Amazon EC2 Metadata Mock

Amazon EC2 Metadata Mock (AEMM) is a tool to simulate Amazon EC2 instance metadata service for local testing.

Table of Contents

• Project Summary
• Major Features
• Supported Metadata Categories
• Getting Started
  • Installation
  • Starting AEMM
  • Making a Request
• Configuration
  • Defaults
  • Overrides
• Usage
  • Spot Interruption
  • Scheduled Events
  • Instance Metadata Service Versions
  • Static Metadata
• Troubleshooting
  • Warnings and Expected Outcome
• Integrations
• Building
• Communication
• Contributing
• License

Summary

AWS EC2 Instance metadata is data about your instance that you can use to configure or manage the running instance. Instance metadata is divided into categories like hostname, instance id, maintenance events, spot instance action. See the complete list of metadata categories here.

The instance metadata can be accessed from within the instance. Some instance metadata is available only when an instance is affected by the event. E.g. A Spot instance's metadata item spot/instance-action is available only when AWS decides to interrupt the Spot instance. These bring forth some challenges like not being able to test one's application in the event of Spot interruption or other such events and requiring an EC2 instance for testing. This project attempts to bridge these gaps by providing mocks for most of these metadata categories. The mock responses are designed to replicate those from the actual instance metadata service for accurate, local testing.

Major Features

• Simulate Spot Instance Interruption (ITN) & EC2 Rebalance Recommendation events for Spot instances
• Delay mock response from the mock serve start time
• Configure metadata in mock responses via CLI flags, config file, env variables
• IMDSv1 and v2 support (configurable for IMDSv2 support only)
• Save processed configuration to a local file

Supported Metadata Categories

AEMM supports most metadata categories except for:

• ancestor-ami-ids
• events/maintenance/history

PRs for any of the above paths are always welcome! Please see our Contributing section for details.

Windows Metadata

Paths specific to Windows instances such as elastic-gpus/associations/elastic-gpu-id will not be supported at this time. Feel free to open an issue to discuss if you would like AEMM to support these paths in the future.

Getting Started

AEMM is simple to get up and running.

Installation

Install w/ Homebrew

brew tap aws/tap
brew install ec2-metadata-mock

Install w/ Curl

MacOS/Linux

curl -Lo ec2-metadata-mock https://github.com/aws/amazon-ec2-metadata-mock/releases/download/v1.8.1/ec2-metadata-mock-`uname | tr '[:upper:]' '[:lower:]'`-amd64
chmod +x ec2-metadata-mock

ARM Linux

curl -Lo ec2-metadata-mock https://github.com/aws/amazon-ec2-metadata-mock/releases/download/v1.8.1/ec2-metadata-mock-linux-arm

curl -Lo ec2-metadata-mock https://github.com/aws/amazon-ec2-metadata-mock/releases/download/v1.8.1/ec2-metadata-mock-linux-arm64

Windows

curl -Lo ec2-metadata-mock https://github.com/aws/amazon-ec2-metadata-mock/releases/download/v1.8.1/ec2-metadata-mock-windows-amd64.exe

Install w/ Docker

docker pull amazon/amazon-ec2-metadata-mock:v1.8.1
docker run -it --rm -p 1338:1338 amazon/amazon-ec2-metadata-mock:v1.8.1

On Kubernetes

Supported versions

• Kubernetes >= 1.14

Helm

See Helm README here.

kubectl

kubectl apply -f https://github.com/aws/amazon-ec2-metadata-mock/releases/download/v1.8.1/all-resources.yaml

Starting AEMM

Use ec2-metadata-mock --help to view examples and explanations of supported flags and commands:

$ ec2-metadata-mock --help

ec2-metadata-mock is a tool to mock Amazon EC2 instance metadata.

Usage:
  ec2-metadata-mock <command> [arguments] [flags]
  ec2-metadata-mock [command]

Examples:
  ec2-metadata-mock --mock-delay-sec 10	mocks all metadata paths
  ec2-metadata-mock spot --action terminate	mocks spot ITN only

Available Commands:
  events      Mock EC2 maintenance events
  help        Help about any command
  spot        Mock EC2 Spot interruption notice

