chore(selenium): use dockerized selenium setup for tests (#17708)

## Description

The selenium tests were previously gated behind a `platform.machine() == "x86_64"` check because `selenium-manager` (bundled with the `selenium` package) has no binary for `linux/aarch64`, making them impossible to run locally on Apple Silicon.

This PR replaces the local `webdriver.Chrome` setup with `webdriver.Remote` pointing at a `selenium/standalone-chrome` Docker service (linux/amd64). This decouples the test runner architecture from the browser architecture, so tests run on any host.

Changes:
- **`docker-compose.yml`**: adds a `selenium-chrome` service (`selenium/standalone-chrome:latest`, `platform: linux/amd64`, `network_mode: host`) so local runs via `scripts/ddtest` work on arm64 hosts
- **`.gitlab/services.yml`**: registers `selenium-chrome` as a named GitLab CI service pointing at the internal registry mirror
- **`tests/ci_visibility/suitespec.yml`**: adds `selenium-chrome` to the selenium suite's required services and sets `SELENIUM_GRID_URL=http://selenium-chrome:4444` for CI (where services are accessed by hostname alias rather than `localhost`)
- **`test_selenium_chrome.py`**: removes the `x86_64` skipif guards and the `platform` import; extracts a `_make_driver()` helper that uses `webdriver.Remote` with `SELENIUM_GRID_URL` (defaults to `http://localhost:4444` for local runs)
- **Snapshots**: updated `test.source.start` / `test.source.end` metrics to reflect the refactored test script line numbers; also added `meta._dd.svc_src` and `meta._dd.tags.process` to the snapshot ignore list (new fields emitted by newer ddtrace versions)

## Testing

- Ran all 4 selenium tests locally via `scripts/run-tests` with the `selenium-chrome` Docker service active — all pass
- `test_selenium_v3_plugin_tags` (mock-based, no real browser) continues to pass as before

## Risks

- `selenium/standalone-chrome:latest` is a mutable tag — if the image is updated it may change browser/driver versions. The snapshot ignore list already excludes `test.browser.version` and `test.browser.driver_version` so this is safe.

## Additional Notes

The `SELENIUM_GRID_URL` env var allows the grid endpoint to be overridden without code changes, which is useful if the service is ever moved or renamed.

Co-authored-by: federico.mon <federico.mon@datadoghq.com>

Author: gnufede

.gitlab/services.yml

@@ -160,3 +160,6 @@
   azurite:
     name: registry.ddbuild.io/images/mirror/azure-storage/azurite:3.34.0
     alias: azurite
+  selenium-chrome:
+    name: registry.ddbuild.io/images/mirror/selenium/standalone-chrome:latest
+    alias: selenium-chrome

docker-compose.yml

@@ -190,6 +190,15 @@ services:
             - "127.0.0.1:10002:10002"
 
 
+    selenium-chrome:
+        image: selenium/standalone-chrome:latest
+        platform: linux/amd64
+        network_mode: host
+        environment:
+            - SE_NODE_MAX_SESSIONS=2
+            - SE_VNC_NO_PASSWORD=1
+        shm_size: 2g
+
     testrunner:
         # DEV uncomment to test local changes to the Dockerfile
         # build:

tests/ci_visibility/suitespec.yml

@@ -157,6 +157,8 @@ suites:
     snapshot: true
   selenium:
     parallelism: 2
+    env:
+      SELENIUM_GRID_URL: http://selenium-chrome:4444
     paths:
       - '@bootstrap'
       - '@core'
@@ -170,6 +172,8 @@ suites:
       - tests/contrib/selenium/*
       - tests/snapshots/test_selenium*
     snapshot: true
+    services:
+      - selenium-chrome
   unittest:
     parallelism: 2
     paths:

