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package aws
import (
"fmt"
"net/http"
"os"
"strconv"
"sync"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/ec2"
"github.com/hairyhenderson/gomplate/v4/env"
)
var describerClient InstanceDescriber
var (
co ClientOptions
coInit sync.Once
sdkSession *session.Session
sdkSessionInit sync.Once
)
// ClientOptions -
type ClientOptions struct {
Timeout time.Duration
}
// Ec2Info -
type Ec2Info struct {
describer func() (InstanceDescriber, error)
metaClient *Ec2Meta
cache map[string]any
}
// InstanceDescriber - A subset of ec2iface.EC2API that we can use to call EC2.DescribeInstances
type InstanceDescriber interface {
DescribeInstances(*ec2.DescribeInstancesInput) (*ec2.DescribeInstancesOutput, error)
}
// GetClientOptions - Centralised reading of AWS_TIMEOUT
// ... but cannot use in vault/auth.go as different strconv.Atoi error handling
func GetClientOptions() ClientOptions {
coInit.Do(func() {
timeout := env.Getenv("AWS_TIMEOUT")
if timeout == "" {
timeout = "500"
}
t, err := strconv.Atoi(timeout)
if err != nil {
panic(fmt.Errorf("invalid AWS_TIMEOUT value '%s' - must be an integer: %w", timeout, err))
}
co.Timeout = time.Duration(t) * time.Millisecond
})
return co
}
// SDKSession -
func SDKSession(region ...string) *session.Session {
sdkSessionInit.Do(func() {
options := GetClientOptions()
timeout := options.Timeout
if timeout == 0 {
timeout = 500 * time.Millisecond
}
config := aws.NewConfig()
config = config.WithHTTPClient(&http.Client{Timeout: timeout})
if env.Getenv("AWS_ANON") == "true" {
config = config.WithCredentials(credentials.AnonymousCredentials)
}
metaRegion := ""
if len(region) > 0 {
metaRegion = region[0]
} else {
var err error
metaRegion, err = getRegion()
if err != nil {
panic(fmt.Errorf("failed to determine EC2 region: %w", err))
}
}
if metaRegion != "" && metaRegion != unknown {
config = config.WithRegion(metaRegion)
}
config = config.WithCredentialsChainVerboseErrors(true)
sdkSession = session.Must(session.NewSessionWithOptions(session.Options{
Config: *config,
SharedConfigState: session.SharedConfigEnable,
}))
})
return sdkSession
}
// Attempts to get the EC2 region to use. If we're running on an EC2 Instance
// and neither AWS_REGION nor AWS_DEFAULT_REGION are set, we'll infer from EC2
// metadata.
// Once https://github.com/aws/aws-sdk-go/issues/1103 is resolve this should be
// tidier!
func getRegion(m ...*Ec2Meta) (string, error) {
region := ""
_, default1 := os.LookupEnv("AWS_REGION")
_, default2 := os.LookupEnv("AWS_DEFAULT_REGION")
if !default1 && !default2 {
// Maybe we're in EC2, let's try to read metadata
var metaClient *Ec2Meta
if len(m) > 0 {
metaClient = m[0]
} else {
metaClient = NewEc2Meta(GetClientOptions())
}
var err error
region, err = metaClient.Region()
if err != nil {
return "", fmt.Errorf("failed to determine EC2 region: %w", err)
}
}
return region, nil
}
// NewEc2Info -
func NewEc2Info(options ClientOptions) (info *Ec2Info) {
metaClient := NewEc2Meta(options)
return &Ec2Info{
describer: func() (InstanceDescriber, error) {
if describerClient == nil {
session := SDKSession()
describerClient = ec2.New(session)
}
return describerClient, nil
},
metaClient: metaClient,
cache: make(map[string]any),
}
}
// Tag -
func (e *Ec2Info) Tag(tag string, def ...string) (string, error) {
output, err := e.describeInstance()
if err != nil {
return "", err
}
if output == nil {
return returnDefault(def), nil
}
if len(output.Reservations) > 0 &&
len(output.Reservations[0].Instances) > 0 &&
len(output.Reservations[0].Instances[0].Tags) > 0 {
for _, v := range output.Reservations[0].Instances[0].Tags {
if *v.Key == tag {
return *v.Value, nil
}
}
}
return returnDefault(def), nil
}
func (e *Ec2Info) Tags() (map[string]string, error) {
tags := map[string]string{}
output, err := e.describeInstance()
if err != nil {
return tags, err
}
if output == nil {
return tags, nil
}
if len(output.Reservations) > 0 &&
len(output.Reservations[0].Instances) > 0 &&
len(output.Reservations[0].Instances[0].Tags) > 0 {
for _, v := range output.Reservations[0].Instances[0].Tags {
tags[*v.Key] = *v.Value
}
}
return tags, nil
}
func (e *Ec2Info) describeInstance() (output *ec2.DescribeInstancesOutput, err error) {
// cache the InstanceDescriber here
d, err := e.describer()
if err != nil || e.metaClient.nonAWS {
return nil, err
}
if cached, ok := e.cache["DescribeInstances"]; ok {
output = cached.(*ec2.DescribeInstancesOutput)
} else {
instanceID, err := e.metaClient.Meta("instance-id")
if err != nil {
return nil, err
}
input := &ec2.DescribeInstancesInput{
InstanceIds: aws.StringSlice([]string{instanceID}),
}
output, err = d.DescribeInstances(input)
if err != nil {
// default to nil if we can't describe the instance - this could be for any reason
return nil, nil
}
e.cache["DescribeInstances"] = output
}
return output, nil
}
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