fix --dns and --network conflict

Close containers#3553
This PR makes --dns and --network flag mutually exclusive for podman build and create. Returns conflict error if both flags are set.

Signed-off-by: Qi Wang <qiwan@redhat.com>

cmd/podman/create.go

@@ -77,6 +77,10 @@ func createInit(c *cliconfig.PodmanCommand) error {
 		logrus.Warn("setting security options with --privileged has no effect")
 	}
 
+	if c.IsSet("dns") && c.IsSet("network") {
+		return errors.Errorf("conflicting options: dns and the network mode.")
+	}
+
 	// Docker-compatibility: the "-h" flag for run/create is reserved for
 	// the hostname (see https://github.com/containers/libpod/issues/1367).
 

test/e2e/run_dns_test.go

@@ -94,4 +94,10 @@ var _ = Describe("Podman run dns", func() {
 		Expect(session.ExitCode()).To(Equal(0))
 		Expect(session.LineInOutputContains("foobar")).To(BeTrue())
 	})
+
+	FIt("podman run mutually excludes --dns and --network", func() {
+		session := podmanTest.Podman([]string{"run", "--dns=1.2.3.4", "--network", "container:ALPINE", ALPINE})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Not(Equal(0)))
+	})
 })