Start preparing application for taking yaml config

kuskoman · Dec 16, 2023 · e05a8c6 · e05a8c6
1 parent c9a9ac7
commit e05a8c6
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Showing 13 changed files with 433 additions and 65 deletions.
diff --git a/cmd/exporter/main.go b/cmd/exporter/main.go
@@ -6,6 +6,7 @@ import (
 	"log"
 	"log/slog"
 	"os"
+	"strconv"
 
 	"github.com/joho/godotenv"
 	"github.com/kuskoman/logstash-exporter/collectors"
@@ -34,16 +35,28 @@ func main() {
 	}
 	slog.SetDefault(logger)
 
-	port, host := config.Port, config.Host
-	logstashUrl := config.LogstashUrl
+	exporterConfig, err := config.GetConfig(config.ExporterConfigLocation)
+	if err != nil {
+		slog.Error("failed to get exporter config", "err", err)
+		os.Exit(1)
+	}
+
+	host := exporterConfig.Server.Host
+	port := strconv.Itoa(exporterConfig.Server.Port)
 
 	slog.Debug("application starting... ")
 	versionInfo := config.GetVersionInfo()
 	slog.Info(versionInfo.String())
 
-	collectorManager := collectors.NewCollectorManager(logstashUrl)
-	appServer := server.NewAppServer(host, port)
-	prometheus.MustRegister(collectorManager)
+	for _, logstashServerConfig := range exporterConfig.Logstash.Servers {
+		logstashUrl := logstashServerConfig.URL
+		slog.Info("booting collector manager for", "logstashUrl", logstashUrl)
+
+		collectorManager := collectors.NewCollectorManager(logstashUrl)
+		prometheus.MustRegister(collectorManager)
+	}
+
+	appServer := server.NewAppServer(host, port, exporterConfig)
 
 	slog.Info("starting server on", "host", host, "port", port)
 	if err := appServer.ListenAndServe(); err != nil {

