startup

README

startup

Contains startup related structs, helpers, and can be used to handle the startup and shutdown of a service.

Install

go get github.com/blutspende/libs-startup

Startup

It is a fully configurable drop-in replacement for most of the boilerplate code in the main() function. It handles .env and configuration reading, database connection, initializations, and graceful shutdown.

It can be configured using the startup.Config struct, and used with the startup.Startup(cfg) method. The configuration allows for granular selection of initialized components and optional injection of custom initialization and shutdown functions.

Property	Description
Configuration	An instance of a Configuration interface (required)
ApplicationName	Required to be set to a non-empty value
BuildVersion	Recommended to be set if OTEL and/or Pyroscope is used
UsePostgres	Enables the setup and connection to a postgres database
UseExtendedPgConfig	Turns on the use of advanced connection configurations options
UseRedis	Enables the setup of a Redis client
UseOtel	Enables the use of OpenTelemetry
UsePyroscope	Enables the use of Pyroscope
UtcLogging	Sets log times to UTC as opposed to local time
StartupExtensionFunc	Custom function injected into the startup process (can be nil)
ShutdownExtensionFunc	Custom function injected into the shutdown process (can be nil)

Config

Contains a base CommonConfiguration struct that can be embedded in other configuration structs to provide common configuration values, and a ReadConfiguration function to read environment variables and do basic common processing.

It also contains a Configuration interface that should be implemented by any service specific configuration struct to be usable in ReadConfiguration and in various things from this library.

Here is an example of a service specific configuration struct:

import startup "github.com/blutspende/libs-startup"

type Configuration struct {
    startup.CommonConfiguration
	
    ServiceSpecific string `envconfig:"SERVICE_SPECIFIC" required:"true"`
}

func (c *Configuration) GetCommonConfig() *startup.CommonConfiguration {
    return &c.CommonConfiguration
}

Documentation

Index

• Constants
• Variables
• func ReadConfiguration(configuration Configuration) error
• func Startup(cfg Config) (ctx context.Context, dbConn db.DbConnection, redisClient *redis.Client)
• type CommonConfiguration
  • func (c *CommonConfiguration) GetCommonConfig() *CommonConfiguration
• type Config
• type Configuration

Constants

const ContextKeyCorrelation = "correlation_id"

Variables

var ErrApplicationNameMissing = errors.New("ApplicationName is required in the startup configuration")

var ErrFailedToLoadDotEnvFile = errors.New("failed to load .env file")

var ErrFailedToParseLogLevel = errors.New("failed to parse log level")

var ErrFailedToReadConfiguration = errors.New("failed to read configuration")

var ErrInvalidLogLevel = errors.New("invalid log level")

Functions

func ReadConfiguration

func ReadConfiguration(configuration Configuration) error

func Startup

func Startup(cfg Config) (ctx context.Context, dbConn db.DbConnection,
	redisClient *redis.Client)

Types

type CommonConfiguration

type CommonConfiguration struct {
	ApplicationName string
	BuildVersion    string

	LogLevel     string `envconfig:"LOG_LEVEL" default:"INFO"`
	ZeroLogLevel zerolog.Level

	PostgresDB struct {
		Host               string `envconfig:"DB_SERVER" required:"true"`
		Port               uint32 `envconfig:"DB_PORT" required:"true"`
		User               string `envconfig:"DB_USER" required:"true"`
		Pass               string `envconfig:"DB_PASS" required:"true"`
		Database           string `envconfig:"DB_DATABASE" required:"true"`
		SSLMode            string `envconfig:"DB_SSL_MODE" required:"true"`
		EnableQueryLogging bool   `envconfig:"DB_QUERY_LOGGING" default:"false"`
		// Extended settings
		MaxOpenConnections           int `envconfig:"DB_MAX_OPEN_CONNECTIONS" default:"8"`
		MaxIdleConnections           int `envconfig:"DB_MAX_IDLE_CONNECTIONS" default:"8"`
		ConnectionMaxLifetimeSeconds int `envconfig:"DB_CONNECTION_MAX_LIFETIME_SECONDS" default:"180"`
		ConnectionMaxIdleTimeSeconds int `envconfig:"DB_CONNECTION_MAX_IDLE_TIME_SECONDS" default:"30"`
	}

	OIDC struct {
		BaseURL      string `envconfig:"OIDC_BASE_URL" required:"false"`
		ClientID     string `envconfig:"OIDC_CLIENT_ID" required:"false"`
		ClientSecret string `envconfig:"OIDC_CLIENT_SECRET" required:"false"`
	}

	Redis struct {
		Enable                   bool   `envconfig:"REDIS_ENABLE" default:"false"`
		Address                  string `envconfig:"REDIS_ADDRESS" default:"redis:6379"`
		Password                 string `envconfig:"REDIS_PASSWORD" default:""`
		DefaultTTLMinutes        int    `envconfig:"REDIS_DEFAULT_TTL_MINUTES" default:"1440"`
		RefreshRetryAttempts     int    `envconfig:"REDIS_REFRESH_RETRY_ATTEMPTS" default:"5"`
		RefreshRetryWaitStartMs  int    `envconfig:"REDIS_REFRESH_RETRY_WAIT_START_MS" default:"500"`
		RefreshRetryWaitExponent int    `envconfig:"REDIS_REFRESH_RETRY_WAIT_EXPONENT" default:"5"`
		MaxRetries               int    `envconfig:"REDIS_MAX_RETRIES" default:"-1"`
		DialerRetries            int    `envconfig:"REDIS_DIALER_RETRIES" default:"1"`
		DialerRetryTimeoutMs     int    `envconfig:"REDIS_DIALER_RETRY_TIMEOUT_MS" default:"50"`
	}

	OpenTelemetry struct {
		Enable                       bool   `envconfig:"OTEL_ENABLE" default:"false"`
		TraceCollectorEndpoint       string `envconfig:"OTEL_TRACE_COLLECTOR_ENDPOINT" default:"otel:4317"`
		TraceCollectorTimeoutSeconds int    `envconfig:"OTEL_TRACE_COLLECTOR_TIMEOUT_SECONDS" default:"5"`
		MetricsCollectorEndpoint     string `envconfig:"OTEL_METRICS_COLLECTOR_ENDPOINT" required:"false" default:"otel:4317"`
		MetricsReaderTimeoutSeconds  int    `envconfig:"OTEL_METRICS_READER_TIMEOUT_SECONDS" default:"5"`
		MetricsReaderIntervalSeconds int    `envconfig:"OTEL_METRICS_READER_INTERVAL_SECONDS" default:"15"`
		ReadMemStatsIntervalSeconds  int    `envconfig:"OTEL_READ_MEMSTATS_INTERVAL_SECONDS" default:"30"`
	}

	Pyroscope struct {
		Enable bool   `envconfig:"PYROSCOPE_ENABLE" default:"false"`
		Server string `envconfig:"PYROSCOPE_SERVER" default:"http://pyroscope:4040"`
	}
}

func (*CommonConfiguration) GetCommonConfig

func (c *CommonConfiguration) GetCommonConfig() *CommonConfiguration

type Config

type Config struct {
	Configuration         Configuration
	ApplicationName       string
	BuildVersion          string
	UsePostgres           bool
	UseExtendedPgConfig   bool
	UseRedis              bool
	UseOtel               bool
	UsePyroscope          bool
	UtcLogging            bool
	StartupExtensionFunc  func(Configuration) error
	ShutdownExtensionFunc func()
}

type Configuration

type Configuration interface {
	GetCommonConfig() *CommonConfiguration
}