Logging

Introducing Sync Gateway’s logging functionality and options

Sync Gateway’s Continuous Logging feature delivers flexible log generation and retention, without compromising the availability of diagnostic information necessary to provide effective support and maintence .

Log Levels

Sync Gateway logs at one (or more) of six defined log levels: none; error; warn; info; debug and trace.

You can set individual retention policies for each log level, with logs for each level being written to separate files.

Set log levels in your configuration file (see the logging.$level reference).

Log levels are additive, so if you enable info level, warn and error logs are also enabled.

The configurable log levels comprise (ordered from least verbose, to most):

Log Level Appearance Description

Log Level	Appearance	Description
`none`	-	Disables log output
`error`	`[ERR]`	Displays errors that need urgent attention
`warn`	`[WRN]`	Displays warnings that need some attention
`info`	`[INF]`	Displays information about normal operations that don’t need attention
`debug`	`[DBG]`	Displays verbose output that might be useful when debugging
`trace`	`[TRC]`	Displays extremely verbose output that might be useful when debugging

none

Disables log output

error

[ERR]

Displays errors that need urgent attention

warn

[WRN]

Displays warnings that need some attention

info

[INF]

Displays information about normal operations that don’t need attention

debug

[DBG]

Displays verbose output that might be useful when debugging

trace

[TRC]

Displays extremely verbose output that might be useful when debugging

Log Keys

Log keys provide fine-grained control over the information to be logged. By default, only HTTP is enabled, other available keys include: Auth; Bucket; CRUD; DCP and Import.

See the logging.console.log_level property reference for a comprehensive list of available keys.

Console Log Output

You can configure console logging independently, providing additional flexibility, without impacting the continuous logging output. For example, System administrators running Sync Gateway at the console may:

tweak log level and Log Keys to suit their needs,
filter console output by log levels and log keys
set a color for log output based on log level if logging.console.color_enabled is set to true

This setting is always disabled on Windows for compatibility reasons.

Log File Outputs

Log files are intended for the use of Couchbase Support. If you require special log handling then use the console log output stream.

Use SGCollect Info to collect diagnostic log data for analysis by Couchbase Support.

The log files are split by log level, with a guaranteed retention period for each.

Log File Default enabled Default max_age Minimum max_age

Log File	Default enabled	Default max_age	Minimum max_age
`sg_error.log`	`true`	360 Days	180 Days
`sg_warn.log`	`true`	180 Days	90 Days
`sg_info.log`	`true`	6 Days	3 Days
`sg_debug.log`	`false`	2 Days	1 Day

sg_error.log

true

360 Days

180 Days

sg_warn.log

true

180 Days

90 Days

sg_info.log

true

6 Days

3 Days

sg_debug.log

false

2 Days

1 Day

Each log level and its parameters are described in the logging.$level property reference.

Output Redirection

Address specialized logging requirements, such as centralized logging, by redirecting the console log output to a file. Then you can apply your own log collection mechanism to feed that data elsewhere.

Example 1. Redirect console log output

# Start Sync Gateway and redirect console output to a file
./sync-gateway > my_sg_logs.txt 2>&1

# Start log collection to send to a centralized log aggregator.
logcollector my_sg_logs.txt

Log File Rotation

Log files are rotated once each exceeds a threshold max_size in megabytes. Once rotated, the log files are compressed (gzip) to reduce the disk usage. Aged logs are cleaned up once their age exceeds max_age days.

Configure log rotation using the logging.level.$rotation property.

For pre-2.1 log rotation — see: Log Rotation pre-2.1

Log Redaction

All log outputs can be redacted, removing any user-data considered private. Enable this feature by setting the logging.redaction_level property.