tests/contrib/selenium/test_selenium_chrome.py

@@ -1,16 +1,16 @@
 """Tests for selenium + RUM integration
 
-IMPORTANT NOTE: these tests only reliably work on Linux/x86_64 due to some annoyingly picky issues with installing
-Selenium and a working browser/webdriver combination on non-x86_64 architectures (at time of writing, at least,
-Selenium's webdriver-manager doesn't support Linux on non-x86_64).
+Uses a Selenium Grid (selenium/standalone-chrome, linux/amd64) via webdriver.Remote so that
+tests work on any host architecture including arm64. The grid URL is controlled by the
+SELENIUM_GRID_URL environment variable (default: http://localhost:4444 for local runs via
+docker-compose network_mode: host; set to http://selenium-chrome:4444 in CI).
 """
 
 import http.server
 import json
 import multiprocessing
 import os
 from pathlib import Path
-import platform
 import socketserver
 import subprocess
 import textwrap
@@ -45,6 +45,23 @@
     "start",
 ]
 
+# Selenium Grid endpoint — standalone-chrome runs with network_mode: host so it binds on localhost
+SELENIUM_GRID_URL = os.environ.get("SELENIUM_GRID_URL", "http://localhost:4444")
+
+_SELENIUM_DRIVER_SETUP = f"""\
+    from selenium import webdriver
+    from selenium.webdriver.common.by import By
+    from selenium.webdriver.chrome.options import Options
+
+    SELENIUM_GRID_URL = "{SELENIUM_GRID_URL}"
+
+    def _make_driver():
+        options = Options()
+        options.add_argument("--headless")
+        options.add_argument("--no-sandbox")
+        return webdriver.Remote(command_executor=SELENIUM_GRID_URL, options=options)
+"""
+
 
 @pytest.fixture
 def _http_server(scope="function"):
@@ -74,39 +91,29 @@ def _run_server():
 
 
 @snapshot(ignores=SELENIUM_SNAPSHOT_IGNORES)
-@pytest.mark.skipif(platform.machine() != "x86_64", reason="Selenium Chrome tests only run on x86_64")
 def test_selenium_chrome_pytest_rum_enabled(_http_server, testdir, git_repo):
     selenium_test_script = textwrap.dedent(
-        """
-            from pathlib import Path
+        _SELENIUM_DRIVER_SETUP
+        + """
+    def test_selenium_local_pass():
+        with _make_driver() as driver:
+            url = "http://localhost:8079/rum_enabled/page_1.html"
 
-            from selenium import webdriver
-            from selenium.webdriver.common.by import By
-            from selenium.webdriver.chrome.options import Options
+            driver.get(url)
 
-            def test_selenium_local_pass():
-                options = Options()
-                options.add_argument("--headless")
-                options.add_argument("--no-sandbox")
+            assert driver.title == "Page 1"
 
-                with webdriver.Chrome(options=options) as driver:
-                    url = "http://localhost:8079/rum_enabled/page_1.html"
+            link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
 
-                    driver.get(url)
+            link_2.click()
 
-                    assert driver.title == "Page 1"
+            assert driver.title == "Page 2"
 
-                    link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
+            link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
+            link_1.click()
 
-                    link_2.click()
-
-                    assert driver.title == "Page 2"
-
-                    link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
-                    link_1.click()
-
-                    assert driver.title == "Page 1"
-        """
+            assert driver.title == "Page 1"
+    """
     )
     testdir.makepyfile(test_selenium=selenium_test_script)
     subprocess.run(
@@ -127,39 +134,29 @@ def test_selenium_local_pass():
 
 
 @snapshot(ignores=SELENIUM_SNAPSHOT_IGNORES)
-@pytest.mark.skipif(platform.machine() != "x86_64", reason="Selenium Chrome tests only run on x86_64")
 def test_selenium_chrome_pytest_rum_disabled(_http_server, testdir, git_repo):
     selenium_test_script = textwrap.dedent(
-        """
-            from pathlib import Path
+        _SELENIUM_DRIVER_SETUP
+        + """
+    def test_selenium_local_pass():
+        with _make_driver() as driver:
+            url = "http://localhost:8079/rum_disabled/page_1.html"
 
-            from selenium import webdriver
-            from selenium.webdriver.common.by import By
-            from selenium.webdriver.chrome.options import Options
+            driver.get(url)
 
-            def test_selenium_local_pass():
-                options = Options()
-                options.add_argument("--headless")
-                options.add_argument("--no-sandbox")
+            assert driver.title == "Page 1"
 
