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provider.go
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provider.go
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package main
import (
"encoding/json"
"errors"
"fmt"
"log"
"time"
"github.com/99designs/aws-vault/keyring"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/service/sts"
)
type stsClient interface {
AssumeRole(input *sts.AssumeRoleInput) (*sts.AssumeRoleOutput, error)
GetSessionToken(input *sts.GetSessionTokenInput) (*sts.GetSessionTokenOutput, error)
}
type VaultProvider struct {
credentials.Expiry
expires time.Time
Keyring keyring.Keyring
Profile string
SessionDuration time.Duration
ExpiryWindow time.Duration
profilesConf profiles
session *sts.Credentials
client stsClient
}
func NewVaultProvider(k keyring.Keyring, profile string, d time.Duration) (*VaultProvider, error) {
if d < time.Minute*15 {
return nil, errors.New("Minimum session duration is 15 minutes")
} else if d > time.Hour*36 {
return nil, errors.New("Maximum session duration is 36 hours")
}
conf, err := parseProfiles()
if err != nil {
return nil, err
}
return &VaultProvider{
Keyring: k,
Profile: profile,
SessionDuration: d,
ExpiryWindow: d - (d / 3),
profilesConf: conf,
}, nil
}
func (p *VaultProvider) Retrieve() (credentials.Value, error) {
session, err := p.getCachedSession()
if err != nil {
if err == keyring.ErrKeyNotFound {
log.Println("Session not found in keyring")
} else {
log.Println(err)
}
session, err = p.getSessionToken(p.SessionDuration)
if err != nil {
return credentials.Value{}, err
}
bytes, err := json.Marshal(session)
if err != nil {
return credentials.Value{}, err
}
p.Keyring.Set(keyring.Item{
Key: sessionKey(p.Profile),
Label: "aws-vault session for " + p.Profile,
Data: bytes,
TrustSelf: true,
})
}
p.SetExpiration(*session.Expiration, p.ExpiryWindow)
p.expires = *session.Expiration
if role, ok := p.profilesConf[p.Profile]["role_arn"]; ok {
session, err = p.assumeRole(session, role)
if err != nil {
return credentials.Value{}, err
}
log.Printf("Role token expires in %s", session.Expiration.Sub(time.Now()))
}
value := credentials.Value{
AccessKeyID: *session.AccessKeyId,
SecretAccessKey: *session.SecretAccessKey,
SessionToken: *session.SessionToken,
}
return value, nil
}
func sessionKey(profile string) string {
return profile + " session"
}
func (p *VaultProvider) getCachedSession() (session sts.Credentials, err error) {
item, err := p.Keyring.Get(sessionKey(p.Profile))
if err != nil {
return session, err
}
if err = json.Unmarshal(item.Data, &session); err != nil {
return session, err
}
if session.Expiration.Before(time.Now()) {
return session, errors.New("Session is expired")
}
return
}
func (p *VaultProvider) getSessionToken(length time.Duration) (sts.Credentials, error) {
source := p.profilesConf.sourceProfile(p.Profile)
params := &sts.GetSessionTokenInput{
DurationSeconds: aws.Int64(int64(length.Seconds())),
}
if mfa, ok := p.profilesConf[p.Profile]["mfa_serial"]; ok {
token, err := promptPassword(fmt.Sprintf("Enter token for %s: ", mfa))
if err != nil {
return sts.Credentials{}, err
}
params.SerialNumber = aws.String(mfa)
params.TokenCode = aws.String(token)
}
client := p.client
if client == nil {
client = sts.New(&aws.Config{Credentials: credentials.NewChainCredentials(
p.defaultProviders(source),
)})
}
log.Printf("Getting new session token for profile %s", p.Profile)
resp, err := client.GetSessionToken(params)
if err != nil {
return sts.Credentials{}, err
}
return *resp.Credentials, nil
}
func (p *VaultProvider) assumeRole(session sts.Credentials, roleArn string) (sts.Credentials, error) {
client := p.client
if client == nil {
client = sts.New(&aws.Config{Credentials: credentials.NewStaticCredentials(
*session.AccessKeyId,
*session.SecretAccessKey,
*session.SessionToken,
)})
}
// Try to work out a role name that will hopefully end up unique.
roleSessionName := fmt.Sprintf("%d", time.Now().UTC().UnixNano())
input := &sts.AssumeRoleInput{
RoleArn: aws.String(roleArn),
RoleSessionName: aws.String(roleSessionName),
DurationSeconds: aws.Int64(int64(time.Hour.Seconds())),
}
log.Printf("Assuming role %s", roleArn)
resp, err := client.AssumeRole(input)
if err != nil {
return sts.Credentials{}, err
}
return *resp.Credentials, nil
}
func (p *VaultProvider) defaultProviders(profile string) []credentials.Provider {
return []credentials.Provider{
&credentials.EnvProvider{},
&credentials.SharedCredentialsProvider{Filename: "", Profile: profile},
&KeyringProvider{Keyring: p.Keyring, Profile: profile},
}
}
type KeyringProvider struct {
Keyring keyring.Keyring
Profile string
}
func (p *KeyringProvider) IsExpired() bool {
return false
}
func (p *KeyringProvider) Retrieve() (val credentials.Value, err error) {
log.Printf("Looking up keyring for %s", p.Profile)
item, err := p.Keyring.Get(p.Profile)
if err != nil {
return val, err
}
err = json.Unmarshal(item.Data, &val)
return
}
func (p *KeyringProvider) Store(val credentials.Value) error {
p.Keyring.Remove(sessionKey(p.Profile))
bytes, err := json.Marshal(val)
if err != nil {
return err
}
return p.Keyring.Set(keyring.Item{
Key: p.Profile,
Data: bytes,
})
}
func (p *KeyringProvider) Delete() error {
p.Keyring.Remove(sessionKey(p.Profile))
return p.Keyring.Remove(p.Profile)
}
type VaultCredentials struct {
*credentials.Credentials
provider *VaultProvider
}
func NewVaultCredentials(k keyring.Keyring, profile string, d time.Duration) (*VaultCredentials, error) {
provider, err := NewVaultProvider(k, profile, d)
if err != nil {
return nil, err
}
return &VaultCredentials{credentials.NewCredentials(provider), provider}, nil
}
func (v *VaultCredentials) Expires() time.Time {
return v.provider.expires
}