tracing_subscriber/fmt/format/json.rs
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use super::{Format, FormatEvent, FormatFields, FormatTime, Writer};
use crate::{
field::{RecordFields, VisitOutput},
fmt::{
fmt_layer::{FmtContext, FormattedFields},
writer::WriteAdaptor,
},
registry::LookupSpan,
};
use serde::ser::{SerializeMap, Serializer as _};
use serde_json::Serializer;
use std::{
collections::BTreeMap,
fmt::{self, Write},
};
use tracing_core::{
field::{self, Field},
span::Record,
Event, Subscriber,
};
use tracing_serde::AsSerde;
#[cfg(feature = "tracing-log")]
use tracing_log::NormalizeEvent;
/// Marker for [`Format`] that indicates that the newline-delimited JSON log
/// format should be used.
///
/// This formatter is intended for production use with systems where structured
/// logs are consumed as JSON by analysis and viewing tools. The JSON output is
/// not optimized for human readability; instead, it should be pretty-printed
/// using external JSON tools such as `jq`, or using a JSON log viewer.
///
/// # Example Output
///
/// <pre><font color="#4E9A06"><b>:;</b></font> <font color="#4E9A06">cargo</font> run --example fmt-json
/// <font color="#4E9A06"><b> Finished</b></font> dev [unoptimized + debuginfo] target(s) in 0.08s
/// <font color="#4E9A06"><b> Running</b></font> `target/debug/examples/fmt-json`
/// {"timestamp":"2022-02-15T18:47:10.821315Z","level":"INFO","fields":{"message":"preparing to shave yaks","number_of_yaks":3},"target":"fmt_json"}
/// {"timestamp":"2022-02-15T18:47:10.821422Z","level":"INFO","fields":{"message":"shaving yaks"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.821495Z","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":1,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.821546Z","level":"TRACE","fields":{"message":"yak shaved successfully"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":1,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.821598Z","level":"DEBUG","fields":{"yak":1,"shaved":true},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.821637Z","level":"TRACE","fields":{"yaks_shaved":1},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.821684Z","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":2,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.821727Z","level":"TRACE","fields":{"message":"yak shaved successfully"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":2,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.821773Z","level":"DEBUG","fields":{"yak":2,"shaved":true},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.821806Z","level":"TRACE","fields":{"yaks_shaved":2},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.821909Z","level":"TRACE","fields":{"message":"hello! I'm gonna shave a yak","excitement":"yay!"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":3,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.821956Z","level":"WARN","fields":{"message":"could not locate yak"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"},{"yak":3,"name":"shave"}]}
/// {"timestamp":"2022-02-15T18:47:10.822006Z","level":"DEBUG","fields":{"yak":3,"shaved":false},"target":"yak_events","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.822041Z","level":"ERROR","fields":{"message":"failed to shave yak","yak":3,"error":"missing yak"},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.822079Z","level":"TRACE","fields":{"yaks_shaved":2},"target":"fmt_json::yak_shave","spans":[{"yaks":3,"name":"shaving_yaks"}]}
/// {"timestamp":"2022-02-15T18:47:10.822117Z","level":"INFO","fields":{"message":"yak shaving completed","all_yaks_shaved":false},"target":"fmt_json"}
/// </pre>
///
/// # Options
///
/// This formatter exposes additional options to configure the structure of the
/// output JSON objects:
///
/// - [`Json::flatten_event`] can be used to enable flattening event fields into
/// the root
/// - [`Json::with_current_span`] can be used to control logging of the current
/// span
/// - [`Json::with_span_list`] can be used to control logging of the span list
/// object.
///
/// By default, event fields are not flattened, and both current span and span
/// list are logged.
///
/// # Valuable Support
///
/// Experimental support is available for using the [`valuable`] crate to record
/// user-defined values as structured JSON. When the ["valuable" unstable
/// feature][unstable] is enabled, types implementing [`valuable::Valuable`] will
/// be recorded as structured JSON, rather than
/// using their [`std::fmt::Debug`] implementations.
///
/// **Note**: This is an experimental feature. [Unstable features][unstable]
/// must be enabled in order to use `valuable` support.
