This error means that your test cannot reach your website.
I had a similar issue using something based on docker for drupal. For me the solution or hack the hosts file on the php container and change to point the domain you want to test to to the ip of the proxy server, in my case traeffik.
So in my host file I had something like this:
once that is done you can use curl to test the connection:
curl -v domain.internal
In my case I had an issue with a self signed certificate.
- Rebuilt URL to: https://domain.internal/
- Trying 172.18.0.5...
- TCP_NODELAY set
- Connected to domain.internal (172.18.0.5) port 443 (#0)
- ALPN, offering http/1.1
- successfully set certificate verify locations:
- CAfile: /etc/ssl/certs/ca-certificates.crt
- TLSv1.2 (OUT), TLS handshake, Client hello (1):
- TLSv1.2 (IN), TLS handshake, Server hello (2):
- TLSv1.2 (IN), TLS handshake, Certificate (11):
- TLSv1.2 (OUT), TLS alert, Server hello (2):
- SSL certificate problem: self signed certificate
- Closing connection 0
curl: (60) SSL certificate problem: self signed certificate
More details here: https://curl.haxx.se/docs/sslcerts.html
curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.
However this should allow you to run your simpletest(s) in your browser.
Ideally there should be a way to configure this in your docker-compose file but I am not sure how?