Flags:
  -c, --config-file string         config file for cli input parameters in json format (default: $HOME/aemm-config.json)
  -h, --help                       help for ec2-metadata-mock
  -n, --hostname string            the HTTP hostname for the mock url (default: 0.0.0.0)
  -I, --imdsv2                     whether to enable IMDSv2 only, requiring a session token when submitting requests (default: false, meaning both IMDS v1 and v2 are enabled)
  -d, --mock-delay-sec int         mock delay in seconds, relative to the application start time (default: 0 seconds)
  -x, --mock-ip-count int          number of IPs in a cluster that can receive a Spot Interrupt Notice and/or Scheduled Event (default 2)
      --mock-trigger-time string   mock trigger time in RFC3339 format. This takes priority over mock-delay-sec (default: none)
  -p, --port string                the HTTP port where the mock runs (default: 1338)
  -s, --save-config-to-file        whether to save processed config from all input sources in .ec2-metadata-mock/.aemm-config-used.json in $HOME or working dir, if homedir is not found (default: false)
      --version                    version for ec2-metadata-mock

Use "ec2-metadata-mock [command] --help" for more information about a command.

Starting AEMM with default configurations using ec2-metadata-mock will start the server on the default host and port:

$ ec2-metadata-mock

Initiating ec2-metadata-mock for all mocks on port 1338
Serving the following routes: /latest/meta-data/product-codes, /latest/meta-data/iam/info, /latest/meta-data/instance-type, ...(truncated for readability)

Making a Request

With the server running, send a request to one of the supported routes above using curl localhost:1338/<route>. Example request to display all supported routes:

$ curl localhost:1338/latest/meta-data

ami-id
ami-launch-index
ami-manifest-path
block-device-mapping/ami
block-device-mapping/ebs0
block-device-mapping/ephemeral0
block-device-mapping/root
block-device-mapping/swap
elastic-inference/associations
elastic-inference/associations/eia-bfa21c7904f64a82a21b9f4540169ce1
events/maintenance/scheduled
events/recommendations/rebalance
hostname
iam/info
iam/security-credentials
iam/security-credentials/baskinc-role
instance-action
instance-id
instance-life-cycle
instance-type
kernel-id
latest
latest/api/token
local-hostname
local-ipv4
mac
network/interfaces/macs/0e:49:61:0f:c3:11/device-number
network/interfaces/macs/0e:49:61:0f:c3:11/interface-id
network/interfaces/macs/0e:49:61:0f:c3:11/ipv4-associations/192.0.2.54
network/interfaces/macs/0e:49:61:0f:c3:11/ipv6s
network/interfaces/macs/0e:49:61:0f:c3:11/local-hostname
network/interfaces/macs/0e:49:61:0f:c3:11/local-ipv4s
network/interfaces/macs/0e:49:61:0f:c3:11/mac
network/interfaces/macs/0e:49:61:0f:c3:11/network-card-index
network/interfaces/macs/0e:49:61:0f:c3:11/owner-id
network/interfaces/macs/0e:49:61:0f:c3:11/public-hostname
network/interfaces/macs/0e:49:61:0f:c3:11/public-ipv4s
network/interfaces/macs/0e:49:61:0f:c3:11/security-group-ids
network/interfaces/macs/0e:49:61:0f:c3:11/security-groups
network/interfaces/macs/0e:49:61:0f:c3:11/subnet-id
network/interfaces/macs/0e:49:61:0f:c3:11/subnet-ipv4-cidr-block
network/interfaces/macs/0e:49:61:0f:c3:11/subnet-ipv6-cidr-blocks
network/interfaces/macs/0e:49:61:0f:c3:11/vpc-id
network/interfaces/macs/0e:49:61:0f:c3:11/vpc-ipv4-cidr-block
network/interfaces/macs/0e:49:61:0f:c3:11/vpc-ipv4-cidr-blocks
network/interfaces/macs/0e:49:61:0f:c3:11/vpc-ipv6-cidr-blocks
placement/availability-zone
placement/availability-zone-id
placement/group-name
placement/host-id
placement/partition-number
placement/region
product-codes
public-hostname
public-ipv4
public-keys/0/openssh-key
ramdisk-id
reservation-id
security-groups
services/domain
services/partition
spot/instance-action
spot/termination-time

Configuration

AEMM's wide-range of configurability ranges from overriding port numbers to enabling IMDSv2-only to updating specific metadata values and paths. These configurations can be loaded from various sources with a deterministic precedence.

Defaults

Defaults for AEMM configuration are sourced throughout code. Examples below:

• CLI flags
  • server config defaults
• Metadata mock responses
  • aemm-metadata-default-values.json
• Commands
  • events

Overrides

AEMM supports configuration from various sources including: cli flags, env variables, and config files. Details regarding configuration steps, behavior, and precedence are outlined here.

Usage

AEMM is primarily used as a developer tool to help test behavior related to Metadata Service. Popular use cases include: emulating spot instance interrupts after a designated delay, mocking scheduled maintenance events, IMDSv2 migrations, and requesting static metadata. This section outlines the common use cases of AEMM; advanced usage and behavior are documented here.

