)
 
 func newEtcd2Backend(conf map[string]string, logger log.Logger) (physical.Backend, error) {
 	// Get the etcd path form the configuration.

physical/etcd/etcd3.go

@@ -41,10 +41,10 @@ const (
 	etcd3RequestTimeout = 5 * time.Second
 )
 
-// Verify interfaces are satisfied
+// Verify EtcdBackend satisfies the correct interfaces
-var _ physical.Backend = &EtcdBackend{}
+var _ physical.Backend = (*EtcdBackend)(nil)
-var _ physical.HABackend = &EtcdBackend{}
+var _ physical.HABackend = (*EtcdBackend)(nil)
-var _ physical.Lock = &EtcdLock{}
+var _ physical.Lock = (*EtcdLock)(nil)
 
 // newEtcd3Backend constructs a etcd3 backend.
 func newEtcd3Backend(conf map[string]string, logger log.Logger) (physical.Backend, error) {

physical/file/file.go

@@ -17,9 +17,10 @@ import (
 	"github.com/hashicorp/vault/physical"
 )
 
-// Verify interfaces are satisfied
+// Verify FileBackend satisfies the correct interfaces
-var _ physical.Backend = &FileBackend{}
+var _ physical.Backend = (*FileBackend)(nil)
-var _ physical.Transactional = &TransactionalFileBackend{}
+var _ physical.Transactional = (*TransactionalFileBackend)(nil)
+var _ physical.PseudoTransactional = (*FileBackend)(nil)
 
 // FileBackend is a physical backend that stores data on disk
 // at a given file path. It can be used for durable single server

physical/gcs/gcs.go

@@ -20,8 +20,8 @@ import (
 	"google.golang.org/api/option"
 )
 
-// Verify interfaces are satisfied
+// Verify GCSBackend satisfies the correct interfaces
-var _ physical.Backend = &GCSBackend{}
+var _ physical.Backend = (*GCSBackend)(nil)
 
 // GCSBackend is a physical backend that stores data
 // within an Google Cloud Storage bucket.

physical/inmem/inmem.go

@@ -12,11 +12,12 @@ import (
 )
 
 // Verify interfaces are satisfied
-var _ physical.Backend = &InmemBackend{}
+var _ physical.Backend = (*InmemBackend)(nil)
-var _ physical.HABackend = &InmemHABackend{}
+var _ physical.HABackend = (*InmemHABackend)(nil)
-var _ physical.Lock = &InmemLock{}
+var _ physical.HABackend = (*TransactionalInmemHABackend)(nil)
-var _ physical.Transactional = &TransactionalInmemBackend{}
+var _ physical.Lock = (*InmemLock)(nil)
-var _ physical.Transactional = &TransactionalInmemHABackend{}
+var _ physical.Transactional = (*TransactionalInmemBackend)(nil)
+var _ physical.Transactional = (*TransactionalInmemHABackend)(nil)
 
 // InmemBackend is an in-memory only physical backend. It is useful
 // for testing and development situations where the data is not

physical/latency.go

@@ -28,6 +28,10 @@ type TransactionalLatencyInjector struct {
 	Transactional
 }
 
+// Verify LatencyInjector satisfies the correct interfaces
+var _ Backend = (*LatencyInjector)(nil)
+var _ Transactional = (*TransactionalLatencyInjector)(nil)
+
 // NewLatencyInjector returns a wrapped physical backend to simulate latency
 func NewLatencyInjector(b Backend, latency time.Duration, jitter int, logger log.Logger) *LatencyInjector {
 	if jitter < 0 || jitter > 100 {

physical/mssql/mssql.go

@@ -17,6 +17,9 @@ import (
 	log "github.com/mgutz/logxi/v1"
 )
 
+// Verify MSSQLBackend satisfies the correct interfaces
+var _ physical.Backend = (*MSSQLBackend)(nil)
+
 type MSSQLBackend struct {
 	dbTable    string
 	client     *sql.DB

physical/mysql/mysql.go

@@ -22,6 +22,9 @@ import (
 	"github.com/hashicorp/vault/physical"
 )
 
+// Verify MySQLBackend satisfies the correct interfaces
+var _ physical.Backend = (*MySQLBackend)(nil)
+
 // Unreserved tls key
 // Reserved values are "true", "false", "skip-verify"
 const mysqlTLSKey = "default"

physical/physical_view.go

@@ -16,6 +16,9 @@ type View struct {
 	prefix  string
 }
 
+// Verify View satisfies the correct interfaces
+var _ Backend = (*View)(nil)
+
 // NewView takes an underlying physical backend and returns
 // a view of it that can only operate with the given prefix.
 func NewView(backend Backend, prefix string) *View {

physical/postgresql/postgresql.go

@@ -16,6 +16,9 @@ import (
 	"github.com/lib/pq"
 )
 
+// Verify PostgreSQLBackend satisfies the correct interfaces
+var _ physical.Backend = (*PostgreSQLBackend)(nil)
+
 // PostgreSQL Backend is a physical backend that stores data
 // within a PostgreSQL database.
 type PostgreSQLBackend struct {

physical/s3/s3.go

@@ -27,6 +27,9 @@ import (
 	"github.com/hashicorp/vault/physical"
 )
 
+// Verify S3Backend satisfies the correct interfaces
+var _ physical.Backend = (*S3Backend)(nil)
+
 // S3Backend is a physical backend that stores data
 // within an S3 bucket.
 type S3Backend struct {

physical/swift/swift.go

@@ -19,6 +19,9 @@ import (
 	"github.com/ncw/swift"
 )
 
+// Verify SwiftBackend satisfies the correct interfaces
+var _ physical.Backend = (*SwiftBackend)(nil)
+
 // SwiftBackend is a physical backend that stores data
 // within an OpenStack Swift container.
 type SwiftBackend struct {

physical/zookeeper/zookeeper.go

@@ -24,6 +24,11 @@ const (
 	ZKNodeFilePrefix = "_"
 )
 
+// Verify ZooKeeperBackend satisfies the correct interfaces
+var _ physical.Backend = (*ZooKeeperBackend)(nil)
+var _ physical.HABackend = (*ZooKeeperBackend)(nil)
+var _ physical.Lock = (*ZooKeeperHALock)(nil)
+
 // ZooKeeperBackend is a physical backend that stores data at specific
 // prefix within ZooKeeper. It is used in production situations as
 // it allows Vault to run on multiple machines in a highly-available manner.