Fix/bind addr ipv6 fallback#219
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Commit 84a119f switched --bind-addr to "[::]:8443" for dual-stack, but binding fails with EAFNOSUPPORT when IPv6 is disabled in the kernel, leaving code-server unreachable. Detect IPv6 via /proc/net/if_inet6 and fall back to 0.0.0.0:8443 when it is unavailable.
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Relates to #218 |
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Description:
Commit 84a119f (#216) switched
--bind-addrto"[::]:8443"so the service listens on both IPv4 and IPv6 via dual-stack. This works fine when an IPv6 stack is present (even on IPv4-only networks), but it fails outright when IPv6 is disabled at the kernel level (e.g.ipv6.disable=1, kernel built withoutCONFIG_IPV6, or the module not loaded). In that case there is noAF_INET6socket family, so binding to[::]fails withEAFNOSUPPORTand code-server never starts — the container becomes unreachable.This PR detects IPv6 availability at startup via the presence of
/proc/net/if_inet6(the standard indicator that the kernel has IPv6 support) and chooses the bind address accordingly:[::]:8443(dual-stack, unchanged behaviour from listen on both ipv4 and ipv6 even when running container as root #216)0.0.0.0:8443(IPv4 fallback)Both the root and non-root exec paths use the shared
BIND_ADDRvariable.Benefits of this PR and context:
Restores the ability to run the container on hosts/kernels with IPv6 disabled, which regressed after #216, while fully preserving the dual-stack behaviour that #216 introduced for everyone else. No configuration or environment variables are required — the correct address is selected automatically.
How Has This Been Tested?
Verified in a container inheriting a host kernel with IPv6 fully disabled
(
/proc/net/if_inet6and/proc/sys/net/ipv6absent):[::]:8443fails with[Errno 97] Address family not supported by protocol(reproduces the regression).0.0.0.0:8443succeeds.[[ -e /proc/net/if_inet6 ]]correctly evaluates false, so the script selects the0.0.0.0fallback.On a normal dual-stack host
/proc/net/if_inet6is present and the script keeps[::]:8443, so existing IPv4+IPv6 behaviour is unchanged.Source / References:
--bind-addr "[::]:8443")(only IPv6-less networks with the stack still present).
Container does not work on host with ipv6 disabled docker-swag#92