Joe Adams 7a29bd2cb4
discovery/aws: Fix region load from IMDS
Loading the local region from the Instance MetaData Service broke in v3.7. This adds the IMDS call back in order to load the local region when no other method has set the region.

fixes #17375

Signed-off-by: Joe Adams <github@joeadams.io>
2025-10-20 22:47:07 -04:00

409 lines
13 KiB
Go

// Copyright 2021 The Prometheus 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 aws
import (
"context"
"errors"
"fmt"
"log/slog"
"net"
"strconv"
"strings"
"time"
"github.com/aws/aws-sdk-go-v2/aws"
awsConfig "github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/credentials"
"github.com/aws/aws-sdk-go-v2/credentials/stscreds"
"github.com/aws/aws-sdk-go-v2/feature/ec2/imds"
"github.com/aws/aws-sdk-go-v2/service/ec2"
ec2Types "github.com/aws/aws-sdk-go-v2/service/ec2/types"
"github.com/aws/aws-sdk-go-v2/service/sts"
"github.com/aws/smithy-go"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/config"
"github.com/prometheus/common/model"
"github.com/prometheus/common/promslog"
"github.com/prometheus/prometheus/discovery"
"github.com/prometheus/prometheus/discovery/refresh"
"github.com/prometheus/prometheus/discovery/targetgroup"
"github.com/prometheus/prometheus/util/strutil"
)
const (
ec2Label = model.MetaLabelPrefix + "ec2_"
ec2LabelAMI = ec2Label + "ami"
ec2LabelAZ = ec2Label + "availability_zone"
ec2LabelAZID = ec2Label + "availability_zone_id"
ec2LabelArch = ec2Label + "architecture"
ec2LabelIPv6Addresses = ec2Label + "ipv6_addresses"
ec2LabelInstanceID = ec2Label + "instance_id"
ec2LabelInstanceLifecycle = ec2Label + "instance_lifecycle"
ec2LabelInstanceState = ec2Label + "instance_state"
ec2LabelInstanceType = ec2Label + "instance_type"
ec2LabelOwnerID = ec2Label + "owner_id"
ec2LabelPlatform = ec2Label + "platform"
ec2LabelPrimaryIPv6Addresses = ec2Label + "primary_ipv6_addresses"
ec2LabelPrimarySubnetID = ec2Label + "primary_subnet_id"
ec2LabelPrivateDNS = ec2Label + "private_dns_name"
ec2LabelPrivateIP = ec2Label + "private_ip"
ec2LabelPublicDNS = ec2Label + "public_dns_name"
ec2LabelPublicIP = ec2Label + "public_ip"
ec2LabelRegion = ec2Label + "region"
ec2LabelSubnetID = ec2Label + "subnet_id"
ec2LabelTag = ec2Label + "tag_"
ec2LabelVPCID = ec2Label + "vpc_id"
ec2LabelSeparator = ","
)
// DefaultEC2SDConfig is the default EC2 SD configuration.
var DefaultEC2SDConfig = EC2SDConfig{
Port: 80,
RefreshInterval: model.Duration(60 * time.Second),
HTTPClientConfig: config.DefaultHTTPClientConfig,
}
func init() {
discovery.RegisterConfig(&EC2SDConfig{})
}
// EC2Filter is the configuration for filtering EC2 instances.
type EC2Filter struct {
Name string `yaml:"name"`
Values []string `yaml:"values"`
}
// EC2SDConfig is the configuration for EC2 based service discovery.
type EC2SDConfig struct {
Endpoint string `yaml:"endpoint"`
Region string `yaml:"region"`
AccessKey string `yaml:"access_key,omitempty"`
SecretKey config.Secret `yaml:"secret_key,omitempty"`
Profile string `yaml:"profile,omitempty"`
RoleARN string `yaml:"role_arn,omitempty"`
RefreshInterval model.Duration `yaml:"refresh_interval,omitempty"`
Port int `yaml:"port"`
Filters []*EC2Filter `yaml:"filters"`
HTTPClientConfig config.HTTPClientConfig `yaml:",inline"`
}
// NewDiscovererMetrics implements discovery.Config.
func (*EC2SDConfig) NewDiscovererMetrics(_ prometheus.Registerer, rmi discovery.RefreshMetricsInstantiator) discovery.DiscovererMetrics {
return &ec2Metrics{
refreshMetrics: rmi,
}
}
// Name returns the name of the EC2 Config.
func (*EC2SDConfig) Name() string { return "ec2" }
// NewDiscoverer returns a Discoverer for the EC2 Config.
func (c *EC2SDConfig) NewDiscoverer(opts discovery.DiscovererOptions) (discovery.Discoverer, error) {
return NewEC2Discovery(c, opts.Logger, opts.Metrics)
}
// UnmarshalYAML implements the yaml.Unmarshaler interface for the EC2 Config.
func (c *EC2SDConfig) UnmarshalYAML(unmarshal func(any) error) error {
*c = DefaultEC2SDConfig
type plain EC2SDConfig
err := unmarshal((*plain)(c))
if err != nil {
return err
}
if c.Region == "" {
cfg, err := awsConfig.LoadDefaultConfig(context.Background())
if err != nil {
return err
}
if cfg.Region != "" {
// If the region is already set in the config, use it.
