pub struct Builder { /* private fields */ }
Expand description
A builder for configuring RollingFileAppender
s.
Implementations§
Source§impl Builder
impl Builder
Sourcepub const fn new() -> Self
pub const fn new() -> Self
Returns a new Builder
for configuring a RollingFileAppender
, with
the default parameters.
§Default Values
The default values for the builder are:
Parameter | Default Value | Notes |
---|---|---|
rotation | Rotation::NEVER | By default, log files will never be rotated. |
filename_prefix | "" | By default, log file names will not have a prefix. |
filename_suffix | "" | By default, log file names will not have a suffix. |
max_log_files | None | By default, there is no limit for maximum log file count. |
Sourcepub fn rotation(self, rotation: Rotation) -> Self
pub fn rotation(self, rotation: Rotation) -> Self
Sets the rotation strategy for log files.
By default, this is Rotation::NEVER
.
§Examples
use tracing_appender::rolling::{Rotation, RollingFileAppender};
let appender = RollingFileAppender::builder()
.rotation(Rotation::HOURLY) // rotate log files once every hour
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
Sourcepub fn filename_prefix(self, prefix: impl Into<String>) -> Self
pub fn filename_prefix(self, prefix: impl Into<String>) -> Self
Sets the prefix for log filenames. The prefix is output before the
timestamp in the file name, and if it is non-empty, it is followed by a
dot (.
).
By default, log files do not have a prefix.
§Examples
Setting a prefix:
use tracing_appender::rolling::RollingFileAppender;
let appender = RollingFileAppender::builder()
.filename_prefix("myapp.log") // log files will have names like "myapp.log.2019-01-01"
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
No prefix:
use tracing_appender::rolling::RollingFileAppender;
let appender = RollingFileAppender::builder()
.filename_prefix("") // log files will have names like "2019-01-01"
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
Sourcepub fn filename_suffix(self, suffix: impl Into<String>) -> Self
pub fn filename_suffix(self, suffix: impl Into<String>) -> Self
Sets the suffix for log filenames. The suffix is output after the
timestamp in the file name, and if it is non-empty, it is preceded by a
dot (.
).
By default, log files do not have a suffix.
§Examples
Setting a suffix:
use tracing_appender::rolling::RollingFileAppender;
let appender = RollingFileAppender::builder()
.filename_suffix("myapp.log") // log files will have names like "2019-01-01.myapp.log"
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
No suffix:
use tracing_appender::rolling::RollingFileAppender;
let appender = RollingFileAppender::builder()
.filename_suffix("") // log files will have names like "2019-01-01"
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
Sourcepub fn max_log_files(self, n: usize) -> Self
pub fn max_log_files(self, n: usize) -> Self
Keeps the last n
log files on disk.
When a new log file is created, if there are n
or more
existing log files in the directory, the oldest will be deleted.
If no value is supplied, the RollingAppender
will not remove any files.
Files are considered candidates for deletion based on the following criteria:
- The file must not be a directory or symbolic link.
- If the appender is configured with a
filename_prefix
, the file name must start with that prefix. - If the appender is configured with a
filename_suffix
, the file name must end with that suffix. - If the appender has neither a filename prefix nor a suffix, then the file name must parse as a valid date based on the appender’s date format.
Files matching these criteria may be deleted if the maximum number of log files in the directory has been reached.
§Examples
use tracing_appender::rolling::RollingFileAppender;
let appender = RollingFileAppender::builder()
.max_log_files(5) // only the most recent 5 log files will be kept
// ...
.build("/var/log")
.expect("failed to initialize rolling file appender");
Sourcepub fn build(
&self,
directory: impl AsRef<Path>,
) -> Result<RollingFileAppender, InitError>
pub fn build( &self, directory: impl AsRef<Path>, ) -> Result<RollingFileAppender, InitError>
Builds a new RollingFileAppender
with the configured parameters,
emitting log files to the provided directory.
Unlike RollingFileAppender::new
, this returns a Result
rather than
panicking when the appender cannot be initialized.
§Examples
use tracing_appender::rolling::{Rotation, RollingFileAppender};
let appender = RollingFileAppender::builder()
.rotation(Rotation::DAILY) // rotate log files once per day
.filename_prefix("myapp.log") // log files will have names like "myapp.log.2019-01-01"
.build("/var/log/myapp") // write log files to the '/var/log/myapp' directory
.expect("failed to initialize rolling file appender");
This is equivalent to
let appender = tracing_appender::rolling::daily("myapp.log", "/var/log/myapp");