Support loading configuration from both YAML files and env vars

internal/command/command.go

@@ -38,7 +38,10 @@ func New() *Command {
 	}
 
 	var cfg icingadbconfig.Config
-	if err := config.FromYAMLFile(flags.Config, &cfg); err != nil {
+	if err := config.Load(&cfg, config.LoadOptions{
+		Flags:      flags,
+		EnvOptions: config.EnvOptions{Prefix: "ICINGADB_"},
+	}); err != nil {
 		if errors.Is(err, config.ErrInvalidArgument) {
 			panic(err)
 		}

internal/config/config.go

@@ -10,12 +10,15 @@ import (
 	"time"
 )
 
+// DefaultConfigPath specifies the default location of Icinga DB's config.yml for package installations.
+const DefaultConfigPath = "/etc/icingadb/config.yml"
+
 // Config defines Icinga DB config.
 type Config struct {
-	Database  database.Config `yaml:"database"`
-	Redis     redis.Config    `yaml:"redis"`
-	Logging   logging.Config  `yaml:"logging"`
-	Retention RetentionConfig `yaml:"retention"`
+	Database  database.Config `yaml:"database" envPrefix:"DATABASE_"`
+	Redis     redis.Config    `yaml:"redis" envPrefix:"REDIS_"`
+	Logging   logging.Config  `yaml:"logging" envPrefix:"LOGGING_"`
+	Retention RetentionConfig `yaml:"retention" envPrefix:"RETENTION_"`
 }
 
 func (c *Config) SetDefaults() {
@@ -46,20 +49,43 @@ func (c *Config) Validate() error {
 }
 
 // Flags defines CLI flags.
+//
+// Flags implements the [github.com/icinga/icinga-go-library/config.Flags] interface.
 type Flags struct {
 	// Version decides whether to just print the version and exit.
 	Version bool `long:"version" description:"print version and exit"`
-	// Config is the path to the config file
-	Config string `short:"c" long:"config" description:"path to config file" required:"true" default:"/etc/icingadb/config.yml"`
+
+	// Config is the path to the config file. If not provided, it defaults to DefaultConfigPath.
+	Config string `short:"c" long:"config" description:"path to config file (default: /etc/icingadb/config.yml)"`
+	// default must be kept in sync with DefaultConfigPath.
+}
+
+// GetConfigPath retrieves the path to the configuration file.
+// It returns the path specified via the command line, or DefaultConfigPath if none is provided.
+//
+// GetConfigPath implements parts of the [github.com/icinga/icinga-go-library/config.Flags] interface.
+func (f Flags) GetConfigPath() string {
+	if f.Config == "" {
+		return DefaultConfigPath
+	}
+
+	return f.Config
+}
+
+// IsExplicitConfigPath indicates whether the configuration file path was explicitly set.
+//
+// IsExplicitConfigPath implements parts of the [github.com/icinga/icinga-go-library/config.Flags] interface.
+func (f Flags) IsExplicitConfigPath() bool {
+	return f.Config != ""
 }
 
 // RetentionConfig defines configuration for history retention.
 type RetentionConfig struct {
-	HistoryDays uint16                   `yaml:"history-days"`
-	SlaDays     uint16                   `yaml:"sla-days"`
-	Interval    time.Duration            `yaml:"interval" default:"1h"`
-	Count       uint64                   `yaml:"count" default:"5000"`
-	Options     history.RetentionOptions `yaml:"options"`
+	HistoryDays uint16                   `yaml:"history-days" env:"HISTORY_DAYS"`
+	SlaDays     uint16                   `yaml:"sla-days" env:"SLA_DAYS"`
+	Interval    time.Duration            `yaml:"interval" env:"INTERVAL" default:"1h"`
+	Count       uint64                   `yaml:"count" env:"COUNT" default:"5000"`
+	Options     history.RetentionOptions `yaml:"options" env:"OPTIONS"`
 }
 
