What is the logging severity level?
This topic discusses the syslog reporting feature of the Delphix Engine, along with severity levels. Show
Syslog is a widely used standard for message logging. It permits the separation of the software that generates messages, the system that stores them, and the software that reports and analyzes them. Delphix makes use of syslog as one of the standard mechanisms, along with SNMP and email, to distribute important user and system events, such as alerts, faults, and audits. In the case of Delphix, each Delphix Engine acts as a syslog client which propagates the events to a centralized syslog server. Every syslog message is attached to a severity level. As the name suggests, the severity level describes the severity of the event in question. Audit records are Informational syslog messages. If you would like to forward Audit records, choose Severity Level Informational. Every syslog message is attached to a severity level number. Delphix defines the severity of syslog messages in accordance with RFC 3164. There are eight severity levels available, as follows:
When setting up the syslog settings for your Delphix Engine, you have the ability to choose what alerts to report. The severity levels above are available for users to select. Once you select a severity level, the Delphix Engine will send messages of the same or higher severity (i.e., the same or lower number) to your syslog server. Therefore, there is no reason to select more than one severity. For example, if the "Notice" severity level is selected, all events less severe than Notice (Informational and Debug) will not be reported. If you want all events to be reported via syslog, the Debug severity level should be chosen. Log levels are labels that indicate the severity or urgency of a log entry. Their primary purpose is to separate messages that are merely informational (meaning that the system is working normally) from those that describe a problem or potential problem, such as when recurring errors are detected in the system. Log levels also provide a way to dynamically control your application's volume of log output (more on this later). In this article, we will discuss the following concepts that should help you get a handle on what log levels are and how to use them to log more effectively.
The history of log levelsSyslog, a logging solution initially developed for the Sendmail project, first introduced the concept of log levels in the 1980s. It came with severity levels that are attached to each log entry to describe the severity of the event in question:
In the following years, Syslog was adopted by various software applications and eventually became a standard for message logging on Unix-like systems. Its severity levels were also adapted and refined by various application logging frameworks such as log4net and log4j, evolving into the various log levels that are commonplace today. 🔭 Want to centralize and monitor your application logs?Head over to Logtail and start ingesting your logs in 5 minutes. Common log levels and their use casesThe log levels available to you will vary depending on the programming language, framework, or service in use. Still, most will include some or all of the following levels: FATALThe Examples of situations that may be logged as
ERRORThe The occurrence of an error condition in the application does not necessarily mean that it should be logged at the Logging significant error conditions is also useful for generating metrics such as Mean Time Between Failures (MTBF) which can be used to assess the quality of the application or to compare different systems or designs. Examples of situations that are typically logged at the
WARNMessages logged at the Events that may be logged at the
INFO
Other events that are typically logged at the
DEBUGThe TRACEThe
As you can see, the information logged at this level generally tries to capture every possible detail about the program's execution. Therefore, Log levels are the primary way to control your application's volume of log entries. Once you select your default level, all log entries that are labeled with a severity lower than the default will not be recorded. For example, logging at the As you go down in default severity, the number of entries that are produced will increase, so it's a good idea to turn on only what is necessary to avoid being flooded with too much information. A typical default for production environments is When troubleshooting a problem in production, you might want to reduce the default severity of recorded messages to The Control your default log level is best done through an environmental variable so that you can change it without modifying the code. However, you might need to restart the application each time the log level needs to be updated. There are also several ways to update the log level at runtime, but the specific technique will depend on the application environment and framework used. Ensure to thoroughly investigate the options available if this is something that interests you. How to use log levels for monitoring and analysisAfter you've configured your application to produce logs with the severity levels included, you might be wondering how to use the recorded labels to make sense of the log messages. The three main ways to use log levels for post-logging analysis are discussed below: 1. FilteringLog levels allow you to quickly sift your logs such that only the relevant ones are displayed. If you use a cloud log management service like Logtail, it's easy to specify filters that display only the 2. AlertingAnother useful way to use log levels is for creating alerts in various scenarios. You can notify relevant members of your team if a notable event occurs on the system, or if an expected event didn't occur within a specified time frame. The example below sends an alert to configured email addresses when more than five Aside from sending alerts to email addresses, you can configure various integrations so that you can receive alerts in Slack or other services in your stack. 3. Calculating various metricsLog levels are also a useful tool for generating various metrics about the application, especially those that help gauge its reliability. For example, the number of Final thoughtsUsing the right log level is a crucial step for effective log management. If your log levels are sound, it will be easy to filter your logs by priority, and you can create alerts for notable events. We hope this article has provided enough information to help you understand log levels and when to use them. For more details on logging techniques and practices to follow, check out the other articles in our logging guide. Thanks for reading, and happy logging! Logs tell stories. |