///
/// [`Json::flatten_event`]: Json::flatten_event()
/// [`Json::with_current_span`]: Json::with_current_span()
/// [`Json::with_span_list`]: Json::with_span_list()
/// [`valuable`]: https://crates.io/crates/valuable
/// [unstable]: crate#unstable-features
/// [`valuable::Valuable`]: https://docs.rs/valuable/latest/valuable/trait.Valuable.html
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct Json {
pub(crate) flatten_event: bool,
pub(crate) display_current_span: bool,
pub(crate) display_span_list: bool,
}
impl Json {
/// If set to `true` event metadata will be flattened into the root object.
pub fn flatten_event(&mut self, flatten_event: bool) {
self.flatten_event = flatten_event;
}
/// If set to `false`, formatted events won't contain a field for the current span.
pub fn with_current_span(&mut self, display_current_span: bool) {
self.display_current_span = display_current_span;
}
/// If set to `false`, formatted events won't contain a list of all currently
/// entered spans. Spans are logged in a list from root to leaf.
pub fn with_span_list(&mut self, display_span_list: bool) {
self.display_span_list = display_span_list;
}
}
struct SerializableContext<'a, 'b, Span, N>(
&'b crate::layer::Context<'a, Span>,
std::marker::PhantomData<N>,
)
where
Span: Subscriber + for<'lookup> crate::registry::LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static;
impl<Span, N> serde::ser::Serialize for SerializableContext<'_, '_, Span, N>
where
Span: Subscriber + for<'lookup> crate::registry::LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static,
{
fn serialize<Ser>(&self, serializer_o: Ser) -> Result<Ser::Ok, Ser::Error>
where
Ser: serde::ser::Serializer,
{
use serde::ser::SerializeSeq;
let mut serializer = serializer_o.serialize_seq(None)?;
if let Some(leaf_span) = self.0.lookup_current() {
for span in leaf_span.scope().from_root() {
serializer.serialize_element(&SerializableSpan(&span, self.1))?;
}
}
serializer.end()
}
}
struct SerializableSpan<'a, 'b, Span, N>(
&'b crate::registry::SpanRef<'a, Span>,
std::marker::PhantomData<N>,
)
where
Span: for<'lookup> crate::registry::LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static;
impl<Span, N> serde::ser::Serialize for SerializableSpan<'_, '_, Span, N>
where
Span: for<'lookup> crate::registry::LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static,
{
fn serialize<Ser>(&self, serializer: Ser) -> Result<Ser::Ok, Ser::Error>
where
Ser: serde::ser::Serializer,
{
let mut serializer = serializer.serialize_map(None)?;
let ext = self.0.extensions();
let data = ext
.get::<FormattedFields<N>>()
.expect("Unable to find FormattedFields in extensions; this is a bug");
// TODO: let's _not_ do this, but this resolves
// https://github.com/tokio-rs/tracing/issues/391.
// We should probably rework this to use a `serde_json::Value` or something
// similar in a JSON-specific layer, but I'd (david)
// rather have a uglier fix now rather than shipping broken JSON.
match serde_json::from_str::<serde_json::Value>(data) {
Ok(serde_json::Value::Object(fields)) => {
for field in fields {
serializer.serialize_entry(&field.0, &field.1)?;
}
}
// We have fields for this span which are valid JSON but not an object.
// This is probably a bug, so panic if we're in debug mode
Ok(_) if cfg!(debug_assertions) => panic!(
"span '{}' had malformed fields! this is a bug.\n error: invalid JSON object\n fields: {:?}",
self.0.metadata().name(),
data
),
// If we *aren't* in debug mode, it's probably best not to
// crash the program, let's log the field found but also an
// message saying it's type is invalid
Ok(value) => {
serializer.serialize_entry("field", &value)?;
serializer.serialize_entry("field_error", "field was no a valid object")?
}
// We have previously recorded fields for this span
// should be valid JSON. However, they appear to *not*
// be valid JSON. This is almost certainly a bug, so
// panic if we're in debug mode
Err(e) if cfg!(debug_assertions) => panic!(
"span '{}' had malformed fields! this is a bug.\n error: {}\n fields: {:?}",
self.0.metadata().name(),
e,
data
),
// If we *aren't* in debug mode, it's probably best not
// crash the program, but let's at least make sure it's clear
// that the fields are not supposed to be missing.
