Struct MessageBuilder 

pub struct MessageBuilder { /* private fields */ }

Fluent builder for a single syslog message with a JSON key-value payload.

Fields default to the RFC 5424 nil value (-) unless set explicitly, except proc_id which defaults to the current process ID.

Keys provided to kv are sorted alphabetically in the serialized JSON object. Duplicate keys are deduplicated — the last value provided for a given key is used.

Call cee_cookie to prefix the JSON payload with @cee:, producing a MITRE CEE-compatible syslog message.

Implementations

impl MessageBuilder

pub fn new(facility: Facility, severity: Severity) -> Self

Create a new builder with the given facility and severity.

The process ID is populated automatically from std::process::id. All other optional header fields default to nil (-).

pub fn cee_cookie(self, enabled: bool) -> Self

Prefix the JSON payload with the MITRE CEE cookie (@cee:).

When enabled, the built message body will be @cee:{...} instead of {...}, making it compatible with CEE-aware log processors (e.g. rsyslog’s mmjsonparse module).

The default is false (no CEE cookie).

pub fn timestamp(self, ts: impl Into<String>) -> Self

Set the RFC 5424 TIMESTAMP field (RFC 3339 formatted string).

Use now_rfc3339 to obtain the current UTC time without pulling in an external time library.

pub fn hostname(self, h: impl Into<String>) -> Self

Set the RFC 5424 HOSTNAME field.

pub fn app_name(self, name: impl Into<String>) -> Self

Set the RFC 5424 APP-NAME field.

pub fn proc_id(self, pid: impl Into<String>) -> Self

Override the RFC 5424 PROCID field (defaults to the current PID).

pub fn msgid(self, id: impl Into<String>) -> Self

Set the RFC 5424 MSGID field.

pub fn kv( self, key: impl Into<String>, val: impl Serialize, ) -> Result<Self, BuildError>

Add a JSON key-value field to the message payload.

val can be any type that implements serde::Serialize: strings, integers, booleans, floats, nested objects, and arrays are all accepted.

If the same key is added more than once, the last value is used.

Errors

Returns BuildError::EmptyKey if key is the empty string. Returns BuildError::Serialize if val cannot be serialized to JSON (rare — only custom Serialize implementations can fail).

pub fn build(self) -> Result<SyslogMessage, BuildError>

Assemble the accumulated fields into a SyslogMessage.

The JSON payload is serialized with keys in alphabetical order.

Errors

Returns BuildError::Serialize if the field map cannot be serialized to a JSON string (should not happen in practice for well-formed values).

pub async fn send<T: Transport>(self, transport: &T) -> Result<(), ClientError>

Build the message and send it via transport in one step.

Errors

Returns ClientError::Build if build fails, or a transport-specific error if delivery fails.

Trait Implementations

impl Debug for MessageBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.