2021-04-06 13:52:07 -07:00

342 lines
10 KiB
Go

package config
import (
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"os"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
)
// CredentialsSourceName provides a name of the provider when config is
// loaded from environment.
const CredentialsSourceName = "EnvConfigCredentials"
// Environment variables that will be read for configuration values.
const (
awsAccessKeyIDEnvVar = "AWS_ACCESS_KEY_ID"
awsAccessKeyEnvVar = "AWS_ACCESS_KEY"
awsSecretAccessKeyEnvVar = "AWS_SECRET_ACCESS_KEY"
awsSecretKeyEnvVar = "AWS_SECRET_KEY"
awsSessionTokenEnvVar = "AWS_SESSION_TOKEN"
awsContainerCredentialsEndpointEnvVar = "AWS_CONTAINER_CREDENTIALS_FULL_URI"
awsContainerCredentialsRelativePathEnvVar = "AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"
awsContainerPProviderAuthorizationEnvVar = "AWS_CONTAINER_AUTHORIZATION_TOKEN"
awsRegionEnvVar = "AWS_REGION"
awsDefaultRegionEnvVar = "AWS_DEFAULT_REGION"
awsProfileEnvVar = "AWS_PROFILE"
awsDefaultProfileEnvVar = "AWS_DEFAULT_PROFILE"
awsSharedCredentialsFileEnvVar = "AWS_SHARED_CREDENTIALS_FILE"
awsConfigFileEnvVar = "AWS_CONFIG_FILE"
awsCustomCABundleEnvVar = "AWS_CA_BUNDLE"
awsWebIdentityTokenFilePathEnvKey = "AWS_WEB_IDENTITY_TOKEN_FILE"
awsRoleARNEnvKey = "AWS_ROLE_ARN"
awsRoleSessionNameEnvKey = "AWS_ROLE_SESSION_NAME"
awsEnableEndpointDiscoveryEnvKey = "AWS_ENABLE_ENDPOINT_DISCOVERY"
awsS3UseARNRegionEnvVar = "AWS_S3_USE_ARN_REGION"
)
var (
credAccessEnvKeys = []string{
awsAccessKeyIDEnvVar,
awsAccessKeyEnvVar,
}
credSecretEnvKeys = []string{
awsSecretAccessKeyEnvVar,
awsSecretKeyEnvVar,
}
regionEnvKeys = []string{
awsRegionEnvVar,
awsDefaultRegionEnvVar,
}
profileEnvKeys = []string{
awsProfileEnvVar,
awsDefaultProfileEnvVar,
}
)
// EnvConfig is a collection of environment values the SDK will read
// setup config from. All environment values are optional. But some values
// such as credentials require multiple values to be complete or the values
// will be ignored.
type EnvConfig struct {
// Environment configuration values. If set both Access Key ID and Secret Access
// Key must be provided. Session Token and optionally also be provided, but is
// not required.
//
// # Access Key ID
// AWS_ACCESS_KEY_ID=AKID
// AWS_ACCESS_KEY=AKID # only read if AWS_ACCESS_KEY_ID is not set.
//
// # Secret Access Key
// AWS_SECRET_ACCESS_KEY=SECRET
// AWS_SECRET_KEY=SECRET # only read if AWS_SECRET_ACCESS_KEY is not set.
//
// # Session Token
// AWS_SESSION_TOKEN=TOKEN
Credentials aws.Credentials
// ContainerCredentialsEndpoint value is the HTTP enabled endpoint to retrieve credentials
// using the endpointcreds.Provider
ContainerCredentialsEndpoint string
// ContainerCredentialsRelativePath is the relative URI path that will be used when attempting to retrieve
// credentials from the container endpoint.
ContainerCredentialsRelativePath string
// ContainerAuthorizationToken is the authorization token that will be included in the HTTP Authorization
// header when attempting to retrieve credentials from the container credentials endpoint.
