Tim Gross 58dd90b996 ensure iptables chain creation is idempotent
Concurrent use of the `portmap` and `firewall` plugins can result in
errors during iptables chain creation:

- The `portmap` plugin has a time-of-check-time-of-use race where it
  checks for existence of the chain but the operation isn't atomic.
- The `firewall` plugin doesn't check for existing chains and just
  returns an error.

This commit makes both operations idempotent by creating the chain and
then discarding the error if it's caused by the chain already
existing. It also factors the chain creation out into `pkg/utils` as a
site for future refactoring work.

Signed-off-by: Tim Gross <tim@0x74696d.com>
2019-11-11 10:00:11 -05:00

79 lines
1.9 KiB
Go

// Copyright 2017-2018 CNI authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package utils
import (
"fmt"
"math/rand"
"runtime"
"github.com/containernetworking/plugins/pkg/ns"
"github.com/containernetworking/plugins/pkg/testutils"
"github.com/coreos/go-iptables/iptables"
. "github.com/onsi/ginkgo"
. "github.com/onsi/gomega"
)
const TABLE = "filter" // We'll monkey around here
var _ = Describe("chain tests", func() {
var testChain string
var ipt *iptables.IPTables
var cleanup func()
BeforeEach(func() {
// Save a reference to the original namespace,
// Add a new NS
currNs, err := ns.GetCurrentNS()
Expect(err).NotTo(HaveOccurred())
testNs, err := testutils.NewNS()
Expect(err).NotTo(HaveOccurred())
testChain = fmt.Sprintf("cni-test-%d", rand.Intn(10000000))
ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
Expect(err).NotTo(HaveOccurred())
runtime.LockOSThread()
err = testNs.Set()
Expect(err).NotTo(HaveOccurred())
cleanup = func() {
if ipt == nil {
return
}
ipt.ClearChain(TABLE, testChain)
ipt.DeleteChain(TABLE, testChain)
currNs.Set()
}
})
AfterEach(func() {
cleanup()
})
It("creates chains idempotently", func() {
err := EnsureChain(ipt, TABLE, testChain)
Expect(err).NotTo(HaveOccurred())
// Create it again!
err = EnsureChain(ipt, TABLE, testChain)
Expect(err).NotTo(HaveOccurred())
})
})