How to Monitor AWS Resources Using CloudWatch

Amazon CloudWatch is a comprehensive monitoring and observability service that provides real-time monitoring of AWS resources and applications. It collects and tracks metrics, monitors log files, sets alarms, and automatically reacts to changes in your AWS resources.

``mermaid

flowchart TB

A[AWS Resources] --> B[CloudWatch]

B --> C[Metrics]

B --> D[Logs]

B --> E[Alarms]

C --> F[Dashboards]

D --> F

E --> G[Actions]

G --> H[SNS]

G --> I[Auto Scaling]

G --> J[Lambda]

style B fill:#f96,stroke:#333,stroke-width:2px

style F fill:#bbf,stroke:#333,stroke-width:2px

`

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CloudWatch metrics structure:

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Example CloudFormation template for custom metrics:

`yaml

Resources:

CustomMetricFunction:

Type: 'AWS::Lambda::Function'

Properties:

Handler: index.handler

Role: !GetAtt LambdaExecutionRole.Arn

Code:

ZipFile: |

const AWS = require('aws-sdk');

const cloudwatch = new AWS.CloudWatch();

exports.handler = async () => {

await cloudwatch.putMetricData({

Namespace: 'CustomMetrics',

MetricData: [{

MetricName: 'BusinessTransactions',

Value: 100,

Unit: 'Count',

Dimensions: [{

Name: 'ServiceName',

Value: 'OrderProcessing'

}]

}]

}).promise();

};

Runtime: nodejs18.x

`

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Log data flow architecture:

`mermaid

graph LR

A[Applications] -->|Log Events| B[CloudWatch Logs]

C[Lambda] -->|Log Events| B

D[EC2] -->|Log Events| B

B -->|Filter| E[Metric Filters]

B -->|Stream| F[Kinesis]

B -->|Archive| G[S3]

E -->|Alert| H[Alarms]

style B fill:#f96,stroke:#333,stroke-width:2px

`

Example log group configuration:

`yaml

Resources:

ApplicationLogGroup:

Type: 'AWS::Logs::LogGroup'

Properties:

LogGroupName: /aws/application/production

RetentionInDays: 30

LogMetricFilter:

Type: 'AWS::Logs::MetricFilter'

Properties:

LogGroupName: !Ref ApplicationLogGroup

FilterPattern: '[timestamp, requestId, errorCode, message]'

MetricTransformations:

- MetricName: ErrorCount

MetricNamespace: CustomMetrics

MetricValue: '1'

`

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Standard metrics by resource type:

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Example monitoring configuration:

`yaml

Resources:

MonitoringRole:

Type: 'AWS::IAM::Role'

Properties:

AssumeRolePolicyDocument:

Version: '2012-10-17'

Statement:

- Effect: Allow

Principal:

Service: ec2.amazonaws.com

Action: sts:AssumeRole

ManagedPolicyArns:

- arn:aws:iam::aws:policy/CloudWatchAgentServerPolicy

EC2Instance:

Type: 'AWS::EC2::Instance'

Properties:

InstanceType: t3.micro

IamInstanceProfile: !Ref MonitoringInstanceProfile

UserData:

Fn::Base64: !Sub |

#!/bin/bash

yum install -y amazon-cloudwatch-agent

/opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-ctl -a fetch-config -m ec2 -s -c ssm:/AmazonCloudWatch/Config

`

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Alarm states and transitions:

`mermaid

stateDiagram-v2

[*] --> OK

OK --> ALARM: Threshold Breached

ALARM --> OK: Threshold Restored

OK --> INSUFFICIENT_DATA: Missing Data

INSUFFICIENT_DATA --> OK: Data Resumed

ALARM --> INSUFFICIENT_DATA: Missing Data

`

Example alarm configuration:

`yaml

Resources:

HighCPUAlarm:

Type: 'AWS::CloudWatch::Alarm'

Properties:

AlarmName: HighCPUUtilization

AlarmDescription: CPU utilization is too high

MetricName: CPUUtilization

Namespace: AWS/EC2

Dimensions:

- Name: InstanceId

Value: !Ref EC2Instance

Statistic: Average

Period: 300

EvaluationPeriods: 2

Threshold: 80

ComparisonOperator: GreaterThanThreshold

AlarmActions:

