azure_instance_metadata.go

/*
Copyright 2018 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License 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 azure

import (
	"encoding/json"
	"io/ioutil"
	"net/http"
)

const metadataURL = "http://169.254.169.254/metadata/"

// NetworkMetadata contains metadata about an instance's network
type NetworkMetadata struct {
	Interface []NetworkInterface `json:"interface"`
}

// NetworkInterface represents an instances network interface.
type NetworkInterface struct {
	IPV4 NetworkData `json:"ipv4"`
	IPV6 NetworkData `json:"ipv6"`
	MAC  string      `json:"macAddress"`
}

// NetworkData contains IP information for a network.
type NetworkData struct {
	IPAddress []IPAddress `json:"ipAddress"`
	Subnet    []Subnet    `json:"subnet"`
}

// IPAddress represents IP address information.
type IPAddress struct {
	PrivateIP string `json:"privateIPAddress"`
	PublicIP  string `json:"publicIPAddress"`
}

// Subnet represents subnet information.
type Subnet struct {
	Address string `json:"address"`
	Prefix  string `json:"prefix"`
}

// InstanceMetadata knows how to query the Azure instance metadata server.
type InstanceMetadata struct {
	baseURL string
}

// NewInstanceMetadata creates an instance of the InstanceMetadata accessor object.
func NewInstanceMetadata() *InstanceMetadata {
	return &InstanceMetadata{
		baseURL: metadataURL,
	}
}

// makeMetadataURL makes a complete metadata URL from the given path.
func (i *InstanceMetadata) makeMetadataURL(path string) string {
	return i.baseURL + path
}

// Object queries the metadata server and populates the passed in object
func (i *InstanceMetadata) Object(path string, obj interface{}) error {
	data, err := i.queryMetadataBytes(path, "json")
	if err != nil {
		return err
	}
	return json.Unmarshal(data, obj)
}

// Text queries the metadata server and returns the corresponding text
func (i *InstanceMetadata) Text(path string) (string, error) {
	data, err := i.queryMetadataBytes(path, "text")
	if err != nil {
		return "", err
	}
	return string(data), err
}

func (i *InstanceMetadata) queryMetadataBytes(path, format string) ([]byte, error) {
	client := &http.Client{}

	req, err := http.NewRequest("GET", i.makeMetadataURL(path), nil)
	if err != nil {
		return nil, err
	}
	req.Header.Add("Metadata", "True")

	q := req.URL.Query()
	q.Add("format", format)
	q.Add("api-version", "2017-04-02")
	req.URL.RawQuery = q.Encode()

	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	return ioutil.ReadAll(resp.Body)
}