Use DescribeScalingActivities with an AWS SDK or CLI

    /// <summary>
    /// Retrieve a list of the Amazon EC2 Auto Scaling activities for an
    /// Amazon EC2 Auto Scaling group.
    /// </summary>
    /// <param name="groupName">The name of the Amazon EC2 Auto Scaling group.</param>
    /// <returns>A list of Amazon EC2 Auto Scaling activities.</returns>
    public async Task<List<Amazon.AutoScaling.Model.Activity>> DescribeScalingActivitiesAsync(
        string groupName)
    {
        var scalingActivitiesRequest = new DescribeScalingActivitiesRequest
        {
            AutoScalingGroupName = groupName,
            MaxRecords = 10,
        };

        var response = await _amazonAutoScaling.DescribeScalingActivitiesAsync(scalingActivitiesRequest);
        return response.Activities;
    }

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::AutoScaling::AutoScalingClient autoScalingClient(clientConfig);

        Aws::AutoScaling::Model::DescribeScalingActivitiesRequest request;
        request.SetAutoScalingGroupName(groupName);

        Aws::Vector<Aws::AutoScaling::Model::Activity> allActivities;
        Aws::String nextToken; // Used for pagination;
        do {
            if (!nextToken.empty()) {
                request.SetNextToken(nextToken);
            }
            Aws::AutoScaling::Model::DescribeScalingActivitiesOutcome outcome =
                    autoScalingClient.DescribeScalingActivities(request);

            if (outcome.IsSuccess()) {
                const Aws::Vector<Aws::AutoScaling::Model::Activity> &activities =
                        outcome.GetResult().GetActivities();
                allActivities.insert(allActivities.end(), activities.begin(), activities.end());
                nextToken  = outcome.GetResult().GetNextToken();
            }
            else {
                std::cerr << "Error with AutoScaling::DescribeScalingActivities. "
                          << outcome.GetError().GetMessage()
                          << std::endl;

            }
        } while (!nextToken.empty());

        std::cout << "Found " << allActivities.size() << " activities."
                  << std::endl;
        std::cout << "Activities are ordered with the most recent first."
                  << std::endl;
        for (const Aws::AutoScaling::Model::Activity &activity: allActivities) {
            std::cout << activity.GetDescription() << std::endl;
            std::cout << activity.GetDetails() << std::endl;
        }

Example 1: To describe scaling activities for the specified group

This example describes the scaling activities for the specified Auto Scaling group.

aws autoscaling describe-scaling-activities \
    --auto-scaling-group-name my-asg

Output:

{
    "Activities": [
        {
            "ActivityId": "f9f2d65b-f1f2-43e7-b46d-d86756459699",
            "Description": "Launching a new EC2 instance: i-0d44425630326060f",
            "AutoScalingGroupName": "my-asg",
            "Cause": "At 2020-10-30T19:35:51Z a user request update of AutoScalingGroup constraints to min: 0, max: 16, desired: 16 changing the desired capacity from 0 to 16.  At 2020-10-30T19:36:07Z an instance was started in response to a difference between desired and actual capacity, increasing the capacity from 0 to 16.",
            "StartTime": "2020-10-30T19:36:09.766Z",
            "EndTime": "2020-10-30T19:36:41Z",
            "StatusCode": "Successful",
            "Progress": 100,
            "Details": "{\"Subnet ID\":\"subnet-5ea0c127\",\"Availability Zone\":\"us-west-2b\"}"
        }
    ]
}

For more information, see Verify a scaling activity for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

Example 2: To describe the scaling activities for a deleted group

To describe scaling activities after the Auto Scaling group has been deleted, add the --include-deleted-groups option.

aws autoscaling describe-scaling-activities \
    --auto-scaling-group-name my-asg \
    --include-deleted-groups

Output:

