The `--userland-proxy` daemon flag makes it possible to rely on hairpin
NAT and additional iptables routes instead of userland proxy for port
publishing and inter-container communication.
Usage of the userland proxy remains the default as hairpin NAT is
unsupported by older kernels.
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
We encountered a situation where concurrent invocations of the docker daemon on a machine with an older version of iptables led to nondeterministic errors related to simultaenous invocations of iptables.
While this is best resolved by upgrading iptables itself, the particular situation would have been avoided if the docker daemon simply took care not to concurrently invoke iptables. Of course, external processes could also cause iptables to fail in this way, but invoking docker in parallel seems like a pretty common case.
Signed-off-by: Aaron Davidson <aaron@databricks.com>
This modifies iptables.Exists so that it must be called with an explicit
table and chain. This allows us (a) to generate an appropriate command
line for "iptables -C", which was not previously possible, and (b) it
allows us to limit our strings.Contains() search to just the table and
chain in question, preventing erroneous matches against unrelated rules.
Resolves#10781
Signed-off-by: Lars Kellogg-Stedman <lars@redhat.com>
