util/cloudenv: add ApproximateLocation to Cloudandrew/cloudenv-location

This function will return the approximate location if running in a cloud
environment with a known region. Currently only AWS is supported.

Change-Id: Ic4f14de4c76c7bd37d71b4eb7813e97f3878ff59

1 files changed, 110 insertions, 0 deletions

diff --git a/util/cloudenv/cloudenv.go b/util/cloudenv/cloudenv.go
index 3c86339e4..03443c9ec 100644
--- a/util/cloudenv/cloudenv.go
+++ b/util/cloudenv/cloudenv.go
@@ -5,8 +5,10 @@
 package cloudenv
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"io"
 	"log"
 	"net"
 	"net/http"
@@ -181,3 +183,111 @@ func getCloud() Cloud {
 	// TODO: more, as needed.
 	return ""
 }
+
+// ApproximateLocation returns the approximate geographic location of the
+// region that the current cloud host is running in.
+//
+// If the current host is not running in the cloud, if cloud provider is not
+// supported, or if the current region could not be determined, then (0, 0)
+// will be returned.
+func (c Cloud) ApproximateLocation() (lat, lon float64) {
+	switch c {
+	case AWS:
+		loc := getApproximateLocationAWS()
+		return loc.lat, loc.lon
+	case GCP:
+		// TODO
+	case Azure:
+		// TODO
+	}
+	return 0, 0
+}
+
+type location struct{ lat, lon float64 }
+
+var noLocation location
+
+var approximateAWSRegionLocation = map[string]location{
+	"af-south-1":     {-33.928992, 18.417396},    // "CPT" / Cape Town, South Africa
+	"ap-east-1":      {22.2793278, 114.1628131},  // "HKG" / Hong Kong
+	"ap-northeast-1": {35.6812665, 139.757653},   // "NRT" / Tokyo, Japan
+	"ap-northeast-2": {37.5666791, 126.9782914},  // "ICN" / Seoul, Korea
+	"ap-northeast-3": {34.661629, 135.4999268},   // "KIX" / Osaka, Japan
+	"ap-south-1":     {19.0785451, 72.878176},    // "BOM" / Mumbai, India
+	"ap-south-2":     {17.38878595, 78.46106473}, // "HYD" / Hyderabad, India
+	"ap-southeast-1": {1.357107, 103.8194992},    // "SIN" / Singapore
+	"ap-southeast-2": {-33.8698439, 151.2082848}, // "SYD" / Sydney, Australia
+	"ap-southeast-3": {-6.1753942, 106.827183},   // "CGK" / Jakarta, Indonesia
+	"ap-southeast-4": {-37.8142176, 144.9631608}, // "MEL" / Melbourne, Australia
+	"ca-central-1":   {45.5031824, -73.5698065},  // "YUL" / Montreal, Canada
+	"cn-north-1":     {39.906217, 116.3912757},   // "BJS" / Beijing
+	"cn-northwest-1": {37.4999947, 105.1928783},  // "ZHY" / Zhongwei
+	"eu-central-1":   {50.1106444, 8.6820917},    // "FRA" / Frankfurt, Germany
+	"eu-central-2":   {47.3744489, 8.5410422},    // "ZRH" / Zurich, Switzerland
+	"eu-north-1":     {59.3251172, 18.0710935},   // "ARN" / Stockholm, Sweden
+	"eu-south-1":     {45.4641943, 9.1896346},    // "MXP" / Milan, Italy
+	"eu-south-2":     {41.6521342, -0.8809428},   // "ZAZ" / Zaragoza, Spain
+	"eu-west-1":      {53.3498006, -6.2602964},   // "DUB" / Dublin, Ireland
+	"eu-west-2":      {51.5073359, -0.12765},     // "LHR" / London, England
+	"eu-west-3":      {48.8588897, 2.32004102},   // "CDG" / Paris, France
+	"me-south-1":     {26.1551249, 50.5344606},   // "BAH" / Bahrain
+	"sa-east-1":      {-23.5506507, -46.6333824}, // "GRU" / São Paulo, Brazil
+	"us-east-1":      {38.8950368, -77.0365427},  // "IAD" / Washington D.C., USA
+	"us-east-2":      {39.9622601, -83.0007065},  // "CMH" / Columbus, Ohio, USA
+	"us-gov-east-1":  {39.9622601, -83.0007065},  // "CMH" / Columbus, Ohio, USA
+	"us-gov-west-1":  {45.5202471, -122.674194},  // "PDX" / Portland, Oregon, USA
+	"us-west-1":      {37.7790262, -122.419906},  // "SFO" / San Francisco, California, USA
+	"us-west-2":      {45.5202471, -122.674194},  // "PDX" / Portland, Oregon, USA
+
+	// NOTE: it's not public where in Dubai this is
+	"me-central-1": {25.07428234, 55.18853865}, // Dubai
+}
+
+func getApproximateLocationAWS() location {
+	const maxWait = 2 * time.Second
+	tr := &http.Transport{
+		DisableKeepAlives: true,
+		Dial: (&net.Dialer{
+			Timeout: maxWait,
+		}).Dial,
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), maxWait)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, "PUT", "http://"+CommonNonRoutableMetadataIP+"/latest/api/token", nil)
+	if err != nil {
+		return noLocation
+	}
+	req.Header.Set("X-aws-ec2-metadata-token-ttl-seconds", "30")
+
+	res, err := tr.RoundTrip(req)
+	if err != nil {
+		return noLocation
+	}
+	token, err := io.ReadAll(res.Body)
+	res.Body.Close()
+	if err != nil {
+		return noLocation
+	}
+
+	req, err = http.NewRequestWithContext(ctx, "GET", "http://"+CommonNonRoutableMetadataIP+"/latest/dynamic/instance-identity/document", nil)
+	if err != nil {
+		return noLocation
+	}
+	req.Header.Set("X-aws-ec2-metadata-token", string(bytes.TrimSpace(token)))
+
+	res, err = tr.RoundTrip(req)
+	if err != nil {
+		return noLocation
+	}
+	defer res.Body.Close()
+
+	var identityDocument struct {
+		Region string `json:"region"`
+	}
+	if err := json.NewDecoder(res.Body).Decode(&identityDocument); err != nil {
+		return noLocation
+	}
+
+	return approximateAWSRegionLocation[identityDocument.Region]
+}