{
    "Activities": [
        {
            "ActivityId": "e1f5de0e-f93e-1417-34ac-092a76fba220",
            "Description": "Launching a new EC2 instance.  Status Reason: Your Spot request price of 0.001 is lower than the minimum required Spot request fulfillment price of 0.0031. Launching EC2 instance failed.",
            "AutoScalingGroupName": "my-asg",
            "Cause": "At 2021-01-13T20:47:24Z a user request update of AutoScalingGroup constraints to min: 1, max: 5, desired: 3 changing the desired capacity from 0 to 3.  At 2021-01-13T20:47:27Z an instance was started in response to a difference between desired and actual capacity, increasing the capacity from 0 to 3.",
            "StartTime": "2021-01-13T20:47:30.094Z",
            "EndTime": "2021-01-13T20:47:30Z",
            "StatusCode": "Failed",
            "StatusMessage": "Your Spot request price of 0.001 is lower than the minimum required Spot request fulfillment price of 0.0031. Launching EC2 instance failed.",
            "Progress": 100,
            "Details": "{\"Subnet ID\":\"subnet-5ea0c127\",\"Availability Zone\":\"us-west-2b\"}",
            "AutoScalingGroupState": "Deleted",
            "AutoScalingGroupARN": "arn:aws:autoscaling:us-west-2:123456789012:autoScalingGroup:283179a2-f3ce-423d-93f6-66bb518232f7:autoScalingGroupName/my-asg"
        }
    ]
}

For more information, see Troubleshoot Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide.

Example 3: To describe a specified number of scaling activities

To return a specific number of activities, use the --max-items option.

aws autoscaling describe-scaling-activities \
    --max-items 1

Output:

{
    "Activities": [
        {
            "ActivityId": "f9f2d65b-f1f2-43e7-b46d-d86756459699",
            "Description": "Launching a new EC2 instance: i-0d44425630326060f",
            "AutoScalingGroupName": "my-asg",
            "Cause": "At 2020-10-30T19:35:51Z a user request update of AutoScalingGroup constraints to min: 0, max: 16, desired: 16 changing the desired capacity from 0 to 16.  At 2020-10-30T19:36:07Z an instance was started in response to a difference between desired and actual capacity, increasing the capacity from 0 to 16.",
            "StartTime": "2020-10-30T19:36:09.766Z",
            "EndTime": "2020-10-30T19:36:41Z",
            "StatusCode": "Successful",
            "Progress": 100,
            "Details": "{\"Subnet ID\":\"subnet-5ea0c127\",\"Availability Zone\":\"us-west-2b\"}"
        }
    ]
}

If the output includes a NextToken field, there are more activities. To get the additional activities, use the value of this field with the --starting-token option in a subsequent call as follows.

aws autoscaling describe-scaling-activities \
    --starting-token Z3M3LMPEXAMPLE

For more information, see Verify a scaling activity for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

    public static void describeScalingActivities(AutoScalingClient autoScalingClient, String groupName) {
        try {
            DescribeScalingActivitiesRequest scalingActivitiesRequest = DescribeScalingActivitiesRequest.builder()
                    .autoScalingGroupName(groupName)
                    .maxRecords(10)
                    .build();

            DescribeScalingActivitiesResponse response = autoScalingClient
                    .describeScalingActivities(scalingActivitiesRequest);
            List<Activity> activities = response.activities();
            for (Activity activity : activities) {
                System.out.println("The activity Id is " + activity.activityId());
                System.out.println("The activity details are " + activity.details());
            }

        } catch (AutoScalingException e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }

suspend fun describeAutoScalingGroups(groupName: String) {
    val groupsReques =
        DescribeAutoScalingGroupsRequest {
            autoScalingGroupNames = listOf(groupName)
            maxRecords = 10
        }

    AutoScalingClient { region = "us-east-1" }.use { autoScalingClient ->
        val response = autoScalingClient.describeAutoScalingGroups(groupsReques)
        response.autoScalingGroups?.forEach { group ->
            println("The service to use for the health checks: ${group.healthCheckType}")
        }
    }
}

    public function describeScalingActivities($autoScalingGroupName)
    {
        return $this->autoScalingClient->describeScalingActivities([
            'AutoScalingGroupName' => $autoScalingGroupName,
        ]);
    }

Example 1: This example describes the scaling activities for the last six weeks for the specified Auto Scaling group.

