awsinstancetag

Documentation

Overview

Package awsinstancetag helps retrieving data from AWS instance metadata.

This is oriented toward software configuration (not infrastructure checking or monitoring). Secrets must NOT be stored in metadata (not safe). Some methods require tags to be explicitly allowed in the instance options.

See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html and https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html

This is opinionated for a specific use:

• Using https://ec2.amazonaws.com/?Action=DescribeInstances (https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html)
• Using "http://169.254.169.254/latest/dynamic/instance-identity/document"
• NOT using "http://169.254.169.254/latest/user-data"
• NOT using "http://169.254.169.254/latest/meta-data"

It returns a custom error for common catch errors (Like "not on AWS" or "instance metadata not configured")

Index

• func Load(ctx context.Context, ims AWSInstanceMetadataService, ...) (*imds.GetInstanceIdentityDocumentOutput, *ec2.DescribeInstancesOutput, error)
• type AWSEC2Service
  • func CreateEC2sDefault(region string) (AWSEC2Service, error)
• type AWSInstanceMetadataService
• type ForbiddenInstanceTagReadingError
  • func (e ForbiddenInstanceTagReadingError) Error() string
  • func (e ForbiddenInstanceTagReadingError) Unwrap() error
• type UnreachableInstanceIdentityDocumentError
  • func (e UnreachableInstanceIdentityDocumentError) Error() string
  • func (e UnreachableInstanceIdentityDocumentError) Unwrap() error

Functions

func Load

func Load(
	ctx context.Context,
	ims AWSInstanceMetadataService,
	ec2s func(region string) (AWSEC2Service, error),
) (
	*imds.GetInstanceIdentityDocumentOutput,
	*ec2.DescribeInstancesOutput,
	error,
)

Load gets instances metadata.

First, it gets the InstanceIdentityDocument for the InstanceID + region. Then it creates a new session with the region and finally it calls DescribeInstances.

It uses CreateEC2sDefault() if ec2s is null.

Types

type AWSEC2Service

type AWSEC2Service interface {
	DescribeInstances(input *ec2.DescribeInstancesInput) (*ec2.DescribeInstancesOutput, error)
}

func CreateEC2sDefault

func CreateEC2sDefault(region string) (AWSEC2Service, error)

type AWSInstanceMetadataService

type AWSInstanceMetadataService interface {
	GetInstanceIdentityDocument(ctx context.Context, params *imds.GetInstanceIdentityDocumentInput, optFns ...func(*imds.Options)) (*imds.GetInstanceIdentityDocumentOutput, error)
}

type ForbiddenInstanceTagReadingError

type ForbiddenInstanceTagReadingError struct {
	Err error
}

see https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-options.html

func (ForbiddenInstanceTagReadingError) Error

func (e ForbiddenInstanceTagReadingError) Error() string

func (ForbiddenInstanceTagReadingError) Unwrap

func (e ForbiddenInstanceTagReadingError) Unwrap() error

type UnreachableInstanceIdentityDocumentError

type UnreachableInstanceIdentityDocumentError struct {
	Err error
}

func (UnreachableInstanceIdentityDocumentError) Error

func (e UnreachableInstanceIdentityDocumentError) Error() string

func (UnreachableInstanceIdentityDocumentError) Unwrap

func (e UnreachableInstanceIdentityDocumentError) Unwrap() error