Err(e) => serializer.serialize_entry("field_error", &format!("{}", e))?,
};
serializer.serialize_entry("name", self.0.metadata().name())?;
serializer.end()
}
}
impl<S, N, T> FormatEvent<S, N> for Format<Json, T>
where
S: Subscriber + for<'lookup> LookupSpan<'lookup>,
N: for<'writer> FormatFields<'writer> + 'static,
T: FormatTime,
{
fn format_event(
&self,
ctx: &FmtContext<'_, S, N>,
mut writer: Writer<'_>,
event: &Event<'_>,
) -> fmt::Result
where
S: Subscriber + for<'a> LookupSpan<'a>,
{
let mut timestamp = String::new();
self.timer.format_time(&mut Writer::new(&mut timestamp))?;
#[cfg(feature = "tracing-log")]
let normalized_meta = event.normalized_metadata();
#[cfg(feature = "tracing-log")]
let meta = normalized_meta.as_ref().unwrap_or_else(|| event.metadata());
#[cfg(not(feature = "tracing-log"))]
let meta = event.metadata();
let mut visit = || {
let mut serializer = Serializer::new(WriteAdaptor::new(&mut writer));
let mut serializer = serializer.serialize_map(None)?;
if self.display_timestamp {
serializer.serialize_entry("timestamp", ×tamp)?;
}
if self.display_level {
serializer.serialize_entry("level", &meta.level().as_serde())?;
}
let format_field_marker: std::marker::PhantomData<N> = std::marker::PhantomData;
let current_span = if self.format.display_current_span || self.format.display_span_list
{
event
.parent()
.and_then(|id| ctx.span(id))
.or_else(|| ctx.lookup_current())
} else {
None
};
if self.format.flatten_event {
let mut visitor = tracing_serde::SerdeMapVisitor::new(serializer);
event.record(&mut visitor);
serializer = visitor.take_serializer()?;
} else {
use tracing_serde::fields::AsMap;
serializer.serialize_entry("fields", &event.field_map())?;
};
if self.display_target {
serializer.serialize_entry("target", meta.target())?;
}
if self.display_filename {
if let Some(filename) = meta.file() {
serializer.serialize_entry("filename", filename)?;
}
}
if self.display_line_number {
if let Some(line_number) = meta.line() {
serializer.serialize_entry("line_number", &line_number)?;
}
}
if self.format.display_current_span {
if let Some(ref span) = current_span {
serializer
.serialize_entry("span", &SerializableSpan(span, format_field_marker))
.unwrap_or(());
}
}
if self.format.display_span_list && current_span.is_some() {
serializer.serialize_entry(
"spans",
&SerializableContext(&ctx.ctx, format_field_marker),
)?;
}
if self.display_thread_name {
let current_thread = std::thread::current();
match current_thread.name() {
Some(name) => {
serializer.serialize_entry("threadName", name)?;
}
// fall-back to thread id when name is absent and ids are not enabled
None if !self.display_thread_id => {
serializer
.serialize_entry("threadName", &format!("{:?}", current_thread.id()))?;
}
_ => {}
}
}
if self.display_thread_id {
serializer
.serialize_entry("threadId", &format!("{:?}", std::thread::current().id()))?;
}
serializer.end()
};
visit().map_err(|_| fmt::Error)?;
writeln!(writer)
}
}
impl Default for Json {
fn default() -> Json {
Json {
flatten_event: false,
display_current_span: true,
display_span_list: true,
}
}
}
/// The JSON [`FormatFields`] implementation.
///
#[derive(Debug)]
pub struct JsonFields {
// reserve the ability to add fields to this without causing a breaking
// change in the future.
_private: (),
}
impl JsonFields {
/// Returns a new JSON [`FormatFields`] implementation.
///
pub fn new() -> Self {
Self { _private: () }
}
}
impl Default for JsonFields {
fn default() -> Self {
Self::new()
}
}
impl<'a> FormatFields<'a> for JsonFields {
/// Format the provided `fields` to the provided `writer`, returning a result.
fn format_fields<R: RecordFields>(&self, mut writer: Writer<'_>, fields: R) -> fmt::Result {
let mut v = JsonVisitor::new(&mut writer);
fields.record(&mut v);
v.finish()
}
/// Record additional field(s) on an existing span.
