forked from aws/aws-sdk-go-v2
/
service.go
110 lines (95 loc) · 3.09 KB
/
service.go
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// Package ec2metadata provides the client for making API calls to the
// EC2 Metadata service.
//
// This package's client can be disabled completely by setting the environment
// variable "AWS_EC2_METADATA_DISABLED=true". This environment variable set to
// true instructs the SDK to disable the EC2 Metadata client. The client cannot
// be used while the environemnt variable is set to true, (case insensitive).
package ec2metadata
import (
"bytes"
"errors"
"io"
"net/http"
"os"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/aws/awserr"
"github.com/aws/aws-sdk-go-v2/aws/defaults"
)
// ServiceName is the name of the service.
const ServiceName = "ec2metadata"
const disableServiceEnvVar = "AWS_EC2_METADATA_DISABLED"
// A EC2Metadata is an EC2 Metadata service Client.
type EC2Metadata struct {
*aws.Client
}
// New creates a new instance of the EC2Metadata client with a Config.
// This client is safe to use across multiple goroutines.
//
// Example:
// // Create a EC2Metadata client from just a config.
// svc := ec2metadata.New(cfg)
func New(config aws.Config) *EC2Metadata {
svc := &EC2Metadata{
Client: aws.NewClient(
config,
aws.Metadata{
ServiceName: ServiceName,
APIVersion: "latest",
},
),
}
svc.Handlers.Unmarshal.PushBack(unmarshalHandler)
svc.Handlers.UnmarshalError.PushBack(unmarshalError)
svc.Handlers.Validate.Clear()
svc.Handlers.Validate.PushBack(validateEndpointHandler)
// Disable the EC2 Metadata service if the environment variable is set.
// This shortcirctes the service's functionality to always fail to send
// requests.
if strings.ToLower(os.Getenv(disableServiceEnvVar)) == "true" {
svc.Handlers.Send.SwapNamed(aws.NamedHandler{
Name: defaults.SendHandler.Name,
Fn: func(r *aws.Request) {
r.Error = awserr.New(
aws.ErrCodeRequestCanceled,
"EC2 IMDS access disabled via "+disableServiceEnvVar+" env var",
nil)
},
})
}
return svc
}
func httpClientZero(c *http.Client) bool {
return c == nil || (c.Transport == nil && c.CheckRedirect == nil && c.Jar == nil && c.Timeout == 0)
}
type metadataOutput struct {
Content string
}
func unmarshalHandler(r *aws.Request) {
defer r.HTTPResponse.Body.Close()
b := &bytes.Buffer{}
if _, err := io.Copy(b, r.HTTPResponse.Body); err != nil {
r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata respose", err)
return
}
if data, ok := r.Data.(*metadataOutput); ok {
data.Content = b.String()
}
}
func unmarshalError(r *aws.Request) {
defer r.HTTPResponse.Body.Close()
b := &bytes.Buffer{}
if _, err := io.Copy(b, r.HTTPResponse.Body); err != nil {
r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata error respose", err)
return
}
// Response body format is not consistent between metadata endpoints.
// Grab the error message as a string and include that as the source error
r.Error = awserr.New("EC2MetadataError", "failed to make EC2Metadata request", errors.New(b.String()))
}
func validateEndpointHandler(r *aws.Request) {
if r.Metadata.Endpoint == "" {
r.Error = aws.ErrMissingEndpoint
}
}