ContainerAuthorizationToken string
// Region value will instruct the SDK where to make service API requests to. If is
// not provided in the environment the region must be provided before a service
// client request is made.
//
// AWS_REGION=us-west-2
// AWS_DEFAULT_REGION=us-west-2
Region string
// Profile name the SDK should load use when loading shared configuration from the
// shared configuration files. If not provided "default" will be used as the
// profile name.
//
// AWS_PROFILE=my_profile
// AWS_DEFAULT_PROFILE=my_profile
SharedConfigProfile string
// Shared credentials file path can be set to instruct the SDK to use an alternate
// file for the shared credentials. If not set the file will be loaded from
// $HOME/.aws/credentials on Linux/Unix based systems, and
// %USERPROFILE%\.aws\credentials on Windows.
//
// AWS_SHARED_CREDENTIALS_FILE=$HOME/my_shared_credentials
SharedCredentialsFile string
// Shared config file path can be set to instruct the SDK to use an alternate
// file for the shared config. If not set the file will be loaded from
// $HOME/.aws/config on Linux/Unix based systems, and
// %USERPROFILE%\.aws\config on Windows.
//
// AWS_CONFIG_FILE=$HOME/my_shared_config
SharedConfigFile string
// Sets the path to a custom Credentials Authority (CA) Bundle PEM file
// that the SDK will use instead of the system's root CA bundle.
// Only use this if you want to configure the SDK to use a custom set
// of CAs.
//
// Enabling this option will attempt to merge the Transport
// into the SDK's HTTP client. If the client's Transport is
// not a http.Transport an error will be returned. If the
// Transport's TLS config is set this option will cause the
// SDK to overwrite the Transport's TLS config's RootCAs value.
//
// Setting a custom HTTPClient in the aws.Config options will override this setting.
// To use this option and custom HTTP client, the HTTP client needs to be provided
// when creating the config. Not the service client.
//
// AWS_CA_BUNDLE=$HOME/my_custom_ca_bundle
CustomCABundle string
// Enables endpoint discovery via environment variables.
//
// AWS_ENABLE_ENDPOINT_DISCOVERY=true
EnableEndpointDiscovery *bool
// Specifies the WebIdentity token the SDK should use to assume a role
// with.
//
// AWS_WEB_IDENTITY_TOKEN_FILE=file_path
WebIdentityTokenFilePath string
// Specifies the IAM role arn to use when assuming an role.
//
// AWS_ROLE_ARN=role_arn
RoleARN string
// Specifies the IAM role session name to use when assuming a role.
//
// AWS_ROLE_SESSION_NAME=session_name
RoleSessionName string
// Specifies if the S3 service should allow ARNs to direct the region
// the client's requests are sent to.
//
// AWS_S3_USE_ARN_REGION=true
S3UseARNRegion *bool
}
// loadEnvConfig reads configuration values from the OS's environment variables.
// Returning the a Config typed EnvConfig to satisfy the ConfigLoader func type.
func loadEnvConfig(ctx context.Context, cfgs configs) (Config, error) {
return NewEnvConfig()
}
// NewEnvConfig retrieves the SDK's environment configuration.
// See `EnvConfig` for the values that will be retrieved.
