Default vs custom metrics in AWS - Visual Side-by-Side Comparison

Process Flow - Default vs custom metrics

Start Monitoring

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AWS Service emits Default Metrics

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Metrics collected automatically

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User wants more details?

No→Use Default Metrics Only

Yes↓

User creates Custom Metrics

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Send Custom Metrics to CloudWatch

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Metrics available for monitoring and alarms

AWS services automatically send default metrics. Users can add custom metrics for more detailed monitoring.

Execution Sample

AWS

1. AWS service sends default CPUUtilization metric
2. User creates custom metric 'AppLatency'
3. User sends 'AppLatency' data points to CloudWatch
4. CloudWatch stores and displays both metrics

Shows how default metrics are automatic and custom metrics require user action.

Process Table

Step	Action	Metric Type	Metric Name	Data Sent?	Result
1	AWS service runs	Default	CPUUtilization	Yes	Metric available in CloudWatch
2	User decides to monitor app latency	Custom	AppLatency	No	Metric not yet available
3	User sends AppLatency data	Custom	AppLatency	Yes	Metric available in CloudWatch
4	User views metrics	Default & Custom	CPUUtilization & AppLatency	Yes	Both metrics visible for alarms and dashboards
5	Monitoring continues	Default & Custom	All metrics	Yes	Metrics update automatically

💡 Monitoring runs continuously; default metrics always present, custom metrics appear after user sends data

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
CPUUtilization metric	Not present	Present	Present	Present	Present
AppLatency metric	Not present	Not present	Not present	Present	Present
Data sent for AppLatency	No	No	No	Yes	Yes

Key Moments - 2 Insights

Why don't custom metrics appear immediately like default metrics?

Custom metrics appear only after the user sends data points, as shown in step 3 of the execution_table.

Are default metrics always available without user action?

Yes, default metrics are automatically sent by AWS services, visible from step 1 in the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table at step 2, is the custom metric 'AppLatency' available in CloudWatch?

A Yes, it is available

B No, it is not available yet

C Only partially available

D It depends on the AWS region

💡 Hint

Check the 'Result' column at step 2 in the execution_table

At which step does the user send data for the custom metric?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Data Sent?' columns in the execution_table

If the user never sends custom metric data, what happens to the custom metric visibility?

A It never appears in CloudWatch

B It appears automatically after some time

C It appears but with zero values

D It appears only in logs

💡 Hint

Refer to the 'Data Sent?' and 'Result' columns in the execution_table steps 2 and 3

Concept Snapshot

AWS services send default metrics automatically.
Custom metrics require user to send data.
Default metrics appear immediately.
Custom metrics appear after data is sent.
Both can be used for monitoring and alarms.

Full Transcript

AWS services automatically send default metrics like CPU utilization to CloudWatch. These metrics are available immediately for monitoring. If users want more detailed information, they create custom metrics by sending their own data points to CloudWatch. Custom metrics do not appear until data is sent. Once sent, both default and custom metrics can be viewed and used for alarms and dashboards. This process ensures basic monitoring is always available, while allowing customization for specific needs.

Practice

1. Which statement best describes AWS default metrics in CloudWatch?

easy

A. They are automatically collected and free within certain limits.

B. They require manual setup and extra charges.

C. They only track custom application data.

D. They are disabled by default and need activation.

Solution

1. Step 1: Understand default metrics collection

   AWS CloudWatch automatically collects default metrics for many services without extra setup.

2. Step 2: Recognize cost and availability

   These default metrics are free within certain usage limits, making them easy to use.

