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awsconfig.go
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awsconfig.go
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package awsconfig
import (
"io/ioutil"
"os"
"path/filepath"
"time"
homedir "github.com/mitchellh/go-homedir"
"github.com/sirupsen/logrus"
"github.com/pkg/errors"
ini "gopkg.in/ini.v1"
)
var (
// ErrCredentialsHomeNotFound returned when a user home directory can't be located.
ErrCredentialsHomeNotFound = errors.New("user home directory not found")
// ErrCredentialsNotFound returned when the required aws credentials don't exist.
ErrCredentialsNotFound = errors.New("aws credentials not found")
logger = logrus.WithField("pkg", "awsconfig")
)
// AWSCredentials represents the set of attributes used to authenticate to AWS with a short lived session
type AWSCredentials struct {
AWSAccessKey string `ini:"aws_access_key_id"`
AWSSecretKey string `ini:"aws_secret_access_key"`
AWSSessionToken string `ini:"aws_session_token"`
AWSSecurityToken string `ini:"aws_security_token"`
PrincipalARN string `ini:"x_principal_arn"`
Expires time.Time `ini:"x_security_token_expires"`
}
// CredentialsProvider loads aws credentials file
type CredentialsProvider struct {
Filename string
Profile string
}
// NewSharedCredentials helper to create the credentials provider
func NewSharedCredentials(profile string) *CredentialsProvider {
return &CredentialsProvider{
Profile: profile,
}
}
// CredsExists verify that the credentials exist
func (p *CredentialsProvider) CredsExists() (bool, error) {
filename, err := p.resolveFilename()
if err != nil {
return false, err
}
err = p.ensureConfigExists()
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, errors.Wrapf(err, "unable to load file %s", filename)
}
return true, nil
}
// Save persist the credentials
func (p *CredentialsProvider) Save(awsCreds *AWSCredentials) error {
filename, err := p.resolveFilename()
if err != nil {
return err
}
err = p.ensureConfigExists()
if err != nil {
if os.IsNotExist(err) {
return createAndSaveProfile(filename, p.Profile, awsCreds)
}
return errors.Wrap(err, "unable to load file")
}
return saveProfile(filename, p.Profile, awsCreds)
}
// Load load the aws credentials file
func (p *CredentialsProvider) Load() (*AWSCredentials, error) {
filename, err := p.resolveFilename()
if err != nil {
return nil, err
}
config, err := ini.Load(filename)
if err != nil {
return nil, err
}
iniProfile, err := config.GetSection(p.Profile)
if err != nil {
return nil, ErrCredentialsNotFound
}
awsCreds := new(AWSCredentials)
err = iniProfile.MapTo(awsCreds)
if err != nil {
return nil, ErrCredentialsNotFound
}
return awsCreds, nil
}
// Expired checks if the current credentials are expired
func (p *CredentialsProvider) Expired() bool {
creds, err := p.Load()
if err != nil {
return true
}
return time.Now().After(creds.Expires)
}
// ensureConfigExists verify that the config file exists
func (p *CredentialsProvider) ensureConfigExists() error {
filename, err := p.resolveFilename()
if err != nil {
return err
}
logger.WithField("filename", filename).Debug("ensureConfigExists")
if _, err := os.Stat(filename); err != nil {
if os.IsNotExist(err) {
dir := filepath.Dir(filename)
err = os.MkdirAll(dir, os.ModePerm)
if err != nil {
return err
}
logger.WithField("dir", dir).Debug("Dir created")
// create an base config file
err = ioutil.WriteFile(filename, []byte("["+p.Profile+"]"), 0600)
if err != nil {
return err
}
logger.WithField("filename", filename).Debug("File created")
}
return err
}
return nil
}
func (p *CredentialsProvider) resolveFilename() (string, error) {
if p.Filename == "" {
filename, err := locateConfigFile()
if err != nil {
return "", err
}
p.Filename = filename
}
return p.Filename, nil
}
func locateConfigFile() (string, error) {
filename := os.Getenv("AWS_SHARED_CREDENTIALS_FILE")
if filename != "" {
return filename, nil
}
name, err := homedir.Expand("~/.aws/credentials")
if err != nil {
return "", ErrCredentialsHomeNotFound
}
logger.WithField("name", name).Debug("Expand")
// is the filename a symlink?
name, err = resolveSymlink(name)
if err != nil {
return "", errors.Wrap(err, "unable to resolve symlink")
}
logger.WithField("name", name).Debug("resolveSymlink")
return name, nil
}
func resolveSymlink(filename string) (string, error) {
sympath, err := filepath.EvalSymlinks(filename)
// return the un modified filename
if os.IsNotExist(err) {
return filename, nil
}
if err != nil {
return "", err
}
return sympath, nil
}
func createAndSaveProfile(filename, profile string, awsCreds *AWSCredentials) error {
dirPath := filepath.Dir(filename)
err := os.Mkdir(dirPath, 0700)
if err != nil {
return errors.Wrapf(err, "unable to create %s directory", dirPath)
}
_, err = os.Create(filename)
if err != nil {
return errors.Wrapf(err, "unable to create configuration")
}
return saveProfile(filename, profile, awsCreds)
}
func saveProfile(filename, profile string, awsCreds *AWSCredentials) error {
config, err := ini.Load(filename)
if err != nil {
return err
}
iniProfile, err := config.NewSection(profile)
if err != nil {
return err
}
err = iniProfile.ReflectFrom(awsCreds)
if err != nil {
return err
}
return config.SaveTo(filename)
}