distribution/configuration/configuration.go
Brian Bland c8ea224f9c Miscellaneous go vet fixes
Fixes some format strings and uses keyed fields for struct construction
2014-11-12 17:19:19 -08:00

266 lines
7.9 KiB
Go

package configuration
import (
"fmt"
"os"
"regexp"
"strconv"
"strings"
"gopkg.in/BrianBland/yaml.v2"
)
// Configuration is a versioned registry configuration, intended to be provided by a yaml file, and
// optionally modified by environment variables
type Configuration struct {
// Version is the version which defines the format of the rest of the configuration
Version Version `yaml:"version"`
// Loglevel is the level at which registry operations are logged
Loglevel Loglevel `yaml:"loglevel"`
// Storage is the configuration for the registry's storage driver
Storage Storage `yaml:"storage"`
}
// v_0_1_Configuration is a Version 0.1 Configuration struct
// This is currently aliased to Configuration, as it is the current version
type v_0_1_Configuration Configuration
// Version is a major/minor version pair of the form Major.Minor
// Major version upgrades indicate structure or type changes
// Minor version upgrades should be strictly additive
type Version string
// MajorMinorVersion constructs a Version from its Major and Minor components
func MajorMinorVersion(major, minor uint) Version {
return Version(fmt.Sprintf("%d.%d", major, minor))
}
func (version Version) major() (uint, error) {
majorPart := strings.Split(string(version), ".")[0]
major, err := strconv.ParseUint(majorPart, 10, 0)
return uint(major), err
}
// Major returns the major version portion of a Version
func (version Version) Major() uint {
major, _ := version.major()
return major
}
func (version Version) minor() (uint, error) {
minorPart := strings.Split(string(version), ".")[1]
minor, err := strconv.ParseUint(minorPart, 10, 0)
return uint(minor), err
}
// Minor returns the minor version portion of a Version
func (version Version) Minor() uint {
minor, _ := version.minor()
return minor
}
// UnmarshalYAML implements the yaml.Unmarshaler interface
// Unmarshals a string of the form X.Y into a Version, validating that X and Y can represent uints
func (version *Version) UnmarshalYAML(unmarshal func(interface{}) error) error {
var versionString string
err := unmarshal(&versionString)
if err != nil {
return err
}
newVersion := Version(versionString)
if _, err := newVersion.major(); err != nil {
return err
}
if _, err := newVersion.minor(); err != nil {
return err
}
*version = newVersion
return nil
}
// CurrentVersion is the most recent Version that can be parsed
var CurrentVersion = MajorMinorVersion(0, 1)
// Loglevel is the level at which operations are logged
// This can be error, warn, info, or debug
type Loglevel string
// UnmarshalYAML implements the yaml.Umarshaler interface
// Unmarshals a string into a Loglevel, lowercasing the string and validating that it represents a
// valid loglevel
func (loglevel *Loglevel) UnmarshalYAML(unmarshal func(interface{}) error) error {
var loglevelString string
err := unmarshal(&loglevelString)
if err != nil {
return err
}
loglevelString = strings.ToLower(loglevelString)
switch loglevelString {
case "error", "warn", "info", "debug":
default:
return fmt.Errorf("Invalid loglevel %s Must be one of [error, warn, info, debug]", loglevelString)
}
*loglevel = Loglevel(loglevelString)
return nil
}
// Storage defines the configuration for registry object storage
type Storage map[string]Parameters
// Type returns the storage driver type, such as filesystem or s3
func (storage Storage) Type() string {
// Return only key in this map
for k := range storage {
return k
}
return ""
}
// Parameters returns the Parameters map for a Storage configuration
func (storage Storage) Parameters() Parameters {
return storage[storage.Type()]
}
// setParameter changes the parameter at the provided key to the new value
func (storage Storage) setParameter(key, value string) {
storage[storage.Type()][key] = value
}
// UnmarshalYAML implements the yaml.Unmarshaler interface
