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Logging Best Practices for Developers

Logging Best Practices for Developers
Nimrod Kramer
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Master logging best practices for developers to ensure smooth application operation, security, and troubleshooting. Learn about what to log, log structure, log levels, security measures, log retention, logging frameworks, and real-time monitoring.

Logging is essential for developers to ensure their applications run smoothly, stay secure, and are easy to troubleshoot. Here’s a straightforward guide to mastering logging:

  • Understand What to Log: Focus on important events, errors, user actions, and include useful details while keeping private information secure.
  • Structure Your Logs: Use a common format like JSON, include essential details, and organize logs for clarity.
  • Use Log Levels Appropriately: Stick to standard log levels (Debug, Info, Warn, Error) and choose the right default level for your application.
  • Ensure Security and Privacy: Anonymize, encrypt, and control access to log data to protect sensitive information.
  • Manage Log Retention: Set rules for how long to keep logs and use tools for automatic archiving and deletion.
  • Leverage Logging Frameworks and Tools: Pick the right tools for structured, centralized logging and consider services for managing logs.
  • Implement Real-time Logging and Monitoring: Stream logs for immediate analysis and use platforms for storing and examining logs in real-time.

By following these best practices, developers can create a logging system that not only helps in identifying and solving issues quickly but also enhances the overall security and efficiency of their applications.

1. Understanding What to Log

When it comes to logging, it's all about knowing what's important to keep track of. Here's how to do it right:

Focus on important events. Keep an eye on things that give you real insights, like when stuff breaks, how your users move through your app, or when something slows down. This helps you fix issues and understand what's happening.

Errors and warnings are key. Always pay extra attention to errors and warnings. Make sure to capture the details like what went wrong and where, so you can sort it out faster.

Track user actions. Note down the big steps users take, like signing up or buying something. It's great for seeing what parts of your app are working well.

Include useful details. Add info like when something happened and unique IDs to make sense of your logs later. This makes it easier to find and connect the dots.

Keep private stuff private. Be careful not to log personal or sensitive information. It's not just about being respectful; it's also about avoiding legal problems.

Don't go overboard. Logging too much can make it hard to find what you need and cost you more. Stick to logging the essentials to keep things manageable.

Use a clear format. Stick with a simple, organized format like JSON for your logs. This makes them easier to work with later on.

Picking what to log wisely helps you catch the important stuff without getting overwhelmed by too much information. It's all about balancing what you need to know with keeping things simple.

2. Structuring Logs for Clarity and Efficiency

Making your logs follow a certain order and format makes them easier to read, search through, and understand. Here's how to do it right:

Stick to a common format like JSON

  • It's simpler for both computers and people to get what's going on
  • You can add more info without messing up how your logs are read
  • Makes it easier to look for specific things in your logs

Don't forget important details

Things you should always include:

  • When it happened (Timestamp)
  • How serious it is (Log level like debug, info, warn, error)
  • What was going on (Operation name)
  • IDs (like user, session, transaction) to track actions
  • Where it came from (class, file, module)
  • Error details if something went wrong

Pick the right level of detail

  • Debug: For developers to figure stuff out
  • Info: Good to know things happening
  • Warn: Heads up on things not looking right
  • Error: Big problems that need attention

Keep all logs in one place

  • Brings together logs from everywhere
  • Helps see the big picture
  • Makes it easier to keep logs for a long time

Keep private info private

  • Remove personal details like emails
  • Use codes instead of real names for people
  • Keeps everyone's info safe

Make old logs smaller

  • Takes up less space
  • Helps your system run faster when looking through logs

Organizing your logs well makes it easier to handle them, helps you spot problems quicker, and keeps your system running smooth.

3. Log Levels and Their Proper Use

Using different levels for your logs helps keep them organized and makes it easier to find what you're looking for. Here's a simple guide on how to use log levels right:

Stick to the standard log levels: Debug, Info, Warn, Error. It's best not to make up your own because it can get confusing.


  • Just for fixing bugs while you're developing
  • Turn this off when your app is live


  • Keeps track of what your app is doing
  • This is a good level to have on all the time


  • For when something odd happens but it's not a full-blown problem
  • It's like a heads-up to check things out


  • For serious issues
  • Really important for fixing big problems

Choose the right default log level

  • Use Info or Warn for apps that are up and running
  • Debug is great for when you're still working on building things

Change levels as needed

  • If you're trying to solve a problem, you might turn on Debug
  • If you're getting too much info, switch to just Warn or Error

Don't log too much

  • Too many logs can slow things down
  • It can also make it hard to spot the real problems

Keep private stuff private

  • Make sure not to log personal details
  • This keeps you on the right side of privacy laws

By sticking to these simple rules for log levels, you'll make it easier to keep an eye on your app, fix problems quickly, and protect user privacy. It's all about finding the right balance between getting the information you need and not getting swamped by too much data.

