forked from segmentio/chamber
/
ssmstore.go
330 lines (281 loc) · 7.82 KB
/
ssmstore.go
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package store
import (
"fmt"
"os"
"regexp"
"strconv"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/ec2metadata"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/ssm"
"github.com/aws/aws-sdk-go/service/ssm/ssmiface"
)
var (
// KeyID is the alias for the KMS key used to encrypt/decrypt secrets
KeyID = "alias/parameter_store_key"
)
// validKeyFormat is the format that is expected for key names inside parameter store
var validKeyFormat = regexp.MustCompile(`^[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$`)
// SSMStore implements the Store interface for storing secrets in SSM Parameter
// Store
type SSMStore struct {
svc ssmiface.SSMAPI
}
// NewSSMStore creates a new SSMStore
func NewSSMStore() *SSMStore {
region, ok := os.LookupEnv("AWS_REGION")
if !ok {
// If region is not set, attempt to determine it via ec2 metadata API
session := session.New()
ec2metadataSvc := ec2metadata.New(session)
region, _ = ec2metadataSvc.Region()
}
ssmSession := session.Must(session.NewSession(&aws.Config{
Region: aws.String(region),
}))
svc := ssm.New(ssmSession)
return &SSMStore{
svc: svc,
}
}
// Write writes a given value to a secret identified by id. If the secret
// already exists, then write a new version.
func (s *SSMStore) Write(id SecretId, value string) error {
version := 1
// first read to get the current version
current, err := s.Read(id, -1)
if err != nil && err != ErrSecretNotFound {
return err
}
if err == nil {
version = current.Meta.Version + 1
}
putParameterInput := &ssm.PutParameterInput{
KeyId: aws.String(KeyID),
Name: aws.String(idToName(id)),
Type: aws.String("SecureString"),
Value: aws.String(value),
Overwrite: aws.Bool(true),
Description: aws.String(strconv.Itoa(version)),
}
// This API call returns an empty struct
_, err = s.svc.PutParameter(putParameterInput)
if err != nil {
return err
}
return nil
}
// Read reads a secret from the parameter store at a specific version.
// To grab the latest version, use -1 as the version number.
func (s *SSMStore) Read(id SecretId, version int) (Secret, error) {
if version == -1 {
return s.readLatest(id)
}
return s.readVersion(id, version)
}
func (s *SSMStore) readVersion(id SecretId, version int) (Secret, error) {
getParameterHistoryInput := &ssm.GetParameterHistoryInput{
Name: aws.String(idToName(id)),
WithDecryption: aws.Bool(true),
}
resp, err := s.svc.GetParameterHistory(getParameterHistoryInput)
if err != nil {
return Secret{}, ErrSecretNotFound
}
for _, history := range resp.Parameters {
thisVersion, _ := strconv.Atoi(*history.Description)
if thisVersion == version {
return Secret{
Value: history.Value,
Meta: SecretMetadata{
Created: *history.LastModifiedDate,
CreatedBy: *history.LastModifiedUser,
Version: thisVersion,
Key: *history.Name,
},
}, nil
}
}
// If we havent found it yet, check the latest version (which
// doesnt get returned from GetParameterHistory)
current, err := s.readLatest(id)
if err != nil {
return Secret{}, err
}
if current.Meta.Version == version {
return current, nil
}
return Secret{}, ErrSecretNotFound
}
func (s *SSMStore) readLatest(id SecretId) (Secret, error) {
getParametersInput := &ssm.GetParametersInput{
Names: []*string{aws.String(idToName(id))},
WithDecryption: aws.Bool(true),
}
resp, err := s.svc.GetParameters(getParametersInput)
if err != nil {
return Secret{}, ErrSecretNotFound
}
if len(resp.Parameters) == 0 {
return Secret{}, ErrSecretNotFound
}
param := resp.Parameters[0]
// To get metadata, we need to use describe parameters
describeParametersInput := &ssm.DescribeParametersInput{
Filters: []*ssm.ParametersFilter{
{
Key: aws.String("Name"),
Values: []*string{aws.String(idToName(id))},
},
},
MaxResults: aws.Int64(1),
}
describeResp, err := s.svc.DescribeParameters(describeParametersInput)
if err != nil {
return Secret{}, err
}
if len(describeResp.Parameters) == 0 {
return Secret{}, ErrSecretNotFound
}
parameterMeta := describeResp.Parameters[0]
secretMeta := parameterMetaToSecretMeta(parameterMeta)
return Secret{
Value: param.Value,
Meta: secretMeta,
}, nil
}
// List lists all secrets for a given service. If includeValues is true,
// then those secrets are decrypted and returned, otherwise only the metadata
// about a secret is returned.
