Support Pyodide

.github/workflows/main.yml

@@ -131,10 +131,30 @@ jobs:
           env_vars: PYTHON
       - run: uv run coverage report --fail-under 100
 
+  test-pyodide:
+    name: test on Pyodide
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v3
+        with:
+          version: "0.4.30"
+          enable-cache: true
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "23"
+
+      - run: make test-pyodide
+        env:
+          UV_PYTHON: ${{ matrix.python-version }}
+
   # https://github.com/marketplace/actions/alls-green#why used for branch protection checks
   check:
     if: always()
-    needs: [lint, docs, test, coverage]
+    needs: [lint, docs, test, coverage, test-pyodide]
     runs-on: ubuntu-latest
     steps:
       - name: Decide whether the needed jobs succeeded or failed

Makefile

@@ -46,6 +46,11 @@ testcov: test
 	@echo "building coverage html"
 	uv run coverage html --show-contexts
 
+.PHONY: test-pyodide  # Check logfire runs with pyodide
+test-pyodide:
+	uv build
+	cd pyodide_test && npm test
+
 .PHONY: docs  # Build the documentation
 docs:
 	uv run mkdocs build

logfire/_internal/config.py

@@ -5,6 +5,7 @@
 import functools
 import json
 import os
+import platform
 import re
 import sys
 import time
@@ -708,6 +709,8 @@ def _initialize(self) -> None:
         if self._initialized:  # pragma: no cover
             return
 
+        emscripten = platform.system().lower() == 'emscripten'
+
         with suppress_instrumentation():
             otel_resource_attributes: dict[str, Any] = {
                 ResourceAttributes.SERVICE_NAME: self.service_name,
@@ -744,7 +747,11 @@ def _initialize(self) -> None:
             ):
                 otel_resource_attributes[RESOURCE_ATTRIBUTES_CODE_WORK_DIR] = os.getcwd()
 
-            resource = Resource.create(otel_resource_attributes)
+            if emscripten:
+                # Resource.create creates a thread pool which fails in Pyodide / Emscripten
+                resource = Resource(otel_resource_attributes)
+            else:
+                resource = Resource.create(otel_resource_attributes)
 
             # Set service instance ID to a random UUID if it hasn't been set already.
             # Setting it above would have also mostly worked and allowed overriding via OTEL_RESOURCE_ATTRIBUTES,
@@ -849,8 +856,11 @@ def check_token():
                         if show_project_link and validated_credentials is not None:
                             validated_credentials.print_token_summary()
 
-                    thread = Thread(target=check_token, name='check_logfire_token')
-                    thread.start()
+                    if emscripten:
+                        check_token()
+                    else:
+                        thread = Thread(target=check_token, name='check_logfire_token')
+                        thread.start()
 
                     headers = {'User-Agent': f'logfire/{VERSION}', 'Authorization': self.token}
                     session = OTLPExporterHttpSession(max_body_size=OTLP_MAX_BODY_SIZE)
@@ -864,10 +874,19 @@ def check_token():
                     span_exporter = RetryFewerSpansSpanExporter(span_exporter)
                     span_exporter = RemovePendingSpansExporter(span_exporter)
                     schedule_delay_millis = _get_int_from_env(OTEL_BSP_SCHEDULE_DELAY) or 500
-                    add_span_processor(BatchSpanProcessor(span_exporter, schedule_delay_millis=schedule_delay_millis))
+                    if emscripten:
+                        # BatchSpanProcessor uses threads which fail in Pyodide / Emscripten
+                        logfire_processor = SimpleSpanProcessor(span_exporter)
+                    else:
+                        logfire_processor = BatchSpanProcessor(
+                            span_exporter, schedule_delay_millis=schedule_delay_millis
+                        )
+                    add_span_processor(logfire_processor)
 
-                    if metric_readers is not None:
-                        metric_readers += [
+                    # TODO should we warn here if we have metrics but we're in emscripten?
+                    # I guess we could do some hack to use InMemoryMetricReader and call it after user code has run?
+                    if metric_readers is not None and not emscripten:
+                        metric_readers.append(
                             PeriodicExportingMetricReader(
                                 QuietMetricExporter(
                                     OTLPMetricExporter(
@@ -883,7 +902,7 @@ def check_token():
                                     preferred_temporality=METRICS_PREFERRED_TEMPORALITY,
                                 )
                             )
-                        ]
+                        )
 
             if processors_with_pending_spans:
                 pending_multiprocessor = SynchronousMultiSpanProcessor()

pyodide_test/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "pyodide_test",
+  "version": "0.0.0",
+  "main": "test.js",
+  "scripts": {
+    "test": "node --experimental-wasm-stack-switching test.mjs"
+  },
+  "author": "",
+  "license": "MIT",
+  "description": "",
+  "dependencies": {
+    "pyodide": "^0.27.2"
+  }
+}

pyodide_test/test.mjs

@@ -0,0 +1,52 @@
+import {opendir} from 'node:fs/promises'
+import path from 'path'
+import assert from 'assert'
+import { loadPyodide } from 'pyodide'
+
+
+async function runTest() {
+  const wheelPath = await findWheel(path.join(path.resolve(import.meta.dirname, '..'), 'dist'));
+  const stdout = []
+  const stderr = []
+  const pyodide = await loadPyodide({
+
+    stdout: (msg) => {
+      stdout.push(msg)
+    },
+    stderr: (msg) => {
+      stderr.push(msg)
+    }
+  })
+  await pyodide.loadPackage(['micropip', 'pygments'])
+  await pyodide.runPythonAsync(`
+import sys
+import micropip
+
+await micropip.install(['file:${wheelPath}'])
+import logfire
+logfire.configure(token='unknown', inspect_arguments=False)
+logfire.info('hello {name}', name='world')
+`)
+  let out = stdout.join('')
+  assert.ok(out.includes('hello world'), `stdout did not include message, stdout: "${out}"`)
+
+  let err = stderr.join('')
+  assert.ok(
+    err.includes(
+      'UserWarning: Logfire API returned status code 401.'
+    ),
+    `stderr did not include warning, stderr: "${err}"`
+  )
+}
+
+
+async function findWheel(dist_dir) {
+  const dir = await opendir(dist_dir);
+  for await (const dirent of dir) {
+    if (dirent.name.endsWith('.whl')) {
+      return path.join(dist_dir, dirent.name);
+    }
+  }
+}
+
+runTest().catch(console.error)

pyproject.toml

@@ -248,17 +248,7 @@ quote-style = "single"
 typeCheckingMode = "strict"
 reportUnnecessaryTypeIgnoreComment = true
 reportMissingTypeStubs = false
-exclude = [
-    "docs/**/*.py",
-    "examples/**/*.py",
-    "site/**/*.py",
-    ".venv",
-    "venv*",
-    "**/venv*",
-    "ignoreme",
-    "out",
-    "logfire-api",
-]
+include = ["logfire", "tests"]
 venvPath = "."
 venv = ".venv"