Switch from json to hcl configs

This is backward-compatible with the JSON config format - this is a
non-breaking change.

HCL treats config blocks as repeated fields so the config has to be
unmarshalled into a struct comprised of []Server, []Auth, []SSH first.

1 files changed, 38 insertions, 8 deletions

diff --git a/server/config/config.go b/server/config/config.go
index 7598f0a..fae823b 100644
--- a/server/config/config.go
+++ b/server/config/config.go
@@ -1,16 +1,25 @@
 package config
 
 import (
+	"errors"
 	"io"
 
+	"github.com/hashicorp/go-multierror"
 	"github.com/spf13/viper"
 )
 
-// Config holds the values from the json config file.
+// Config holds the server configuration.
 type Config struct {
-	Server Server `mapstructure:"server"`
-	Auth   Auth   `mapstructure:"auth"`
-	SSH    SSH    `mapstructure:"ssh"`
+	Server `mapstructure:"server"`
+	Auth   `mapstructure:"auth"`
+	SSH    `mapstructure:"ssh"`
+}
+
+// unmarshalled holds the raw config.
+type unmarshalled struct {
+	Server []Server `mapstructure:"server"`
+	Auth   []Auth   `mapstructure:"auth"`
+	SSH    []SSH    `mapstructure:"ssh"`
 }
 
 // Server holds the configuration specific to the web server and sessions.
@@ -39,16 +48,37 @@ type SSH struct {
 	Permissions          []string `mapstructure:"permissions"`
 }
 
+func verifyConfig(u *unmarshalled) error {
+	var err error
+	if len(u.SSH) == 0 {
+		err = multierror.Append(errors.New("missing ssh config block"))
+	}
+	if len(u.Auth) == 0 {
+		err = multierror.Append(errors.New("missing auth config block"))
+	}
+	if len(u.Server) == 0 {
+		err = multierror.Append(errors.New("missing server config block"))
+	}
+	return err
+}
+
 // ReadConfig parses a JSON configuration file into a Config struct.
 func ReadConfig(r io.Reader) (*Config, error) {
-	config := &Config{}
+	u := &unmarshalled{}
 	v := viper.New()
-	v.SetConfigType("json")
+	v.SetConfigType("hcl")
 	if err := v.ReadConfig(r); err != nil {
 		return nil, err
 	}
-	if err := v.Unmarshal(config); err != nil {
+	if err := v.Unmarshal(u); err != nil {
+		return nil, err
+	}
+	if err := verifyConfig(u); err != nil {
 		return nil, err
 	}
-	return config, nil
+	return &Config{
+		Server: u.Server[0],
+		Auth:   u.Auth[0],
+		SSH:    u.SSH[0],
+	}, nil
 }