4. Security and Privacy Considerations in Logging

When we log info about our app, we sometimes catch sensitive bits that we really shouldn't leave lying around. Here's how to keep things tight and respectful:

Anonymize user data

  • Before you log personal info like someone's name or email, change it to something generic. Think of using random IDs instead.
  • Always stick to rules that keep people's data safe.

Encrypt log data

  • Make sure logs are scrambled (encrypted) so only people with the key can read them, whether they're just sitting there or being sent over the internet.
  • Tools like rsyslog and syslog-ng are your friends here, along with using secure connections (TLS, SSL).

Control access

  • Only let people who really need to see the logs get to them, and set up rules (role-based access) to control this.

Log data retention

  • You don't need to keep logs forever. Decide how long to keep them, stick to it, and then get rid of them according to your plan.

Mask sensitive data

  • For super private info like credit card or social security numbers, hide most of it. If you have to log any part of it, just use the last few digits.

Log data integrity

  • To stop anyone from messing with your logs, use tricks like hashing and signatures. This way, you can prove they haven't been changed if someone asks.

Monitor your logging

  • Keep an eye out for any weird increases in logging or if someone's looking at the logs who shouldn't be. Set up alerts to catch this stuff.

By keeping these points in mind, you'll manage to gather all the important info you need while making sure everyone's data stays private and secure. It's all about balancing the need to know with the need to keep things under wraps.

5. Log Retention and Management

Keeping logs organized and stored correctly over time is key for fixing problems and keeping an eye on how your system is doing. Here are some smart ways to handle it:

Set up a rule for how long to keep logs

  • Figure out how long you need to keep different kinds of logs. For example, you might need to keep logs of application errors for a few months (like 3-6 months), while logs that are important for following rules might need to be kept for several years.
  • Get rid of less important logs, like debug logs, more often (maybe every two weeks).

Make archiving and deleting logs automatic

  • Doing this by hand can be a real pain.
  • Use tools to automatically move logs to where they'll be stored for a long time and delete them when it's time, according to your rules.
  • Tools for managing logs, like Elastic Stack or Splunk, can help with this.

Keep an eye on how many logs you have

  • Too many logs can make things messy and hard to manage.
  • Set up warnings for when you suddenly have a lot more logs than usual.
  • Find out why it's happening and fix it (like if a process is out of control).

Think about costs

  • Keeping logs for a long time can start to cost a lot.
  • Find a good balance between what you need and how much it costs.
  • Use different levels of storage (hot, warm, cold) to save money.

Keep your stored logs safe

  • Important logs can be messed with or deleted over time.
  • Lock them up with encryption to show they haven't been changed.
  • Make sure only the right people can get to them to stop bad stuff from happening.

Make sure you can get your logs back

  • Logs are no good if you can't access them when you need to.
  • Try getting back some of your stored logs now and then to make sure everything's working right.
  • If something's broken, fix it fast.

By following these steps for managing your logs, you'll be able to use your logs to help with daily tasks and when unexpected problems pop up.

6. Leveraging Logging Frameworks and Tools

When you're dealing with a lot of logs, especially from big or complicated systems, it's smart to use some tools and frameworks that help you handle everything more easily. Here's how to do it in a straightforward way:

Pick a logging framework that fits what you're working with

Some well-known free tools include:

  • Log4j/Logback for Java
  • log4net/NLog for .NET
  • Winston/Bunyan for Node.js

Use structured logging

Keep your logs in a common format like JSON because it lets you:

  • Easily sort and look into your logs with other tools
  • Add extra info without messing things up

Send your logs to one place to look at them

Putting all your logs together helps you:

  • Connect dots across different parts of your app to figure out issues
  • Notice patterns or things that stand out
  • Store logs safely and decide how long to keep them

Think about using a service that handles logs for you

Services like Splunk, Datadog, and offer:

  • Ready-to-use dashboards and alerts
  • Help with managing, saving, and finding logs
  • A way to grow without worrying about the tech stuff

Make collecting and sending logs automatic

Tools like Fluentd can take care of moving your logs where they need to go without you having to do it by hand.

Keep personal info out of your logs

Before your logs go anywhere, make sure to hide sensitive details to stay out of trouble with privacy rules.

