These logs are crucial for the AWS Certified SysOps Administrator – Associate (SOA-C02) exam. Therefore, getting an understanding of how to work with them makes you a more effective AWS SysOps Administrator.
I. Collecting Logs in AWS
Let’s first talk about some of the various logs you might encounter when operating in the AWS environment.
- VPC Flow Logs: These logs capture information about the IP traffic going to and from network interfaces within a Virtual Private Cloud (VPC). Details include source and destination IP addresses, packet and byte counts, start and end times of flows, action status (ACCEPT or REJECT), and more.
- ELB Access Logs: These logs record all requests sent to your load balancer, detailing information like request time, client IP address, latencies, request path, and server responses.
- AWS WAF Web ACL Logs: These logs contain information about web requests, including the originating IP address, HTTP headers, URI, and more. These logs are highly useful for identifying malicious activities and patterns.
- CloudFront Logs: These logs provide detailed records about every user request that CloudFront receives.
In AWS, you have a few methods to collect these logs. The common approach is to use AWS CloudWatch, where logs get aggregated, monitored, and stored. You can also employ AWS S3 buckets to store logs and AWS Athena or Redshift to analyze log data.
II. Interpreting Logs in AWS
With logs in hand, interpretation is the next step. Below are some tips:
- VPC Flow Logs: Generally, interpret these logs for troubleshooting connectivity and security issues within your network. For example, if the ‘Action’ field status is ‘REJECT’, it implies a packet was not delivered due to security rules.
- ELB Access Logs: ELB access logs provide insights into application’s performance issues. For instance, if the ‘Backend Processing Time’ is high, this could indicate a performance issue with your backend servers.
- AWS WAF Web ACL Logs: These logs assist in identifying the potential source of a web attack. If you see numerous requests originating from a single IP address continuously, it may indicate a potential threat.
- CloudFront Logs: Use these logs for diagnosing and troubleshooting content delivery issues. High ‘TimeTaken’ values, for example, could imply content delivery problems.
III. AWS Log Analysis Example
Let’s look at an example of collecting and interpreting CloudFront logs, which are stored in AWS S3 buckets.
- First, enable CloudFront logs through the CloudFront console.
- Choose the desired distribution for which you want logging.
- In the settings, choose to write logs into your desired S3 bucket.
- After collecting logs, you can then use Athena to run SQL-like queries on logs data. For instance, to find all records for a specific HTTP status code, the command would be:
SELECT *
FROM cloudfront_logs
WHERE sc_status = '200'
This command retrieves all log entries where the HTTP status code was ‘200.’
Collecting and interpreting logs is essential for maintaining and troubleshooting your AWS infrastructure, and these skills are crucial for the AWS Certified SysOps Administrator – Associate (SOA-C02) exam. Familiarize yourself with different types of logs and practice interpreting and analyzing this data to boost your AWS sysops competency level.
Practice Test
True or False: VPC Flow Logs can help you understand, forecast, and manage the costs incurred by your AWS resources.
- Answer: False
Explanation: VPC Flow Logs capture information about the IP traffic going to and from network interfaces in your VPC, it does not manage costs.
Which of the following AWS services provides access logs for analysis? (Select all that apply)
- A. ELB
- B. VPC
- C. EC2
- D. CloudFront
Answer: A, B, D
Explanation: ELB, VPC Flow Logs, and CloudFront logs provide access logs for analysis, but AWS EC2 does not.
True or False: AWS WAF web ACL logs records all requests that are made to your web application.
- Answer: True
Explanation: AWS WAF web ACL logs keep track of all requests made to your web application, allowing you to identify potential threats.
What is the benefit of analyzing ELB access logs?
- A. Identifying the source of high traffic
- B. Troubleshoot issues
- C. Understand the nature of requests
- D. All of the above
Answer: D. All of the above
Explanation: ELB access logs provide detailed records about the requests that are made to your load balancer, which can be used to identify high traffic sources, troubleshoot issues, and understand the nature of incoming requests.
True or False: You need to manually enable logging in AWS WAF.
- Answer: True
Explanation: By default, AWS WAF does not send logs. You need to manually enable logging.
Which of the following are true about VPC Flow logs? (Select all that apply)
- A. VPC Flow logs can be viewed in CloudWatch logs
- B. VPC Flow logs capture all activity of the network interfaces
- C. VPC Flow logs can be sent to an S3 bucket
- D. VPC Flow logs monitor the network interfaces for EC2 instances
Answer: A, B, C, D
Explanation: All above statements are true pertaining to the VPC flow logs.
