Make the internal DNS resolver for Windows containers forward requests
to upsteam DNS servers when it cannot respond itself, rather than
returning SERVFAIL.
Windows containers are normally configured with the internal resolver
first for service discovery (container name lookup), then external
resolvers from '--dns' or the host's networking configuration.
When a tool like ping gets a SERVFAIL from the internal resolver, it
tries the other nameservers. But, nslookup does not, and with this
change it does not need to.
The internal resolver learns external server addresses from the
container's HNSEndpoint configuration, so it will use the same DNS
servers as processes in the container.
The internal resolver for Windows containers listens on the network's
gateway address, and each container may have a different set of external
DNS servers. So, the resolver uses the source address of the DNS request
to select external resolvers.
On Windows, daemon.json feature option 'windows-no-dns-proxy' can be used
to prevent the internal resolver from forwarding requests (restoring the
old behaviour).
Signed-off-by: Rob Murray <rob.murray@docker.com>
Partially reverts 0046b16 "daemon: set libnetwork sandbox key w/o OCI hook"
Running SetKey to store the OCI Sandbox key after task creation, rather
than from the OCI prestart hook, meant it happened after sysctl settings
were applied by the runtime - which was the intention, we wanted to
complete Sandbox configuration after IPv6 had been disabled by a sysctl
if that was going to happen.
But, it meant '--sysctl' options for a specfic network interface caused
container task creation to fail, because the interface is only moved into
the network namespace during SetKey.
This change restores the SetKey prestart hook, and regenerates config
files that depend on the container's support for IPv6 after the task has
been created. It also adds a regression test that makes sure it's possible
to set an interface-specfic sysctl.
Signed-off-by: Rob Murray <rob.murray@docker.com>
When IPv6 is disabled in a container by, for example, using the --sysctl
option - an IPv6 address/gateway is still allocated. Don't attempt to
apply that config because doing so enables IPv6 on the interface.
Signed-off-by: Rob Murray <rob.murray@docker.com>
Some configuration in a container depends on whether it has support for
IPv6 (including default entries for '::1' etc in '/etc/hosts').
Before this change, the container's support for IPv6 was determined by
whether it was connected to any IPv6-enabled networks. But, that can
change over time, it isn't a property of the container itself.
So, instead, detect IPv6 support by looking for '::1' on the container's
loopback interface. It will not be present if the kernel does not have
IPv6 support, or the user has disabled it in new namespaces by other
means.
Once IPv6 support has been determined for the container, its '/etc/hosts'
is re-generated accordingly.
The daemon no longer disables IPv6 on all interfaces during initialisation.
It now disables IPv6 only for interfaces that have not been assigned an
IPv6 address. (But, even if IPv6 is disabled for the container using the
sysctl 'net.ipv6.conf.all.disable_ipv6=1', interfaces connected to IPv6
networks still get IPv6 addresses that appear in the internal DNS. There's
more to-do!)
Signed-off-by: Rob Murray <rob.murray@docker.com>
The github.com/containerd/containerd/log package was moved to a separate
module, which will also be used by upcoming (patch) releases of containerd.
This patch moves our own uses of the package to use the new module.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
InterfaceOptions() returned an IfaceOptionSetter interface, which contained
"methods" that returned functional options. Such a construct could have made
sense if the functional options returned would (e.g.) be pre-propagated with
information from the Sandbox (network namespace), but none of that was the case.
There was only one implementation of IfaceOptionSetter (networkNamespace),
which happened to be the same as the only implementation of Sandbox, so remove
the interface as well, to help networkNamespace with its multi-personality
disorder.
This patch:
- removes Sandbox.Bridge() and makes it a regular function (WithIsBridge)
- removes Sandbox.Master() and makes it a regular function (WithMaster)
- removes Sandbox.MacAddress() and makes it a regular function (WithMACAddress)
- removes Sandbox.Address() and makes it a regular function (WithIPv4Address)
- removes Sandbox.AddressIPv6() and makes it a regular function (WithIPv6Address)
- removes Sandbox.LinkLocalAddresses() and makes it a regular function (WithLinkLocalAddresses)
- removes Sandbox.Routes() and makes it a regular function (WithRoutes)
- removes Sandbox.InterfaceOptions().
- removes the IfaceOptionSetter interface.
Note that the IfaceOption signature was changes as well to allow returning
an error. This is not currently used, but will be used for some options
in the near future, so adding that in preparation.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
osl.NewSandbox() always returns a nil interface on Windows (and other non-Linux
platforms). This means that any code that these fields are always nil, and
any code using these fields must be considered Linux-only.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
