Allow Pino transport to be used as transport

.changesets/allow-pino-transport-to-be-used-as-a-transport.md

@@ -0,0 +1,50 @@
+---
+bump: patch
+type: fix
+---
+
+Allow Pino transport to be used as a transport. Before, our Pino transport could only be used as a destination:
+
+```js
+import pino from "pino";
+import { Appsignal, AppsignalPinoTransport } from "@appsignal/nodejs";
+
+pino(AppsignalPinoTransport({
+  client: Appsignal.client,
+  group: "pino"
+}));
+```
+
+This meant it was not possible to log both to our transport and to another destination.
+
+Now, it is also possible to use it as a Pino transport, with the `transport` Pino config option or the `pino.transport()` function:
+
+```js
+import pino from "pino";
+
+pino({
+  transport: {
+    target: "@appsignal/nodejs/pino",
+    options: {
+      group: "pino"
+    }
+  }
+});
+```
+
+It is no longer necessary to pass the AppSignal client to the Pino transport. AppSignal must be active for the Pino transport to work.
+
+By enabling its use as a transport, it is now possible to use it alongside other transports:
+
+```js
+pino({
+  transport: {
+    targets: [
+      // Send logs to AppSignal...
+      { target: "@appsignal/nodejs/pino" },
+      // ... and to standard output!
+      { target: "pino/file" }
+    ]
+  }
+});
+```

.npmignore

@@ -1,5 +1,6 @@
 *
 !/dist/**/*
+!/pino/**/*
 !/scripts/**/*
 scripts/**/*.test.js
 !/ext/appsignal_extension.cpp

pino/index.js

@@ -0,0 +1,2 @@
+"use strict"
+module.exports = require("../dist/pino_transport")

src/pino_transport.ts

@@ -1,44 +1,47 @@
-import { LOGGER_LEVEL_SEVERITY } from "./logger"
+import { LOGGER_LEVEL_SEVERITY, LOGGER_FORMAT } from "./logger"
 import build from "pino-abstract-transport"
-import { Client } from "./client"
+import { Extension } from "./extension"
 
 type PinoTransportOptions = {
-  client: Client
-  group: string
+  group?: string
 }
 
-const appsignalPinoTransport = ({
-  client,
-  group = "app"
-}: PinoTransportOptions) => {
+type LogData = {
+  severity: number
+  message: string
+  attributes: Record<string, any>
+}
+
+const appsignalPinoTransport = ({ group = "app" }: PinoTransportOptions) => {
   return build(async (source: any) => {
+    // We expect this code to be running in a worker thread and for the
+    // extension to have already been loaded and started on the main thread.
+    // Since we expect the extension to already have been initialised, we
+    // pass `{ active: false }` to avoid initialising it again.
+    const extension = new Extension({ active: false })
+
     for await (const obj of source) {
-      sendLogs(parseInfo(obj, group), client)
+      sendLogs(extension, group, parseInfo(obj))
     }
   })
+}
 
-  async function sendLogs(data: Record<string, any>, client: Client) {
-    client.extension.log(
-      data.group || "app",
-      data.severity,
-      0,
-      data.msg,
-      data.attributes
-    )
-  }
+async function sendLogs(extension: Extension, group: string, data: LogData) {
+  extension.log(
+    group,
+    data.severity,
+    LOGGER_FORMAT.plaintext,
+    data.message,
+    data.attributes
+  )
 }
 
-function parseInfo(
-  obj: Record<string, any>,
-  group: string
-): Record<string, any> {
-  const { hostname, level, msg, ...attributes } = obj
+function parseInfo(obj: Record<string, any>): LogData {
+  const { level, msg, ...attributes } = obj
 
   return {
     severity: getSeverity(level),
-    hostname,
-    group,
-    msg,
+    message: msg,
     attributes: flattenAttributes(attributes)
   }
 }