Remove default for database flag (#708)

* Change database.uri flag to default to empty

This could theoretically break deployments of the configs service that relied
on the default being set.

In practice, we anticipate very few configs deployments expecting a database
at `configs-db.weave.local`

* Only serve DB-backed stuff if DB set

In #649, we only served DB-backed endpoints for ruler if the configs API flag
was _not_ set. This turns out to be hostile to a smooth migration, as we want
to have points where we are serving _both_ sets of endpoints so we can update
the service-ui to go from pointing at one to pointing at the other.

Author: jml

cmd/lite/main.go

@@ -172,10 +172,10 @@ func main() {
 		})
 	}
 
-	// Only serve the API for setting & getting rules configs if we're not
-	// serving configs from the configs API. Allows for smoother
-	// migration. See https://github.com/weaveworks/cortex/issues/619
-	if configStoreConfig.ConfigsAPIURL.URL == nil {
+	// Only serve the API for setting & getting rules configs if we have a
+	// database. Allows for smoother migration. See
+	// https://github.com/weaveworks/cortex/issues/619
+	if configStoreConfig.DBConfig.URI != "" {
 		a, err := ruler.NewAPIFromConfig(configStoreConfig.DBConfig)
 		if err != nil {
 			level.Error(util.Logger).Log("msg", "error initializing public rules API", "err", err)

cmd/ruler/main.go

@@ -103,10 +103,10 @@ func main() {
 	}
 	defer server.Shutdown()
 
-	// Only serve the API for setting & getting rules configs if we're not
-	// serving configs from the configs API. Allows for smoother
-	// migration. See https://github.com/weaveworks/cortex/issues/619
-	if configStoreConfig.ConfigsAPIURL.URL == nil {
+	// Only serve the API for setting & getting rules configs if we have a
+	// database. Allows for smoother migration. See
+	// https://github.com/weaveworks/cortex/issues/619
+	if configStoreConfig.DBConfig.URI != "" {
 		a, err := ruler.NewAPIFromConfig(configStoreConfig.DBConfig)
 		if err != nil {
 			level.Error(util.Logger).Log("msg", "error initializing public rules API", "err", err)

pkg/configs/db/db.go

@@ -18,7 +18,7 @@ type Config struct {
 
 // RegisterFlags adds the flags required to configure this to the given FlagSet.
 func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
-	flag.StringVar(&cfg.URI, "database.uri", "postgres://[email protected]/configs?sslmode=disable", "URI where the database can be found (for dev you can use memory://)")
+	flag.StringVar(&cfg.URI, "database.uri", "", "URI where the database can be found (for dev you can use memory://)")
 	flag.StringVar(&cfg.MigrationsDir, "database.migrations", "", "Path where the database migration files can be found")
 }
 

pkg/ruler/configs.go

@@ -43,7 +43,7 @@ func NewRulesAPI(cfg ConfigStoreConfig) (RulesAPI, error) {
 	// All of this falderal is to allow for a smooth transition away from
 	// using the configs server and toward directly connecting to the database.
 	// See https://github.com/weaveworks/cortex/issues/619
-	if cfg.ConfigsAPIURL.URL != nil {
+	if cfg.DBConfig.URI != "" {
 		return configsClient{
 			URL:     cfg.ConfigsAPIURL.URL,
 			Timeout: cfg.ClientTimeout,