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service.go
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service.go
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package ec2metadata
import (
"io/ioutil"
"net/http"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/request"
"github.com/aws/aws-sdk-go/aws/service"
"github.com/aws/aws-sdk-go/aws/service/serviceinfo"
)
// DefaultRetries states the default number of times the service client will
// attempt to retry a failed request before failing.
const DefaultRetries = 3
// A Config provides the configuration for the EC2 Metadata service.
type Config struct {
// An optional endpoint URL (hostname only or fully qualified URI)
// that overrides the default service endpoint for a client. Set this
// to nil, or `""` to use the default service endpoint.
Endpoint *string
// The HTTP client to use when sending requests. Defaults to
// `http.DefaultClient`.
HTTPClient *http.Client
// An integer value representing the logging level. The default log level
// is zero (LogOff), which represents no logging. To enable logging set
// to a LogLevel Value.
Logger aws.Logger
// The logger writer interface to write logging messages to. Defaults to
// standard out.
LogLevel *aws.LogLevelType
// The maximum number of times that a request will be retried for failures.
// Defaults to DefaultRetries for the number of retries to be performed
// per request.
MaxRetries *int
}
// A Client is an EC2 Metadata service Client.
type Client struct {
*service.Service
}
// New creates a new instance of the EC2 Metadata service client.
//
// In the general use case the configuration for this service client should not
// be needed and `nil` can be provided. Configuration is only needed if the
// `ec2metadata.Config` defaults need to be overridden. Eg. Setting LogLevel.
//
// @note This configuration will NOT be merged with the default AWS service
// client configuration `defaults.DefaultConfig`. Due to circular dependencies
// with the defaults package and credentials EC2 Role Provider.
func New(config *Config) *Client {
service := &service.Service{
ServiceInfo: serviceinfo.ServiceInfo{
Config: copyConfig(config),
ServiceName: "Client",
Endpoint: "http://169.254.169.254/latest",
APIVersion: "latest",
},
}
service.Initialize()
service.Handlers.Unmarshal.PushBack(unmarshalHandler)
service.Handlers.UnmarshalError.PushBack(unmarshalError)
service.Handlers.Validate.Clear()
service.Handlers.Validate.PushBack(validateEndpointHandler)
return &Client{service}
}
func copyConfig(config *Config) *aws.Config {
if config == nil {
config = &Config{}
}
c := &aws.Config{
Credentials: credentials.AnonymousCredentials,
Endpoint: config.Endpoint,
HTTPClient: config.HTTPClient,
Logger: config.Logger,
LogLevel: config.LogLevel,
MaxRetries: config.MaxRetries,
}
if c.HTTPClient == nil {
c.HTTPClient = http.DefaultClient
}
if c.Logger == nil {
c.Logger = aws.NewDefaultLogger()
}
if c.LogLevel == nil {
c.LogLevel = aws.LogLevel(aws.LogOff)
}
if c.MaxRetries == nil {
c.MaxRetries = aws.Int(DefaultRetries)
}
return c
}
type metadataOutput struct {
Content string
}
func unmarshalHandler(r *request.Request) {
defer r.HTTPResponse.Body.Close()
b, err := ioutil.ReadAll(r.HTTPResponse.Body)
if err != nil {
r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata respose", err)
}
data := r.Data.(*metadataOutput)
data.Content = string(b)
}
func unmarshalError(r *request.Request) {
defer r.HTTPResponse.Body.Close()
_, err := ioutil.ReadAll(r.HTTPResponse.Body)
if err != nil {
r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata error respose", err)
}
// TODO extract the error...
}
func validateEndpointHandler(r *request.Request) {
if r.Service.Endpoint == "" {
r.Error = aws.ErrMissingEndpoint
}
}