func (s *SSMStore) List(service string, includeValues bool) ([]Secret, error) {
secrets := map[string]Secret{}
var nextToken *string
for {
describeParametersInput := &ssm.DescribeParametersInput{
Filters: []*ssm.ParametersFilter{
{
Key: aws.String("Name"),
Values: []*string{aws.String(service + ".")},
},
},
NextToken: nextToken,
}
resp, err := s.svc.DescribeParameters(describeParametersInput)
if err != nil {
return nil, err
}
for _, meta := range resp.Parameters {
if !validKeyFormat.MatchString(*meta.Name) {
continue
}
secretMeta := parameterMetaToSecretMeta(meta)
secrets[secretMeta.Key] = Secret{
Value: nil,
Meta: secretMeta,
}
}
if resp.NextToken == nil {
break
}
nextToken = resp.NextToken
}
if includeValues {
secretKeys := keys(secrets)
for i := 0; i < len(secretKeys); i += 10 {
batchEnd := i + 10
if i+10 > len(secretKeys) {
batchEnd = len(secretKeys)
}
batch := secretKeys[i:batchEnd]
getParametersInput := &ssm.GetParametersInput{
Names: stringsToAWSStrings(batch),
WithDecryption: aws.Bool(true),
}
resp, err := s.svc.GetParameters(getParametersInput)
if err != nil {
return nil, err
}
for _, param := range resp.Parameters {
secret := secrets[*param.Name]
secret.Value = param.Value
secrets[*param.Name] = secret
}
}
}
return values(secrets), nil
}
// History returns a list of events that have occured regarding the given
// secret.
func (s *SSMStore) History(id SecretId) ([]ChangeEvent, error) {
events := []ChangeEvent{}
getParameterHistoryInput := &ssm.GetParameterHistoryInput{
Name: aws.String(idToName(id)),
WithDecryption: aws.Bool(false),
}
resp, err := s.svc.GetParameterHistory(getParameterHistoryInput)
if err != nil {
return events, ErrSecretNotFound
}
for _, history := range resp.Parameters {
// Disregard error here, if Atoi fails (secret created outside of
// Chamber), then we use version 0
version, _ := strconv.Atoi(*history.Description)
events = append(events, ChangeEvent{
Type: getChangeType(version),
Time: *history.LastModifiedDate,
User: *history.LastModifiedUser,
Version: version,
})
}
// The current version is not included in the GetParameterHistory response
current, err := s.Read(id, -1)
if err != nil {
return events, err
}
events = append(events, ChangeEvent{
Type: getChangeType(current.Meta.Version),
Time: current.Meta.Created,
User: current.Meta.CreatedBy,
Version: current.Meta.Version,
})
return events, nil
}
func idToName(id SecretId) string {
return fmt.Sprintf("%s.%s", id.Service, id.Key)
}
func parameterMetaToSecretMeta(p *ssm.ParameterMetadata) SecretMetadata {
version, _ := strconv.Atoi(*p.Description)
return SecretMetadata{
Created: *p.LastModifiedDate,
CreatedBy: *p.LastModifiedUser,
Version: version,
Key: *p.Name,
}
}
func keys(m map[string]Secret) []string {
keys := []string{}
for k := range m {
keys = append(keys, k)
}
return keys
}
func values(m map[string]Secret) []Secret {
values := []Secret{}
for _, v := range m {
values = append(values, v)
}
return values
}
func stringsToAWSStrings(slice []string) []*string {
ret := []*string{}
for _, s := range slice {
ret = append(ret, aws.String(s))
}
return ret
}
func getChangeType(version int) ChangeEventType {
if version == 1 {
return Created
}
return Updated
}