traefik/vendor/github.com/docker/libcompose/config/hash.go

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2017-02-07 21:33:23 +00:00
package config
import (
"crypto/sha1"
"encoding/hex"
"fmt"
"io"
"reflect"
"sort"
"github.com/docker/libcompose/yaml"
)
// GetServiceHash computes and returns a hash that will identify a service.
// This hash will be then used to detect if the service definition/configuration
// have changed and needs to be recreated.
func GetServiceHash(name string, config *ServiceConfig) string {
hash := sha1.New()
io.WriteString(hash, name)
//Get values of Service through reflection
val := reflect.ValueOf(config).Elem()
//Create slice to sort the keys in Service Config, which allow constant hash ordering
serviceKeys := []string{}
//Create a data structure of map of values keyed by a string
unsortedKeyValue := make(map[string]interface{})
//Get all keys and values in Service Configuration
for i := 0; i < val.NumField(); i++ {
valueField := val.Field(i)
keyField := val.Type().Field(i)
serviceKeys = append(serviceKeys, keyField.Name)
unsortedKeyValue[keyField.Name] = valueField.Interface()
}
//Sort serviceKeys alphabetically
sort.Strings(serviceKeys)
//Go through keys and write hash
for _, serviceKey := range serviceKeys {
serviceValue := unsortedKeyValue[serviceKey]
io.WriteString(hash, fmt.Sprintf("\n %v: ", serviceKey))
switch s := serviceValue.(type) {
case yaml.SliceorMap:
sliceKeys := []string{}
for lkey := range s {
sliceKeys = append(sliceKeys, lkey)
}
sort.Strings(sliceKeys)
for _, sliceKey := range sliceKeys {
io.WriteString(hash, fmt.Sprintf("%s=%v, ", sliceKey, s[sliceKey]))
}
case yaml.MaporEqualSlice:
for _, sliceKey := range s {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case yaml.MaporColonSlice:
for _, sliceKey := range s {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case yaml.MaporSpaceSlice:
for _, sliceKey := range s {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case yaml.Command:
for _, sliceKey := range s {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case yaml.Stringorslice:
sort.Strings(s)
for _, sliceKey := range s {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case []string:
sliceKeys := s
sort.Strings(sliceKeys)
for _, sliceKey := range sliceKeys {
io.WriteString(hash, fmt.Sprintf("%s, ", sliceKey))
}
case *yaml.Networks:
io.WriteString(hash, fmt.Sprintf("%s, ", s.HashString()))
case *yaml.Volumes:
io.WriteString(hash, fmt.Sprintf("%s, ", s.HashString()))
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default:
io.WriteString(hash, fmt.Sprintf("%v, ", serviceValue))
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}
}
return hex.EncodeToString(hash.Sum(nil))
}