[DBPW 3/5] Add DBv5 plugin serving & management functions

[pcman312]

Overview

This PR is part of a larger feature adding support for password policies into the combined database engine. This feature is being split into multiple PRs to make for smaller reviews & earlier feedback.

Adds plugin serving/handling code for Database v5. This is nearly identical to the Database v4 code, but references the updated interface.

Database v4 version:

• sdk/database/dbplugin/plugin.go
• sdk/database/dbplugin/server.go
• sdk/database/dbplugin/client.go

Prerequisites

• [DBPW 2/5] Create middleware for Database v5 #9642 merged
• Change base branch to master

Related PRs

Original password policies PR
1/X - Database interface & gRPC
2/X - Middleware
4/X - Database engine

[calvn]

We don't need to wrap d.Impl with DatabaseErrorSanitizerMiddleware?

[pcman312]

Unfortunately we can't at this point in the code. The DatabaseErrorSantizerMiddleware doesn't know what secret values to redact at this point. It only knows those values within the database plugin itself. Here's an example from the existing MongoDB plugin:

vault/plugins/database/mongodb/mongodb.go

Line 33 in 049c1a7

dbType := dbplugin.NewDatabaseErrorSanitizerMiddleware(db, db.secretValues)

vault/plugins/database/mongodb/connection_producer.go

Line 160 in 049c1a7

func (c *mongoDBConnectionProducer) secretValues() map[string]interface{} {

[calvn]

I believe that in this case it's more of a passthrough/no-op in terms of sanitizing secret values, but sanitize is also performing an specific error check:

vault/sdk/database/dbplugin/databasemiddleware.go

Lines 313 to 315 in 7807d45

	if errwrap.ContainsType(err, new(url.Error)) {
	return errors.New("unable to parse connection url")
	}

.