Understand how best practices apply to writing logs so that humans can read and troubleshoot errors. Using expressive and contextual messages to describe application behavior.

1. Farming LOGs to save
the weekend
Antonio Spinelli
@tonicospinelli

2. 01
What is it for?
02 03
LOGs are the BEST FRIEND
of the software engineer
Best practices Tooling
Building dashboards to
visualize the application
behavior in real-time
Understand log severity,
meaningful messages
and avoid sensible data
know why it is the most
important resource to
monitor your application

3. What is it for?
- a monitoring resource
- giving visibility for application behavior
- criticality through severity

4. Best practices
- meaningful messages
- logging severity
- avoid sensible information

5. Meaningful
Messages

6. Best practices Meaningful Messages
- avoid cryptic log entries
- anticipate any emergencies
- write contextualized messages

7. Best practices Meaningful Messages
- add remediation information
- purpose the operation and its outcome
- messages must be independent

8. Best practices Meaningful Messages
- make messages Human-Readable
- think of your audience, be empathic
- never log sensitive information

9. Best practices Avoid Sensible Information
- Credentials, Social security numbers
- Session identifiers, Authorization tokens
- PII (Personal Identifiable Information)
- personal name, credit card numbers,
emails, birthdate

10. Best practices Example
cryptic
The database is down
contextualized
Fail to find attributes for customer id=1. Database out of
service. It will retry again in 5 minutes.

11. Severity

12. Best practices SEVERITY RFC-5424
0
Emergency
system is unusable
1
Alert
team must take action immediately
2
Critical
system may stop
3
Error
unexpected behavior
4
Warning
possibility of side-effect
5
Notice
normal but significant condition
6
Informational
informational messages
7
Debug
explicitly behavior

13. Best practices SEVERITY 7 Debug
condition
tracing information useful for debugging purposes.
example
A product=SKU was added to the cart=10 by the
customer=1. The cart has 3 products and the total
price was updated to R$ 350.00.

14. Best practices SEVERITY 6 Informational
condition
general information about system operations.
example
A new item was added to the cart by the customer.
The cart has 3 products and the total price was updated.

15. Best practices SEVERITY 5 Notice
condition
notable events that do not affect the functionality.
example
The product is out of stock. There are some orders to
be finished locking the availability of the product.

16. Best practices SEVERITY 4 Warning
condition
functionality may be affected.
example
The product width is empty in the webstore. This field
is required to calculate the shipping cost.

17. Best practices SEVERITY 3 Error
condition
there is an error and functionality is affected.
example
The payment gateway is out of service, and the order
will be stand by until it's available.

18. Best practices SEVERITY 2 Critical
condition
the application may stop.
example
The database connection has gone away. The
connection will be established as soon as possible.

19. Best practices SEVERITY 1 Alert
condition
the team must take action immediately.
example
No space left on the device. The hard disk reached the
current capacity, increases the available volume, or
archives the oldest files.

20. Best practices SEVERITY 0 Emergency
condition
the system is unusable or not responding.
example
The database server is not reached by application.
Verify the network is available.

21. Tooling
log management solutions

22. Tooling

23. Tooling New Relic

24. Antonio Spinelli
@tonicospinelli
references
- The 10 commandments of logging
- RFC-5424 (The Syslog Protocol)
- 12Factors (Log)