ECS container network loss

ECS container network loss disrupts the state of infrastructure resources.

The fault induces chaos on the AWS ECS container using Amazon SSM Run command, which is carried out using SSM docs that comes in-built in the fault.
It causes network disruption on containers of the ECS task in the cluster name.
To select the Task Under Chaos (TUC), use the service name associated with the task. If you provide the service name along with cluster name, all the tasks associated with the given service will be selected as chaos targets.
It tests the ECS task sanity (service availability) and recovery of the task containers subjected to network chaos.
This experiment induces chaos within a container and depends on an EC2 instance. Typically, these are prefixed with "ECS container" and involve direct interaction with the EC2 instances hosting the ECS containers.

ECS Container Network Loss

Use cases

This fault degrades the network of the task container without the container being marked as unhealthy/ (or unworthy) of traffic. It simulates issues within the ECS task network or communication across services in different availability zones (or regions).
- This can be resolved using middleware that switches traffic based on certain SLOs (or performance parameters).
- This can also be resolved by highlighting the degradation using notifications (or alerts).
It also determines the impact of the fault on the microservice. The task may stall or get corrupted while waiting endlessly for a packet. The fault limits the impact (blast radius) to only the traffic you wish to test by specifying the service to find TUC (Task Under Chaos).
It simulates degraded network with varied percentages of dropped packets between microservices, loss of access to specific third party (or dependent) services (or components), blackhole against traffic to a given AZ (failure simulation of availability zones), and network partitions (split-brain) between peer replicas for a stateful application.
This fault helps improve the resilience of the services over time.

Prerequisites

Kubernetes >= 1.17
The ECS container instance should be in a healthy state.
Adequate AWS access to stop and start an EC2 instance.
Create a Kubernetes secret that has the AWS access configuration(key) in the CHAOS_NAMESPACE. Below is a 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 = XXXXXXXXXXXXXXX

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": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "ecs:UpdateContainerInstancesState",
                "ecs:RegisterContainerInstance",
                "ecs:ListContainerInstances",
                "ecs:DeregisterContainerInstance",
                "ecs:DescribeContainerInstances",
                "ecs:ListTasks",
                "ecs:DescribeClusters"

            ],
            "Resource": "*"
        },
        {
            "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:DescribeInstances"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

note

Refer to AWS Named Profile For Chaos to know how to use a different profile for AWS faults.
Refer to the superset permission/policy to execute all AWS faults.
Refer to the common attributes and AWS-specific tunables to tune the common tunables for all faults and aws specific tunables.

Mandatory tunables

Variables	Description	Notes
CLUSTER_NAME	Name of the target ECS cluster	For example, cluster-1
REGION	The region name of the target ECS cluster	For example, us-east-1

Optional tunables

Variables	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	The interval (in sec) between successive instance termination.	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`
NETWORK_PACKET_LOSS_PERCENTAGE	Provide the value of loss in percentage	Default: 100. For more information, go to network 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). If not provided, network chaos is induced for all IPs/destinations. For more information, go to destination IPs.
DESTINATION_HOSTS	DNS Names of the services, the accessibility to which, is impacted	If not provided, network chaos is induced 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.

Network loss

Network loss (in ms) to be injected in the target container. Tune it by using the NETWORK_PACKET_LOSS_PERCENTAGE environment variable.

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

# injects network loss for a certain chaos duration
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ecs-container-network-loss
    spec:
      components:
        env:
        # network loss to be injected
        - name: NETWORK_PACKET_LOSS_PERCENTAGE
          value: '100' #in ms
        - name: TOTAL_CHAOS_DURATION
          value: '60'

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:

# provide the network interface
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ecs-container-network-loss
    spec:
      components:
        env:
        # name of the network interface
        - name: NETWORK_INTERFACE
          value: 'eth0'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

Destination IPs and destination hosts

The network faults interrupt traffic for all the IPs/hosts by default. Tune the interruption of specific IPs/Hosts using DESTINATION_IPS and DESTINATION_HOSTS environment variables.

DESTINATION_IPS: It contains the IP addresses of the services or pods or the CIDR blocks(range of IPs), the accessibility to which is impacted.
DESTINATION_HOSTS: It contains the DNS Names/FQDN names of the services, the accessibility to which, is impacted.

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

# it inject the chaos for the ingress/egress traffic for specific ips/hosts
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ecs-container-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: 'nginx.default.svc.cluster.local,google.com'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

Use cases​

Prerequisites​

Mandatory tunables​

Optional tunables​

Network loss​

Network interface​

Destination IPs and destination hosts​

Use cases

Prerequisites

Mandatory tunables

Optional tunables

Network loss

Network interface

Destination IPs and destination hosts