Files
nomad/client/fingerprint/env_aws.go
2025-01-09 17:27:19 -05:00

309 lines
8.0 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1
package fingerprint
import (
"context"
"errors"
"fmt"
"io"
"net/http"
"regexp"
"strings"
"time"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/feature/ec2/imds"
smithyHttp "github.com/aws/smithy-go/transport/http"
"github.com/hashicorp/go-cleanhttp"
log "github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/nomad/structs"
)
const (
// AwsMetadataTimeout is the timeout used when contacting the AWS metadata
// services.
AwsMetadataTimeout = 2 * time.Second
)
// map of instance type to approximate speed, in Mbits/s
// Estimates from http://stackoverflow.com/a/35806587
// This data is meant for a loose approximation
var ec2NetSpeedTable = map[*regexp.Regexp]int{
regexp.MustCompile("t2.nano"): 30,
regexp.MustCompile("t2.micro"): 70,
regexp.MustCompile("t2.small"): 125,
regexp.MustCompile("t2.medium"): 300,
regexp.MustCompile("m3.medium"): 400,
regexp.MustCompile("c4.8xlarge"): 4000,
regexp.MustCompile("x1.16xlarge"): 5000,
regexp.MustCompile(`.*\.large`): 500,
regexp.MustCompile(`.*\.xlarge`): 750,
regexp.MustCompile(`.*\.2xlarge`): 1000,
regexp.MustCompile(`.*\.4xlarge`): 2000,
regexp.MustCompile(`.*\.8xlarge`): 10000,
regexp.MustCompile(`.*\.10xlarge`): 10000,
regexp.MustCompile(`.*\.16xlarge`): 10000,
regexp.MustCompile(`.*\.32xlarge`): 10000,
}
// EnvAWSFingerprint is used to fingerprint AWS metadata
type EnvAWSFingerprint struct {
StaticFingerprinter
// used to override IMDS endpoint for testing
endpoint string
logger log.Logger
}
// NewEnvAWSFingerprint is used to create a fingerprint from AWS metadata
func NewEnvAWSFingerprint(logger log.Logger) Fingerprint {
f := &EnvAWSFingerprint{
logger: logger.Named("env_aws"),
}
return f
}
func (f *EnvAWSFingerprint) Fingerprint(request *FingerprintRequest, response *FingerprintResponse) error {
cfg := request.Config
timeout := AwsMetadataTimeout
// Check if we should tighten the timeout
if cfg.ReadBoolDefault(TightenNetworkTimeoutsConfig, false) {
timeout = 1 * time.Millisecond
}
ctx, cancel := context.WithTimeout(context.TODO(), timeout)
defer cancel()
imdsClient, err := f.imdsClient(ctx)
if err != nil {
return fmt.Errorf("failed to setup IMDS client: %v", err)
}
if !isAWS(ctx, imdsClient) {
f.logger.Debug("error querying AWS IDMS URL, skipping")
return nil
}
// Keys and whether they should be namespaced as unique. Any key whose value
// uniquely identifies a node, such as ip, should be marked as unique. When
// marked as unique, the key isn't included in the computed node class.
keys := map[string]bool{
"ami-id": false,
"hostname": true,
"instance-id": true,
"instance-life-cycle": false,
"instance-type": false,
"local-hostname": true,
"local-ipv4": true,
"public-hostname": true,
"public-ipv4": true,
"mac": true,
"placement/availability-zone": false,
}
for k, unique := range keys {
resp, err := imdsClient.GetMetadata(ctx, &imds.GetMetadataInput{
Path: k,
})
if err := f.handleImdsError(err, k); err != nil {
return err
}
if resp == nil {
continue
}
v, err := readMetadataResponse(resp)
if err != nil {
return err
}
if v == "" {
f.logger.Debug("read an empty value", "attribute", k)
continue
}
// assume we want blank entries
key := "platform.aws." + strings.ReplaceAll(k, "/", ".")