// This can happen if the user has set the region in the AWS config file or environment variables.
c.Region = cfg.Region
}
if c.Region == "" {
// Try to get the region from the instance metadata service (IMDS).
imdsClient := imds.NewFromConfig(cfg)
region, err := imdsClient.GetRegion(context.Background(), &imds.GetRegionInput{})
if err != nil {
return err
}
c.Region = region.Region
}
}
if c.Region == "" {
return errors.New("EC2 SD configuration requires a region")
}
for _, f := range c.Filters {
if len(f.Values) == 0 {
return errors.New("EC2 SD configuration filter values cannot be empty")
}
}
return c.HTTPClientConfig.Validate()
}
type ec2Client interface {
DescribeAvailabilityZones(ctx context.Context, params *ec2.DescribeAvailabilityZonesInput, optFns ...func(*ec2.Options)) (*ec2.DescribeAvailabilityZonesOutput, error)
DescribeInstances(ctx context.Context, params *ec2.DescribeInstancesInput, optFns ...func(*ec2.Options)) (*ec2.DescribeInstancesOutput, error)
}
// EC2Discovery periodically performs EC2-SD requests. It implements
// the Discoverer interface.
type EC2Discovery struct {
*refresh.Discovery
logger *slog.Logger
cfg *EC2SDConfig
ec2 ec2Client
// azToAZID maps this account's availability zones to their underlying AZ
// ID, e.g. eu-west-2a -> euw2-az2. Refreshes are performed sequentially, so
// no locking is required.
azToAZID map[string]string
}
// NewEC2Discovery returns a new EC2Discovery which periodically refreshes its targets.
func NewEC2Discovery(conf *EC2SDConfig, logger *slog.Logger, metrics discovery.DiscovererMetrics) (*EC2Discovery, error) {
m, ok := metrics.(*ec2Metrics)
if !ok {
return nil, errors.New("invalid discovery metrics type")
}
if logger == nil {
logger = promslog.NewNopLogger()
}
d := &EC2Discovery{
logger: logger,
cfg: conf,
}
d.Discovery = refresh.NewDiscovery(
refresh.Options{
Logger: logger,
Mech: "ec2",
Interval: time.Duration(d.cfg.RefreshInterval),
RefreshF: d.refresh,
MetricsInstantiator: m.refreshMetrics,
},
)
return d, nil
}
func (d *EC2Discovery) ec2Client(ctx context.Context) (ec2Client, error) {
if d.ec2 != nil {
return d.ec2, nil
}
credProvider := credentials.NewStaticCredentialsProvider(d.cfg.AccessKey, string(d.cfg.SecretKey), "")
// Build the HTTP client from the provided HTTPClientConfig.
httpClient, err := config.NewClientFromConfig(d.cfg.HTTPClientConfig, "ec2_sd")
if err != nil {
return nil, err
}
// Build the AWS config with the provided region and credentials.
cfg, err := awsConfig.LoadDefaultConfig(
ctx,
awsConfig.WithRegion(d.cfg.Region),
awsConfig.WithCredentialsProvider(credProvider),
awsConfig.WithSharedConfigProfile(d.cfg.Profile),
awsConfig.WithHTTPClient(httpClient),
)
if err != nil {
return nil, fmt.Errorf("could not create aws config: %w", err)
}
// If the role ARN is set, assume the role to get credentials and set the credentials provider in the config.
if d.cfg.RoleARN != "" {
assumeProvider := stscreds.NewAssumeRoleProvider(sts.NewFromConfig(cfg), d.cfg.RoleARN)
cfg.Credentials = aws.NewCredentialsCache(assumeProvider)
}
d.ec2 = ec2.NewFromConfig(cfg)
return d.ec2, nil
}
func (d *EC2Discovery) refreshAZIDs(ctx context.Context) error {
azs, err := d.ec2.DescribeAvailabilityZones(ctx, &ec2.DescribeAvailabilityZonesInput{})
if err != nil {
return err
}
d.azToAZID = make(map[string]string, len(azs.AvailabilityZones))
for _, az := range azs.AvailabilityZones {
d.azToAZID[*az.ZoneName] = *az.ZoneId
}
return nil
}
func (d *EC2Discovery) refresh(ctx context.Context) ([]*targetgroup.Group, error) {
ec2Client, err := d.ec2Client(ctx)
if err != nil {
return nil, err
}
tg := &targetgroup.Group{
Source: d.cfg.Region,
}
var filters []ec2Types.Filter
for _, f := range d.cfg.Filters {
filters = append(filters, ec2Types.Filter{
Name: aws.String(f.Name),
Values: f.Values,
})
}
// Only refresh the AZ ID map if we have never been able to build one.
