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Fix dnsname when joining a different network namespace in a pod

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When creating a container in a pod the podname was always set as
the dns entry. This is incorrect when the container is not part
of the pods network namespace. This happend both rootful and
rootless. To fix this check if we are part of the pods network
namespace and if not use the container name as dns entry.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>
This commit is contained in:
Paul Holzinger 2020-10-30 15:38:54 +01:00
parent 228396a99d
commit 2704dfbb7a
3 changed files with 46 additions and 17 deletions
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12
libpod/networking_linux.go
View file

@ -102,17 +102,7 @@ func (r *Runtime) configureNetNS(ctr *Container, ctrNS ns.NetNS) ([]*cnitypes.Re
requestedMAC = ctr.config.StaticMAC
}
// If we are in a pod use the pod name for the network, otherwise the container name
var podName string
if ctr.PodID() != "" {
pod, err := r.GetPod(ctr.PodID())
if err == nil {
podName = pod.Name()
}
}
if podName == "" {
podName = ctr.Name()
}
podName := getCNIPodName(ctr)
podNetwork := r.getPodNetwork(ctr.ID(), podName, ctrNS.Path(), ctr.config.Networks, ctr.config.PortMappings, requestedIP, requestedMAC)

16
libpod/rootless_cni_linux.go
View file

@ -53,7 +53,7 @@ func AllocRootlessCNI(ctx context.Context, c *Container) (ns.NetNS, []*cnitypes.
if err != nil {
return nil, nil, err
}
k8sPodName := getPodOrContainerName(c) // passed to CNI as K8S_POD_NAME
k8sPodName := getCNIPodName(c) // passed to CNI as K8S_POD_NAME
cniResults := make([]*cnitypes.Result, len(c.config.Networks))
for i, nw := range c.config.Networks {
cniRes, err := rootlessCNIInfraCallAlloc(infra, c.ID(), nw, k8sPodName)
@ -115,12 +115,16 @@ func getRootlessCNIInfraLock(r *Runtime) (lockfile.Locker, error) {
return lockfile.GetLockfile(fname)
}
func getPodOrContainerName(c *Container) string {
pod, err := c.runtime.GetPod(c.PodID())
if err != nil || pod.config.Name == "" {
return c.Name()
// getCNIPodName return the pod name (hostname) used by CNI and the dnsname plugin.
// If we are in the pod network namespace use the pod name otherwise the container name
func getCNIPodName(c *Container) string {
if c.config.NetMode.IsPod() || c.IsInfra() {
pod, err := c.runtime.GetPod(c.PodID())
if err == nil {
return pod.Name()
}
}
return pod.config.Name
return c.Name()
}
func rootlessCNIInfraCallAlloc(infra *Container, id, nw, k8sPodName string) (*cnitypes.Result, error) {

35
test/e2e/run_networking_test.go
View file

@ -594,4 +594,39 @@ var _ = Describe("Podman run networking", func() {
Expect(run.ExitCode()).To(BeZero())
Expect(strings.Contains(run.OutputToString(), hostname)).To(BeTrue())
})
It("podman run check dnsname plugin", func() {
pod := "testpod"
session := podmanTest.Podman([]string{"pod", "create", "--name", pod})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
net := "dnsNetTest"
session = podmanTest.Podman([]string{"network", "create", net})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
defer podmanTest.removeCNINetwork(net)
pod2 := "testpod2"
session = podmanTest.Podman([]string{"pod", "create", "--network", net, "--name", pod2})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
session = podmanTest.Podman([]string{"run", "--name", "con1", "--network", net, ALPINE, "nslookup", "con1"})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
session = podmanTest.Podman([]string{"run", "--name", "con2", "--pod", pod, "--network", net, ALPINE, "nslookup", "con2"})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
session = podmanTest.Podman([]string{"run", "--name", "con3", "--pod", pod2, ALPINE, "nslookup", "con3"})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(Equal(1))
Expect(session.ErrorToString()).To(ContainSubstring("can't resolve 'con3'"))
session = podmanTest.Podman([]string{"run", "--name", "con4", "--network", net, ALPINE, "nslookup", pod2})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(BeZero())
})
})