For fast datapath, the router core will only be invoked upon datapath
misses. And it needs to yield routing decisions in a form that can be
used to configure the in-kernel datapath. So here we make the router
core yield FlowOps, which represent operations which actually do
something with a packet. The router core obtains these in turn from
the Bridge or the Overlay, depending on what it wants to do with
a packet.
For fast datapath, it's critical that the router makes decisions based
only on the required packet header information (as the same header
information will be used when configuring the ODP flow rules). So we
pass only that information into the router core, in the form of
PacketKeys.
The overall effect is to curry the router core: Rather than taking a
packet and doing something with it, it takes packet header information
and returns a function that does something with a packet.
This introduces interfaces to represent the packet forwarding
mechanism, and brings all the scattered UDP-related code together into
a single implementation.
This is not a pure refactoring, although much of the code in sleeve.go
has been copied from pre-existing code, and the UDP protocol remains
the same in spirit. The biggest change is the organization of the
forwarder goroutines (there is now one instead of two, and that
goroutine does a lot of auxiliary work as well as forwarding).
Performance testing between VMs on my laptop suggests that packet
throughput has not gone down, and may even have improved slightly.
The standard mflags error reporting produces s.t. like
```
flag provided but not defined: -p
See '/home/weave/weaver --help'.
```
on stderr. This is misleading since the program name is container
local, so not something the user actually invoked.
Fixes#1321.
- Nameserver holds a sorted list of (hostname, peer, container id, ip) tuples.
- Entries are gossiped using topology gossip / broadcast - only new/updated entries
are propogated as expected.
- Entries for a given peer are removed when the connection to the peer is lost.
- Entries are tombstoned when containers die. Tombstones are kept for 10mins,
as they do not need to survive partition, only gossip propagation delay.
Provides to new two new flags: `--hostname-match <regexp>`
and `--hostname-replacement <replacement>`. When launching a container, its name
matched against regular expression `<regexp>`. Then, based on that match,
`<replacement>` will be used to generate a hostname, which will ultimately be
handed over to weaveDNS for registration.
The substitution is implemented with
https://golang.org/pkg/regexp/#Regexp.ReplaceAllString . Thus, references to
regexp substitution groups should be prepended with a dollar sign.
For instance, if we provide `--hostname-match '^aws-[0-9]+-(.*)$'` and
`--hostname-replacement 'my-app-$1'`, running a container named
`aws-12798186823-foo` through WeaveProxy will lead to WeaveDNS registering
`my-app-foo`.
Closes#1018
Matthias Radestock