Struct tracing_journald::Layer

pub struct Layer { /* private fields */ }

Sends events and their fields to journald

journald conventions for structured field names differ from typical tracing idioms, and journald discards fields which violate its conventions. Hence, this layer automatically sanitizes field names by translating .s into _s, stripping leading _s and non-ascii-alphanumeric characters other than _, and upcasing.

Levels are mapped losslessly to journald PRIORITY values as follows:

• ERROR => Error (3)
• WARN => Warning (4)
• INFO => Notice (5)
• DEBUG => Informational (6)
• TRACE => Debug (7)

Note that the naming scheme differs slightly for the latter half.

The standard journald CODE_LINE and CODE_FILE fields are automatically emitted. A TARGET field is emitted containing the event’s target. Enclosing spans are numbered counting up from the root, and their fields and metadata are included in fields prefixed by Sn_ where n is that number.

User-defined fields other than the event message field have a prefix applied by default to prevent collision with standard fields.

Implementations

impl Layer

pub fn new() -> Result<Self>

Construct a journald layer

Fails if the journald socket couldn’t be opened. Returns a NotFound error unconditionally in non-Unix environments.

pub fn with_field_prefix(self, x: Option<String>) -> Self

Sets the prefix to apply to names of user-defined fields other than the event message field. Defaults to Some("F").

pub fn with_syslog_identifier(self, identifier: String) -> Self

Sets the syslog identifier for this logger.

The syslog identifier comes from the classic syslog interface (openlog() and syslog()) and tags log entries with a given identifier. Systemd exposes it in the SYSLOG_IDENTIFIER journal field, and allows filtering log messages by syslog identifier with journalctl -t. Unlike the unit (journalctl -u) this field is not trusted, i.e. applications can set it freely, and use it e.g. to further categorize log entries emitted under the same systemd unit or in the same process. It also allows to filter for log entries of processes not started in their own unit.

See Journal Fields and journalctl for more information.

Defaults to the file name of the executable of the current process, if any.

pub fn syslog_identifier(&self) -> &str

Returns the syslog identifier in use.

Trait Implementations

impl<S> Layer<S> for Layer where
    S: Subscriber + for<'span> LookupSpan<'span>, 

fn on_new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<'_, S>)

Notifies this layer that a new span was constructed with the given Attributes and Id.

fn on_record(&self, id: &Id, values: &Record<'_>, ctx: Context<'_, S>)

Notifies this layer that a span with the given Id recorded the given values.

fn on_event(&self, event: &Event<'_>, ctx: Context<'_, S>)

Notifies this layer that an event has occurred.

fn on_layer(&mut self, subscriber: &mut S)

Performs late initialization when attaching a Layer to a Subscriber.

fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest

Registers a new callsite with this layer, returning whether or not the layer is interested in being notified about the callsite, similarly to Subscriber::register_callsite.

fn enabled(&self, metadata: &Metadata<'_>, ctx: Context<'_, S>) -> bool

Returns true if this layer is interested in a span or event with the given metadata in the current Context, similarly to Subscriber::enabled.

fn on_follows_from(&self, _span: &Id, _follows: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span with the ID span recorded that it follows from the span with the ID follows.

fn on_enter(&self, _id: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span with the given ID was entered.

fn on_exit(&self, _id: &Id, _ctx: Context<'_, S>)

Notifies this layer that the span with the given ID was exited.

fn on_close(&self, _id: Id, _ctx: Context<'_, S>)

Notifies this layer that the span with the given ID has been closed.

fn on_id_change(&self, _old: &Id, _new: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span ID has been cloned, and that the subscriber returned a different ID.

fn and_then<L>(self, layer: L) -> Layered<L, Self, S> where
    L: Layer<S>, 

Composes this layer around the given Layer, returning a Layered struct implementing Layer.

fn with_subscriber(self, inner: S) -> Layered<Self, S, S>

Composes this Layer with the given Subscriber, returning a Layered struct that implements Subscriber.

fn with_filter<F>(self, filter: F) -> Filtered<Self, F, S> where
    F: Filter<S>, 

Combines self with a Filter, returning a Filtered layer.