// Unmarshals a single item map into a Storage or a string into a Storage type with no parameters
func (storage *Storage) UnmarshalYAML(unmarshal func(interface{}) error) error {
var storageMap map[string]Parameters
err := unmarshal(&storageMap)
if err == nil {
if len(storageMap) > 1 {
types := make([]string, 0, len(storageMap))
for k := range storageMap {
types = append(types, k)
}
return fmt.Errorf("Must provide exactly one storage type. Provided: %v", types)
}
*storage = storageMap
return nil
}
var storageType string
err = unmarshal(&storageType)
if err == nil {
*storage = Storage{storageType: Parameters{}}
return nil
}
return err
}
// MarshalYAML implements the yaml.Marshaler interface
func (storage Storage) MarshalYAML() (interface{}, error) {
if storage.Parameters() == nil {
return storage.Type, nil
}
return map[string]Parameters(storage), nil
}
// Parameters defines a key-value parameters mapping
type Parameters map[string]string
// Parse parses an input configuration yaml document into a Configuration struct
// This should generally be capable of handling old configuration format versions
//
// Environment variables may be used to override configuration parameters other than version,
// following the scheme below:
// Configuration.Abc may be replaced by the value of REGISTRY_ABC,
// Configuration.Abc.Xyz may be replaced by the value of REGISTRY_ABC_XYZ, and so forth
func Parse(in []byte) (*Configuration, error) {
var untypedConfig struct {
Version Version
}
var config *Configuration
err := yaml.Unmarshal(in, &untypedConfig)
if err != nil {
return nil, err
}
if untypedConfig.Version == "" {
return nil, fmt.Errorf("Please specify a configuration version. Current version is %s", CurrentVersion)
}
// Parse the remainder of the configuration depending on the provided version
switch untypedConfig.Version {
case "0.1":
config, err = parseV_0_1_Registry(in)
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("Unsupported configuration version %s Current version is %s", untypedConfig.Version, CurrentVersion)
}
return config, nil
}
// parseV_0_1_Registry parses a registry Configuration for Version 0.1
func parseV_0_1_Registry(in []byte) (*Configuration, error) {
envMap := getEnvMap()
var config v_0_1_Configuration
err := yaml.Unmarshal(in, &config)
if err != nil {
return nil, err
}
// Override config.Loglevel if environment variable is provided
if loglevel, ok := envMap["REGISTRY_LOGLEVEL"]; ok {
var newLoglevel Loglevel
err := yaml.Unmarshal([]byte(loglevel), &newLoglevel)
if err != nil {
return nil, err
}
config.Loglevel = newLoglevel
}
// Override config.Storage if environment variable is provided
if storageType, ok := envMap["REGISTRY_STORAGE"]; ok {
if storageType != config.Storage.Type() {
// Reset the storage parameters because we're using a different storage type
config.Storage = Storage{storageType: Parameters{}}
}
}
if config.Storage.Type() == "" {
return nil, fmt.Errorf("Must provide exactly one storage type, optionally with parameters. Provided: %v", config.Storage)
}
// Override storage parameters with all environment variables of the format:
// REGISTRY_STORAGE_<storage driver type>_<parameter name>
storageParamsRegexp, err := regexp.Compile(fmt.Sprintf("^REGISTRY_STORAGE_%s_([A-Z0-9]+)$", strings.ToUpper(config.Storage.Type())))
if err != nil {
return nil, err
}
for k, v := range envMap {
if submatches := storageParamsRegexp.FindStringSubmatch(k); submatches != nil {
config.Storage.setParameter(strings.ToLower(submatches[1]), v)
}
}
return (*Configuration)(&config), nil
}
// getEnvMap reads the current environment variables and converts these into a key/value map
// This is used to distinguish between empty strings returned by os.GetEnv(key) because of undefined
// environment variables and explicitly empty ones
func getEnvMap() map[string]string {
envMap := make(map[string]string)
for _, env := range os.Environ() {
envParts := strings.SplitN(env, "=", 2)
envMap[envParts[0]] = envParts[1]
}
return envMap
}