True or False: You can enable AWS CloudFront logs to Amazon S3 bucket for analysis.
- Answer: True
Explanation: AWS CloudFront logs can be enabled and stored into Amazon S3 buckets for later analysis.
Which of the following services would you use to collect, monitor, and analyze logs from your AWS resources?
- A. Amazon CloudWatch
- B. AWS Data Pipeline
- C. Amazon Redshift
- D. AWS Direct Connect
Answer: A. Amazon CloudWatch
Explanation: Amazon CloudWatch is a cloud monitoring tool designed to collect and track metrics for AWS resources and applications.
True or False: VPC Flow Logs cannot capture the source IP addresses.
- Answer: False
Explanation: VPC Flow logs not only capture source and destination IP addresses but also the packet or byte data.
Which of the following Amazon CloudFront logs is used to troubleshoot user request issues to the edge locations?
- A. CloudFront event logs
- B. CloudFront access logs
- C. CloudFront error logs
- D. CloudFront security logs
Answer: B. CloudFront access logs
Explanation: CloudFront access logs provide information about each user request in raw log format, which can be useful for troubleshooting.
Interview Questions
1. What are VPC Flow Logs in AWS?
VPC Flow Logs is a feature that enables you to capture information about the IP traffic going to and from network interfaces in your VPC.
2. How can you view VPC Flow Logs?
You can view the VPC Flow Logs by navigating to the “Flow Logs” tab in the VPC dashboard on AWS console, by using AWS CLI or SDKs, and from Amazon CloudWatch if you have integrated it.
3. What is the purpose of ELB Access Logs?
ELB Access Logs is an AWS feature that collects detailed records for the requests that are made to the Elastic Load Balancer, providing visibility for diagnosing issues, tracking request patterns, and ensuring network security.
4. What information is captured in ELB access logs?
ELB access logs captures information such as the client’s IP address, request path, request processing time, backend processing time, response processing time, ELB status code, and backend status code.
5. Can you automate the collection of ELB Access Logs?
Yes, you can automate the collection of ELB Access Logs by setting up an Access Logging Policy to automatically store the logs in an S3 bucket.
6. What is AWS WAF Web ACL logs?
AWS WAF Web ACL logs are records of all the web requests that AWS WAF inspects and lets through or blocks based on the conditions in the associated web access control list (web ACL).
7. What elements are included in a web ACL log record?
Each web ACL log record includes the AWS resource name, the action AWS WAF took on the request (ALLOW, BLOCK, or COUNT), rule within the web ACL that took the action, and details about the HTTP request.
8. How are CloudFront logs used in AWS?
CloudFront logs provide detailed records about each user request that CloudFront receives. They can be used to troubleshoot and improve the quality of service, detect security incidents, and understand user behavior and website performance.
9. How to configure CloudFront to create access logs?
You can configure CloudFront to create access logs by specifying the Amazon S3 bucket to store the log files, the log file prefix, and the distribution for which you want to collect log files.
10. What can you glean from interpreting AWS logs?
Interpreting AWS logs can help you understand traffic patterns, diagnose service and security issues, audit behavior, identify application performance bottlenecks, and keep track of requests made to your resources.
11. Can VPC Flow Logs capture all IP traffic?
No, VPC Flow Logs do not capture all IP traffic. They do not log traffic to or from the metadata service, DHCP, the reserved IP address for the default VPC router, or traffic within the instance metadata service.
12. How can you enable AWS WAF logging?
You can enable AWS WAF logging by configuring a CloudWatch Logs group for the web ACL, and specifying a Kinesis Data Firehose.
13. What’s one way to enhance management and interpretation of logs in AWS?
One way to enhance management and interpretation of logs in AWS is by integrating with AWS CloudTrail and Amazon CloudWatch, which offer analytics and automated reactions to specific events.
14. Can you filter VPC Flow Logs?
Yes, you can filter VPC Flow Logs by using the filter pattern syntax of CloudWatch Logs.
15. What cost considerations should you make when enabling logs in AWS?
While enabling logs can assist in monitoring and troubleshooting, it can also result in additional charges. Factors to consider include the cost of storing log files in S3, the cost of data transfer and network usage, and costs associated with CloudWatch log ingestion and retention.
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