Get-ASScalingActivity -AutoScalingGroupName my-asg

Output:

ActivityId           : 063308ae-aa22-4a9b-94f4-9fae4EXAMPLE
AutoScalingGroupName : my-asg
Cause                : At 2015-11-22T15:45:16Z a user request explicitly set group desired capacity changing the desired
                       capacity from 1 to 2.  At 2015-11-22T15:45:34Z an instance was started in response to a difference
                       between desired and actual capacity, increasing the capacity from 1 to 2.
Description          : Launching a new EC2 instance: i-26e715fc
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 11/22/2015 7:46:09 AM
Progress             : 100
StartTime            : 11/22/2015 7:45:35 AM
StatusCode           : Successful
StatusMessage        :

ActivityId           : ce719997-086d-4c73-a2f1-ab703EXAMPLE
AutoScalingGroupName : my-asg
Cause                : At 2015-11-20T22:57:53Z a user request created an AutoScalingGroup changing the desired capacity
                        from 0 to 1.  At 2015-11-20T22:57:58Z an instance was started in response to a difference betwe
                       en desired and actual capacity, increasing the capacity from 0 to 1.
Description          : Launching a new EC2 instance: i-93633f9b
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 11/20/2015 2:58:32 PM
Progress             : 100
StartTime            : 11/20/2015 2:57:59 PM
StatusCode           : Successful
StatusMessage        :

Example 2: This example describes the specified scaling activity.

Get-ASScalingActivity -ActivityId "063308ae-aa22-4a9b-94f4-9fae4EXAMPLE"

Example 3: This example describes the scaling activities for the last six weeks for all your Auto Scaling groups.

Get-ASScalingActivity

class AutoScalingWrapper:
    """Encapsulates Amazon EC2 Auto Scaling actions."""

    def __init__(self, autoscaling_client):
        """
        :param autoscaling_client: A Boto3 Amazon EC2 Auto Scaling client.
        """
        self.autoscaling_client = autoscaling_client


    def describe_scaling_activities(self, group_name: str) -> List[Dict[str, Any]]:
        """
        Gets information about scaling activities for the group. Scaling activities
        are things like instances stopping or starting in response to user requests
        or capacity changes.

        :param group_name: The name of the group to look up.
        :return: A list of dictionaries representing the scaling activities for the
                 group, ordered with the most recent activity first.
        :raises ClientError: If there is an error describing the scaling activities.
        """
        try:
            paginator = self.autoscaling_client.get_paginator(
                "describe_scaling_activities"
            )
            response_iterator = paginator.paginate(AutoScalingGroupName=group_name)
            activities = []
            for response in response_iterator:
                activities.extend(response.get("Activities", []))

            logger.info(
                f"Successfully described scaling activities for group '{group_name}'."
            )

        except ClientError as err:
            error_code = err.response["Error"]["Code"]
            logger.error(
                f"Couldn't describe scaling activities for group '{group_name}'. Error code: {error_code}, Message: {err.response['Error']['Message']}"
            )

            if error_code == "ResourceContentionFault":
                logger.error(
                    f"There is a conflict with another operation that is modifying the Auto Scaling group '{group_name}'. "
                    "Please try again later."
                )
            raise
        else:
            return activities

    pub async fn describe_scenario(&self) -> AutoScalingScenarioDescription {
        let group = self
            .autoscaling
            .describe_auto_scaling_groups()
            .auto_scaling_group_names(self.auto_scaling_group_name.clone())
            .send()
            .await
            .map(|s| {
                s.auto_scaling_groups()
                    .iter()
                    .map(|s| {
                        format!(
                            "{}: {}",
                            s.auto_scaling_group_name().unwrap_or("Unknown"),
                            s.status().unwrap_or("Unknown")
                        )
                    })
                    .collect::<Vec<String>>()
            })
            .map_err(|e| {
                ScenarioError::new("Failed to describe auto scaling groups for scenario", &e)
            });

        let instances = self
            .list_instances()
            .await
            .map_err(|e| anyhow!("There was an error listing instances: {e}",));

        // 10. DescribeScalingActivities: list the scaling activities that have occurred for the group so far.
        //   Bonus: use CloudWatch API to get and show some metrics collected for the group.
        //   CW.ListMetrics with Namespace='AWS/AutoScaling' and Dimensions=[{'Name': 'AutoScalingGroupName', 'Value': }]
        //   CW.GetMetricStatistics with Statistics='Sum'. Start and End times must be in UTC!
        let activities = self
            .autoscaling
            .describe_scaling_activities()
            .auto_scaling_group_name(self.auto_scaling_group_name.clone())
            .into_paginator()
            .items()
            .send()
            .collect::<Result<Vec<_>, _>>()
            .await
            .map_err(|e| {
                anyhow!(
                    "There was an error retrieving scaling activities: {}",
                    DisplayErrorContext(&e)
                )
            });

        AutoScalingScenarioDescription {
            group,
            instances,
            activities,
        }
    }