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feat(fmt): support systemd journal priority prefixes #408

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143 changes: 141 additions & 2 deletions src/fmt/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,6 @@ use std::io::prelude::Write;
use std::rc::Rc;
use std::{fmt, io, mem};

#[cfg(feature = "color")]
use log::Level;
use log::Record;

Expand All @@ -84,6 +83,18 @@ pub use crate::writer::WriteStyle;

use crate::writer::{Buffer, Writer};

/// Controls whether systemd journal priority prefixes are prepended to log lines.
#[derive(Copy, Clone, Debug, Default)]
pub enum JournalPrefix {
/// Prepend `<N>` prefix based on log level when `JOURNAL_STREAM` is set.
#[default]
Auto,
/// Always prepend `<N>` prefix.
Enable,
/// Never prepend prefix.
Disable,
}

/// Formatting precision of timestamps.
///
/// Seconds give precision of full seconds, milliseconds give thousands of a
Expand Down Expand Up @@ -218,6 +229,7 @@ pub(crate) type FormatFn = Box<dyn RecordFormat + Sync + Send>;
pub(crate) struct Builder {
pub(crate) default_format: ConfigurableFormat,
pub(crate) custom_format: Option<FormatFn>,
pub(crate) journal_prefix: JournalPrefix,
built: bool,
}

Expand All @@ -241,7 +253,13 @@ impl Builder {
if let Some(fmt) = built.custom_format {
fmt
} else {
Box::new(built.default_format)
let mut format = built.default_format;
format.journal_prefix = match built.journal_prefix {
JournalPrefix::Enable => true,
JournalPrefix::Disable => false,
JournalPrefix::Auto => std::env::var_os("JOURNAL_STREAM").is_some(),
};
Box::new(format)
}
}
}
Expand Down Expand Up @@ -286,6 +304,7 @@ pub struct ConfigurableFormat {
pub(crate) source_line_number: bool,
pub(crate) indent: Option<usize>,
pub(crate) suffix: &'static str,
pub(crate) journal_prefix: bool,
#[cfg(feature = "kv")]
pub(crate) kv_format: Option<Box<KvFormatFn>>,
}
Expand Down Expand Up @@ -355,6 +374,12 @@ impl ConfigurableFormat {
self
}

/// Whether or not to prepend systemd journal priority prefixes (e.g. `<3>` for error).
pub fn journal_prefix(&mut self, write: bool) -> &mut Self {
self.journal_prefix = write;
self
}

/// Set the format for structured key/value pairs in the log record
///
/// With the default format, this function is called for each record and should format
Expand Down Expand Up @@ -386,6 +411,7 @@ impl Default for ConfigurableFormat {
source_line_number: false,
indent: Some(4),
suffix: "\n",
journal_prefix: false,
#[cfg(feature = "kv")]
kv_format: None,
}
Expand All @@ -409,6 +435,7 @@ struct ConfigurableFormatWriter<'a> {

impl ConfigurableFormatWriter<'_> {
fn write(mut self, record: &Record<'_>) -> io::Result<()> {
self.write_journal_prefix(record)?;
self.write_timestamp()?;
self.write_level(record)?;
self.write_module_path(record)?;
Expand All @@ -422,6 +449,21 @@ impl ConfigurableFormatWriter<'_> {
write!(self.buf, "{}", self.format.suffix)
}

fn write_journal_prefix(&mut self, record: &Record<'_>) -> io::Result<()> {
if !self.format.journal_prefix {
return Ok(());
}

let priority = match record.level() {
Level::Error => 3,
Level::Warn => 4,
Level::Info => 6,
Level::Debug | Level::Trace => 7,
};

write!(self.buf, "<{priority}>")
}

fn subtle_style(&self, text: &'static str) -> SubtleStyle {
#[cfg(feature = "color")]
{
Expand Down Expand Up @@ -672,6 +714,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -696,6 +739,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -720,6 +764,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: Some(4),
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -744,6 +789,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: Some(0),
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -768,6 +814,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: Some(4),
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -792,6 +839,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -816,6 +864,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: Some(4),
suffix: "\n\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -842,6 +891,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -867,6 +917,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -893,6 +944,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand All @@ -918,6 +970,7 @@ mod tests {
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
Expand Down Expand Up @@ -999,4 +1052,90 @@ mod tests {
written
);
}