///
/// By default, this appends a space to the current set of fields if it is
/// non-empty, and then calls `self.format_fields`. If different behavior is
/// required, the default implementation of this method can be overridden.
fn add_fields(
&self,
current: &'a mut FormattedFields<Self>,
fields: &Record<'_>,
) -> fmt::Result {
if current.is_empty() {
// If there are no previously recorded fields, we can just reuse the
// existing string.
let mut writer = current.as_writer();
let mut v = JsonVisitor::new(&mut writer);
fields.record(&mut v);
v.finish()?;
return Ok(());
}
// If fields were previously recorded on this span, we need to parse
// the current set of fields as JSON, add the new fields, and
// re-serialize them. Otherwise, if we just appended the new fields
// to a previously serialized JSON object, we would end up with
// malformed JSON.
//
// XXX(eliza): this is far from efficient, but unfortunately, it is
// necessary as long as the JSON formatter is implemented on top of
// an interface that stores all formatted fields as strings.
//
// We should consider reimplementing the JSON formatter as a
// separate layer, rather than a formatter for the `fmt` layer —
// then, we could store fields as JSON values, and add to them
// without having to parse and re-serialize.
let mut new = String::new();
let map: BTreeMap<&'_ str, serde_json::Value> =
serde_json::from_str(current).map_err(|_| fmt::Error)?;
let mut v = JsonVisitor::new(&mut new);
v.values = map;
fields.record(&mut v);
v.finish()?;
current.fields = new;
Ok(())
}
}
/// The [visitor] produced by [`JsonFields`]'s [`MakeVisitor`] implementation.
///
/// [visitor]: crate::field::Visit
/// [`MakeVisitor`]: crate::field::MakeVisitor
pub struct JsonVisitor<'a> {
values: BTreeMap<&'a str, serde_json::Value>,
writer: &'a mut dyn Write,
}
impl fmt::Debug for JsonVisitor<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_fmt(format_args!("JsonVisitor {{ values: {:?} }}", self.values))
}
}
impl<'a> JsonVisitor<'a> {
/// Returns a new default visitor that formats to the provided `writer`.
///
/// # Arguments
/// - `writer`: the writer to format to.
/// - `is_empty`: whether or not any fields have been previously written to
/// that writer.
pub fn new(writer: &'a mut dyn Write) -> Self {
Self {
values: BTreeMap::new(),
writer,
}
}
}
impl crate::field::VisitFmt for JsonVisitor<'_> {
fn writer(&mut self) -> &mut dyn fmt::Write {
self.writer
}
}
impl crate::field::VisitOutput<fmt::Result> for JsonVisitor<'_> {
fn finish(self) -> fmt::Result {
let inner = || {
let mut serializer = Serializer::new(WriteAdaptor::new(self.writer));
let mut ser_map = serializer.serialize_map(None)?;
for (k, v) in self.values {
ser_map.serialize_entry(k, &v)?;
}
ser_map.end()
};
if inner().is_err() {
Err(fmt::Error)
} else {
Ok(())
}
}
}
impl field::Visit for JsonVisitor<'_> {
#[cfg(all(tracing_unstable, feature = "valuable"))]
fn record_value(&mut self, field: &Field, value: valuable_crate::Value<'_>) {
let value = match serde_json::to_value(valuable_serde::Serializable::new(value)) {
Ok(value) => value,
Err(_e) => {
#[cfg(debug_assertions)]
unreachable!(
"`valuable::Valuable` implementations should always serialize \
successfully, but an error occurred: {}",
_e,
);
#[cfg(not(debug_assertions))]
return;
}
};
self.values.insert(field.name(), value);
}
/// Visit a double precision floating point value.
fn record_f64(&mut self, field: &Field, value: f64) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
/// Visit a signed 64-bit integer value.
fn record_i64(&mut self, field: &Field, value: i64) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
/// Visit an unsigned 64-bit integer value.
fn record_u64(&mut self, field: &Field, value: u64) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
/// Visit a boolean value.
fn record_bool(&mut self, field: &Field, value: bool) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
/// Visit a string value.
