ec2_metadata_client.go

// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may
// not use this file except in compliance with the License. A copy of the
// License is located at
//
//	http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file is distributed
// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
// express or implied. See the License for the specific language governing
// permissions and limitations under the License.

package ec2

import (
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/ec2metadata"
	"github.com/aws/aws-sdk-go/aws/session"
)

const (
	SecurityCrednetialsResource               = "iam/security-credentials/"
	InstanceIdentityDocumentResource          = "instance-identity/document"
	InstanceIdentityDocumentSignatureResource = "instance-identity/signature"
	MacResource                               = "mac"
	AllMacResource                            = "network/interfaces/macs"
	VPCIDResourceFormat                       = "network/interfaces/macs/%s/vpc-id"
	SubnetIDResourceFormat                    = "network/interfaces/macs/%s/subnet-id"
	SpotInstanceActionResource                = "spot/instance-action"
	InstanceIDResource                        = "instance-id"
	PrivateIPv4Resource                       = "local-ipv4"
	PublicIPv4Resource                        = "public-ipv4"
	OutpostARN                                = "outpost-arn"
)

const (
	metadataRetries = 5
)

// RoleCredentials contains the information associated with an IAM role
type RoleCredentials struct {
	Code            string    `json:"Code"`
	LastUpdated     time.Time `json:"LastUpdated"`
	Type            string    `json:"Type"`
	AccessKeyId     string    `json:"AccessKeyId"`
	SecretAccessKey string    `json:"SecretAccessKey"`
	Token           string    `json:"Token"`
	Expiration      time.Time `json:"Expiration"`
}

type HttpClient interface {
	GetMetadata(string) (string, error)
	GetDynamicData(string) (string, error)
	GetInstanceIdentityDocument() (ec2metadata.EC2InstanceIdentityDocument, error)
	GetUserData() (string, error)
	Region() (string, error)
}

// EC2MetadataClient is the client used to get metadata from instance metadata service
type EC2MetadataClient interface {
	DefaultCredentials() (*RoleCredentials, error)
	GetMetadata(string) (string, error)
	GetDynamicData(string) (string, error)
	InstanceIdentityDocument() (ec2metadata.EC2InstanceIdentityDocument, error)
	VPCID(mac string) (string, error)
	SubnetID(mac string) (string, error)
	PrimaryENIMAC() (string, error)
	AllENIMacs() (string, error)
	InstanceID() (string, error)
	GetUserData() (string, error)
	Region() (string, error)
	PrivateIPv4Address() (string, error)
	PublicIPv4Address() (string, error)
	SpotInstanceAction() (string, error)
	OutpostARN() (string, error)
}

type ec2MetadataClientImpl struct {
	client HttpClient
}

// NewEC2MetadataClient creates an ec2metadata client to retrieve metadata
func NewEC2MetadataClient(client HttpClient) EC2MetadataClient {
	if client == nil {
		return &ec2MetadataClientImpl{
			client: ec2metadata.New(
				session.New(), aws.NewConfig().WithMaxRetries(metadataRetries)),
		}
	} else {
		return &ec2MetadataClientImpl{client: client}
	}
}

// DefaultCredentials returns the credentials associated with the instance iam role
func (c *ec2MetadataClientImpl) DefaultCredentials() (*RoleCredentials, error) {
	securityCredential, err := c.client.GetMetadata(SecurityCrednetialsResource)
	if err != nil {
		return nil, err
	}

	securityCredentialList := strings.Split(strings.TrimSpace(securityCredential), "\n")
	if len(securityCredentialList) == 0 {
		return nil, errors.New("No security credentials in response")
	}

	defaultCredentialName := securityCredentialList[0]

	defaultCredentialStr, err := c.client.GetMetadata(SecurityCrednetialsResource + defaultCredentialName)
	if err != nil {
		return nil, err
	}
	var credential RoleCredentials
	err = json.Unmarshal([]byte(defaultCredentialStr), &credential)
	if err != nil {
		return nil, err
	}
	return &credential, nil
}

// GetDynamicData returns the dynamic data with provided path from instance metadata
func (c *ec2MetadataClientImpl) GetDynamicData(path string) (string, error) {
	return c.client.GetDynamicData(path)
}

// InstanceIdentityDocument returns instance identity documents
// http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html
func (c *ec2MetadataClientImpl) InstanceIdentityDocument() (ec2metadata.EC2InstanceIdentityDocument, error) {
	return c.client.GetInstanceIdentityDocument()
}

// GetMetadata returns the metadata from instance metadata service specified by the path
func (c *ec2MetadataClientImpl) GetMetadata(path string) (string, error) {
	return c.client.GetMetadata(path)
}

// PrimaryENIMAC returns the MAC address for the primary
// network interface of the instance
func (c *ec2MetadataClientImpl) PrimaryENIMAC() (string, error) {
	return c.client.GetMetadata(MacResource)
}

// AllENIMacs returns the mac addresses for all the network interfaces attached to the instance
func (c *ec2MetadataClientImpl) AllENIMacs() (string, error) {
	return c.client.GetMetadata(AllMacResource)
}

// VPCID returns the VPC id for the network interface, given
// its mac address
func (c *ec2MetadataClientImpl) VPCID(mac string) (string, error) {
	return c.client.GetMetadata(fmt.Sprintf(VPCIDResourceFormat, mac))
}

// SubnetID returns the subnet id for the network interface,
// given its mac address
func (c *ec2MetadataClientImpl) SubnetID(mac string) (string, error) {
	return c.client.GetMetadata(fmt.Sprintf(SubnetIDResourceFormat, mac))
}

// InstanceID returns the id of this instance.
func (c *ec2MetadataClientImpl) InstanceID() (string, error) {
	return c.client.GetMetadata(InstanceIDResource)
}

// GetUserData returns the userdata that was configured for the
func (c *ec2MetadataClientImpl) GetUserData() (string, error) {
	return c.client.GetUserData()
}

// Region returns the region the instance is running in.
func (c *ec2MetadataClientImpl) Region() (string, error) {
	return c.client.Region()
}

// PublicIPv4Address returns the public IPv4 of this instance
// if this instance has a public address
func (c *ec2MetadataClientImpl) PublicIPv4Address() (string, error) {
	return c.client.GetMetadata(PublicIPv4Resource)
}

// PrivateIPv4Address returns the private IPv4 of this instance
func (c *ec2MetadataClientImpl) PrivateIPv4Address() (string, error) {
	return c.client.GetMetadata(PrivateIPv4Resource)
}

// SpotInstanceAction returns the spot instance-action, if it has been set.
// If the time has not been set (ie, the instance is not scheduled for interruption)
// then this function returns an error.
// see https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-interruptions.html#using-spot-instances-managing-interruptions
func (c *ec2MetadataClientImpl) SpotInstanceAction() (string, error) {
	return c.client.GetMetadata(SpotInstanceActionResource)
}

func (c *ec2MetadataClientImpl) OutpostARN() (string, error) {
	return c.client.GetMetadata(OutpostARN)
}