We don't need to parse out the counter values from the iptables-save
output (since they are always 0 for the chains we care about). Just
parse the chain names themselves.
Also, all of the callers of GetChainLines() pass it input that
contains only a single table, so just assume that, rather than
carefully parsing only a single table's worth of the input.
The test was calling GetChainLines() on invalid pseudo-iptables-save
output where most of the lines were indented. GetChainLines() happened
to still parse this "correctly", but it would be better to be testing
it on actually-correct data.
FakeIPTables barely implemented any of the iptables interface, and the
main part that it did implement, it implemented incorrectly. Fix it:
- Implement EnsureChain, DeleteChain, EnsureRule, and DeleteRule, not
just SaveInto/Restore/RestoreAll.
- Restore/RestoreAll now correctly merge the provided state with the
existing state, rather than simply overwriting it.
- SaveInto now returns the table that was requested, rather than just
echoing back the Restore/RestoreAll.
There were previously some strange iptables-rule-parsing functions
that were only used by two unit tests in pkg/proxy/ipvs. Get rid of
them and replace them with some much better iptables-rule-parsing
functions.
Fix some warnings from go-staticcheck.
"should use buffer.String() instead of string(buffer.Bytes()) (S1030)"
This warning is explained at this link.
https://staticcheck.io/docs/checks#S1030
the iptables restore function, if it considers that the --wait flag
is not supported, creates a lock file to mimic the iptables behaviour.
The test should take this into account and remove the file.
1. For iptables mode, add KUBE-NODEPORTS chain in filter table. Add
rules to allow healthcheck node port traffic.
2. For ipvs mode, add KUBE-NODE-PORT chain in filter table. Add
KUBE-HEALTH-CHECK-NODE-PORT ipset to allow traffic to healthcheck
node port.
the iptables monitor was using iptables -L to list the chains,
without the -n option, so it was trying to do reverse DNS lookups.
A side effect is that it was holding the lock, so other components
could not use it.
We can use -S instead of -L -n to avoid this, since we only want
to check the chain exists.
iptables has two options to modify the behaviour trying to
acquire the lock.
--wait -w [seconds] maximum wait to acquire xtables lock
before give up
--wait-interval -W [usecs] wait time to try to acquire xtables
lock
interval to wait for xtables lock
default is 1 second
Kubernetes uses -w 5 that means that wait 5 seconds to try to
acquire the lock. If we are not able to acquire it, kube-proxy
fails and retries in 30 seconds, that is an important penalty
on sensitive applications.
We can be a bit more aggresive and try to acquire the lock every
100 msec, that means that we have to fail 50 times to not being
able to succeed.