fn record_str(&mut self, field: &Field, value: &str) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
fn record_bytes(&mut self, field: &Field, value: &[u8]) {
self.values
.insert(field.name(), serde_json::Value::from(value));
}
fn record_debug(&mut self, field: &Field, value: &dyn fmt::Debug) {
match field.name() {
// Skip fields that are actually log metadata that have already been handled
#[cfg(feature = "tracing-log")]
name if name.starts_with("log.") => (),
name if name.starts_with("r#") => {
self.values
.insert(&name[2..], serde_json::Value::from(format!("{:?}", value)));
}
name => {
self.values
.insert(name, serde_json::Value::from(format!("{:?}", value)));
}
};
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::fmt::{format::FmtSpan, test::MockMakeWriter, time::FormatTime, SubscriberBuilder};
use tracing::{self, subscriber::with_default};
use std::fmt;
use std::path::Path;
struct MockTime;
impl FormatTime for MockTime {
fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
write!(w, "fake time")
}
}
fn subscriber() -> SubscriberBuilder<JsonFields, Format<Json>> {
SubscriberBuilder::default().json()
}
#[test]
fn json() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":42,\"name\":\"json_span\",\"number\":3,\"slice\":[97,98,99]},\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3,\"slice\":[97,98,99]}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_span_list(true);
test_json(expected, subscriber, || {
let span = tracing::span!(
tracing::Level::INFO,
"json_span",
answer = 42,
number = 3,
slice = &b"abc"[..]
);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_filename() {
let current_path = Path::new("tracing-subscriber")
.join("src")
.join("fmt")
.join("format")
.join("json.rs")
.to_str()
.expect("path must be valid unicode")
// escape windows backslashes
.replace('\\', "\\\\");
let expected =
&format!("{}{}{}",
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":42,\"name\":\"json_span\",\"number\":3},\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"filename\":\"",
current_path,
"\",\"fields\":{\"message\":\"some json test\"}}\n");
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_file(true)
.with_span_list(true);
test_json(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_line_number() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":42,\"name\":\"json_span\",\"number\":3},\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"line_number\":42,\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_line_number(true)
.with_span_list(true);
test_json_with_line_number(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_flattened_event() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":42,\"name\":\"json_span\",\"number\":3},\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"message\":\"some json test\"}\n";
let subscriber = subscriber()
.flatten_event(true)
.with_current_span(true)
.with_span_list(true);
test_json(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_disabled_current_span_event() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(false)
.with_span_list(true);
test_json(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_disabled_span_list_event() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":42,\"name\":\"json_span\",\"number\":3},\"target\":\"tracing_subscriber::fmt::format::json::test\",\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_span_list(false);
test_json(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_nested_span() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"span\":{\"answer\":43,\"name\":\"nested_json_span\",\"number\":4},\"spans\":[{\"answer\":42,\"name\":\"json_span\",\"number\":3},{\"answer\":43,\"name\":\"nested_json_span\",\"number\":4}],\"target\":\"tracing_subscriber::fmt::format::json::test\",\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_span_list(true);
test_json(expected, subscriber, || {
let span = tracing::span!(tracing::Level::INFO, "json_span", answer = 42, number = 3);
let _guard = span.enter();
let span = tracing::span!(
tracing::Level::INFO,
"nested_json_span",
answer = 43,
number = 4
);
let _guard = span.enter();
tracing::info!("some json test");
});
}
#[test]
fn json_no_span() {
let expected =
"{\"timestamp\":\"fake time\",\"level\":\"INFO\",\"target\":\"tracing_subscriber::fmt::format::json::test\",\"fields\":{\"message\":\"some json test\"}}\n";
let subscriber = subscriber()
.flatten_event(false)
.with_current_span(true)
.with_span_list(true);
test_json(expected, subscriber, || {
tracing::info!("some json test");
});
}
#[test]
fn record_works() {
// This test reproduces issue #707, where using `Span::record` causes
// any events inside the span to be ignored.
