CloudWatch metrics in AWS - Step-by-Step Execution

Process Flow - CloudWatch metrics

Start Monitoring

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Collect Metrics Data

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Send Data to CloudWatch

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CloudWatch Stores Metrics

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User Views Metrics & Sets Alarms

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Alarms Trigger Actions if Thresholds Met

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End

Metrics data is collected from resources, sent to CloudWatch, stored, and then users can view or set alarms that trigger actions.

Execution Sample

AWS

aws cloudwatch put-metric-data --namespace MyApp --metric-name PageViews --value 100

This command sends a metric named PageViews with value 100 to CloudWatch under the MyApp namespace.

Process Table

Step	Action	Input/Condition	CloudWatch State	Output/Result
1	Start Monitoring	Resource begins sending metrics	No metrics stored yet	Ready to receive data
2	Collect Metrics Data	PageViews = 100	No metrics stored yet	Metric data prepared
3	Send Data to CloudWatch	PutMetricData command with PageViews=100	Receives metric data	Metric stored under MyApp/PageViews
4	CloudWatch Stores Metrics	Metric data received	PageViews metric stored with value 100	Data available for queries
5	User Views Metrics	User queries PageViews metric	Metric data stored	Displays value 100
6	User Sets Alarm	Threshold set at 90	Metric data stored	Alarm created for PageViews > 90
7	Metric Value Updates	New value 85 sent	PageViews metric updated to 85	Alarm not triggered
8	Metric Value Updates	New value 95 sent	PageViews metric updated to 95	Alarm triggered
9	Alarm Triggers Action	Alarm state ALARM	Alarm active	Notification or action executed
10	End	Monitoring continues	Metrics and alarms active	System ready for next data

💡 Monitoring continues indefinitely; this trace shows one cycle of metric data flow and alarm triggering.

Status Tracker

Variable	Start	After Step 2	After Step 4	After Step 7	After Step 8	Final
PageViews Metric Value	None	100	100	85	95	95
Alarm State	INSUFFICIENT_DATA	INSUFFICIENT_DATA	INSUFFICIENT_DATA	OK	ALARM	ALARM

Key Moments - 3 Insights

Why does the alarm not trigger when the metric value is 85 even though the threshold is 90?

Because 85 is less than the threshold 90, so the alarm state remains OK as shown in step 7 of the execution_table.

What happens inside CloudWatch when metric data is sent?

CloudWatch stores the metric data under the specified namespace and metric name, making it available for queries and alarms, as seen in step 4.

Can metrics be viewed before setting alarms?

Yes, metrics are stored and can be viewed anytime after data is sent, before alarms are set, as shown in step 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the PageViews metric value after step 7?

A 100

B 95

C 85

D None

💡 Hint

Check the 'PageViews Metric Value' row in variable_tracker after step 7.

At which step does the alarm state change to ALARM?

A Step 8

B Step 6

C Step 7

D Step 9

💡 Hint

Look at the 'Alarm State' variable in variable_tracker and the execution_table rows for alarm triggering.

If the threshold was set to 80 instead of 90, at which step would the alarm trigger?

A Step 6

B Step 7

C Step 8

D Step 9

💡 Hint

Compare metric values at steps 7 and 8 with the new threshold and check alarm state changes.

Concept Snapshot

CloudWatch metrics collect data from resources.
Data is sent using PutMetricData commands.
Metrics are stored under namespaces and names.
Users can view metrics and set alarms.
Alarms trigger actions when thresholds are crossed.

Full Transcript

CloudWatch metrics work by collecting data from your resources and sending it to CloudWatch. This data is stored and can be viewed anytime. You can set alarms on these metrics to notify or act when certain thresholds are met. For example, sending a PageViews metric with value 100 stores it in CloudWatch. If you set an alarm at 90, it will trigger when the metric value goes above 90. This process repeats continuously as new data arrives.