- !Ref AlertSNSTopic

`

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Dashboard layout example:

`mermaid

graph TB

subgraph Dashboard

A[CPU Metrics] --> E[Overview]

B[Memory Metrics] --> E

C[Network Metrics] --> E

D[Custom Metrics] --> E

end

subgraph Widgets

E --> F[Line Graphs]

E --> G[Counters]

E --> H[Heat Maps]

end

`

Example dashboard configuration:

`yaml

Resources:

MonitoringDashboard:

Type: 'AWS::CloudWatch::Dashboard'

Properties:

DashboardName: ApplicationMonitoring

DashboardBody: !Sub |

{

"widgets": [

{

"type": "metric",

"properties": {

"metrics": [

["AWS/EC2", "CPUUtilization", "InstanceId", "${EC2Instance}"],

[".", "NetworkIn", ".", "."],

[".", "NetworkOut", ".", "."]

],

"period": 300,

"stat": "Average",

"region": "${AWS::Region}",

"title": "EC2 Performance"

}

}

]

}

`

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Log analysis workflow:

`mermaid

sequenceDiagram

participant App

participant CloudWatch

participant Insights

participant Lambda

App->>CloudWatch: Send logs

CloudWatch->>Insights: Query logs

Insights->>Lambda: Process results

Lambda->>CloudWatch: Create metrics

CloudWatch->>CloudWatch: Trigger alarms

`

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Application monitoring architecture:

`mermaid

graph TB

subgraph Application Layer

A[Web Servers]

B[App Servers]

C[Databases]

end

subgraph Monitoring Layer

D[CloudWatch]

E[X-Ray]

F[ServiceLens]

end

A --> D

B --> D

C --> D

D --> E

E --> F

`

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Resource metrics configuration:

`yaml

Resources:

MetricsCollection:

Type: 'AWS::AutoScaling::AutoScalingGroup'

Properties:

MetricsCollection:

- Granularity: 1Minute

Metrics:

- GroupMinSize

- GroupMaxSize

- GroupDesiredCapacity

- GroupInServiceInstances

- GroupPendingInstances

- GroupTerminatingInstances

- GroupTotalInstances

`

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Security monitoring workflow:

`mermaid

graph LR

A[CloudTrail] -->|Logs| B[CloudWatch]

C[GuardDuty] -->|Findings| B

D[Security Hub] -->|Alerts| B

B -->|Analyze| E[Security Team]

B -->|AutoRemediate| F[Lambda]

`

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Authentication monitoring setup:

`yaml

Resources:

LoginMonitoringFunction:

Type: 'AWS::Lambda::Function'

Properties:

Handler: index.handler

Role: !GetAtt LambdaExecutionRole.Arn

Code:

ZipFile: |

exports.handler = async (event) => {

if (event.detail.eventName === 'ConsoleLogin') {

// Process login event

console.log('Console login detected:', event);

}

};

Runtime: nodejs18.x

LoginEventRule:

Type: 'AWS::Events::Rule'

Properties:

EventPattern:

source:

- aws.signin

detail-type:

- AWS Console Sign In via CloudTrail

Targets:

- Arn: !GetAtt LoginMonitoringFunction.Arn

Id: ProcessLoginEvents

`

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Cost monitoring dashboard:

`mermaid

graph TB

A[Cost Explorer API] --> B[CloudWatch]

C[Budget API] --> B

B --> D[Cost Dashboard]

D --> E[Daily Costs]

D --> F[Monthly Trends]

D --> G[Service Breakdown]

D --> H[Budget Alerts]

`

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Example resource cleanup function:

`yaml

Resources:

CleanupFunction:

Type: 'AWS::Lambda::Function'

Properties:

Handler: index.handler

Role: !GetAtt LambdaExecutionRole.Arn

Code:

ZipFile: |

const AWS = require('aws-sdk');

exports.handler = async () => {

// Find and terminate unused resources

const ec2 = new AWS.EC2();

const instances = await ec2.describeInstances({

Filters: [{

Name: 'instance-state-name',

Values: ['running']

}]

}).promise();

// Add cleanup logic here

};

Runtime: nodejs18.x

``