I am attempting to use uber fx to do dependency injection for a go microservice project.
Since all the microservices will need to construct a base server, and set up a variety of config options (common middleware, buffer sizes etc) (I am using fiber). But these different microservices also have config options unique to the microservice. Maybe a database connection string, jwt keys etc.
I created an interface to use in the shared function that creates the common base app, with the common options, but any function needing a dependency of the config struct fails with expecting the specific version of config for that microservice.
failed to build *fiber.App: missing dependencies for function "some-path/http".CreateServer (some-path/http/http.go:65): missing type: *http.Config exit status 1
Minimal example:
package http
import (
"time"
"github.com/gofiber/fiber/v2"
)
type BaseConfig interface {
GetPort() string
GetTimeout() int
}
type Config struct {
Port string `env:"LISTEN_ADDR" envDefault:":3000"`
Timeout uint64 `env:"TIMEOUT" envDefault:"10"`
}
func (c *Config) GetPort() string {
return c.Port
}
func (c *Config) GetTimeout() int {
return int(c.Timeout)
}
func CreateServer(config *Config) *fiber.App {
fiberConfig := fiber.Config{
ReadTimeout: time.Second * time.Duration(config.GetTimeout()),
WriteTimeout: time.Second * time.Duration(config.GetTimeout()),
}
app := fiber.New(fiberConfig)
// do setup and other stuff
return app
}
package config
import (
"github.com/caarlos0/env/v6"
"github.com/rs/zerolog/log"
)
type Config struct {
Port string `env:"LISTEN_ADDR" envDefault:":3000"`
Timeout uint64 `env:"TIMEOUT" envDefault:"10"`
// some service specific stuff as well
}
func Parse() (*Config, error) {
cfg := Config{}
if err := env.Parse(&cfg); err != nil {
return nil, err
}
return &cfg, nil
}
func (c *Config) GetPort() string {
return c.Port
}
func (c *Config) GetTimeout() int {
return int(c.Timeout)
}
package main
import (
"context"
"time"
"some-path/http"
"some-path/config"
"some-path/controllers"
"github.com/gofiber/fiber/v2"
"go.uber.org/fx"
)
func main() {
opts := []fx.Option{}
opts = append(opts, provideOptions()...)
opts = append(opts, fx.Invoke(run))
app := fx.New(opts...)
app.Run()
}
func provideOptions() []fx.Option {
return []fx.Option{
fx.Invoke(utils.ConfigureLogger),
fx.Provide(config.Parse),
fx.Invoke(controllers.SomeController),
}
}
func run(app *fiber.App, config *config.Config, lc fx.Lifecycle) {
lc.Append(fx.Hook{
OnStart: func(ctx context.Context) error {
errChan := make(chan error)
go func() {
errChan <- app.Listen(config.Port)
}()
select {
case err := <-errChan:
return err
case <-time.After(100 * time.Millisecond):
return nil
}
},
OnStop: func(ctx context.Context) error {
return app.Shutdown()
},
})
}
package controllers
import "some-path/config"
func SomeController (config *config.Config) {
// do stuff
}
You're missing *http.Config
object, create a function that return that object, e.g. NewConfig()
package http
import (
"time"
"github.com/caarlos0/env/v6"
"github.com/gofiber/fiber/v2"
)
type BaseConfig interface {
GetPort() string
GetTimeout() int
}
type Config struct {
Port string `env:"LISTEN_ADDR" envDefault:":3000"`
Timeout uint64 `env:"TIMEOUT" envDefault:"10"`
}
func NewConfig() (*Config, error) {
cfg := Config{}
if err := env.Parse(&cfg); err != nil {
return nil, err
}
return &cfg, nil
}
func (c *Config) GetPort() string {
return c.Port
}
func (c *Config) GetTimeout() int {
return int(c.Timeout)
}
func CreateServer(config *Config) *fiber.App {
fiberConfig := fiber.Config{
ReadTimeout: time.Second * time.Duration(config.GetTimeout()),
WriteTimeout: time.Second * time.Duration(config.GetTimeout()),
}
app := fiber.New(fiberConfig)
// do setup and other stuff
return app
}
then change your provideOptions()
, maybe like this:
func provideOptions() []fx.Option {
return []fx.Option{
fx.Invoke(utils.ConfigureLogger),
fx.Provide(config.Parse, http.NewConfig),
fx.Invoke(controllers.SomeController),
fx.Provide(http.CreateServer),
}
}