config: not properly loaded error

When a wrong config file was used, it result in a panic.
Adding some check condition to validate the Unmarshaled configuration
before using it

fixes #134

config/config.go

@@ -19,6 +19,7 @@ import (
 	"os"
 	"time"
 
+	cerrors "github.com/coreos/clair/utils/errors"
 	"github.com/fernet/fernet-go"
 	"gopkg.in/yaml.v2"
 )
@@ -111,7 +112,10 @@ func Load(path string) (config *Config, err error) {
 		return
 	}
 	config = &cfgFile.Clair
-
+	if config.API == nil || config.Database == nil || config.Notifier == nil || config.Updater == nil {
+		err = cerrors.ErrConfigNotLoaded
+		return
+	}
 	// Generate a pagination key if none is provided.
 	if config.API.PaginationKey == "" {
 		var key fernet.Key

config/config_test.go

@@ -0,0 +1,41 @@
+package config
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+
+	cerrors "github.com/coreos/clair/utils/errors"
+	"github.com/stretchr/testify/assert"
+)
+
+const wrongConfig = `
+dummyKey:
+    wrong:true
+`
+
+func TestLoadWrongConfiguration(t *testing.T) {
+	tmpfile, err := ioutil.TempFile("", "clair-config")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	defer os.Remove(tmpfile.Name()) // clean up
+
+	if _, err := tmpfile.Write([]byte(wrongConfig)); err != nil {
+		log.Fatal(err)
+	}
+	if err := tmpfile.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	_, err = Load(tmpfile.Name())
+
+	assert.EqualError(t, err, cerrors.ErrConfigNotLoaded.Error())
+}
+
+func TestLoad(t *testing.T) {
+	_, err := Load("../config.example.yaml")
+	assert.NoError(t, err)
+}

utils/errors/errors.go

@@ -29,6 +29,9 @@ var (
 
 	// ErrCouldNotParse is returned when a fetcher fails to parse the update data.
 	ErrCouldNotParse = errors.New("updater/fetchers: could not parse")
+
+	//ErrConfigNotLoaded is returned when the configuration file is not loaded properly
+	ErrConfigNotLoaded = errors.New("could not load configuration properly")
 )
 
 // ErrBadRequest occurs when a method has been passed an inappropriate argument.