The net dialer sorts the addresses according to RFC6724, which means that since you don't have ipv6 enabled they go to the end of the list, but doesn't remove them entirely. Also if you're using the DefaultTransport from the net/http package, it has DualStack enabled which means that ipv4 and ipv6 are tried nearly concurrently (RFC6555), so if the ipv4 host takes longer than 300ms to connect, the ipv6 racer will kick off too and you might get the ipv6 error as the final error if the connection fails.
In this case, you're only getting that error because the ipv4 connection has already failed, so it's harmless albeit somewhat confusing. If you disable DualStack all 8 ipv4 hosts would have to be down before the ipv6 address is attempted, and if you never want to even see ipv6 addresses, set the dialer to only use the "tcp4" network. On Saturday, December 30, 2017 at 11:51:39 AM UTC-5, bryan...@gmail.com wrote: > > I've done quite a bit of searching and can't seem to find a definitive > answer to my problem. > > I am periodically seeing errors where my code is doing an http get request > to a web service which offers both IPv4 and IPv6 connectivity. My code is > running in a docker container without IPv6 enabled on a machine that also > doesn't have IPv6 enabled. Yet go is trying to connect to this website via > IPv6 and I get a failure like dial tcp [XXXX:XXXX:XXXX:XXX::XXXa]:443: > connect: cannot assign requested address. The error makes sense, IPv6 > connections aren't going to work from this machine. The question is why is > go even trying to connect via IPv6 when that isn't an option on the machine? > > I've gone through and read quite a bit about the Go resolver and confirmed > it does request both the A and AAAA records for a domain name. This > particular service advertises 8 different IPv4 addresses and 1 IPv6 address > when I look at the returned address options. I want to make sure Go > doesn't try the IPv6 address. > > Any suggestions on how I can keep Go from trying to use the IPv6 address > or better yet have it not even query for the AAAA record? Most of the time > I don't have problems but I'm seeing this error in my logs often enough > that it is concerning. > > Thanks! > > Bryan > > > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