 // Validate checks constraints in the supplied retention configuration and

internal/config/config_test.go

@@ -3,14 +3,36 @@ package config
 import (
 	"github.com/creasty/defaults"
 	"github.com/icinga/icinga-go-library/config"
+	"github.com/icinga/icinga-go-library/database"
 	"github.com/icinga/icinga-go-library/logging"
+	"github.com/icinga/icinga-go-library/redis"
+	"github.com/icinga/icinga-go-library/testutils"
+	"github.com/icinga/icingadb/pkg/icingadb/history"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap/zapcore"
 	"os"
 	"testing"
 )
 
-func TestFromYAMLFile(t *testing.T) {
-	const miniConf = `
+// testFlags is a struct that implements the Flags interface.
+// It holds information about the configuration file path and whether it was explicitly set.
+type testFlags struct {
+	configPath         string // The path to the configuration file.
+	explicitConfigPath bool   // Indicates if the config path was explicitly set.
+}
+
+// GetConfigPath returns the path to the configuration file.
+func (f testFlags) GetConfigPath() string {
+	return f.configPath
+}
+
+// IsExplicitConfigPath indicates whether the configuration file path was explicitly set.
+func (f testFlags) IsExplicitConfigPath() bool {
+	return f.explicitConfigPath
+}
+
+func TestConfig(t *testing.T) {
+	const yamlConfig = `
 database:
   host: 192.0.2.1
   database: icingadb
@@ -20,52 +42,180 @@ database:
 redis:
   host: 2001:db8::1
 `
-
-	subtests := []struct {
-		name   string
-		input  string
-		output *Config
-	}{
+	loadTests := []testutils.TestCase[config.Validator, testutils.ConfigTestData]{
 		{
-			name:  "mini",
-			input: miniConf,
-			output: func() *Config {
-				c := &Config{}
-				_ = defaults.Set(c)
-
-				c.Database.Host = "192.0.2.1"
-				c.Database.Database = "icingadb"
-				c.Database.User = "icingadb"
-				c.Database.Password = "icingadb"
+			Name: "Load from YAML only",
+			Data: testutils.ConfigTestData{
+				Yaml: yamlConfig + `
+logging:
+  options:
+    database: debug
+    redis: debug
 