diff --git a/config/exporter_config.go b/config/exporter_config.go
@@ -0,0 +1,115 @@
+package config
+
+import (
+	"log/slog"
+	"os"
+
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	defaultConfigLocation = "config.yml"
+	defaultPort           = 9198
+	defaultLogLevel       = "info"
+	defaultLogstashURL    = "http://localhost:9600"
+)
+
+var (
+	ExporterConfigLocation = getEnvWithDefault("EXPORTER_CONFIG_LOCATION", defaultConfigLocation)
+)
+
+// LogstashServer represents individual Logstash server configuration
+type LogstashServer struct {
+	URL string `yaml:"url"`
+}
+
+// LogstashConfig holds the configuration for all Logstash servers
+type LogstashConfig struct {
+	Servers []LogstashServer `yaml:"servers"`
+}
+
+// ServerConfig represents the server configuration
+type ServerConfig struct {
+	// Host is the host the exporter will listen on.
+	// Defaults to an empty string, which will listen on all interfaces
+	// Can be overridden by setting the HOST environment variable
+	// For windows, use "localhost", because an empty string will not work
+	// with the default windows firewall configuration.
+	// Alternatively you can change the firewall configuration to allow
+	// connections to the port from all interfaces.
+	Host string `yaml:"host"`
+	Port int    `yaml:"port"`
+}
+
+// LoggingConfig represents the logging configuration
+type LoggingConfig struct {
+	Level string `yaml:"level"`
+}
+
+// Config represents the overall configuration loaded from the YAML file
+type Config struct {
+	Logstash LogstashConfig `yaml:"logstash"`
+	Server   ServerConfig   `yaml:"server"`
+	Logging  LoggingConfig  `yaml:"logging"`
+}
+
+// loadConfig loads the configuration from the YAML file.
+func loadConfig(location string) (*Config, error) {
+	data, err := os.ReadFile(location)
+	if err != nil {
+		return nil, err
+	}
+
+	var config Config
+	err = yaml.Unmarshal(data, &config)
+	if err != nil {
+		return nil, err
+	}
+
+	return &config, nil
+}
+
+// mergeWithDefault merges the loaded configuration with the default configuration values.
+func mergeWithDefault(config *Config) *Config {
+	if config == nil {
+		config = &Config{}
+	}
+
+	if config.Server.Port == 0 {
+		slog.Debug("using default port", "port", defaultPort)
+		config.Server.Port = defaultPort
+	}
+
+	if config.Logging.Level == "" {
+		slog.Debug("using default log level", "level", defaultLogLevel)
+		config.Logging.Level = defaultLogLevel
+	}
+
+	if len(config.Logstash.Servers) == 0 {
+		slog.Debug("using default logstash server", "url", defaultLogstashURL)
+		config.Logstash.Servers = append(config.Logstash.Servers, LogstashServer{
+			URL: defaultLogstashURL,
+		})
+	}
+
+	return config
+}
+
+// GetConfig combines loadConfig and mergeWithDefault to get the final configuration.
+func GetConfig(location string) (*Config, error) {
+	config, err := loadConfig(location)
+	if err != nil {
+		return nil, err
+	}
+
+	mergedConfig := mergeWithDefault(config)
+	return mergedConfig, nil
+}
+
+func (cfg *Config) GetLogstashUrls() []string {
+	urls := make([]string, len(cfg.Logstash.Servers))
+	for i, server := range cfg.Logstash.Servers {
+		urls[i] = server.URL
+	}
+	return urls
+}
diff --git a/config/exporter_config_test.go b/config/exporter_config_test.go
@@ -0,0 +1,173 @@
+package config
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestLoadConfig(t *testing.T) {
+	t.Parallel()
+	t.Run("loads valid config", func(t *testing.T) {
+		t.Parallel()
+
+		location := "../fixtures/valid_config.yml"
+		config, err := loadConfig(location)
+
+		if err != nil {
+			t.Fatalf("got an error %v", err)
+		}
+		if config == nil {
+			t.Fatal("expected config to be non-nil")
+		}
+		if config.Logstash.Servers[0].URL != "http://localhost:9601" {
+			t.Errorf("expected URL to be %v, got %v", "http://localhost:9601", config.Logstash.Servers[0].URL)
+		}
+	})
+
+	t.Run("returns error for non-existent file", func(t *testing.T) {
+		t.Parallel()
+
+		location := "../fixtures/non_existent.yml"
+		config, err := loadConfig(location)
+
+		if err == nil {
+			t.Fatal("expected error, got none")
+		}
+		if config != nil {
+			t.Fatal("expected config to be nil")
+		}
+	})
+
+	t.Run("returns error for invalid config", func(t *testing.T) {
+		t.Parallel()
+
+		location := "../fixtures/invalid_config.toml"
+		config, err := loadConfig(location)
+
+		if err == nil {
+			t.Fatal("expected error, got none")
+		}
+
