Feature/infrastructure roles (#91)

* Add infrastructure roles configured globally.

Those are the roles defined in the operator itself. The operator's
configuration refers to the secret containing role names, passwords
and membership information. While they are referred to as roles, in
reality those are users.

In addition, improve the regex to filter out invalid users and
make sure user secret names are compatible with DNS name spec.

Add an example manifest for the infrastructure roles.

pkg/util/config/config.go

@@ -24,12 +24,13 @@ type Resources struct {
 }
 
 type Auth struct {
-	PamRoleName          string `split_words:"true" default:"zalandos"`
-	PamConfiguration     string `split_words:"true" default:"https://info.example.com/oauth2/tokeninfo?access_token= uid realm=/employees"`
-	TeamsAPIUrl          string `envconfig:"teams_api_url" default:"https://teams.example.com/api/"`
-	OAuthTokenSecretName string `envconfig:"oauth_token_secret_name" default:"postgresql-operator"`
-	SuperUsername        string `split_words:"true" default:"postgres"`
-	ReplicationUsername  string `split_words:"true" default:"replication"`
+	PamRoleName                   string `split_words:"true" default:"zalandos"`
+	PamConfiguration              string `split_words:"true" default:"https://info.example.com/oauth2/tokeninfo?access_token= uid realm=/employees"`
+	TeamsAPIUrl                   string `envconfig:"teams_api_url" default:"https://teams.example.com/api/"`
+	OAuthTokenSecretName          string `envconfig:"oauth_token_secret_name" default:"postgresql-operator"`
+	InfrastructureRolesSecretName string `split_words:"true"`
+	SuperUsername                 string `split_words:"true" default:"postgres"`
+	ReplicationUsername           string `split_words:"true" default:"replication"`
 }
 
 type Config struct {

pkg/util/teams/teams.go

@@ -1,10 +1,10 @@
 package teams
 
 import (
-	"fmt"
-	"strings"
 	"encoding/json"
+	"fmt"
 	"net/http"
+	"strings"
 
 	"github.com/Sirupsen/logrus"
 )