0548fe251c
In release 27.0, ip6tables was enabled by default. That caused a
problem on some hosts where iptables was explicitly disabled and
loading the br_netfilter module (which loads with its nf-call-iptables
settings enabled) caused user-defined iptables rules to block traffic
on bridges, breaking inter-container communication.
In 27.3.0, commit 5c499fc4b2 delayed
loading of the br_netfilter module until it was needed. The load
now happens in the function that sets bridge-nf-call-ip[6]tables when
needed. It was only called for icc=false networks.
However, br_netfilter is also needed when userland-proxy=false.
Without it, packets addressed to a host-mapped port for a container
on the same network are not DNAT'd properly (responses have the server
container's address instead of the host's).
That means, in all releases including 26.x, if br_netfilter was loaded
before the daemon started - and the OS/user/other-application had
disabled bridge-nf-call-ip[6]tables, it would not be enabled by the
daemon. So, ICC would fail for host-mapped ports with the userland-proxy
disabled.
The change in 27.3.0 made this worse - previously, loading br_netfilter
whenever iptables/ip6tables was enabled meant that bridge-netfiltering
got enabled, even though the daemon didn't check it was enabled.
So... check that br_netfilter is loaded, with bridge-nf-call-ip[6]tables
enabled, if userland-proxy=false.
Signed-off-by: Rob Murray <rob.murray@docker.com>
The Moby Project
Moby is an open-source project created by Docker to enable and accelerate software containerization.
It provides a "Lego set" of toolkit components, the framework for assembling them into custom container-based systems, and a place for all container enthusiasts and professionals to experiment and exchange ideas. Components include container build tools, a container registry, orchestration tools, a runtime and more, and these can be used as building blocks in conjunction with other tools and projects.
Principles
Moby is an open project guided by strong principles, aiming to be modular, flexible and without too strong an opinion on user experience. It is open to the community to help set its direction.
- Modular: the project includes lots of components that have well-defined functions and APIs that work together.
- Batteries included but swappable: Moby includes enough components to build fully featured container systems, but its modular architecture ensures that most of the components can be swapped by different implementations.
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The components and tools in the Moby Project are initially the open source components that Docker and the community have built for the Docker Project. New projects can be added if they fit with the community goals. Docker is committed to using Moby as the upstream for the Docker Product. However, other projects are also encouraged to use Moby as an upstream, and to reuse the components in diverse ways, and all these uses will be treated in the same way. External maintainers and contributors are welcomed.
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