From 1b288a35ba931c0b524af550749a7c1fd48b452f Mon Sep 17 00:00:00 2001 From: Matthew Heon Date: Mon, 19 Oct 2020 15:25:06 -0400 Subject: [PATCH] Ensure that hostname is added to hosts with net=host When a container uses --net=host the default hostname is set to the host's hostname. However, we were not creating any entries in `/etc/hosts` despite having a hostname, which is incorrect. This hostname, for Docker compat, will always be the hostname of the host system, not the container, and will be assigned to IP 127.0.1.1 (not the standard localhost address). Also, when `--hostname` and `--net=host` are both passed, still use the hostname from `--hostname`, not the host's hostname (we still use the host's hostname by default in this case if the `--hostname` flag is not passed). Fixes #8054 Signed-off-by: Matthew Heon --- libpod/container_internal_linux.go | 28 ++++++++++++++++++++++++---- pkg/specgen/generate/namespaces.go | 2 +- test/e2e/run_networking_test.go | 15 +++++++++++++++ 3 files changed, 40 insertions(+), 5 deletions(-) diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go index eff390e46d..ffb2f5b73c 100644 --- a/libpod/container_internal_linux.go +++ b/libpod/container_internal_linux.go @@ -1541,11 +1541,31 @@ func (c *Container) getHosts() string { } } - if c.config.NetMode.IsSlirp4netns() { - // When using slirp4netns, the interface gets a static IP - hosts += fmt.Sprintf("# used by slirp4netns\n%s\t%s %s\n", "10.0.2.100", c.Hostname(), c.Config().Name) - } hosts += c.cniHosts() + + // If not making a network namespace, add our own hostname. + if c.Hostname() != "" { + if c.config.NetMode.IsSlirp4netns() { + // When using slirp4netns, the interface gets a static IP + hosts += fmt.Sprintf("# used by slirp4netns\n%s\t%s %s\n", "10.0.2.100", c.Hostname(), c.config.Name) + } else { + hasNetNS := false + for _, ns := range c.config.Spec.Linux.Namespaces { + if ns.Type == spec.NetworkNamespace { + hasNetNS = true + break + } + } + 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) + } + } + } return hosts } diff --git a/pkg/specgen/generate/namespaces.go b/pkg/specgen/generate/namespaces.go index 7adb8be6ab..7e4f09dc4c 100644 --- a/pkg/specgen/generate/namespaces.go +++ b/pkg/specgen/generate/namespaces.go @@ -342,7 +342,7 @@ func specConfigureNamespaces(s *specgen.SpecGenerator, g *generate.Generator, rt return errors.Wrapf(err, "error looking up container to share uts namespace with") } hostname = utsCtr.Hostname() - case s.NetNS.NSMode == specgen.Host || s.UtsNS.NSMode == specgen.Host: + case (s.NetNS.NSMode == specgen.Host && hostname == "") || s.UtsNS.NSMode == specgen.Host: tmpHostname, err := os.Hostname() if err != nil { return errors.Wrap(err, "unable to retrieve hostname of the host") diff --git a/test/e2e/run_networking_test.go b/test/e2e/run_networking_test.go index e14482db79..540ac5409c 100644 --- a/test/e2e/run_networking_test.go +++ b/test/e2e/run_networking_test.go @@ -571,4 +571,19 @@ var _ = Describe("Podman run networking", func() { podrm.WaitWithDefaultTimeout() Expect(podrm.ExitCode()).To(BeZero()) }) + + It("podman run net=host adds entry to /etc/hosts", func() { + run := podmanTest.Podman([]string{"run", "--net=host", ALPINE, "cat", "/etc/hosts"}) + run.WaitWithDefaultTimeout() + Expect(run.ExitCode()).To(BeZero()) + Expect(strings.Contains(run.OutputToString(), "127.0.1.1")).To(BeTrue()) + }) + + It("podman run with --net=host and --hostname sets correct hostname", func() { + hostname := "testctr" + run := podmanTest.Podman([]string{"run", "--net=host", "--hostname", hostname, ALPINE, "hostname"}) + run.WaitWithDefaultTimeout() + Expect(run.ExitCode()).To(BeZero()) + Expect(strings.Contains(run.OutputToString(), "testctr")).To(BeTrue()) + }) })