let make_writer = MockMakeWriter::default();
let subscriber = crate::fmt()
.json()
.with_writer(make_writer.clone())
.finish();
with_default(subscriber, || {
tracing::info!("an event outside the root span");
assert_eq!(
parse_as_json(&make_writer)["fields"]["message"],
"an event outside the root span"
);
let span = tracing::info_span!("the span", na = tracing::field::Empty);
span.record("na", "value");
let _enter = span.enter();
tracing::info!("an event inside the root span");
assert_eq!(
parse_as_json(&make_writer)["fields"]["message"],
"an event inside the root span"
);
});
}
#[test]
fn json_span_event_show_correct_context() {
let buffer = MockMakeWriter::default();
let subscriber = subscriber()
.with_writer(buffer.clone())
.flatten_event(false)
.with_current_span(true)
.with_span_list(false)
.with_span_events(FmtSpan::FULL)
.finish();
with_default(subscriber, || {
let context = "parent";
let parent_span = tracing::info_span!("parent_span", context);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "new");
assert_eq!(event["span"]["context"], "parent");
let _parent_enter = parent_span.enter();
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "enter");
assert_eq!(event["span"]["context"], "parent");
let context = "child";
let child_span = tracing::info_span!("child_span", context);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "new");
assert_eq!(event["span"]["context"], "child");
let _child_enter = child_span.enter();
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "enter");
assert_eq!(event["span"]["context"], "child");
drop(_child_enter);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "exit");
assert_eq!(event["span"]["context"], "child");
drop(child_span);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "close");
assert_eq!(event["span"]["context"], "child");
drop(_parent_enter);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "exit");
assert_eq!(event["span"]["context"], "parent");
drop(parent_span);
let event = parse_as_json(&buffer);
assert_eq!(event["fields"]["message"], "close");
assert_eq!(event["span"]["context"], "parent");
});
}
#[test]
fn json_span_event_with_no_fields() {
// Check span events serialize correctly.
// Discussion: https://github.com/tokio-rs/tracing/issues/829#issuecomment-661984255
let buffer = MockMakeWriter::default();
let subscriber = subscriber()
.with_writer(buffer.clone())
.flatten_event(false)
.with_current_span(false)
.with_span_list(false)
.with_span_events(FmtSpan::FULL)
.finish();
with_default(subscriber, || {
let span = tracing::info_span!("valid_json");
assert_eq!(parse_as_json(&buffer)["fields"]["message"], "new");
let _enter = span.enter();
assert_eq!(parse_as_json(&buffer)["fields"]["message"], "enter");
drop(_enter);
assert_eq!(parse_as_json(&buffer)["fields"]["message"], "exit");
drop(span);
assert_eq!(parse_as_json(&buffer)["fields"]["message"], "close");
});
}
fn parse_as_json(buffer: &MockMakeWriter) -> serde_json::Value {
let buf = String::from_utf8(buffer.buf().to_vec()).unwrap();
let json = buf
.lines()
.last()
.expect("expected at least one line to be written!");
match serde_json::from_str(json) {
Ok(v) => v,
Err(e) => panic!(
"assertion failed: JSON shouldn't be malformed\n error: {}\n json: {}",
e, json
),
}
}
fn test_json<T>(
expected: &str,
builder: crate::fmt::SubscriberBuilder<JsonFields, Format<Json>>,
producer: impl FnOnce() -> T,
) {
let make_writer = MockMakeWriter::default();
let subscriber = builder
.with_writer(make_writer.clone())
.with_timer(MockTime)
.finish();
with_default(subscriber, producer);
let buf = make_writer.buf();
let actual = std::str::from_utf8(&buf[..]).unwrap();
assert_eq!(
serde_json::from_str::<std::collections::HashMap<&str, serde_json::Value>>(expected)
.unwrap(),
serde_json::from_str(actual).unwrap()
);
}
fn test_json_with_line_number<T>(
expected: &str,
builder: crate::fmt::SubscriberBuilder<JsonFields, Format<Json>>,
producer: impl FnOnce() -> T,
) {
let make_writer = MockMakeWriter::default();
let subscriber = builder
.with_writer(make_writer.clone())
.with_timer(MockTime)
.finish();
with_default(subscriber, producer);
let buf = make_writer.buf();
let actual = std::str::from_utf8(&buf[..]).unwrap();
let mut expected =
serde_json::from_str::<std::collections::HashMap<&str, serde_json::Value>>(expected)
.unwrap();
let expect_line_number = expected.remove("line_number").is_some();
let mut actual: std::collections::HashMap<&str, serde_json::Value> =
serde_json::from_str(actual).unwrap();
let line_number = actual.remove("line_number");
if expect_line_number {
assert_eq!(line_number.map(|x| x.is_number()), Some(true));
} else {
assert!(line_number.is_none());
}
assert_eq!(actual, expected);
}
}