What is Amazon CloudWatch Logs?
You can use Amazon CloudWatch Logs to monitor, store, and access your log files from Amazon Elastic Compute Cloud (Amazon EC2) instances, AWS CloudTrail, and other sources. You can then retrieve the associated log data from CloudWatch Logs.
Monitor Logs from Amazon EC2 Instances in Real-time—You can use CloudWatch Logs to monitor applications and systems using log data. For example, CloudWatch Logs can track the number of errors that occur in your application logs and send you a notification whenever the rate of errors exceeds a threshold you specify. CloudWatch Logs uses your log data for monitoring; so, no code changes are required. For example, you can monitor application logs for specific literal terms (such as "NullReferenceException") or count the number of occurrences of a literal term at a particular position in log data (such as "404" status codes in an Apache access log). When the term you are searching for is found, CloudWatch Logs reports the data to a CloudWatch metric that you specify. Log data is encrypted while in transit and while it is at rest. To get started, see Getting Started with CloudWatch Logs.
Monitor AWS CloudTrail Logged Events—You can create alarms in CloudWatch and receive notifications of particular API activity as captured by CloudTrail and use the notification to perform troubleshooting. To get started, see Sending CloudTrail Events to CloudWatch Logs in the AWS CloudTrail User Guide.
Archive Log Data—You can use CloudWatch Logs to store your log data in highly durable storage. You can change the log retention setting so that any log events older than this setting are automatically deleted. The CloudWatch Logs agent makes it easy to quickly send both rotated and non-rotated log data off of a host and into the log service. You can then access the raw log data when you need it.
Related AWS Services
The following services are used in conjunction with CloudWatch Logs:
AWS CloudTrail is a web service that enables you to monitor the calls made to the CloudWatch Logs API for your account, including calls made by the AWS Management Console, command line interface (CLI), and other services. When CloudTrail logging is turned on, CloudWatch will write log files into the Amazon S3 bucket that you specified when you configured CloudTrail. Each log file can contain one or more records, depending on how many actions must be performed to satisfy a request. For more information about AWS CloudTrail, see What is AWS CloudTrail? in the AWS CloudTrail User Guide. For an example of the type of data that CloudWatch writes into CloudTrail log files, see Logging Amazon CloudWatch Logs API Calls in AWS CloudTrail.
AWS Identity and Access Management (IAM) is a web service that helps you securely control access to AWS resources for your users. Use IAM to control who can use your AWS resources (authentication) and what resources they can use in which ways (authorization). For more information, see What is IAM? in the IAM User Guide.
Amazon Kinesis Streams is a web service you can use for rapid and continuous data intake and aggregation. The type of data used includes IT infrastructure log data, application logs, social media, market data feeds, and web clickstream data. Because the response time for the data intake and processing is in real time, processing is typically lightweight. For more information, see What is Amazon Kinesis Streams? in the Amazon Kinesis Streams Developer Guide.
AWS Lambda is a web service you can use to build applications that respond quickly to new information. Upload your application code as Lambda functions and Lambda runs your code on high-availability compute infrastructure and performs all the administration of the compute resources, including server and operating system maintenance, capacity provisioning and automatic scaling, code and security patch deployment, and code monitoring and logging. All you need to do is supply your code in one of the languages that Lambda supports. For more information, see What is AWS Lambda? in the AWS Lambda Developer Guide.
When you sign up for AWS, you can get started with CloudWatch Logs for free using the AWS Free Tier.
Standard rates apply for logs stored by other services using CloudWatch Logs (for example, Amazon VPC flow logs and Lambda logs).
For more information, see Amazon CloudWatch Pricing.