Add env var: MESOP_APP_BASE_PATH (#1057)

.github/workflows/ci.yml

@@ -96,6 +96,14 @@ jobs:
           name: playwright-report-with-static-folder
           path: playwright-report-with-static-folder/
           retention-days: 30
+      - name: Run playwright test with app base
+        run: MESOP_APP_BASE_PATH=$PWD/mesop/examples/app_base MESOP_STATIC_FOLDER=static PLAYWRIGHT_HTML_OUTPUT_DIR=playwright-report-with-static-folder yarn playwright test mesop/tests/e2e/app_base_test.ts
+      - uses: actions/upload-artifact@a8a3f3ad30e3422c9c7b888a15615d19a852ae32 # v3.1.3
+        if: always()
+        with:
+          name: playwright-report-with-static-folder
+          path: playwright-report-with-static-folder/
+          retention-days: 30
   # Deploy docs
   deploy-docs:
     # Only deploy docs if we're pushing to main (see on.push.branches)

docs/api/config.md

@@ -252,6 +252,10 @@ By default, this is not enabled. You can enable this by setting it to `true`.
 
 This uses WebSockets instead of HTTP Server-Sent Events (SSE) as the transport protocol for UI updates. If you set this environment variable to `true`, then [`MESOP_CONCURRENT_UPDATES_ENABLED`](#MESOP_CONCURRENT_UPDATES_ENABLED) will automatically be enabled as well.
 
+### MESOP_APP_BASE_PATH
+
+This is the base path used to resolve other paths, particularly for serving static files. Must be an absolute path. This is rarely needed because the default of using the current working directory is usually sufficient.
+
 ## Usage Examples
 
 ### One-liner

mesop/env/env.py

@@ -1,9 +1,30 @@
 import os
 
+from mesop.exceptions import MesopDeveloperException
+
 AI_SERVICE_BASE_URL = os.environ.get(
   "MESOP_AI_SERVICE_BASE_URL", "http://localhost:43234"
 )
 
+MESOP_APP_BASE_PATH = os.environ.get("MESOP_APP_BASE_PATH", "")
+if MESOP_APP_BASE_PATH:
+  if not os.path.isabs(MESOP_APP_BASE_PATH):
+    raise MesopDeveloperException(
+      f"MESOP_APP_BASE_PATH must be an absolute path, but got {MESOP_APP_BASE_PATH} instead."
+    )
+  if not os.path.isdir(MESOP_APP_BASE_PATH):
+    raise MesopDeveloperException(
+      f"MESOP_APP_BASE_PATH is not a valid directory: {MESOP_APP_BASE_PATH}"
+    )
+  print(f"MESOP_APP_BASE_PATH set to {MESOP_APP_BASE_PATH}")
+
+
+def get_app_base_path() -> str:
+  if not MESOP_APP_BASE_PATH:
+    return os.getcwd()
+  return MESOP_APP_BASE_PATH
+
+
 MESOP_WEBSOCKETS_ENABLED = (
   os.environ.get("MESOP_WEBSOCKETS_ENABLED", "false").lower() == "true"
 )

mesop/examples/BUILD

@@ -47,6 +47,7 @@ py_library(
         "//mesop/components/text/e2e",
         "//mesop/examples/web_component",
         "//mesop/examples/docs",
+        "//mesop/examples/app_base",
         "//mesop/examples/integrations",
         "//mesop/examples/shared",
         "//mesop/examples/starter_kit",

mesop/examples/__init__.py

@@ -2,6 +2,7 @@
 from mesop.examples import (
   allowed_iframe_parents as allowed_iframe_parents,
 )
+from mesop.examples import app_base as app_base
 from mesop.examples import async_await as async_await
 from mesop.examples import (
   boilerplate_free_event_handlers as boilerplate_free_event_handlers,

mesop/examples/app_base/BUILD

@@ -0,0 +1,16 @@
+load("//build_defs:defaults.bzl", "py_library")
+
+package(
+    default_visibility = ["//build_defs:mesop_examples"],
+)
+
+py_library(
+    name = "app_base",
+    srcs = glob(["*.py"]),
+    data = glob([
+        "static/**/*",
+    ]),
+    deps = [
+        "//mesop",
+    ],
+)

mesop/examples/app_base/__init__.py

@@ -0,0 +1 @@
+from mesop.examples.app_base import main as main

mesop/examples/app_base/main.py

@@ -0,0 +1,11 @@
+import os
+
+import mesop as me
+
+
+@me.page(path="/examples/app_base")
+def page():
+  me.text(
+    "Testing: MESOP_APP_BASE_PATH="
+    + os.getenv("MESOP_APP_BASE_PATH", "<not set>")
+  )

mesop/examples/app_base/static/test.txt

@@ -0,0 +1 @@
+test MESOP_APP_BASE_PATH works

mesop/labs/web_component.py

@@ -3,6 +3,7 @@
 from functools import wraps
 from typing import Any, Callable, TypeVar, cast
 
+from mesop.env.env import get_app_base_path
 from mesop.runtime import runtime
 from mesop.utils.validate import validate
 
@@ -54,4 +55,4 @@ def format_filename(filename: str) -> str:
     return filename.split(".runfiles", 1)[1]
   else:
     # Handle pip CLI case
-    return os.path.relpath(filename, os.getcwd())
+    return os.path.relpath(filename, get_app_base_path())

mesop/server/server_utils.py

@@ -10,7 +10,7 @@
 from werkzeug.security import safe_join
 
 import mesop.protos.ui_pb2 as pb
-from mesop.env.env import EXPERIMENTAL_EDITOR_TOOLBAR_ENABLED
+from mesop.env.env import EXPERIMENTAL_EDITOR_TOOLBAR_ENABLED, get_app_base_path
 from mesop.exceptions import MesopDeveloperException
 from mesop.runtime import runtime
 from mesop.server.config import app_config
@@ -148,7 +148,7 @@ def get_static_folder() -> str | None:
       "Static folder cannot be an absolute path: static_folder_name}"
     )
 
-  static_folder_path = safe_join(os.getcwd(), static_folder_name)
+  static_folder_path = safe_join(get_app_base_path(), static_folder_name)
 
   if not static_folder_path:
     raise MesopDeveloperException(

mesop/server/static_file_serving.py

@@ -12,6 +12,7 @@
 from flask import Flask, Response, g, make_response, request, send_file
 from werkzeug.security import safe_join
 
+from mesop.env.env import get_app_base_path
 from mesop.exceptions import MesopException
 from mesop.runtime import runtime
 from mesop.server.constants import WEB_COMPONENTS_PATH_SEGMENT
@@ -100,7 +101,7 @@ def serve_web_components(path: str):
     serving_path = (
       get_runfile_location(path)
       if has_runfiles()
-      else safe_join(os.getcwd(), path)
+      else safe_join(get_app_base_path(), path)
     )
 
     file_name = os.path.basename(path)

mesop/tests/e2e/app_base_test.ts

@@ -0,0 +1,13 @@
+import {test, expect} from '@playwright/test';
+
+test.describe('MESOP_APP_BASE_PATH', () => {
+  if (process.env['MESOP_APP_BASE_PATH'] === undefined) {
+    test.skip('Test skipped because MESOP_APP_BASE_PATH is not set.');
+  }
+  test('serves static file relative to MESOP_APP_BASE_PATH', async ({page}) => {
+    const response = await page.goto('/static/test.txt');
+    expect(response!.status()).toBe(200);
+    const text = await response!.text();
+    expect(text).toContain('test MESOP_APP_BASE_PATH works');
+  });
+});