+		if config != nil {
+			t.Fatal("expected config to be nil")
+		}
+	})
+}
+
+func TestMergeWithDefault(t *testing.T) {
+	t.Parallel()
+
+	t.Run("merge with empty config", func(t *testing.T) {
+		t.Parallel()
+
+		config := &Config{}
+		mergedConfig := mergeWithDefault(config)
+
+		if mergedConfig.Server.Port != defaultPort {
+			t.Errorf("expected port to be %v, got %v", defaultPort, mergedConfig.Server.Port)
+		}
+		if mergedConfig.Logging.Level != defaultLogLevel {
+			t.Errorf("expected level to be %v, got %v", defaultLogLevel, mergedConfig.Logging.Level)
+		}
+		if mergedConfig.Logstash.Servers[0].URL != defaultLogstashURL {
+			t.Errorf("expected URL to be %v, got %v", defaultLogstashURL, mergedConfig.Logstash.Servers[0].URL)
+		}
+	})
+
+	t.Run("merge with nil config", func(t *testing.T) {
+		t.Parallel()
+
+		mergedConfig := mergeWithDefault(nil)
+
+		if mergedConfig.Server.Port != defaultPort {
+			t.Errorf("expected port to be %v, got %v", defaultPort, mergedConfig.Server.Port)
+		}
+		if mergedConfig.Logging.Level != defaultLogLevel {
+			t.Errorf("expected level to be %v, got %v", defaultLogLevel, mergedConfig.Logging.Level)
+		}
+		if mergedConfig.Logstash.Servers[0].URL != defaultLogstashURL {
+			t.Errorf("expected URL to be %v, got %v", defaultLogstashURL, mergedConfig.Logstash.Servers[0].URL)
+		}
+	})
+
+	t.Run("merge with non-empty config", func(t *testing.T) {
+		t.Parallel()
+
+		config := &Config{
+			Server: ServerConfig{
+				Port: 1234,
+			},
+			Logging: LoggingConfig{
+				Level: "debug",
+			},
+			Logstash: LogstashConfig{
+				Servers: []LogstashServer{
+					{URL: "http://localhost:9601"},
+					{URL: "http://localhost:9602"},
+				},
+			},
+		}
+
+		mergedConfig := mergeWithDefault(config)
+
+		if mergedConfig.Server.Port != 1234 {
+			t.Errorf("expected port to be %v, got %v", 1234, mergedConfig.Server.Port)
+		}
+
+		if mergedConfig.Logging.Level != "debug" {
+			t.Errorf("expected level to be %v, got %v", "debug", mergedConfig.Logging.Level)
+		}
+
+		if mergedConfig.Logstash.Servers[0].URL != "http://localhost:9601" {
+			t.Errorf("expected URL to be %v, got %v", "http://localhost:9601", mergedConfig.Logstash.Servers[0].URL)
+		}
+
+		if mergedConfig.Logstash.Servers[1].URL != "http://localhost:9602" {
+			t.Errorf("expected URL to be %v, got %v", "http://localhost:9602", mergedConfig.Logstash.Servers[1].URL)
+		}
+	})
+}
+
+func TestGetConfig(t *testing.T) {
+	t.Run("returns valid config", func(t *testing.T) {
+
+		location := "../fixtures/valid_config.yml"
+		config, err := GetConfig(location)
+
+		if err != nil {
+			t.Fatalf("got an error %v", err)
+		}
+		if config == nil {
+			t.Fatal("expected config to be non-nil")
+		}
+	})
+
+	t.Run("returns error for invalid config", func(t *testing.T) {
+		location := "../fixtures/invalid_config.yml"
+		config, err := GetConfig(location)
+
+		if err == nil {
+			t.Fatal("expected error, got none")
+		}
+		if config != nil {
+			t.Fatal("expected config to be nil")
+		}
+	})
+}
+
+func TestGetLogstashUrls(t *testing.T) {
+	t.Run("gets Logstash URLs correctly", func(t *testing.T) {
+		config := &Config{
+			Logstash: LogstashConfig{
+				Servers: []LogstashServer{{URL: "http://localhost:9601"}},
+			},
+		}
+
+		urls := config.GetLogstashUrls()
+		expectedUrls := []string{"http://localhost:9601"}
+
+		if !reflect.DeepEqual(urls, expectedUrls) {
+			t.Errorf("expected urls to be %v, got %v", expectedUrls, urls)
+		}
+	})
+}
diff --git a/config/logstash_config.go b/config/logstash_config.go
diff --git a/config/server_config.go b/config/server_config.go
diff --git a/fixtures/invalid_config.toml b/fixtures/invalid_config.toml
@@ -0,0 +1,2 @@
+[config]
+theConfigShouldBe = 'yaml'
diff --git a/fixtures/valid_config.yml b/fixtures/valid_config.yml
@@ -0,0 +1,8 @@
+logstash:
+  servers:
+    - url: "http://localhost:9601"
+server:
+  host: "127.0.0.1"
+  port: 9200
+logging:
+  level: "debug"
diff --git a/go.mod b/go.mod
@@ -7,6 +7,7 @@ toolchain go1.21.4
 require (
 	github.com/joho/godotenv v1.5.1
 	github.com/prometheus/client_golang v1.17.0
+	gopkg.in/yaml.v2 v2.4.0
 )
 
 require (

diff --git a/go.sum b/go.sum
@@ -53,3 +53,8 @@ golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8T
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.31.0 h1:g0LDEJHgrBl9N9r17Ru3sqWhkIx2NB67okBHPwC7hs8=
 google.golang.org/protobuf v1.31.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=