README
¶
STRV env
Go package for runtime environment configuration.
env package leverage Go's reflection functionality for scanning structures. If the env tag is found, a value of this tag is used for
env lookup. If the env variable is set, the value in the structure is overridden. There are two ways how to process structures:
- If a tag value contains
,dive, inner fields of a structure are processed (Sessionin the example). - If a structure implements the
encoding.TextUnmarshalerinterface,UnmarshalTextis called for the given structure (AccessTokenExpirationorzap.AtomicLevelin the example).
A good practice when overriding a config with env variables is to use an app prefix. If the env variable APP_PREFIX contains some
value (MY_APP for example), each defined env variable has to contain the prefix MY_APP (MY_APP_PORT in the example). There is also an option
to choose a custom prefix for env variables by calling MustApplyWithPrefix.
It may happen that the app needs to consume an env variable set by a third party. It's no exception that a cloud provider sets a port your app needs to listen on
and you are unable to modify it. In this case, there is an option to enhance the env tag with the ignoreprefix clause (env:"PORT,ignoreprefix"). While
other env variables will be searched with a prefix included, PORT not.
Examples
package main
import (
envx "go.strv.io/env"
timex "go.strv.io/time"
"go.uber.org/zap"
)
type config struct {
Port uint `json:"port" env:"PORT"`
StorageAddr string `json:"storage_addr" env:"STORAGE_ADDR"`
Session struct {
AccessTokenExpiration timex.Duration `json:"access_token_expiration" env:"SESSION_ACCESS_TOKEN_EXPIRATION"`
} `json:"session" env:",dive"`
LogLevel zap.AtomicLevel `json:"log_level" env:"LOG_LEVEL"`
}
func main() {
cfg := config{}
envx.MustApply(&cfg)
}
See detailed example.
Documentation
¶
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Apply ¶
Apply applies the environment variables to the given target.
Example ¶
package main
import (
"context"
"fmt"
"net/http"
"os"
"strconv"
"time"
envx "go.strv.io/env"
)
type debug bool
func (d *debug) UnmarshalText(text []byte) error {
if d == nil {
return fmt.Errorf("debug: UnmarshalText: nil pointer")
}
b, err := strconv.ParseBool(string(text))
if err != nil {
return err
}
*d = debug(b)
return nil
}
type serviceConfig struct {
Addr string `env:"ADDR"`
Debug *debug `env:"DEBUG"`
Metrics metricsConfig `env:",dive"`
}
type metricsConfig struct {
Namespace string `env:"METRICS_NAMESPACE"`
}
func main() {
cfg := serviceConfig{}
err := os.Setenv("APP_PREFIX", "EXAMPLE")
if err != nil {
panic(err)
}
err = os.Setenv("EXAMPLE_ADDR", ":8080")
if err != nil {
panic(err)
}
envx.MustApply(&cfg)
//nolint:gosec
server := &http.Server{Addr: cfg.Addr}
fmt.Println("Starting HTTP server on address: ", cfg.Addr)
go func() {
if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
panic(err)
}
}()
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
if err := server.Shutdown(ctx); err != nil {
panic(err)
}
}
Output: Starting HTTP server on address: :8080
func ApplyWithPrefix ¶
ApplyWithPrefix applies the environment variables to the given target.
The prefix is used to prefix the environment variables specified by the `env` tag.
func MustApplyWithPrefix ¶
MustApplyWithPrefix calls ApplyWithPrefix and panics on error.
Types ¶
type InvalidTypeError ¶
InvalidTypeError is returned when the type of the target is not a valid type.
func (*InvalidTypeError) Error ¶
func (e *InvalidTypeError) Error() string
Source Files