Spot Interruption

To view the available flags for the Spot Interruption command use spot --help:

$ ec2-metadata-mock spot --help
Mock EC2 Spot interruption notice

Usage:
  ec2-metadata-mock spot [--action ACTION] [flags]

Aliases:
  spot

Examples:
  ec2-metadata-mock spot -h 	spot help
  ec2-metadata-mock spot -d 5 --action terminate		mocks spot interruption only

Flags:
  -a, --action string                  action in the spot interruption notice (default: terminate)
                                       action can be one of the following: terminate,hibernate,stop
  -h, --help                           help for spot
  -r, --rebalance-rec-time string      rebalance rec time specifies the approximate time when the rebalance recommendation notification will be emitted in RFC3339 format
  -t, --time string                    termination time specifies the approximate time when the spot instance will receive the shutdown signal in RFC3339 format to execute instance action E.g. 2020-01-07T01:03:47Z (default: request time + 2 minutes in UTC)

Global Flags:
  -c, --config-file string         config file for cli input parameters in json format (default: $HOME/aemm-config.json)
  -h, --help                       help for ec2-metadata-mock
  -n, --hostname string            the HTTP hostname for the mock url (default: 0.0.0.0)
  -I, --imdsv2                     whether to enable IMDSv2 only, requiring a session token when submitting requests (default: false, meaning both IMDS v1 and v2 are enabled)
  -d, --mock-delay-sec int         mock delay in seconds, relative to the application start time (default: 0 seconds)
  -x, --mock-ip-count int          number of IPs in a cluster that can receive a Spot Interrupt Notice and/or Scheduled Event (default 2)
      --mock-trigger-time string   mock trigger time in RFC3339 format. This takes priority over mock-delay-sec (default: none)
  -p, --port string                the HTTP port where the mock runs (default: 1338)
  -s, --save-config-to-file        whether to save processed config from all input sources in .ec2-metadata-mock/.aemm-config-used.json in $HOME or working dir, if homedir is not found (default: false)

1.) Starting AEMM with spot: spot routes available immediately:

$ ec2-metadata-mock spot
Initiating ec2-metadata-mock for EC2 Spot interruption notice on port 1338
Serving the following routes: ... (truncated for readability)

Send the request:

$ curl localhost:1338/latest/meta-data/spot/instance-action
{
	"action": "terminate",
	"time": "2020-04-24T17:11:44Z"
}

2.) Starting AEMM with spot after Delay: Users can apply a delay duration in seconds for when the spot metadata will become available:

$ ec2-metadata-mock spot -d 10
Initiating ec2-metadata-mock for EC2 Spot interruption notice on port 1338

Flags:
mock-delay-sec: 10

Serving the following routes: ... (truncated for readability)

Sending a request to spot paths before the delay has passed will return 404 - Not Found:

$ curl localhost:1338/latest/meta-data/spot/instance-action

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 <head>
  <title>404 - Not Found</title>
 </head>
 <body>
  <h1>404 - Not Found</h1>
 </body>
</html>


// Server log
Delaying the response by 10s as requested. The mock response will be available in 2s. Returning `notFoundResponse` for now

Once the delay is complete, querying spot paths return expected results:

$ curl localhost:1338/latest/meta-data/spot/instance-action

{
	"action": "terminate",
	"time": "2020-04-24T17:19:32Z"
}

Alternatively a trigger time can be configured using --mock-trigger-time which can be useful to synchronize spot interruption simulation over multiple instances.

EC2 Instance Rebalance Recommendation

The Rebalance Recommendation notification is also available under the spot command as it is sent when EC2 emits this signal when Spot Instances are at an elevated risk of interruption:

$ ec2-metadata-mock spot
Initiating ec2-metadata-mock for EC2 Spot interruption notice on port 1338
Serving the following routes: ... (truncated for readability)

Send the request:

$ curl localhost:1338/latest/meta-data/events/recommendations/rebalance
{
        "noticeTime": "2020-10-16T19:18:24Z"
}

Note: although Rebalance Recommendation path contains events it will not be available when starting AEMM with the events command

Events

Similar to spot, the events command, view the local flags using events --help:

$ ec2-metadata-mock events --help
Mock EC2 Scheduled Events

Usage:
  ec2-metadata-mock events [--code CODE] [--state STATE] [--not-after] [--not-before-deadline] [flags]