Picking the right tools and knowing how to use them can really make a difference in managing your logs, especially as your app gets bigger and more complex.

7. Real-time Logging and Monitoring

Keeping an eye on your application logs as things happen is key to quickly spotting and fixing issues. Here's how to do it in a straightforward way:

Stream logs as they come in

  • Instead of waiting to process logs later, send them straight to a place where you can see them right away.
  • This lets you catch problems fast and figure out what to do next.

Pick a platform for storing and looking at logs

Some good choices include:

  • Elasticsearch - A tool that helps you search and analyze logs easily.
  • Splunk - A powerful system for managing and understanding logs.
  • Datadog - A service that monitors your systems and includes log analysis.

Set up dashboards

  • Create custom screens that show you what's happening in your logs.
  • Keep an eye on important things happening in your app.
  • Get alerts when something big goes wrong.

Link related events

  • Connect dots between what's happening in different parts of your app.
  • This helps you get to the bottom of tricky problems.
  • See the app from your users' perspective.

Keep personal info out of logs

  • Make sure to remove private details from logs before they go anywhere.
  • This helps protect your customers' privacy.

Save the original logs

  • Keep a copy of the raw log data for looking into issues later on.
  • This is really helpful when you're trying to solve tough problems.

Manage who can see logs

  • Make sure only the right people can see your real-time logs.
  • This helps keep sensitive information safe.

By keeping an eye on your logs as things happen, you can quickly spot and fix issues, making sure your app runs smoothly and is always available.


Making sure you're good at logging is super important for developers who want to make apps that work well, are safe, and don't have too many problems. By using the logging tips we talked about, developers can get a bunch of benefits:

Better at Fixing Bugs

Logs that are easy to read and have all the right details make it way easier to figure out what went wrong and why. This is super helpful whether you're trying to squash bugs or make your app run smoother.

Keeping Things Safer

Making sure logs don't give away secrets, using passwords to protect them, and keeping an eye out for anything fishy helps keep your app safe from hackers.

Working Smarter, Not Harder

Using smart tricks like picking what to log, making logs easy to read, putting them all in one place, and setting up automatic clean-up helps you handle tons of log info without getting buried.

Making Your App Better

By keeping track of how users interact with your app and how well it performs, you can use that info to make your app better, faster, and more fun to use.

Staying Out of Trouble

Good logging helps you follow the rules, especially when it comes to keeping user info private and secure.

In short, getting logging right is a big deal. It not only makes your app stronger but also gives you the insights you need to keep improving. Following these logging tips is a smart move for any developer wanting to make their software better.


What is the best method of logging?

When it comes to logging, there are a few smart ways to do it:

  • Structured logging: This means keeping your logs in a neat format, like JSON. It's easier to work with and helps when you're trying to figure things out.
  • Centralized logging: This is about putting all your logs in one place. It makes it simpler to look through them and find what you need.
  • Selective logging: This is about being picky with what you log. It helps keep the amount of logs manageable and focuses on what's really important.

Putting it all together, using structured logs and keeping them centralized is the best approach. Being selective about what you log helps keep things from getting too crowded.

What are the five levels of logging?

Here are the five main levels of logging, from least to most serious:

  • Debug - Helps fix problems during the making of your app
  • Info - Keeps track of normal stuff your app does
  • Warn - Flags things that might be a problem for users
  • Error - Big issues that stop your app from working right
  • Fatal - Major problems that make your app crash or shut down

Using these levels helps you sort your logs by how serious they are. This way, you can focus on the big issues.

How do you optimize logging?

To make logging work best, you can:

  • Use structured logging for easier analysis
  • Centralize your logs for a clearer view
  • Be selective about what you log to avoid too much information
  • Rotate and keep logs for a set time to manage space
  • Use async logging to avoid slowing down your app
  • Sample logs in busy areas to reduce volume
  • Set up alerts for errors or unusual activity
  • Use tracing to follow what happens in a transaction
  • Create dashboards to easily see important info

The aim is to get useful insights without being overwhelmed by too much data.

What should logging practices ensure?

Good logging practices should make sure you can:

  • Troubleshoot effectively by having all the details you need about problems
  • See clearly how your app is used and how it's performing
  • Work together in DevOps by using logs to keep tabs on your systems and apps
  • Follow rules for auditing and compliance by keeping track of actions and changes
  • Protect privacy and security by being careful with sensitive data

Great logs are like a reliable source of information that helps everyone from developers to business teams.

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