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How i learned to stop worrying and love the logs
This document discusses best practices for application logging. It recommends structuring logs with standardized date/time, process ID, application details, location, and event type. Logs should separate by area of interest, not log and throw exceptions, and add context to error messages. Logging key events and changes can help trace issues. Formats like log levels, tickets, and flow markers aid analysis. Logs from all sources should be aggregated while avoiding junk. Proper logging improves issue detection.
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How i learned to stop worrying and love the logs
- 1. How I Learnedto Stop Worrying and Love the Logs
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- 3. DISCLAIMER The bearing ofa child takes nine months, no matter how many women are assigned. Brooks's Law: Adding manpower to a late software project makes it later. This second is the most dangerous system a man ever designs. Never go to sea with two chronometers; take one or three.
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- 5. How I Learnedto Stop Worrying and Love the Logs
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- 8. Your program isgoing to die anyway, the leastit can do is tell you who killed it
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- 14. W ? W?W ? W ?W ?
- 15. W ? Log dateand time (international format) Resolution - Milliseconds processID / threadId
- 16. W ? Application identifiere.g. name and version Code location e.g. script name, module name Geolocation Window/form/page
- 17. W ? Source address Useridentity (if authenticated or otherwise known) Or session context
- 18. W ? Type ofevent Severity security General description
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- 20. Message Priorities/Levels •Fatal Severeerrors that cause premature termination. •Error Other runtime errors or unexpected conditions. •Warn are undesirable or unexpected, but not necessarily "wrong". •Info Interesting runtime events (startup/shutdown). •Debug detailed information on the flow through the system. •Trace more detailed information.
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- 23. •Input validation failures •Outputvalidation failures •Authentication successes and failures•Authorization (access control) failures•Session management failures•Application errors and system events•Application and related systems start-upsand shut-downs, and logging initialization(starting, stopping or pausing)•Use of higher-risk functionality•Legal and other opt-ins •Sequencing failure •Excessive use •Data changes •Fraud and other criminal activities •Suspicious, unacceptable or unexpected behavior •Modifications to configuration •Application code file and/or memory changes W ?
- 24. W ? Service origin Flowmarker
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- 26. B Log locally tofiles Rotate log files to keep them current Keep multi-line events to a minimum Window/form/page
- 27. Collect events from everything, everywhere •Applicationlogs •Database logs •Network logs •Configuration files •Performance data (iostat, vmstat, ps, etc.) •Anything that has a time component
- 28. Separate logs to areas ofinterest Line.log Uut-0141409124.log Uut-0141409125.log Uut-0141409126.log Uut-0141409127.log
- 29. Don’t log and throw try{ // Code that generates an IOException } catch (IOException e) { logger.fatal("Caught IOException", e); throw e; }
- 30. Don’t catch and drop try{ // Code that generates an IOException } catch (IOException e) {}
- 32. void transfer(Account fromAcc,Account toAcc,int amount, User user) { if (!isUserAuthorised(user, fromAcc)) { throw new UnauthorisedUserException(); } if (fromAcc.getBalance() < amount) { throw new InsufficientFundsException(); } fromAcc.withdraw(amount); toAcc.deposit(amount); database.commitChanges(); // Atomic operation. }
- 33. void transfer(Account fromAcc,Account toAcc,int amount, User user) { logger.info("Transferring money..."); if (!isUserAuthorised(user, fromAcc)) { throw new UnauthorisedUserException(); } if (fromAcc.getBalance() < amount) { throw new InsufficientFundsException(); } fromAcc.withdraw(amount); toAcc.deposit(amount); database.commitChanges(); // Atomic operation. } .
- 34. void transfer(Account fromAcc,Account toAcc,int amount, User user) { logger.info("Transferring money from {} to {} amount {} user {}“, fromAcc, toAcc, amount, user); if (!isUserAuthorised(user, fromAcc)) { logger.info("User has no permission."); throw new UnauthorisedUserException(); } if (fromAcc.getBalance() < amount) { logger.info("Insufficient funds."); throw new InsufficientFundsException(); } fromAcc.withdraw(amount); toAcc.deposit(amount); database.commitChanges(); // Atomic operation. }
- 35. void transfer(Account fromAcc,Account toAcc,int amount, User user) { logger.info("Transferring money from {} to {} amount {} user {}“, fromAcc, toAcc, amount, user); if (!isUserAuthorised(user, fromAcc)) { logger.info("User has no permission."); throw new UnauthorisedUserException(); } if (fromAcc.getBalance() < amount) { logger.info("Insufficient funds."); throw new InsufficientFundsException(); } fromAcc.withdraw(amount); toAcc.deposit(amount); database.commitChanges(); // Atomic operation. logger.info("Transaction successful."); }
- 36. private String phone; publicString getPhone() { return (phone == null) ? "none" : phone; } public void setPhone(String arg, MfDate changeDate) { log(changeDate, this, "change of phone", phone, arg); phone = arg; } public void setPhone(String arg) { setPhone(arg, MfDate.today()); } private static void log(MfDate validDate, Customer customer, String description, Object oldValue, Object newValue) { try { logfile().write(validDate.toString() + customer.name() + "t" + description + "t" + oldValue + "t" + newValue + "t" + MfDate.today() + "n"); logfile().flush(); } catch (IOException e) { throw new ApplicationException("Unable to write to log"); } }
- 37. LOG.debug(arg.toString()); LOG.debug("Method called witharg {}", arg); LOG.debug("{}", arg);
- 38. LOG.debug( "Something interestingis happening: event=" + event.type + ", message=" + message); LOG.debug( "Something interesting is happening:event={0}, message={1}", event.type, message);
- 39. try { doSomething(arg);... } catch (SomeException ex) { } try { doSomething(arg); ... } catch (SomeException ignore) { LOG.warn( "Failed to do something with {}, ignoring it", arg); } try { doSomething(arg);} catch (SomeException ex) { LOG.warn(ex.getMessage()); }
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- 48. Enumerate logger errors LOGGER.error("001 -Error writing to device”); LOGGER.error("002 - Error writing to device”); LOGGER.error("003 - Error writing to device”);
- 49. Use ALM markers incode LOGGER.error(“JIRA-1231 : threshold has been exceeded.”) LOGGER.warn(“TFS-1231 : Map server not found. No tiles will be shown.”)
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- 53. Use categories and flowmarkers LOGGER.info("MESSAGE-FLOW 7a-SUCESS - {0} got ACK for {1}", sender, alert); LOGGER.info("MESSAGE-FLOW 7b-RETRY - {0} will resend {1}", sender, alert);
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- 57. C f Lack ofcommon log formats Not all activities are logged, or aggregated Requires learning High volume of junk
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