-				c.Redis.Host = "2001:db8::1"
-				c.Logging.Output = logging.CONSOLE
-
-				return c
-			}(),
+retention:
+  options:
+    comment: 31
+    downtime: 365
+`,
+			},
+			Expected: &Config{
+				Database: database.Config{
+					Host:     "192.0.2.1",
+					Database: "icingadb",
+					User:     "icingadb",
+					Password: "icingadb",
+				},
+				Redis: redis.Config{
+					Host: "2001:db8::1",
+				},
+				Logging: logging.Config{
+					Options: logging.Options{
+						"database": zapcore.DebugLevel,
+						"redis":    zapcore.DebugLevel,
+					},
+				},
+				Retention: RetentionConfig{
+					Options: history.RetentionOptions{
+						"comment":  31,
+						"downtime": 365,
+					},
+				},
+			},
 		},
 		{
-			name:   "mini-with-unknown",
-			input:  miniConf + "\nunknown: 42",
-			output: nil,
+			Name: "Load from Env only",
+			Data: testutils.ConfigTestData{
+				Env: map[string]string{
+					"ICINGADB_DATABASE_HOST":     "192.0.2.1",
+					"ICINGADB_DATABASE_DATABASE": "icingadb",
+					"ICINGADB_DATABASE_USER":     "icingadb",
+					"ICINGADB_DATABASE_PASSWORD": "icingadb",
+					"ICINGADB_REDIS_HOST":        "2001:db8::1",
+					"ICINGADB_LOGGING_OPTIONS":   "database:debug,redis:debug",
+					"ICINGADB_RETENTION_OPTIONS": "comment:31,downtime:365",
+				},
+			},
+			Expected: &Config{
+				Database: database.Config{
+					Host:     "192.0.2.1",
+					Database: "icingadb",
+					User:     "icingadb",
+					Password: "icingadb",
+				},
+				Redis: redis.Config{
+					Host: "2001:db8::1",
+				},
+				Logging: logging.Config{
+					Options: logging.Options{
+						"database": zapcore.DebugLevel,
+						"redis":    zapcore.DebugLevel,
+					},
+				},
+				Retention: RetentionConfig{
+					Options: history.RetentionOptions{
+						"comment":  31,
+						"downtime": 365,
+					},
+				},
+			},
+		},
+		{
+			Name: "YAML and Env; Env overrides",
+			Data: testutils.ConfigTestData{
+				Yaml: yamlConfig,
+				Env: map[string]string{
+					"ICINGADB_DATABASE_HOST": "192.168.0.1",
+					"ICINGADB_REDIS_HOST":    "localhost",
+				},
+			},
+			Expected: &Config{
+				Database: database.Config{
+					Host:     "192.168.0.1",
+					Database: "icingadb",
+					User:     "icingadb",
+					Password: "icingadb",
+				},
+				Redis: redis.Config{
+					Host: "localhost",
+				},
+			},
+		},
+		{
+			Name: "YAML and Env; Env supplements",
+			Data: testutils.ConfigTestData{
+				Yaml: yamlConfig,
+				Env: map[string]string{
+					"ICINGADB_REDIS_USERNAME": "icingadb",
+					"ICINGADB_REDIS_PASSWORD": "icingadb",
+				}},
+			Expected: &Config{
+				Database: database.Config{
+					Host:     "192.0.2.1",
+					Database: "icingadb",
+					User:     "icingadb",
+					Password: "icingadb",
+				},
+				Redis: redis.Config{
+					Host:     "2001:db8::1",
+					Username: "icingadb",
+					Password: "icingadb",
+				},
+			},
+		},
+		{
+			Name: "YAML and Env; Env overrides defaults",
+			Data: testutils.ConfigTestData{
+				Yaml: yamlConfig,
+				Env: map[string]string{
+					"ICINGADB_DATABASE_PORT": "3307",
+				}},
+			Expected: &Config{
+				Database: database.Config{
+					Host:     "192.0.2.1",
+					Port:     3307,
+					Database: "icingadb",
+					User:     "icingadb",
+					Password: "icingadb",
+				},
+				Redis: redis.Config{
+					Host: "2001:db8::1",
+				},
+			},
+		},
+		{
+			Name: "Unknown YAML field",
+			Data: testutils.ConfigTestData{
+				Yaml: `unknown: unknown`,
+			},
+			Error: testutils.ErrorContains(`unknown field "unknown"`),
 		},
 	}
 
-	for _, st := range subtests {
-		t.Run(st.name, func(t *testing.T) {
-			tempFile, err := os.CreateTemp("", "")
-			require.NoError(t, err)
-			defer func() { _ = os.Remove(tempFile.Name()) }()
+	for _, tc := range loadTests {
+		t.Run(tc.Name, tc.F(func(data testutils.ConfigTestData) (config.Validator, error) {
+			if tc.Error == nil {
+				// Set defaults for the expected configuration if no error is expected.
+				require.NoError(t, defaults.Set(tc.Expected), "setting defaults")
+			}
 
-			require.NoError(t, os.WriteFile(tempFile.Name(), []byte(st.input), 0o600))
+			actual := new(Config)
 
-			var actual Config
-			if err := config.FromYAMLFile(tempFile.Name(), &actual); st.output == nil {
-				require.Error(t, err)
+			var err error
+			if data.Yaml != "" {
+				testutils.WithYAMLFile(t, data.Yaml, func(file *os.File) {
+					err = config.Load(actual, config.LoadOptions{
+						Flags:      testFlags{configPath: file.Name(), explicitConfigPath: true},
+						EnvOptions: config.EnvOptions{Prefix: "ICINGADB_", Environment: data.Env},
+					})
+				})
 			} else {
-				require.NoError(t, err)
-				require.Equal(t, *st.output, actual)
+				err = config.Load(actual, config.LoadOptions{
+					Flags:      testFlags{},
+					EnvOptions: config.EnvOptions{Prefix: "ICINGADB_", Environment: data.Env},
+				})
 			}
-		})
+
+			return actual, err
+		}))
 	}
 }