#[test]
fn format_journal_prefix_enabled() {
let mut f = formatter();

let written = write(ConfigurableFormatWriter {
format: &ConfigurableFormat {
timestamp: None,
module_path: false,
target: false,
level: true,
source_file: false,
source_line_number: false,
#[cfg(feature = "kv")]
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: true,
},
written_header_value: false,
buf: &mut f,
});

assert_eq!("<6>[INFO ] log\nmessage\n", written);
}

#[test]
fn format_journal_prefix_error_level() {
let mut f = formatter();

let record = Record::builder()
.args(format_args!("oops"))
.level(Level::Error)
.build();

let buf = f.buf.clone();

let fmt = ConfigurableFormatWriter {
format: &ConfigurableFormat {
timestamp: None,
module_path: false,
target: false,
level: false,
source_file: false,
source_line_number: false,
#[cfg(feature = "kv")]
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: true,
},
written_header_value: false,
buf: &mut f,
};

fmt.write(&record).unwrap();
let buf = buf.borrow();
let written = String::from_utf8(buf.as_bytes().to_vec()).unwrap();

assert_eq!("<3>oops\n", written);
}

#[test]
fn format_journal_prefix_disabled() {
let mut f = formatter();

let written = write(ConfigurableFormatWriter {
format: &ConfigurableFormat {
timestamp: None,
module_path: false,
target: false,
level: true,
source_file: false,
source_line_number: false,
#[cfg(feature = "kv")]
kv_format: Some(Box::new(hidden_kv_format)),
indent: None,
suffix: "\n",
journal_prefix: false,
},
written_header_value: false,
buf: &mut f,
});

assert_eq!("[INFO ] log\nmessage\n", written);
}
}
85 changes: 85 additions & 0 deletions src/logger.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -336,6 +336,22 @@ impl Builder {
self
}

/// Whether or not to prepend systemd journal priority prefixes.
///
/// Defaults to [`Auto`](fmt::JournalPrefix::Auto), which enables prefixes
/// when `JOURNAL_STREAM` is set.
///
/// ```
/// use env_logger::{Builder, fmt::JournalPrefix};
///
/// let mut builder = Builder::new();
/// builder.format_journal_prefix(JournalPrefix::Disable);
/// ```
pub fn format_journal_prefix(&mut self, value: fmt::JournalPrefix) -> &mut Self {
self.format.journal_prefix = value;
self
}

/// Set the format for structured key/value pairs in the log record
///
/// With the default format, this function is called for each record and should format
Expand Down Expand Up @@ -1055,4 +1071,73 @@ mod tests {

assert_eq!(builder.filter.build().filter(), LevelFilter::Debug);
}

#[test]
fn journal_prefix_auto_enabled_when_journal_stream_set() {
env::set_var("JOURNAL_STREAM", "8:12345");

let buf = std::sync::Arc::new(std::sync::Mutex::new(Vec::new()));
let buf2 = buf.clone();

let mut builder = Builder::new();
builder
.target(fmt::Target::Pipe(Box::new(SharedBuf(buf2))))
.format_timestamp(None)
.format_journal_prefix(fmt::JournalPrefix::Auto)
.filter_level(LevelFilter::Info);
let logger = builder.build();

logger.log(
&Record::builder()
.args(format_args!("hello"))
.level(log::Level::Warn)
.target("")
.build(),
);

let output = String::from_utf8(buf.lock().unwrap().clone()).unwrap();
assert!(output.starts_with("<4>"), "expected journal prefix, got: {output}");

env::remove_var("JOURNAL_STREAM");
}

#[test]
fn journal_prefix_auto_disabled_when_journal_stream_unset() {
env::remove_var("JOURNAL_STREAM");

let buf = std::sync::Arc::new(std::sync::Mutex::new(Vec::new()));
let buf2 = buf.clone();

let mut builder = Builder::new();
builder
.target(fmt::Target::Pipe(Box::new(SharedBuf(buf2))))
.format_timestamp(None)
.format_journal_prefix(fmt::JournalPrefix::Auto)
.filter_level(LevelFilter::Info);
let logger = builder.build();

logger.log(
&Record::builder()
.args(format_args!("hello"))
.level(log::Level::Warn)
.target("")
.build(),
);

let output = String::from_utf8(buf.lock().unwrap().clone()).unwrap();
assert!(!output.starts_with("<"), "unexpected journal prefix, got: {output}");
}

#[derive(Clone)]
struct SharedBuf(std::sync::Arc<std::sync::Mutex<Vec<u8>>>);

impl io::Write for SharedBuf {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.0.lock().unwrap().extend_from_slice(buf);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
}