Inverting deps on SQL, Log and MQ plugins to make them optional dependencies of extended servers, Removing some dead code that brought in unused dependencies Filtering out some non-linux transitive deps. (#1057)

* initial Db helper split - make SQL and datastore packages optional

* abstracting log store

* break out DB, MQ and log drivers as extensions

* cleanup

* fewer deps

* fixing docker test

* hmm dbness

* updating db startup

* Consolidate all your extensions into one convenient package

* cleanup

* clean up dep constraints

api/datastore/sql/dbhelper/dbhelper.go

@@ -0,0 +1,43 @@
+// dbhelpers wrap SQL and specific capabilities of an SQL db
+package dbhelper
+
+import (
+	"fmt"
+	"github.com/jmoiron/sqlx"
+	"github.com/sirupsen/logrus"
+	"net/url"
+)
+
+var sqlHelpers []Helper
+
+//Add registers a new SQL helper
+func Add(helper Helper) {
+	logrus.Infof("Registering DB helper %s", helper)
+	sqlHelpers = append(sqlHelpers, helper)
+}
+
+//Helper provides DB-specific SQL capabilities
+type Helper interface {
+	fmt.Stringer
+	//Supports indicates if this helper supports this driver name
+	Supports(driverName string) bool
+	//PreConnect calculates the connect URL for the db from a canonical URL used in Fn config
+	PreConnect(url *url.URL) (string, error)
+	//PostCreate  Apply any configuration to the DB prior to use
+	PostCreate(db *sqlx.DB) (*sqlx.DB, error)
+	//CheckTableExists checks if a table exists in the DB
+	CheckTableExists(tx *sqlx.Tx, table string) (bool, error)
+	//IsDuplicateKeyError determines if an error indicates if the prior error was caused by a duplicate key insert
+	IsDuplicateKeyError(err error) bool
+}
+
+//GetHelper returns a helper for a specific driver
+func GetHelper(driverName string) (Helper, bool) {
+	for _, helper := range sqlHelpers {
+		if helper.Supports(driverName) {
+			return helper, true
+		}
+		logrus.Printf("%s does not support %s", helper, driverName)
+	}
+	return nil, false
+}