Why is my containerized Selenium application failing only in AWS Lambda? - docker

Question

I'm trying to get a function to run in AWS Lambda that uses Selenium and Firefox/geckodriver in order to run. I've decided to go the route of creating a container image, and then uploading and running that instead of using a pre-configured runtime. I was able to create a Dockerfile that correctly installs Firefox and Python, downloads geckodriver, and installs my test code:
FROM alpine:latest
RUN apk add firefox python3 py3-pip
RUN pip install requests selenium
RUN mkdir /app
WORKDIR /app
RUN wget -qO gecko.tar.gz https://github.com/mozilla/geckodriver/releases/download/v0.28.0/geckodriver-v0.28.0-linux64.tar.gz
RUN tar xf gecko.tar.gz
RUN mv geckodriver /usr/bin
COPY *.py ./
ENTRYPOINT ["/usr/bin/python3","/app/lambda_function.py"]
The Selenium test code:
#!/usr/bin/env python3
import util
import os
import sys
import requests
def lambda_wrapper():
api_base = f'http://{os.environ["AWS_LAMBDA_RUNTIME_API"]}/2018-06-01'
response = requests.get(api_base + '/runtime/invocation/next')
request_id = response.headers['Lambda-Runtime-Aws-Request-Id']
try:
result = selenium_test()
# Send result back
requests.post(api_base + f'/runtime/invocation/{request_id}/response', json={'url': result})
except Exception as e:
# Error reporting
import traceback
requests.post(api_base + f'/runtime/invocation/{request_id}/error', json={'errorMessage': str(e), 'traceback': traceback.format_exc(), 'logs': open('/tmp/gecko.log', 'r').read()})
raise
def selenium_test():
from selenium.webdriver import Firefox
from selenium.webdriver.firefox.options import Options
options = Options()
options.add_argument('-headless')
options.add_argument('--window-size 1920,1080')
ffx = Firefox(options=options, log_path='/tmp/gecko.log')
ffx.get("https://google.com")
url = ffx.current_url
ffx.close()
print(url)
return url
def main():
# For testing purposes, currently not using the Lambda API even in AWS so that
# the same container can run on my local machine.
# Call lambda_wrapper() instead to get geckodriver logs as well (not informative).
selenium_test()
if __name__ == '__main__':
main()
I'm able to successfully build this container on my local machine with docker build -t lambda-test . and then run it with docker run -m 512M lambda-test.
However, the exact same container crashes with an error when I try and upload it to Lambda to run. I set the memory limit to 1024M and the timeout to 30 seconds. The traceback says that Firefox was unexpectedly killed by a signal:
START RequestId: 52adeab9-8ee7-4a10-a728-82087ec9de30 Version: $LATEST
/app/lambda_function.py:29: DeprecationWarning: use service_log_path instead of log_path
ffx = Firefox(options=options, log_path='/tmp/gecko.log')
Traceback (most recent call last):
File "/app/lambda_function.py", line 45, in <module>
main()
File "/app/lambda_function.py", line 41, in main
lambda_wrapper()
File "/app/lambda_function.py", line 12, in lambda_wrapper
result = selenium_test()
File "/app/lambda_function.py", line 29, in selenium_test
ffx = Firefox(options=options, log_path='/tmp/gecko.log')
File "/usr/lib/python3.8/site-packages/selenium/webdriver/firefox/webdriver.py", line 170, in __init__
RemoteWebDriver.__init__(
File "/usr/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py", line 157, in __init__
self.start_session(capabilities, browser_profile)
File "/usr/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py", line 252, in start_session
response = self.execute(Command.NEW_SESSION, parameters)
File "/usr/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
self.error_handler.check_response(response)
File "/usr/lib/python3.8/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Process unexpectedly closed with status signal
END RequestId: 52adeab9-8ee7-4a10-a728-82087ec9de30
REPORT RequestId: 52adeab9-8ee7-4a10-a728-82087ec9de30 Duration: 20507.74 ms Billed Duration: 21350 ms Memory Size: 1024 MB Max Memory Used: 131 MB Init Duration: 842.11 ms
Unknown application error occurred
I had it upload the geckodriver logs as well, but there wasn't much useful information in there:
1608506540595 geckodriver INFO Listening on 127.0.0.1:41597
1608506541569 mozrunner::runner INFO Running command: "/usr/bin/firefox" "--marionette" "-headless" "--window-size 1920,1080" "-foreground" "-no-remote" "-profile" "/tmp/rust_mozprofileQCapHy"
*** You are running in headless mode.
How can I even begin to debug this? The fact that the exact same container behaves differently depending upon where it's run seems fishy to me, but I'm not knowledgeable enough about Selenium, Docker, or Lambda to pinpoint exactly where the problem is.
Is my docker run command not accurately recreating the environment in Lambda? If so, then what command would I run to better simulate the Lambda environment? I'm not really sure where else to go from here, seeing as I can't actually reproduce the error locally to test with.
If anyone wants to take a look at the full code and try building it themselves, the repository is here - the lambda code is in lambda_function.py.
As for prior research, this question a) is about ChromeDriver and b) has no answers from over a year ago. The link from that one only has information about how to run a container in Lambda, which I'm already doing. This answer is almost my problem, but I know that there's not a version mismatch because the container works on my laptop just fine.

Answer 1

I have exactly the same problem and a possible explanation.
I think what you want is not possible for the time being.
According to AWS DevOps Blog Firefox relies on fallocate system call and /dev/shm.
However AWS Lambda does not mount /dev/shm so Firefox will crash when trying to allocate memory. Unfortunately, this handling cannot be disabled for Firefox.
However if you can live with Chromium, there is an option for chromedriver --disable-dev-shm-usage that disables the usage of /dev/shm and instead writes shared memory files to /tmp.
chromedriver works fine for me on AWS Lambda, if that is an option for you.
According to AWS DevOps Blog you can also use AWS Fargate to run Firefox/geckodriver.
There is an entry in the AWS forum from 2015 that requests mounting /dev/shm in Lambdas, but nothing happened since then.