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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.

ECS Container Network Loss

Usage

View fault usage
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
  • 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
  • If you change the secret key name (from cloud_config.yml), ensure that you update the AWS_SHARED_CREDENTIALS_FILE environment variable in the chaos experiment with the new name.

Permissions required

Here is an example AWS policy to execute the fault.

View policy for 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": [
"*"
]
}
]
}

Refer to the superset permission/policy to execute all AWS faults.

Default validations

The ECS container instance should be in a healthy state.

Fault tunables

Fault tunables

Mandatory fields

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 fields

Variables Description Notes
TOTAL_CHAOS_DURATION Duration that you specify, through which chaos is injected into the target resource (in seconds). Defaults to 30s.
CHAOS_INTERVAL The interval (in sec) between successive instance termination. Defaults to 30s
AWS_SHARED_CREDENTIALS_FILE Provide the path for aws secret credentials Defaults to /tmp/cloud_config.yml
NETWORK_PACKET_LOSS_PERCENTAGE Provide the value of loss in percentage Defaults to 100
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, it will induce network chaos for all ips/destinations
DESTINATION_HOSTS DNS Names of the services, the accessibility to which, is impacted if not provided, it will induce network chaos for all ips/destinations or DESTINATION_IPS if already defined
NETWORK_INTERFACE Name of ethernet interface considered for shaping traffic Defaults to eth0
SEQUENCE It defines sequence of chaos execution for multiple instance Defaults to parallel. Supports serial sequence as well.
RAMP_TIME Period to wait before and after injecting chaos (in seconds). For example, 30

Fault examples

Common and AWS-specific tunables

Refer to the common attributes and AWS-specific tunables to tune the common tunables for all faults and aws specific tunables.

Network loss

It defines the network loss(in ms) to be injected in the targeted container. You can tune it using the NETWORK_PACKET_LOSS_PERCENTAGE ENV.

Use the following example to tune it:

# 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

The defined name of the ethernet interface, which is considered for shaping traffic. You can tune it using the NETWORK_INTERFACE ENV. Its default value is eth0.

Use the following example to tune it:

# 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. The interruption of specific IPs/Hosts can be tuned via DESTINATION_IPS and DESTINATION_HOSTS ENV.

  • 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.

Use the following example to tune it:

# it inject the chaos for the 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'