3. Final Answer:

   They are automatically collected and free within certain limits. -> Option A

4. Quick Check:

   Default metrics = automatic + free [OK]

Hint: Default metrics are automatic and free within limits [OK]

Common Mistakes:

• Thinking default metrics need manual setup
• Assuming default metrics track custom data
• Believing default metrics are disabled by default

2. Which of the following is the correct way to send a custom metric to AWS CloudWatch using the AWS CLI?

easy

A. aws cloudwatch send-metric --name CPUUtilization --value 70

B. aws cloudwatch add-metric-data --metric-name CPUUtilization --value 70

C. aws cloudwatch create-metric --metric CPUUtilization --value 70

D. aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70

Solution

1. Step 1: Identify the correct AWS CLI command

   The correct command to send custom metric data is put-metric-data under aws cloudwatch.

2. Step 2: Check the syntax and parameters

   The command requires --metric-name, --namespace, and --value parameters as shown in aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70.

3. Final Answer:

   aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70 -> Option D

4. Quick Check:

   Use put-metric-data with metric-name and namespace [OK]

Hint: Use 'put-metric-data' with metric-name and namespace [OK]

Common Mistakes:

• Using incorrect command names like send-metric or create-metric
• Omitting the namespace parameter
• Confusing metric creation with data sending

3. Given the following AWS CloudWatch custom metric data sent every minute:

aws cloudwatch put-metric-data --metric-name PageViews --namespace MyApp --value 5

What will be the average value shown in CloudWatch after 3 minutes if the command is run 3 times with values 5, 7, and 8 respectively?

medium

A. 6.67

B. 7

C. 20

D. 5

Solution

1. Step 1: Sum the metric values sent

   The values sent are 5, 7, and 8. Their sum is 5 + 7 + 8 = 20.

2. Step 2: Calculate the average over 3 data points

   Average = Total sum / Number of data points = 20 / 3 ≈ 6.67.

3. Final Answer:

   6.67 -> Option A

4. Quick Check:

   Average = sum/3 = 6.67 [OK]

Hint: Average = sum of values divided by count [OK]

Common Mistakes:

• Adding values but not dividing by count
• Taking the last value as average
• Multiplying values instead of averaging

4. You tried to send a custom metric to CloudWatch but it does not appear in the console. Which of the following is the most likely cause?

medium

A. CloudWatch only shows metrics after 24 hours delay.

B. You forgot to specify the metric namespace in the command.

C. Custom metrics are automatically visible without sending data.

D. Default metrics do not require namespaces, so this is normal.

Solution

1. Step 1: Check required parameters for custom metrics

   Custom metrics require a namespace to organize and display them properly in CloudWatch.

2. Step 2: Understand impact of missing namespace

   If the namespace is missing, CloudWatch cannot categorize the metric, so it won't appear in the console.

3. Final Answer:

   You forgot to specify the metric namespace in the command. -> Option B

4. Quick Check:

   Missing namespace hides custom metric [OK]

Hint: Always specify namespace when sending custom metrics [OK]

Common Mistakes:

• Assuming default metrics need namespaces
• Expecting immediate visibility without data sent
• Believing CloudWatch delays metric display by 24 hours

5. You want to monitor a custom application metric that tracks the number of user logins per hour. The default AWS metrics do not provide this data. What is the best approach to achieve this?

hard

A. Enable detailed monitoring on EC2 instances to get user login data.

B. Use the default CPUUtilization metric to estimate user logins.

C. Send custom metric data for user logins to CloudWatch using a unique namespace and metric name.

D. Create an alarm on default network metrics to infer user logins.

Solution

1. Step 1: Identify the need for custom data

   User logins per hour is specific to the application and not tracked by default AWS metrics.

2. Step 2: Use custom metrics for application-specific data

   Sending custom metric data with a unique namespace and metric name allows tracking exactly this information in CloudWatch.

3. Final Answer:

   Send custom metric data for user logins to CloudWatch using a unique namespace and metric name. -> Option C

4. Quick Check:

   Custom metrics track app-specific data [OK]

Hint: Use custom metrics for app-specific tracking [OK]

Common Mistakes:

• Trying to use unrelated default metrics for app data
• Assuming detailed monitoring tracks application events
• Using alarms on unrelated metrics to guess user activity