1. Logging Microservice Deep Dive
Tech Talks – Session 9

2. Agenda What and Why a Logging Microservice? Logging Service Technology
Spring/Java core
Logback Wrapped
Persistence options
Basics of how it works
Adding Logging to your microservice
Configuration
Logging objects
REST API
Adding log entries
Query the logs
Upcoming Tech Talks
Q&A

3. Jim White EdgeX Core/Supporting Services WG Chair
Dell Distinguished Engineer & Senior Software Architect
From Dell End User Computing (EUC) CTO
Chief Architect and lead developer of Fuse
I wrote code line #1 
Fuse => EdgeX Foundry

4. Big Picture and Logging

5. Logging’s Role
Provides centralized management of microservice log entries.
Offering long term persistence of log messages for query/analysis/bug diagnosis
Consolidated picture of participating microservice log events – assisting with broader issues
Well defined API allows for improved/value add logging in the future (security auditing, push of logs to remote server,…)
At a high level, the logging microservice
Provides a RESTful API for other microservices to request log entries in a non-blocking manner with minimal impact to system performance
Provides RESTful APIs to query, clear, or prune log entries based on any combination timestamp, log level, tag, origination, etc.
Allows log entries to be associated to its originating service (to faciliate easy search/filtering).
Supports multiple logging levels, for example trace, debug, info, warn, error, fatal, and so forth.
Supports log entry tagging; tags can be anything dictated by the calling services.
Persist log entries (in either file or database), and the persistence storage should be managed at configurable levels
Take advantage of an existing logging framework internally and provide the “wrapper” for use by EdgeX Foundry
Follow applicable standards for logging where possible
Handle a mundane activity with little or now dev effort - allow developers the ability to stay focused on value add capability
Use of the Logging microservice is optional!
Microservices can (and do) log independently as needed
This is often the case during development

6. Logging Implementation Details
Created with Java/Spring Framework/Spring Boot
Uses Spring MVC for REST communications
Internally, the logging microservice utilizes LOGBack as its underneath logging framework
“Successor” to popular log4j
I.e. – the logging microservice is a wrapper around LOGBack
Log entries can be persisted in (based on configuration)
MongoDB (recommended)
File system logs (used primarily for development)
Client services can…
Use the REST API to add/remove/query log entries
Use a Java client library to incorporate the logging services

7. Logging Microservice Architecture

8. Logging Microservice Implementation
MVC Controller
(provides REST interface)

9. Configuring the Logging Microservice
Property
Default Value(s)
Description
logging.persistence
file
"file" to save logging in file;
"mongodb" to save logging in MongoDB
Following config only take effect when logging.persistence=file
logging.persistence.file
File path to save logging entries; ex: c:/users/public/edgex/logs
logging.persistence.file.maxsize
10MB
Threshold to roll and archive the logging file. It can be specified in bytes, kilobytes, megabytes or gigabytes by suffixing a numeric value with KB, MB and respectively GB. For example, , 5000KB, 5MB and 2GB are all valid values, with the first three being equivalent.
Following config only take effect when logging.persistence=mongodb
spring.data.mongodb.username
logging
MongoDB user name
spring.data.mongodb.password
password
MongoDB password
spring.data.mongodb.host
localhost
MongoDB host name
spring.data.mongodb.port
27017
MongoDB port number
spring.data.mongodb.database
MongoDB database name

10. Using the logging services
2 choices
Use the REST APIs directly
If using Java, use the Logging Client
Convenience classes/methods

11. Logging API See service API RAML for more details
Make a log entry (POST)
{"logLevel": "WARN",
"originService": “core-data",
"message": "Hello, Logging Service!",
"labels": [“greeting", “non-problem"]}
Fetch log entries (GET)
10 is the number of log entries you want returned
Many query and delete log entry APIs. By…
Time/time range
Label(s)
Originating service(s)
Keyword(s) - text in entry
Log level(s) [ERROR, WARN, INFO, DEBUG, TRACE]
Many combinations of above
Example:
Get log entries with keyword “rocks” between 0 & timestamps, and limit 10 entry return
See service API RAML for more details
NOTE: TRACE entries are not persisted in MongoDB!!

12. Logging Client Add support-logging-client to your pom.xml
See any existing Java service as an example
In classes that need to log…
Add the following static
Add your log statement requests
Add the appropriate configuration
private static final org.edgexfoundry.support.logging.client.EdgeXLogger logger =
org.edgexfoundry.support.logging.client.EdgeXLoggerFactory.getEdgeXLogger(YourClassHere.class);
logger.error("Error getting command: " + e.getMessage());
logging.remote.enable=true
logging.remote.url=
#default origin service name is determined by app name
spring.application.name=core-metadata

13. Upcoming Tech Talks Using the SDK to generate a device service
Next week – presented by Tyler Cox (Dell) – 9am EST, Thursday
Suspending Tech Talks after next week
Focusing on Barcelona release
Restart Tech Talks after Barcelona (mid – October)
Suggestions welcome on other topics/direction of tech talks
me suggestions

14. Questions and Answer Time