Aliases:
  events, se, scheduledevents

Examples:
  ec2-metadata-mock events -h 	events help
  ec2-metadata-mock events -o instance-stop --state active -d		mocks an active and upcoming scheduled event for instance stop with a deadline for the event start time

Flags:
  -o, --code string                  event code in the scheduled event (default: system-reboot)
                                     event-code can be one of the following: instance-reboot,system-reboot,system-maintenance,instance-retirement,instance-stop
  -h, --help                         help for events
  -a, --not-after string             the latest end time for the scheduled event in RFC3339 format E.g. 2020-01-07T01:03:47Z default: application start time + 7 days in UTC))
  -b, --not-before string            the earliest start time for the scheduled event in RFC3339 format E.g. 2020-01-07T01:03:47Z (default: application start time in UTC)
  -l, --not-before-deadline string   the deadline for starting the event in RFC3339 format E.g. 2020-01-07T01:03:47Z (default: application start time + 9 days in UTC)
  -t, --state string                 state of the scheduled event (default: active)
                                     state can be one of the following: active,completed,canceled

(Truncated Global Flags for readability)

1.) Starting AEMM with events: events route available immediately and spot routes will no longer be available due to the implementation of Commands detailed here:

$ ec2-metadata-mock events --code instance-reboot -a 2020-01-07T01:03:47Z  -b 2020-01-01T01:03:47Z -l 2020-01-10T01:03:47Z --state completed
Initiating ec2-metadata-mock for EC2 Events on port 1338
Serving the following routes: ... (truncated for readability)

Send the request:

$ curl localhost:1338/latest/meta-data/events/maintenance/scheduled
{
	"Code": "instance-reboot",
	"Description": "The instance is scheduled for instance-reboot",
	"State": "completed",
	"EventId": "instance-event-1234567890abcdef0",
	"NotBefore": "1 Jan 2020 01:03:47 GMT",
	"NotAfter": "7 Jan 2020 01:03:47 GMT",
	"NotBeforeDeadline": "10 Jan 2020 01:03:47 GMT"
}

Instance Metadata Service Versions

AEMM supports both versions of Instance Metadata service. By default, AEMM starts with supporting v1 and v2; however, it is possible to enable IMDSv2 only via overrides.

1.) Starting AEMM with IMDSv2 only: session tokens are required for all requests; v1 requests will return 401 - Unauthorized:

$ ec2-metadata-mock --imdsv2

Send a v1 request:

$ curl localhost:1338/latest/meta-data/mac

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
   <head>
      <title>401 - Unauthorized</title>
   </head>
   <body>
      <h1>401 - Unauthorized</h1>
   </body>
</html>

Send a v2 request:

TOKEN=`curl -X PUT "localhost:1338/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` \
&& curl -H "X-aws-ec2-metadata-token: $TOKEN" localhost:1338/latest/meta-data/mac
0e:49:61:0f:c3:11

Requesting a token outside the TTL bounds (between 1-2600 seconds) will return 400 - Bad Request:

$ curl -X PUT "localhost:1338/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 0"
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
   <head>
      <title>400 - Bad Request</title>
   </head>
   <body>
      <h1>400 - Bad Request</h1>
   </body>
</html>

Providing an expired token is synonymous to no token at all resulting in 401 - Unauthorized.

Static Metadata

Static metadata is classified as instance-specific metadata that is always available regardless of which command is used to start the tool.

Examples of static metadata include all metadata categories from the non-dynamic category table (ami-id, instance-id, mac) except for events and spot categories (classified as commands in AEMM).

Note that 'static' naming is used within the context of this tool ONLY

1.) Requesting static metadata instance-id:

$ ec2-metadata-mock

Send the request:

$ curl localhost:1338/latest/meta-data/instance-id
i-1234567890abcdef0

Details on overriding static metadata values and behavior can be found here

Troubleshooting

Warnings and Expected Outcome

Integrations

aws-node-termination-handler uses AEMM in its e2e test suite to mock the metadata service and interrupt events.

In the NTH imds-v2-test, Helm is used to download the latest AEMM release, install it onto the cluster, and start it with imdsv2-only access. NTH then acquires the v2 token from AEMM, consumes the interrupt event, then cordons the worker node and evicts the test pod, thus validating NTH functionality. For more details on NTH e2e tests refer to the documentation here.

Building

For build instructions, please consult BUILD.md

Communication

If you've run into a bug or have a new feature request, please open an issue.

Check out the open source Amazon EC2 Spot Instances Integrations Roadmap to see what we're working on and give us feedback!

Contributing

Contributions are welcome! Please read our guidelines and our Code of Conduct

License

This project is licensed under the Apache-2.0 License.