Curl: Retry on connection refused

[gaul]

Could curl add a --retry-connrefused flag? Some users requested this several times over the years and @gnawhleinad provided a patch:

• https://curl.haxx.se/mail/lib-2014-08/0137.html
• https://curl.haxx.se/mail/archive-2010-05/0066.html
• https://sourceforge.net/p/curl/feature-requests/61/

[gnawhleinad]

@gnawhleinad provided a patch

When I have some time (this week), I can work on creating a pull request for this change (with tests).

[bagder]

Feel free to submit a pull request for this at any time. Even adding it as an idea to TODO could be a pull request. The option could possibly be made to work like --retry-for "connrefused|timeouts|ufolandings" to avoid having to do specific options for other conditions for which we could offer retries...

[robhaswell]

The --retry-connrefused has suddenly started failing for us in our Docker builds using 7.52.1-r3, has anything changed?

[bagder]

No...

[jay]

The --retry-connrefused has suddenly started failing for us in our Docker builds using 7.52.1-r3, has anything changed?

Check that you are using --retry with --retry-connrefused. Check if the error code is ECONNREFUSED, maybe curl is getting a different error code. I don't know of any way to get the OS ERRNO from the tool (maybe we should add that to --write-out?) but you can change this code to print the errno. Also please check the discussion at #1603. We are going to allow more error codes to be considered connrefused. It would be helpful to know which error code you are experiencing for connrefused. Thanks

[robhaswell]

Thanks for your advice. Perhaps this transcript will provide some more information. I'm using Docker for Mac.

cloudfind@spirit:~
$ docker --version
Docker version 17.06.0-ce, build 02c1d87
cloudfind@spirit:~
$ docker run -ti alpine
/ # apk add -U curl
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ca-certificates (20161130-r2)
(2/4) Installing libssh2 (1.8.0-r1)
(3/4) Installing libcurl (7.54.0-r0)
(4/4) Installing curl (7.54.0-r0)
Executing busybox-1.26.2-r5.trigger
Executing ca-certificates-20161130-r2.trigger
OK: 5 MiB in 15 packages
/ # curl --retry 1 --retry-connrefused http://localhost/
curl: (7) Failed to connect to localhost port 80: Connection refused
/ # curl --retry 1 --retry-connrefused http://127.0.0.1/
Warning: Transient problem: connection refused Will retry in 1 seconds. 1 
Warning: retries left.
curl: (7) Failed to connect to 127.0.0.1 port 80: Connection refused
/ # nslookup localhost
nslookup: can't resolve '(null)': Name does not resolve

Name:      localhost
Address 1: 127.0.0.1 localhost
Address 2: ::1 localhost
/ # 

Does this belong in a different ticket?