func NewEnvConfig() (EnvConfig, error) {
var cfg EnvConfig
creds := aws.Credentials{
Source: CredentialsSourceName,
}
setStringFromEnvVal(&creds.AccessKeyID, credAccessEnvKeys)
setStringFromEnvVal(&creds.SecretAccessKey, credSecretEnvKeys)
if creds.HasKeys() {
creds.SessionToken = os.Getenv(awsSessionTokenEnvVar)
cfg.Credentials = creds
}
cfg.ContainerCredentialsEndpoint = os.Getenv(awsContainerCredentialsEndpointEnvVar)
cfg.ContainerCredentialsRelativePath = os.Getenv(awsContainerCredentialsRelativePathEnvVar)
cfg.ContainerAuthorizationToken = os.Getenv(awsContainerPProviderAuthorizationEnvVar)
setStringFromEnvVal(&cfg.Region, regionEnvKeys)
setStringFromEnvVal(&cfg.SharedConfigProfile, profileEnvKeys)
cfg.SharedCredentialsFile = os.Getenv(awsSharedCredentialsFileEnvVar)
cfg.SharedConfigFile = os.Getenv(awsConfigFileEnvVar)
cfg.CustomCABundle = os.Getenv(awsCustomCABundleEnvVar)
cfg.WebIdentityTokenFilePath = os.Getenv(awsWebIdentityTokenFilePathEnvKey)
cfg.RoleARN = os.Getenv(awsRoleARNEnvKey)
cfg.RoleSessionName = os.Getenv(awsRoleSessionNameEnvKey)
if err := setBoolPtrFromEnvVal(&cfg.EnableEndpointDiscovery, []string{awsEnableEndpointDiscoveryEnvKey}); err != nil {
return cfg, err
}
if err := setBoolPtrFromEnvVal(&cfg.S3UseARNRegion, []string{awsS3UseARNRegionEnvVar}); err != nil {
return cfg, err
}
return cfg, nil
}
// GetRegion returns the AWS Region if set in the environment. Returns an empty
// string if not set.
func (c EnvConfig) getRegion(ctx context.Context) (string, bool, error) {
if len(c.Region) == 0 {
return "", false, nil
}
return c.Region, true, nil
}
// GetSharedConfigProfile returns the shared config profile if set in the
// environment. Returns an empty string if not set.
func (c EnvConfig) getSharedConfigProfile(ctx context.Context) (string, bool, error) {
if len(c.SharedConfigProfile) == 0 {
return "", false, nil
}
return c.SharedConfigProfile, true, nil
}
// getSharedConfigFiles returns a slice of filenames set in the environment.
//
// Will return the filenames in the order of:
// * Shared Config
func (c EnvConfig) getSharedConfigFiles(context.Context) ([]string, bool, error) {
var files []string
if v := c.SharedConfigFile; len(v) > 0 {
files = append(files, v)
}
if len(files) == 0 {
return nil, false, nil
}
return files, true, nil
}
// getSharedCredentialsFiles returns a slice of filenames set in the environment.
//
// Will return the filenames in the order of:
// * Shared Credentials
func (c EnvConfig) getSharedCredentialsFiles(context.Context) ([]string, bool, error) {
var files []string
if v := c.SharedCredentialsFile; len(v) > 0 {
files = append(files, v)
}
if len(files) == 0 {
return nil, false, nil
}
return files, true, nil
}
// GetCustomCABundle returns the custom CA bundle's PEM bytes if the file was
func (c EnvConfig) getCustomCABundle(context.Context) (io.Reader, bool, error) {
if len(c.CustomCABundle) == 0 {
return nil, false, nil
}
b, err := ioutil.ReadFile(c.CustomCABundle)
if err != nil {
return nil, false, err
}
return bytes.NewReader(b), true, nil
}
// GetS3UseARNRegion returns whether to allow ARNs to direct the region
// the S3 client's requests are sent to.
func (c EnvConfig) GetS3UseARNRegion(ctx context.Context) (value, ok bool, err error) {
if c.S3UseARNRegion == nil {
return false, false, nil
}
return *c.S3UseARNRegion, true, nil
}
func setStringFromEnvVal(dst *string, keys []string) {
for _, k := range keys {
if v := os.Getenv(k); len(v) > 0 {
*dst = v
break
}
}
}
func setBoolPtrFromEnvVal(dst **bool, keys []string) error {
for _, k := range keys {
value := os.Getenv(k)
if len(value) == 0 {
continue
}
if *dst == nil {
*dst = new(bool)
}
switch {
case strings.EqualFold(value, "false"):
**dst = false
case strings.EqualFold(value, "true"):
**dst = true
default:
return fmt.Errorf(
"invalid value for environment variable, %s=%s, need true or false",
k, value)
}
break
}
return nil
}