Add --hosts-file flag

* Add --hosts-file flag to container create, container run, and pod create * Add tests for base_hosts_file in containers.conf Signed-off-by: Gavin Lam <[email protected]>
containers · Nov 12, 2024 · 451a94e · 451a94e
1 parent 483a132
commit 451a94e
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diff --git a/cmd/podman/common/completion.go b/cmd/podman/common/completion.go
@@ -716,6 +716,13 @@ func AutocompleteNetworks(cmd *cobra.Command, args []string, toComplete string)
 	return getNetworks(cmd, toComplete, completeDefault)
 }
 
+// AutocompleteHostsFile - Autocomplete hosts file options.
+// -> "image", "none", paths
+func AutocompleteHostsFile(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	hostsFileModes := []string{"image", "none"}
+	return hostsFileModes, cobra.ShellCompDirectiveDefault
+}
+
 // AutocompleteDefaultOneArg - Autocomplete path only for the first argument.
 func AutocompleteDefaultOneArg(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 	if len(args) == 0 {

diff --git a/cmd/podman/common/netflags.go b/cmd/podman/common/netflags.go
@@ -26,6 +26,13 @@ func DefineNetFlags(cmd *cobra.Command) {
 	)
 	_ = cmd.RegisterFlagCompletionFunc(addHostFlagName, completion.AutocompleteNone)
 
+	hostsFileFlagName := "hosts-file"
+	netFlags.String(
+		hostsFileFlagName, "",
+		`Path to a hosts file to copy the entries into the container, or one of the special values. ("image"|"none")`,
+	)
+	_ = cmd.RegisterFlagCompletionFunc(hostsFileFlagName, AutocompleteHostsFile)
+
 	dnsFlagName := "dns"
 	netFlags.StringSlice(
 		dnsFlagName, podmanConfig.ContainersConf.DNSServers(),

diff --git a/cmd/podman/containers/create.go b/cmd/podman/containers/create.go
@@ -313,6 +313,9 @@ func CreateInit(c *cobra.Command, vals entities.ContainerCreateOptions, isInfra
 	if c.Flag("shm-size-systemd").Changed {
 		vals.ShmSizeSystemd = c.Flag("shm-size-systemd").Value.String()
 	}
+	if c.Flag("hosts-file").Changed {
+		vals.HostsFile = c.Flag("hosts-file").Value.String()
+	}
 	if (c.Flag("dns").Changed || c.Flag("dns-option").Changed || c.Flag("dns-search").Changed) && vals.Net != nil && (vals.Net.Network.NSMode == specgen.NoNetwork || vals.Net.Network.IsContainer()) {
 		return vals, errors.New("conflicting options: dns and the network mode: " + string(vals.Net.Network.NSMode))
 	}

diff --git a/docs/source/markdown/options/hosts-file.md b/docs/source/markdown/options/hosts-file.md
@@ -0,0 +1,12 @@
+####> This option file is used in:
+####>   podman create, pod create, run
+####> If file is edited, make sure the changes
+####> are applicable to all of those.
+#### **--hosts-file**=*path* | *none* | *image*
+
+Base file to create the `/etc/hosts` file inside the container. This must either
+be an absolute path to a file on the host system, or one of the following
+special flags:
+  ""      Follow the `base_hosts_file` configuration in _containers.conf_ (the default)
+  `none`  Do not use a base file (i.e. start with an empty file)
+  `image` Use the container image's `/etc/hosts` file as base file
diff --git a/docs/source/markdown/podman-create.1.md.in b/docs/source/markdown/podman-create.1.md.in
@@ -199,6 +199,8 @@ Print usage statement
 
 @@option hostname.container
 
+@@option hosts-file
+
 @@option hostuser
 
 @@option http-proxy

diff --git a/docs/source/markdown/podman-pod-create.1.md.in b/docs/source/markdown/podman-pod-create.1.md.in
@@ -88,6 +88,8 @@ Print usage statement.
 
 @@option hostname.pod
 
+@@option hosts-file
+
 #### **--infra**
 
 Create an infra container and associate it with the pod. An infra container is a lightweight container used to coordinate the shared kernel namespace of a pod. Default: true.

diff --git a/docs/source/markdown/podman-run.1.md.in b/docs/source/markdown/podman-run.1.md.in
@@ -233,6 +233,8 @@ Print usage statement
 
 @@option hostname.container
 
+@@option hosts-file
+
 @@option hostuser
 
 @@option http-proxy

diff --git a/pkg/domain/entities/pods.go b/pkg/domain/entities/pods.go
@@ -178,6 +178,7 @@ type ContainerCreateOptions struct {
 	HealthTimeout        string
 	HealthOnFailure      string
 	Hostname             string `json:"hostname,omitempty"`
+	HostsFile            string
 	HTTPProxy            bool
 	HostUsers            []string
 	ImageVolume          string

diff --git a/pkg/specgenutil/specgen.go b/pkg/specgenutil/specgen.go
@@ -642,6 +642,11 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *entities.ContainerCreateOptions
 	if len(s.Hostname) == 0 || len(c.Hostname) != 0 {
 		s.Hostname = c.Hostname
 	}
+
+	if len(s.BaseHostsFile) == 0 || len(c.HostsFile) != 0 {
+		s.BaseHostsFile = c.HostsFile
+	}
+
 	sysctl := map[string]string{}
 	if ctl := c.Sysctl; len(ctl) > 0 {
 		sysctl, err = util.ValidateSysctls(ctl)

diff --git a/test/e2e/containers_conf_test.go b/test/e2e/containers_conf_test.go
@@ -463,6 +463,60 @@ var _ = Describe("Verify podman containers.conf usage", func() {
 		Expect(session.OutputToString()).To(ContainSubstring("test"))
 	})
 
