test: CI test with DNS resolved feature is flaky

[u5surf]

Nevertheless the PR only be modified the README.md doc, the CI is failed which completely unrelated to the changes.
#2492

https://github.com/openresty/lua-nginx-module/actions/runs/23824388575/job/69443965578?pr=2492

#   Failed test 't/058-tcp-socket.t TEST 50: cosocket resolving aborted by coroutine yielding failures (require) - pattern "resolve name done" should match a line in error.log (req 0)'

058-tcp-socket.t is used an external DNS server which cause occasionally a communication failure

lua-nginx-module/t/058-tcp-socket.t

Line 13 in c81c951

$ENV{TEST_NGINX_RESOLVER} ||= '8.8.8.8';

Indeed it would be highly successful to be extended wait time but it cannot be solved fundamentally.

lua-nginx-module/t/058-tcp-socket.t

Line 3087 in c81c951

--- wait: 0.3

How can we solved it?

[zhuizhuhaomeng]

Depends on the internet， so it is flaky.

[u5surf]

@zhuizhuhaomeng Thanks! To avoid flakiness this test, how about build a local DNS cache with dnsmasq in this CI like that.

.github/workflows/build_and_test.yml

  - name: Start local DNS cache
    run: |
      sudo apt-get install -y dnsmasq
      sudo dnsmasq --no-daemon --port=5353 --server=8.8.4.4 --cache-size=1000 &
      sleep 1
      dig +short @127.0.0.1 -p 5353 openresty.org

If you don't have any time, I would like to resolve this issue.

[zhuizhuhaomeng]

Sure.
Please add dnsmasq.