-                with webdriver.Chrome(options=options) as driver:
-                    url = "http://localhost:8079/rum_disabled/page_1.html"
+            link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
 
-                    driver.get(url)
+            link_2.click()
 
-                    assert driver.title == "Page 1"
+            assert driver.title == "Page 2"
 
-                    link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
+            link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
+            link_1.click()
 
-                    link_2.click()
-
-                    assert driver.title == "Page 2"
-
-                    link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
-                    link_1.click()
-
-                    assert driver.title == "Page 1"
-        """
+            assert driver.title == "Page 1"
+    """
     )
     testdir.makepyfile(test_selenium=selenium_test_script)
     subprocess.run(
@@ -180,42 +177,32 @@ def test_selenium_local_pass():
 
 
 @snapshot(ignores=SELENIUM_SNAPSHOT_IGNORES)
-@pytest.mark.skipif(platform.machine() != "x86_64", reason="Selenium Chrome tests only run on x86_64")
 def test_selenium_chrome_pytest_unpatch_does_not_record_selenium_tags(_http_server, testdir, git_repo):
     selenium_test_script = textwrap.dedent(
-        """
-            from pathlib import Path
+        _SELENIUM_DRIVER_SETUP
+        + """
+    from ddtrace.contrib.internal.selenium.patch import unpatch
 
-            from selenium import webdriver
-            from selenium.webdriver.common.by import By
-            from selenium.webdriver.chrome.options import Options
+    def test_selenium_local_unpatch():
+        unpatch()
+        with _make_driver() as driver:
+            url = "http://localhost:8079/rum_disabled/page_1.html"
 
-            from ddtrace.contrib.internal.selenium.patch import unpatch
+            driver.get(url)
 
-            def test_selenium_local_unpatch():
-                unpatch()
-                options = Options()
-                options.add_argument("--headless")
-                options.add_argument("--no-sandbox")
+            assert driver.title == "Page 1"
 
-                with webdriver.Chrome(options=options) as driver:
-                    url = "http://localhost:8079/rum_disabled/page_1.html"
+            link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
 
-                    driver.get(url)
+            link_2.click()
 
-                    assert driver.title == "Page 1"
+            assert driver.title == "Page 2"
 
-                    link_2 = driver.find_element(By.LINK_TEXT, "Page 2")
+            link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
+            link_1.click()
 
-                    link_2.click()
-
-                    assert driver.title == "Page 2"
-
-                    link_1 = driver.find_element(By.LINK_TEXT, "Back to page 1.")
-                    link_1.click()
-
-                    assert driver.title == "Page 1"
-        """
+            assert driver.title == "Page 1"
+    """
     )
     testdir.makepyfile(test_selenium=selenium_test_script)
     subprocess.run(

tests/snapshots/test_selenium_chrome.test_selenium_chrome_pytest_rum_disabled.json

@@ -178,8 +178,8 @@
       "_dd.tracer_kr": 1.0,
       "_sampling_priority_v1": 1,
       "process_id": 13623,
-      "test.source.end": 29,
-      "test.source.start": 7
+      "test.source.end": 31,
+      "test.source.start": 13
     },
     "duration": 1035420043,
     "start": 1733243045320806200

tests/snapshots/test_selenium_chrome.test_selenium_chrome_pytest_rum_enabled.json

@@ -179,8 +179,8 @@
       "_dd.tracer_kr": 1.0,
       "_sampling_priority_v1": 1,
       "process_id": 13453,
-      "test.source.end": 29,
-      "test.source.start": 7
+      "test.source.end": 31,
+      "test.source.start": 13
     },
     "duration": 1056245299,
     "start": 1733243043078204615

tests/snapshots/test_selenium_chrome.test_selenium_chrome_pytest_unpatch_does_not_record_selenium_tags.json

@@ -173,8 +173,8 @@
       "_dd.tracer_kr": 1.0,
       "_sampling_priority_v1": 1,
       "process_id": 12386,
-      "test.source.end": 32,
-      "test.source.start": 9
+      "test.source.end": 34,
+      "test.source.start": 15
     },
     "duration": 534785315,
     "start": 1733242640750308571