/
secretsmanager.go
120 lines (100 loc) · 3.37 KB
/
secretsmanager.go
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package token
import (
"encoding/base64"
"encoding/json"
"fmt"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/secretsmanager"
)
// SecretsManagerOpt represents a configuration option for the AWS SecretsManager Buildkite token provider.
type SecretsManagerOpt func(opts *secretsManagerProvider) error
// SecretsManagerClient represents the minimal interactions required to retrieve a Buildkite API token from
// AWS Secrets Manager.
type SecretsManagerClient interface {
GetSecretValue(*secretsmanager.GetSecretValueInput) (*secretsmanager.GetSecretValueOutput, error)
}
type secretsManagerProvider struct {
Client SecretsManagerClient
SecretID string
JSONKey string
}
// WithSecretsManagerJSONSecret instructs SecretsManager Buidlkite token provider that the token is stored within a JSON
// payload. The key parameter specifies the JSON field holding the secret value within the JSON blob.
//
// This configuration option works for both AWS supported secret formats (SecretString and SecretBinary). However, for
// the later case, the binary payload must be a valid JSON document containing the 'key' field.
func WithSecretsManagerJSONSecret(key string) SecretsManagerOpt {
return func(provider *secretsManagerProvider) error {
provider.JSONKey = key
return nil
}
}
// NewSecretsManager constructs a Buildkite API token provider backed by AWS Secrets Manager.
func NewSecretsManager(client SecretsManagerClient, secretID string, opts ...SecretsManagerOpt) (Provider, error) {
provider := &secretsManagerProvider{
Client: client,
SecretID: secretID,
}
for _, opt := range opts {
err := opt(provider)
if err != nil {
return nil, err
}
}
return provider, nil
}
func (p secretsManagerProvider) Get() (string, error) {
res, err := p.Client.GetSecretValue(&secretsmanager.GetSecretValueInput{
SecretId: aws.String(p.SecretID),
})
if err != nil {
return "", fmt.Errorf("failed to retrieve secret '%s' from SecretsManager: %v", p.SecretID, err)
}
secret, err := p.parseResponse(res)
if err != nil {
return "", fmt.Errorf("failed to parse SecretsManager's response for '%s': %v", p.SecretID, err)
}
return secret, nil
}
func (p secretsManagerProvider) parseResponse(res *secretsmanager.GetSecretValueOutput) (string, error) {
var err error
var secretBytes []byte
if res.SecretString != nil {
secretBytes = []byte(*res.SecretString)
} else {
secretBytes, err = decodeBase64(res.SecretBinary)
if err != nil {
return "", err
}
}
if p.JSONKey != "" {
secret, err := extractStringKeyFromJSON(secretBytes, p.JSONKey)
if err != nil {
return "", err
}
return secret, nil
}
return string(secretBytes), nil
}
func extractStringKeyFromJSON(data []byte, key string) (string, error) {
contents := map[string]interface{}{}
err := json.Unmarshal(data, &contents)
if err != nil {
return "", err
}
// Checks whether the provided data is a valid JSON, contains the requested key and its corresponding value
// is a string.
if secretValue, ok := contents[key].(string); ok {
return secretValue, nil
} else {
return "", fmt.Errorf("key '%s' doesn't exist or isn't a string value", key)
}
}
func decodeBase64(data []byte) ([]byte, error) {
decodedBytes := make([]byte, base64.StdEncoding.DecodedLen(len(data)))
size, err := base64.StdEncoding.Decode(decodedBytes, data)
if err != nil {
return nil, err
}
return decodedBytes[:size], nil
}