Combined Database Backend: Static Accounts (#6834)

* Add priority queue to sdk

* fix issue of storing pointers and now copy

* update to use copy structure

* Remove file, put Item struct def. into other file

* add link

* clean up docs

* refactor internal data structure to hide heap method implementations. Other cleanup after feedback

* rename PushItem and PopItem to just Push/Pop, after encapsulating the heap methods

* updates after feedback

* refactoring/renaming

* guard against pushing a nil item

* minor updates after feedback

* Add SetCredentials, GenerateCredentials gRPC methods to combined database backend gPRC

* Initial Combined database backend implementation of static accounts and automatic rotation

* vendor updates

* initial implementation of static accounts with Combined database backend, starting with PostgreSQL implementation

* add lock and setup of rotation queue

* vendor the queue

* rebase on new method signature of queue

* remove mongo tests for now

* update default role sql

* gofmt after rebase

* cleanup after rebasing to remove checks for ErrNotFound error

* rebase cdcr-priority-queue

* vendor dependencies with 'go mod vendor'

* website database docs for Static Role support

* document the rotate-role API endpoint

* postgres specific static role docs

* use constants for paths

* updates from review

* remove dead code

* combine and clarify error message for older plugins

* Update builtin/logical/database/backend.go

Co-Authored-By: Jim Kalafut <jim@kalafut.net>

* cleanups from feedback

* code and comment cleanups

* move db.RLock higher to protect db.GenerateCredentials call

* Return output with WALID if we failed to delete the WAL

* Update builtin/logical/database/path_creds_create.go

Co-Authored-By: Jim Kalafut <jim@kalafut.net>

* updates after running 'make fmt'

* update after running 'make proto'

* Update builtin/logical/database/path_roles.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/path_roles.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* update comment and remove and rearrange some dead code

* Update website/source/api/secret/databases/index.html.md

Co-Authored-By: Jim Kalafut <jim@kalafut.net>

* cleanups after review

* Update sdk/database/dbplugin/grpc_transport.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* code cleanup after feedback

* remove PasswordLastSet; it's not used

* document GenerateCredentials and SetCredentials

* Update builtin/logical/database/path_rotate_credentials.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* wrap pop and popbykey in backend methods to protect against nil cred rotation queue

* use strings.HasPrefix instead of direct equality check for path

* Forgot to commit this

* updates after feedback

* re-purpose an outdated test to now check that static and dynamic roles cannot share a name

* check for unique name across dynamic and static roles

* refactor loadStaticWALs to return a map of name/setCredentialsWAL struct to consolidate where we're calling set credentials

* remove commented out code

* refactor to have loadstaticwals filter out wals for roles that no longer exist

* return error if nil input given

* add nil check for input into setStaticAccount

* Update builtin/logical/database/path_roles.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* add constant for queue tick time in seconds, used for comparrison in updates

* Update builtin/logical/database/path_roles.go

Co-Authored-By: Jim Kalafut <jim@kalafut.net>

* code cleanup after review

* remove misplaced code comment

* remove commented out code

* create a queue in the Factory method, even if it's never used

* update path_roles to use a common set of fields, with specific overrides for dynamic/static roles by type

* document new method

* move rotation things into a specific file

* rename test file and consolidate some static account tests

* Update builtin/logical/database/path_roles.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/rotation.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/rotation.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/rotation.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/rotation.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* Update builtin/logical/database/rotation.go

Co-Authored-By: Brian Kassouf <briankassouf@users.noreply.github.com>

* update code comments, method names, and move more methods into rotation.go

* update comments to be capitalized

* remove the item from the queue before we try to destroy it

* findStaticWAL returns an error

* use lowercase keys when encoding WAL entries

* small cleanups

* remove vestigial static account check

* remove redundant DeleteWAL call in populate queue

* if we error on loading role, push back to queue with 10 second backoff

* poll in initqueue to make sure the backend is setup and can write/delete data

* add revoke_user_on_delete flag to allow users to opt-in to revoking the static database user on delete of the Vault role. Default false

* add code comments on read-only loop

* code comment updates

* re-push if error returned from find static wal

* add locksutil and acquire locks when pop'ing from the queue

* grab exclusive locks for updating static roles

* Add SetCredentials and GenerateCredentials stubs to mockPlugin

* add a switch in initQueue to listen for cancelation

* remove guard on zero time, it should have no affect

* create a new context in Factory to pass on and use for closing the backend queue

* restore master copy of vendor dir

sdk/queue/priority_queue.go

@@ -113,7 +113,7 @@ func (pq *PriorityQueue) Push(i *Item) error {
 	if _, ok := pq.dataMap[i.Key]; ok {
 		return ErrDuplicateItem
 	}
-	// copy the item value(s) so that modifications to the source item does not
+	// Copy the item value(s) so that modifications to the source item does not
 	// affect the item on the queue
 	clone, err := copystructure.Copy(i)
 	if err != nil {
@@ -126,8 +126,8 @@ func (pq *PriorityQueue) Push(i *Item) error {
 }
 
 // PopByKey searches the queue for an item with the given key and removes it
-// from the queue if found. Returns ErrItemNotFound(key) if not found. This
-// method must fix the queue after removal.
+// from the queue if found. Returns nil if not found. This method must fix the
+// queue after removing any key.
 func (pq *PriorityQueue) PopByKey(key string) (*Item, error) {
 	pq.lock.Lock()
 	defer pq.lock.Unlock()
@@ -137,7 +137,7 @@ func (pq *PriorityQueue) PopByKey(key string) (*Item, error) {
 		return nil, nil
 	}
 
-	// remove the item the heap and delete it from the dataMap
+	// Remove the item the heap and delete it from the dataMap
 	itemRaw := heap.Remove(&pq.data, item.index)
 	delete(pq.dataMap, key)