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scrimp_config.go
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scrimp_config.go
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package scrimplb
import (
"encoding/json"
"fmt"
"io/ioutil"
"log"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/sgtcodfish/scrimplb/constants"
"github.com/sgtcodfish/scrimplb/resolver"
"github.com/sgtcodfish/scrimplb/seed"
)
const (
defaultPushPeriod = "60s"
defaultPushJitter = "5s"
defaultTLSChainLocation = "/etc/ssl/chain.pem"
defaultTLSKeyLocation = "/etc/ssl/key.pem"
)
// ScrimpConfig describes JSON configuration options for Scrimp overall.
type ScrimpConfig struct {
IsLoadBalancer bool `json:"lb"`
BindAddress string `json:"bind-address"`
PortRaw string `json:"port"`
ProviderName string `json:"provider"`
ProviderConfig map[string]interface{} `json:"provider-config"`
ResolverName string `json:"resolver"`
LoadBalancerConfig *LoadBalancerConfig `json:"load-balancer-config"`
BackendConfig *BackendConfig `json:"backend-config"`
Port int
Provider seed.Provider
Resolver resolver.IPResolver
}
// LoadScrimpConfig loads the given config file and parses fields which need to be parsed
func LoadScrimpConfig(configFile string) (*ScrimpConfig, error) {
data, err := ioutil.ReadFile(configFile)
if err != nil {
return nil, err
}
config := ScrimpConfig{
BindAddress: "0.0.0.0",
PortRaw: constants.DefaultPort,
IsLoadBalancer: false,
}
err = json.Unmarshal(data, &config)
if err != nil {
return nil, err
}
if config.IsLoadBalancer {
err = initialiseLoadBalancerConfig(&config)
} else {
err = initialiseBackendConfig(&config)
}
if err != nil {
return nil, err
}
config.ProviderName = strings.ToLower(config.ProviderName)
if config.ProviderName != "" {
err = initProvider(&config)
if err != nil {
return nil, err
}
}
// a load balancer needs a resolver of some kind
config.ResolverName = strings.ToLower(config.ResolverName)
if config.IsLoadBalancer && config.ResolverName == "" {
return nil, fmt.Errorf("a load balancer require a valid IP resolver in config")
}
if config.ResolverName != "" {
err = initResolver(&config)
if err != nil {
return nil, err
}
}
intPort, err := strconv.Atoi(config.PortRaw)
if err != nil {
return nil, err
}
config.Port = intPort
return &config, nil
}
func initResolver(config *ScrimpConfig) error {
var resolverObject resolver.IPResolver
var err error
switch config.ResolverName {
case "dummy":
resolverObject = resolver.NewDummyIPResolver()
case "ec2":
resolverObject = resolver.NewEC2IPResolver()
case "ipv6":
resolverObject, err = resolver.NewIPv6UnicastResolver()
default:
return fmt.Errorf("invalid resolver '%s'", config.ResolverName)
}
if err != nil {
return fmt.Errorf("couldn't create IP resolver: %w", err)
}
config.Resolver = resolverObject
return nil
}
func initProvider(config *ScrimpConfig) error {
var providerObject seed.Provider
var err error
switch config.ProviderName {
case "dummy":
providerObject, err = seed.NewDummyProvider(config.ProviderConfig)
case "manual":
providerObject, err = seed.NewManualProvider(config.ProviderConfig)
case "s3":
providerObject, err = seed.NewS3Provider(config.ProviderConfig)
}
if err != nil {
return fmt.Errorf("couldn't initialise provider '%s': %w", config.ProviderName, err)
}
config.Provider = providerObject
return nil
}
// configDirWalker iterates over JSON config files in a directory and
// returns the parsed JSON config. This is useful for an upstream server
// so that each installed application can install its config
// into a pre-known location.
func configDirWalker(path string) (applications []JSONApplication, err error) {
type configFile struct {
Path string
File os.FileInfo
}
var configFiles []configFile
err = filepath.Walk(path, func(path string, f os.FileInfo, err error) error {
configFiles = append(configFiles, configFile{path, f})
return nil
})
if err != nil {
if os.IsNotExist(err) {
return nil, fmt.Errorf("config folder does not exist: %s", path)
}
return nil, fmt.Errorf("couldn't read files from %s: %w", path, err)
}
if len(configFiles) == 0 {
return nil, nil
}
for _, f := range configFiles {
if f.File == nil || f.File.IsDir() {
continue
}
fd, err := os.Open(f.Path)
if err != nil {
log.Printf("couldn't load %s: %v", f.Path, err)
continue
}
rawContents, err := ioutil.ReadAll(fd)
if err != nil {
log.Printf("couldn't read %s: %v", f.Path, err)
continue
}
var application JSONApplication
err = json.Unmarshal(rawContents, &application)
if err != nil {
log.Printf("couldn't parse %s: %v", f.Path, err)
continue
}
applications = append(applications, application)
log.Printf("loaded application from %s: %s", f.Path, application.Name)
}
return applications, nil
}