chore: simplify init functions (#863)

This commit removes the init() function which initializes the
`providerFactories` variable. This mechanism is fragile because it
assumes that no other init() function will call `onboardNewProvider()`
before the map is initialized. In practice the Go compiler evaluates the
init() functions from a single package in lexical filename order meaning
that we could have a Go file evaluated before
`authentication/authentication.go` in the future.

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

Author: simonpasquier

authentication/authentication.go

@@ -19,14 +19,13 @@ var providerFactories map[string]ProviderFactory
 // providersMtx is used to protect the providerFactories.
 var providersMtx sync.RWMutex
 
-func init() {
-	providerFactories = make(map[string]ProviderFactory)
-}
-
 // onboardNewProvider is used by the providers to register themselves.
 func onboardNewProvider(providerType string, factory ProviderFactory) {
 	providersMtx.Lock()
 	defer providersMtx.Unlock()
+	if providerFactories == nil {
+		providerFactories = map[string]ProviderFactory{}
+	}
 
 	providerFactories[providerType] = factory
 }