EC2 network loss

EC2 network loss causes flaky access to the application (or services) by injecting network packet loss to EC2 instance(s). This fault:

Degrades the network without marking the EC2 instance as unhealthy (or unworthy) of traffic, which is resolved using a middleware that switches traffic based on SLOs (performance parameters).
May stall the EC2 instance or get corrupted waiting endlessly for a packet.
Limits the impact (blast radius) to the traffic that you wish to test, by specifying the IP addresses.

EC2 Network Loss

Use cases

EC2 network loss:

Determines the performance of the application (or process) running on the EC2 instances.
Simulates a consistently slow network connection between microservices (for example, cross-region connectivity between active-active peers of a given service or across services or poor cni-performance in the inter-pod-communication network).
Simulates jittery connection with transient latency spikes between microservices.
Simulates a slow response on specific third party (or dependent) components (or services), and degraded data-plane of service-mesh infrastructure.

Prerequisites

Kubernetes >= 1.17
SSM agent is installed and running on the target EC2 instance.
The EC2 instance should be in a healthy state.

The Kubernetes secret should have the AWS Access Key ID and Secret Access Key credentials in the CHAOS_NAMESPACE. Below is the sample secret file:

apiVersion: v1
kind: Secret
metadata:
  name: cloud-secret
type: Opaque
stringData:
  cloud_config.yml: |-
    # Add the cloud AWS credentials respectively
    [default]
    aws_access_key_id = XXXXXXXXXXXXXXXXXXX
    aws_secret_access_key = XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

tip

HCE recommends that you use the same secret name, that is, cloud-secret. Otherwise, you will need to update the AWS_SHARED_CREDENTIALS_FILE environment variable in the fault template with the new secret name and you won't be able to use the default health check probes.

Below is an example AWS policy to execute the fault.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ssm:GetDocument",
                "ssm:DescribeDocument",
                "ssm:GetParameter",
                "ssm:GetParameters",
                "ssm:SendCommand",
                "ssm:CancelCommand",
                "ssm:CreateDocument",
                "ssm:DeleteDocument",
                "ssm:GetCommandInvocation",          
                "ssm:UpdateInstanceInformation",
                "ssm:DescribeInstanceInformation"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2messages:AcknowledgeMessage",
                "ec2messages:DeleteMessage",
                "ec2messages:FailMessage",
                "ec2messages:GetEndpoint",
                "ec2messages:GetMessages",
                "ec2messages:SendReply"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstanceStatus",
                "ec2:DescribeInstances"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

note

Go to AWS named profile for chaos to use a different profile for AWS faults and the superset permission/policy to execute all AWS faults.
Go to the common tunables to tune the common tunables for all the faults.

Mandatory tunables

Tunable	Description	Notes
EC2_INSTANCE_ID	ID of the target EC2 instance.	For example, `i-044d3cb4b03b8af1f`. For more information, go to EC2 instance ID.
REGION	The AWS region ID where the EC2 instance has been created.	For example, `us-east-1`.

Optional tunables

Tunable	Description	Notes
TOTAL_CHAOS_DURATION	Duration that you specify, through which chaos is injected into the target resource (in seconds).	Default: 30 s. For more information, go to duration of the chaos.
CHAOS_INTERVAL	Time interval between two successive instance terminations (in seconds).	Default: 30 s. For more information, go to chaos interval.
AWS_SHARED_CREDENTIALS_FILE	Provide the path for aws secret credentials.	Default: `/tmp/cloud_config.yml`.
INSTALL_DEPENDENCY	Select to install dependencies used to run the network chaos. It can be either True or False.	If the dependency already exists, you can turn it off. Default: True.
NETWORK_PACKET_LOSS_PERCENTAGE	The packet loss in percentage.	Default: 100 %. For more information, go to network packet loss.
DESTINATION_IPS	IP addresses of the services or the CIDR blocks(range of IPs), the accessibility to which is impacted.	Comma-separated IP(S) or CIDR(S) can be provided. If not provided, the fault induces network chaos for all IPs/destinations. For more information, go to destination IPs.
DESTINATION_HOSTS	DNS Names of the services, the accessibility to which, is impacted.	Ff not provided, the fault induces network chaos for all IPs/destinations or DESTINATION_IPS if already defined. For more information, go to destination hosts.
NETWORK_INTERFACE	Name of ethernet interface considered for shaping traffic.	Default: `eth0`. For more information, go to network interface.
SEQUENCE	It defines sequence of chaos execution for multiple instance.	Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30 s. For more information, go to ramp time.

tip

If the environment variables DESTINATION_HOSTS or DESTINATION_IPS are left empty, the default behaviour is to target all hosts. To limit the impact on all the hosts, you can specify the IP addresses of the service (use commas to separate multiple values) or the DNS or the FQDN names of the services in DESTINATION_HOSTS.

Network packet loss

Network packet loss percentage that is injected on the EC2 instances. Tune it by using the NETWORK_PACKET_LOSS_PERCENTAGE environment variable.

The following YAML snippet illustrates the use of this environment variable:

# it injects the chaos into the egress traffic
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ec2-network-loss
    spec:
      components:
        env:
        # network packet loss percentage
        - name: NETWORK_PACKET_LOSS_PERCENTAGE
          value: '100'
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        - name: REGION
          value: 'us-west-2'

Run with destination IPs and destination hosts

Interruption of IPs/hosts. By default, all IPs/hosts are interrupted. Tune specific IPs/hosts by using the DESTINATION_IPS and DESTINATION_HOSTS environment variables, respectively.

DESTINATION_IPS: It contains the IP addresses of the services or the CIDR blocks (range of IPs) whose accessibility is impacted. DESTINATION_HOSTS: It contains the DNS names of the services whose accessibility is impacted.

The following YAML snippet illustrates the use of this environment variable:

# it injects the chaos into the egress traffic for specific IPs/hosts
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ec2-network-loss
    spec:
      components:
        env:
        # supports comma-separated destination ips
        - name: DESTINATION_IPS
          value: '8.8.8.8,192.168.5.6'
        # supports comma-separated destination hosts
        - name: DESTINATION_HOSTS
          value: 'google.com'
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        - name: REGION
          value: 'us-west-2'

Network interface

Name of the ethernet interface considered for shaping traffic. Tune it by using the NETWORK_INTERFACE environment variable. Its default value is eth0.

The following YAML snippet illustrates the use of this environment variable:

# it injects the chaos into the egress traffic for specific network interface
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ec2-network-loss
    spec:
      components:
        env:
        # name of the network interface
        - name: NETWORK_INTERFACE
          value: 'eth0'
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        - name: REGION
          value: 'us-west-2'

Use cases​

Prerequisites​

Mandatory tunables​

Optional tunables​

Network packet loss​

Run with destination IPs and destination hosts​

Network interface​

Use cases

Prerequisites

Mandatory tunables

Optional tunables

Network packet loss

Run with destination IPs and destination hosts

Network interface