if unique {
key = structs.UniqueNamespace(key)
}
response.AddAttribute(key, v)
}
// accumulate resource information, then assign to response
nodeResources := new(structs.NodeResources)
// copy over network specific information
if val, ok := response.Attributes["unique.platform.aws.local-ipv4"]; ok && val != "" {
response.AddAttribute("unique.network.ip-address", val)
nodeResources.Networks = []*structs.NetworkResource{
{
Mode: "host",
Device: "eth0",
IP: val,
CIDR: val + "/32",
MBits: f.throughput(request, imdsClient, val),
},
}
}
// copy over IPv6 network specific information
if val, ok := response.Attributes["unique.platform.aws.mac"]; ok && val != "" {
k := "network/interfaces/macs/" + val + "/ipv6s"
resp, err := imdsClient.GetMetadata(ctx, &imds.GetMetadataInput{
Path: k,
})
if err := f.handleImdsError(err, k); err != nil {
return err
}
if resp != nil {
addrsStr, err := readMetadataResponse(resp)
if err != nil {
return err
}
if addrsStr == "" {
f.logger.Debug("read an empty value", "attribute", k)
} else {
addrs := strings.SplitN(addrsStr, "\n", 2)
response.AddAttribute("unique.platform.aws.public-ipv6", addrs[0])
}
}
}
response.NodeResources = nodeResources
// populate Links
response.AddLink("aws.ec2", fmt.Sprintf("%s.%s",
response.Attributes["platform.aws.placement.availability-zone"],
response.Attributes["unique.platform.aws.instance-id"]))
response.Detected = true
return nil
}
// See https://aws.github.io/aws-sdk-go-v2/docs/handling-errors for
// recommended error handling with aws-sdk-go-v2.
// See also: https://github.com/aws/aws-sdk-go-v2/issues/1306
func (f *EnvAWSFingerprint) handleImdsError(err error, attr string) error {
var apiErr *smithyHttp.ResponseError
if errors.As(err, &apiErr) {
// In the event of a request error while fetching attributes, just log and return nil.
// This will happen if attributes do not exist for this instance (ex. ipv6, public-ipv4s).
f.logger.Debug("could not read attribute value", "attribute", attr, "error", err)
return nil
}
return err
}
func (f *EnvAWSFingerprint) instanceType(client *imds.Client) (string, error) {
output, err := client.GetMetadata(context.TODO(), &imds.GetMetadataInput{
Path: "instance-type",
})
if err != nil {
return "", err
}
content, err := io.ReadAll(output.Content)
if err != nil {
return "", err
}
return strings.TrimSpace(string(content)), nil
}
func (f *EnvAWSFingerprint) throughput(request *FingerprintRequest, client *imds.Client, ip string) int {
throughput := request.Config.NetworkSpeed
if throughput != 0 {
return throughput
}
throughput = f.linkSpeed(client)
if throughput != 0 {
return throughput
}
if request.Node.Resources != nil && len(request.Node.Resources.Networks) > 0 {
for _, n := range request.Node.Resources.Networks {
if n.IP == ip {
return n.MBits
}
}
}
return defaultNetworkSpeed
}
// EnvAWSFingerprint uses lookup table to approximate network speeds
func (f *EnvAWSFingerprint) linkSpeed(client *imds.Client) int {
instanceType, err := f.instanceType(client)
if err != nil {
f.logger.Error("error reading instance-type", "error", err)
return 0
}
netSpeed := 0
for reg, speed := range ec2NetSpeedTable {
if reg.MatchString(instanceType) {
netSpeed = speed
break
}
}
return netSpeed
}
func (f *EnvAWSFingerprint) imdsClient(ctx context.Context) (*imds.Client, error) {
client := &http.Client{
Transport: cleanhttp.DefaultTransport(),
}
cfg, err := config.LoadDefaultConfig(ctx,
config.WithHTTPClient(client),
config.WithRetryMaxAttempts(0),
)
if err != nil {
return nil, err
}
imdsClient := imds.NewFromConfig(cfg, func(o *imds.Options) {
// endpoint should only be overridden for testing
if f.endpoint != "" {
o.Endpoint = f.endpoint
}
})
return imdsClient, nil
}
func isAWS(ctx context.Context, client *imds.Client) bool {
resp, err := client.GetMetadata(ctx, &imds.GetMetadataInput{
Path: "ami-id",
})
if err != nil {
return false
}
s, err := readMetadataResponse(resp)
if err != nil {
return false
}
return s != ""
}
// readImdsResponse reads and formats the IMDS response
// and most importantly, closes the io.ReadCloser
func readMetadataResponse(resp *imds.GetMetadataOutput) (string, error) {
defer resp.Content.Close()
b, err := io.ReadAll(resp.Content)
if err != nil {
return "", err
}
return strings.TrimSpace(string(b)), nil
}