Fix configuration parsing of lists (#328)

* Fix configuration parsing of lists

Don't use `ucfg.Merge` because this will merge the contents
of two slices by copying them on top of each other.

Use a much simpler approach and just join the configuration
strings together before parsing them.

Fixes #327

* Handle configurations with yaml doc separators

Yaml doc separators would get in the way of merging the configuration
with the default.

* Be more explicit about empty lists in the configuration

Author: mpfz0r

cfgfile/cfgfile.go

@@ -16,9 +16,9 @@
 package cfgfile
 
 import (
+	"bufio"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"runtime"
 	"strings"
@@ -39,24 +39,12 @@ func init() {
 	validateConfiguration = flag.Bool("configtest", false, "Validate configuration file and exit.")
 }
 
-func ConfigDefaults() *SidecarConfig {
-	userConfig := SidecarConfig{}
-	defaults, err := yaml.NewConfig([]byte(CommonDefaults), ucfg.PathSep("."))
-	if err != nil {
-		log.Fatal("Could not parse default config", err)
-	}
+func ConfigDefaults() []byte {
+	defaults := []byte(CommonDefaults)
 	if runtime.GOOS == "windows" {
-		winDefaults, err := yaml.NewConfig([]byte(WindowsDefaults), ucfg.PathSep("."))
-		if err != nil {
-			log.Fatal("Could not parse default config", err)
-		}
-		defaults.Merge(winDefaults)
+		defaults = append(defaults, WindowsDefaults...)
 	}
-	err = defaults.Unpack(&userConfig)
-	if err != nil {
-		log.Fatal("Could not unpack default config", err)
-	}
-	return &userConfig
+	return defaults
 }
 
 // Read reads the configuration from a yaml file into the given interface structure.
@@ -67,10 +55,20 @@ func Read(out interface{}, path string) error {
 		path = configurationFile
 	}
 
-	filecontent, err := ioutil.ReadFile(path)
+	configfile, err := os.Open(path)
 	if err != nil {
 		return fmt.Errorf("[ConfigFile] Failed to read %s: %v. Exiting.", path, err)
 	}
+	// start with configuration defaults
+	filecontent := ConfigDefaults()
+
+	// append configuration, but strip away possible yaml doc separators
+	scanner := bufio.NewScanner(configfile)
+	for scanner.Scan() {
+		if line := scanner.Text(); line != "---" {
+			filecontent = append(filecontent, []byte(line+"\n")...)
+		}
+	}
 	filecontent = expandEnv(filecontent)
 
 	config, err := yaml.NewConfig(filecontent, ucfg.PathSep("."))

cfgfile/schema.go

@@ -41,7 +41,7 @@ node_id: "file:/etc/graylog/sidecar/node-id"
 update_interval: 10
 tls_skip_verify: false
 send_status: true
-list_log_files:
+list_log_files: []
 cache_path: "/var/cache/graylog-sidecar"
 log_path: "/var/log/graylog-sidecar"
 log_rotate_max_file_size: "10MiB"

context/context.go

@@ -40,8 +40,7 @@ type Ctx struct {
 
 func NewContext() *Ctx {
 	return &Ctx{
-		Inventory:  system.NewInventory(),
-		UserConfig: cfgfile.ConfigDefaults(),
+		Inventory: system.NewInventory(),
 	}
 }
 

sidecar-example.yml

@@ -42,7 +42,7 @@ server_api_token: ""
 #       - "/opt/app/logs"
 #
 # Default: empty list
-#list_log_files:
+#list_log_files: []
 
 # Directory where the sidecar stores internal data.
 #cache_path: "/var/cache/graylog-sidecar"
@@ -67,7 +67,7 @@ server_api_token: ""
 #       - "/opt/collectors/*"
 #
 # Example disable whitelisting:
-#     collector_binaries_whitelist:
+#     collector_binaries_whitelist: []
 #
 # Default:
 # collector_binaries_whitelist:

sidecar-windows-example.yml

@@ -47,7 +47,7 @@ send_status: <SENDSTATUS>
 #       - "/opt/app/logs"
 #
 # Default: empty list
-#list_log_files:
+#list_log_files: []
 
 # Directory where the sidecar stores internal data.
 #cache_path: "C:\\Program Files\\Graylog\\sidecar\\cache"
@@ -72,7 +72,7 @@ send_status: <SENDSTATUS>
 #       - "C:\\Program Files\\Filebeat\\filebeat.exe"
 #
 # Example disable whitelisting:
-#     collector_binaries_whitelist:
+#     collector_binaries_whitelist: []
 #
 # Default:
 # collector_binaries_whitelist: