config/config.go

// Copyright (c) 2023 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package config

import (
	"os"

	zanzibar "github.com/uber/zanzibar/runtime"
)

// EnvConfig map from environment variable to config key and data type
type EnvConfig map[string]struct {
	Key      string `json:"key"`
	DataType string `json:"dataType"`
}

type RoutingConfig struct {
	HeaderName      string  `yaml:"headerName" json:"headerName"`
	HeaderValue     string  `yaml:"headerValue" json:"headerValue"`
	ServiceName     string  `yaml:"serviceName" json:"serviceName"`
	RoutingDelegate *string `yaml:"rd,omitempty" json:"rd,omitempty"`
}

type ServiceRouting struct {
	IP   string `yaml:"ip" json:"ip"`
	Port int    `yaml:"port" json:"port"`
}

type AlternateServiceDetail struct {
	RoutingConfigs    []RoutingConfig            `yaml:"routingConfigs" json:"routingConfigs"`
	ServicesDetailMap map[string]*ServiceRouting `yaml:"servicesDetail" json:"servicesDetail"`
}

// NewRuntimeConfigOrDie returns a static config struct
// that is pre-set with the service configuration defaults
// and overridden by service.env.config
func NewRuntimeConfigOrDie(
	files []string,
	seedConfig map[string]interface{},
) *zanzibar.StaticConfig {
	defaultConfig, err := defaultConfig()
	if err != nil {
		panic("error getting default config")
	}

	serviceConfig := make([]*zanzibar.ConfigOption, 0, len(files)+1)
	serviceConfig = append(serviceConfig, defaultConfig)
	for _, configFilePath := range files {
		serviceConfig = append(serviceConfig, zanzibar.ConfigFilePath(configFilePath))
	}

	staticConfig := zanzibar.NewStaticConfigOrDie(serviceConfig, seedConfig)
	setEnvConfig(staticConfig)

	return staticConfig
}

func defaultConfig() (*zanzibar.ConfigOption, error) {
	bytes, err := Asset("production.yaml")
	if err == nil {
		return zanzibar.ConfigFileContents(bytes), nil
	}

	// try json version
	bytes, err = Asset("production.json")
	if err == nil {
		return zanzibar.ConfigFileContents(bytes), nil
	}
	return nil, err
}

func setEnvConfig(cfg *zanzibar.StaticConfig) {
	var envConfig EnvConfig
	cfg.MustGetStruct("service.env.config", &envConfig)
	for envVar, configKey := range envConfig {
		if value, ok := os.LookupEnv(envVar); ok {
			cfg.SetConfigValueOrDie(
				configKey.Key, []byte(value), configKey.DataType)
		}
	}
}