+	Describe("base_hosts_file in containers.conf", func() {
+		var baseHostsFile string
+		var session *PodmanSessionIntegration
+
+		JustBeforeEach(func() {
+			confFile := filepath.Join(podmanTest.TempDir, "containers.conf")
+			err = os.WriteFile(confFile, []byte(fmt.Sprintf("[containers]\nbase_hosts_file=\"%s\"\nno_hosts=false\n", baseHostsFile)), 0755)
+			Expect(err).ToNot(HaveOccurred())
+			os.Setenv("CONTAINERS_CONF_OVERRIDE", confFile)
+			if IsRemote() {
+				podmanTest.RestartRemoteService()
+			}
+
+			session = podmanTest.Podman([]string{"run", "--rm", ALPINE, "cat", "/etc/hosts"})
+			session.WaitWithDefaultTimeout()
+			Expect(session).Should(ExitCleanly())
+		})
+
+		Describe("base_hosts_file=/path/to/hosts", func() {
+			BeforeEach(func() {
+				hostsFile := filepath.Join(podmanTest.TempDir, "hosts")
+				err := os.WriteFile(hostsFile, []byte("12.34.56.78 test.example.com"), 0755)
+				Expect(err).ToNot(HaveOccurred())
+
+				baseHostsFile = hostsFile
+			})
+
+			It("should use the hosts file from the file path", func() {
+				Expect(session.OutputToString()).To(ContainSubstring("12.34.56.78 test.example.com"))
+			})
+		})
+
+		Describe("base_hosts_file=image", func() {
+			BeforeEach(func() {
+				baseHostsFile = "image"
+			})
+
+			It("should use the hosts file from the container image", func() {
+				Expect(session.OutputToString()).To(ContainSubstring("localhost localhost.localdomain"))
+			})
+		})
+
+		Describe("base_hosts_file=none", func() {
+			BeforeEach(func() {
+				baseHostsFile = "none"
+			})
+
+			It("should not use any hosts files", func() {
+				Expect(session.OutputToString()).ToNot(ContainSubstring("localhost.localdomain"))
+				Expect(session.OutputToString()).To(ContainSubstring("localhost"))
+			})
+		})
+	})
+
 	It("seccomp profile path", func() {
 		configPath := filepath.Join(podmanTest.TempDir, "containers.conf")
 		os.Setenv("CONTAINERS_CONF", configPath)

diff --git a/test/e2e/pod_create_test.go b/test/e2e/pod_create_test.go
@@ -149,6 +149,34 @@ var _ = Describe("Podman pod create", func() {
 		Expect(podCreate).Should(ExitWithError(125, "NoInfra and HostAdd are mutually exclusive pod options: invalid pod spec"))
 	})
 
+	It("podman create pod with --hosts-file", func() {
+		// This test only work locally
+		if IsRemote() {
+			GinkgoWriter.Println("Bypassing subsequent tests due to remote environment")
+			return
+		}
+
+		confFile := filepath.Join(podmanTest.TempDir, "containers.conf")
+		err := os.WriteFile(confFile, []byte("[containers]\nbase_hosts_file=\"none\"\n"), 0755)
+		Expect(err).ToNot(HaveOccurred())
+		os.Setenv("CONTAINERS_CONF", confFile)
+
+		hostsFile := filepath.Join(podmanTest.TempDir, "hosts")
+		err = os.WriteFile(hostsFile, []byte("12.34.56.78 test.example.com"), 0755)
+		Expect(err).ToNot(HaveOccurred())
+
+		// Create flag should override containers.conf
+		name := "test"
+		podCreate := podmanTest.Podman([]string{"pod", "create", "--hosts-file=" + hostsFile, "--name", name})
+		podCreate.WaitWithDefaultTimeout()
+		Expect(podCreate).Should(ExitCleanly())
+
+		session := podmanTest.Podman([]string{"run", "--pod", name, "--rm", ALPINE, "cat", "/etc/hosts"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(ExitCleanly())
+		Expect(session.OutputToString()).To(ContainSubstring("12.34.56.78 test.example.com"))
+	})
+
 	It("podman create pod with DNS server set", func() {
 		name := "test"
 		server := "12.34.56.78"

diff --git a/test/e2e/run_test.go b/test/e2e/run_test.go
@@ -1519,6 +1519,22 @@ VOLUME %s`, ALPINE, volPath, volPath)
 		Expect(session).To(ExitWithError(125, "--no-hosts and --add-host cannot be set together"))
 	})
 
+	It("podman run with --hosts-file", func() {
+		confFile := filepath.Join(podmanTest.TempDir, "containers.conf")
+		err = os.WriteFile(confFile, []byte("[containers]\nbase_hosts_file=\"none\"\n"), 0755)
+		Expect(err).ToNot(HaveOccurred())
+		os.Setenv("CONTAINERS_CONF_OVERRIDE", confFile)
+		if IsRemote() {
+			podmanTest.RestartRemoteService()
+		}
+
+		// Hosts file flag should override base_hosts_file in containers.conf
+		session := podmanTest.Podman([]string{"run", "--rm", "--hosts-file=image", ALPINE, "cat", "/etc/hosts"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(ExitCleanly())
+		Expect(session.OutputToString()).To(ContainSubstring("localhost localhost.localdomain"))
+	})
+
 	It("podman run with restart-policy always restarts containers", func() {
 		testDir := filepath.Join(podmanTest.RunRoot, "restart-test")
 		err := os.MkdirAll(testDir, 0755)