// Prometheus requires a reload if AWS adds a new AZ to the region.
if d.azToAZID == nil {
if err := d.refreshAZIDs(ctx); err != nil {
d.logger.Debug(
"Unable to describe availability zones",
"err", err)
}
}
input := &ec2.DescribeInstancesInput{Filters: filters}
paginator := ec2.NewDescribeInstancesPaginator(ec2Client, input)
for paginator.HasMorePages() {
p, err := paginator.NextPage(ctx)
if err != nil {
var awsErr smithy.APIError
if errors.As(err, &awsErr) && (awsErr.ErrorCode() == "AuthFailure" || awsErr.ErrorCode() == "UnauthorizedOperation") {
d.ec2 = nil
}
return nil, fmt.Errorf("could not describe instances: %w", err)
}
for _, r := range p.Reservations {
for _, inst := range r.Instances {
if inst.PrivateIpAddress == nil {
continue
}
labels := model.LabelSet{
ec2LabelInstanceID: model.LabelValue(*inst.InstanceId),
ec2LabelRegion: model.LabelValue(d.cfg.Region),
}
if r.OwnerId != nil {
labels[ec2LabelOwnerID] = model.LabelValue(*r.OwnerId)
}
labels[ec2LabelPrivateIP] = model.LabelValue(*inst.PrivateIpAddress)
if inst.PrivateDnsName != nil {
labels[ec2LabelPrivateDNS] = model.LabelValue(*inst.PrivateDnsName)
}
addr := net.JoinHostPort(*inst.PrivateIpAddress, strconv.Itoa(d.cfg.Port))
labels[model.AddressLabel] = model.LabelValue(addr)
if inst.Platform != "" {
labels[ec2LabelPlatform] = model.LabelValue(inst.Platform)
}
if inst.PublicIpAddress != nil {
labels[ec2LabelPublicIP] = model.LabelValue(*inst.PublicIpAddress)
labels[ec2LabelPublicDNS] = model.LabelValue(*inst.PublicDnsName)
}
labels[ec2LabelAMI] = model.LabelValue(*inst.ImageId)
labels[ec2LabelAZ] = model.LabelValue(*inst.Placement.AvailabilityZone)
azID, ok := d.azToAZID[*inst.Placement.AvailabilityZone]
if !ok && d.azToAZID != nil {
d.logger.Debug(
"Availability zone ID not found",
"az", *inst.Placement.AvailabilityZone)
}
labels[ec2LabelAZID] = model.LabelValue(azID)
labels[ec2LabelInstanceState] = model.LabelValue(inst.State.Name)
labels[ec2LabelInstanceType] = model.LabelValue(inst.InstanceType)
if inst.InstanceLifecycle != "" {
labels[ec2LabelInstanceLifecycle] = model.LabelValue(inst.InstanceLifecycle)
}
if inst.Architecture != "" {
labels[ec2LabelArch] = model.LabelValue(inst.Architecture)
}
if inst.VpcId != nil {
labels[ec2LabelVPCID] = model.LabelValue(*inst.VpcId)
labels[ec2LabelPrimarySubnetID] = model.LabelValue(*inst.SubnetId)
var subnets []string
var ipv6addrs []string
var primaryipv6addrs []string
subnetsMap := make(map[string]struct{})
for _, eni := range inst.NetworkInterfaces {
if eni.SubnetId == nil {
continue
}
// Deduplicate VPC Subnet IDs maintaining the order of the subnets returned by EC2.
if _, ok := subnetsMap[*eni.SubnetId]; !ok {
subnetsMap[*eni.SubnetId] = struct{}{}
subnets = append(subnets, *eni.SubnetId)
}
for _, ipv6addr := range eni.Ipv6Addresses {
ipv6addrs = append(ipv6addrs, *ipv6addr.Ipv6Address)
if *ipv6addr.IsPrimaryIpv6 {
// we might have to extend the slice with more than one element
// that could leave empty strings in the list which is intentional
// to keep the position/device index information
for int32(len(primaryipv6addrs)) <= *eni.Attachment.DeviceIndex {
primaryipv6addrs = append(primaryipv6addrs, "")
}
primaryipv6addrs[*eni.Attachment.DeviceIndex] = *ipv6addr.Ipv6Address
}
}
}
labels[ec2LabelSubnetID] = model.LabelValue(
ec2LabelSeparator +
strings.Join(subnets, ec2LabelSeparator) +
ec2LabelSeparator)
if len(ipv6addrs) > 0 {
labels[ec2LabelIPv6Addresses] = model.LabelValue(
ec2LabelSeparator +
strings.Join(ipv6addrs, ec2LabelSeparator) +
ec2LabelSeparator)
}
if len(primaryipv6addrs) > 0 {
labels[ec2LabelPrimaryIPv6Addresses] = model.LabelValue(
ec2LabelSeparator +
strings.Join(primaryipv6addrs, ec2LabelSeparator) +
ec2LabelSeparator)
}
}
for _, t := range inst.Tags {
if t.Key == nil || t.Value == nil {
continue
}
name := strutil.SanitizeLabelName(*t.Key)
labels[ec2LabelTag+model.LabelName(name)] = model.LabelValue(*t.Value)
}
tg.Targets = append(tg.Targets, labels)
}
}
}
return []*targetgroup.Group{tg}, nil
}