Make sure /etc/hosts populated correctly with networks

The --hostname and containername should always be added to containers.

Added some tests to make sure you can always ping the hostname and container
name from within the container.

Fixes: https://github.com/containers/podman/issues/8095

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

2 files changed, 49 insertions, 9 deletions

diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index 83d5c20cb..7b21e284b 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -1354,6 +1354,14 @@ func (c *Container) makeBindMounts() error {
 				return err
 			}
 		}
+	} else {
+		if !c.config.UseImageHosts && c.state.BindMounts["/etc/hosts"] == "" {
+			newHosts, err := c.generateHosts("/etc/hosts")
+			if err != nil {
+				return errors.Wrapf(err, "error creating hosts file for container %s", c.ID())
+			}
+			c.state.BindMounts["/etc/hosts"] = newHosts
+		}
 	}
 
 	// SHM is always added when we mount the container
@@ -1614,14 +1622,11 @@ func (c *Container) getHosts() string {
 			}
 			if !hasNetNS {
 				// 127.0.1.1 and host's hostname to match Docker
-				osHostname, err := os.Hostname()
-				if err != nil {
-					osHostname = c.Hostname()
-				}
-				hosts += fmt.Sprintf("127.0.1.1 %s\n", osHostname)
+				osHostname, _ := os.Hostname()
+				hosts += fmt.Sprintf("127.0.1.1 %s %s %s\n", osHostname, c.Hostname(), c.config.Name)
 			}
 			if netNone {
-				hosts += fmt.Sprintf("127.0.1.1 %s\n", c.Hostname())
+				hosts += fmt.Sprintf("127.0.1.1 %s %s\n", c.Hostname(), c.config.Name)
 			}
 		}
 	}
diff --git a/test/e2e/run_networking_test.go b/test/e2e/run_networking_test.go
index e9c1bab21..3e80e953e 100644
--- a/test/e2e/run_networking_test.go
+++ b/test/e2e/run_networking_test.go
@@ -551,6 +551,10 @@ var _ = Describe("Podman run networking", func() {
 		run.WaitWithDefaultTimeout()
 		Expect(run.ExitCode()).To(BeZero())
 		Expect(run.OutputToString()).To(ContainSubstring(ipAddr))
+
+		create = podmanTest.Podman([]string{"network", "rm", netName})
+		create.WaitWithDefaultTimeout()
+		Expect(create.ExitCode()).To(BeZero())
 	})
 
 	It("podman run with new:pod and static-ip", func() {
@@ -588,7 +592,7 @@ var _ = Describe("Podman run networking", func() {
 		Expect(strings.Contains(run.OutputToString(), hostname)).To(BeTrue())
 	})
 
-	It("podman run with --net=none adds hostname to /etc/hosts", func() {
+	It("podman run with --net=none sets hostname", func() {
 		hostname := "testctr"
 		run := podmanTest.Podman([]string{"run", "--net=none", "--hostname", hostname, ALPINE, "hostname"})
 		run.WaitWithDefaultTimeout()
@@ -596,6 +600,37 @@ var _ = Describe("Podman run networking", func() {
 		Expect(strings.Contains(run.OutputToString(), hostname)).To(BeTrue())
 	})
 
+	It("podman run with --net=none adds hostname to /etc/hosts", func() {
+		hostname := "testctr"
+		run := podmanTest.Podman([]string{"run", "--net=none", "--hostname", hostname, ALPINE, "cat", "/etc/hosts"})
+		run.WaitWithDefaultTimeout()
+		Expect(run.ExitCode()).To(BeZero())
+		Expect(strings.Contains(run.OutputToString(), hostname)).To(BeTrue())
+	})
+
+	ping_test := func(netns string) {
+		hostname := "testctr"
+		run := podmanTest.Podman([]string{"run", netns, "--hostname", hostname, ALPINE, "ping", "-c", "1", hostname})
+		run.WaitWithDefaultTimeout()
+		Expect(run.ExitCode()).To(BeZero())
+
+		run = podmanTest.Podman([]string{"run", netns, "--hostname", hostname, "--name", "test", ALPINE, "ping", "-c", "1", "test"})
+		run.WaitWithDefaultTimeout()
+		Expect(run.ExitCode()).To(BeZero())
+	}
+
+	It("podman attempt to ping container name and hostname --net=none", func() {
+		ping_test("--net=none")
+	})
+
+	It("podman attempt to ping container name and hostname --net=host", func() {
+		ping_test("--net=host")
+	})
+
+	It("podman attempt to ping container name and hostname --net=private", func() {
+		ping_test("--net=private")
+	})
+
 	It("podman run check dnsname plugin", func() {
 		pod := "testpod"
 		session := podmanTest.Podman([]string{"pod", "create", "--name", pod})
@@ -621,10 +656,10 @@ var _ = Describe("Podman run networking", func() {
 		session.WaitWithDefaultTimeout()
 		Expect(session.ExitCode()).To(BeZero())
 
-		session = podmanTest.Podman([]string{"run", "--name", "con3", "--pod", pod2, ALPINE, "nslookup", "con3"})
+		session = podmanTest.Podman([]string{"run", "--name", "con3", "--pod", pod2, ALPINE, "nslookup", "con1"})
 		session.WaitWithDefaultTimeout()
 		Expect(session.ExitCode()).To(Equal(1))
-		Expect(session.ErrorToString()).To(ContainSubstring("can't resolve 'con3'"))
+		Expect(session.ErrorToString()).To(ContainSubstring("can't resolve 'con1'"))
 
 		session = podmanTest.Podman([]string{"run", "--name", "con4", "--network", net, ALPINE, "nslookup", pod2})
 		session.WaitWithDefaultTimeout()