Add --hosts-file flag to container and pod commands

* Add --hosts-file flag to container create, container run and pod create
* Add HostsFile field to pod inspect and container inspect results
* Test BaseHostsFile config in containers.conf

Signed-off-by: Gavin Lam <[email protected]>

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 {

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, "",
+		`Base file to create the /etc/hosts file inside the container, or one of the special values. ("image"|"none")`,
+	)
+	_ = cmd.RegisterFlagCompletionFunc(hostsFileFlagName, AutocompleteHostsFile)
+
 	dnsFlagName := "dns"
 	netFlags.StringSlice(
 		dnsFlagName, podmanConfig.ContainersConf.DNSServers(),
@@ -116,6 +123,13 @@ func NetFlagsToNetOptions(opts *entities.NetOptions, flags pflag.FlagSet) (*enti
 		}
 	}
 
+	if flags.Changed("hosts-file") {
+		opts.HostsFile, err = flags.GetString("hosts-file")
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	if flags.Changed("dns") {
 		servers, err := flags.GetStringSlice("dns")
 		if err != nil {

cmd/podman/containers/create.go

@@ -323,6 +323,9 @@ func CreateInit(c *cobra.Command, vals entities.ContainerCreateOptions, isInfra
 	if noHosts && c.Flag("add-host").Changed {
 		return vals, errors.New("--no-hosts and --add-host cannot be set together")
 	}
+	if noHosts && c.Flag("hosts-file").Changed {
+		return vals, errors.New("--no-hosts and --hosts-file cannot be set together")
+	}
 
 	if !isInfra && c.Flag("entrypoint").Changed {
 		val := c.Flag("entrypoint").Value.String()

cmd/podman/pods/create.go

@@ -265,6 +265,7 @@ func create(cmd *cobra.Command, args []string) error {
 		}
 		podSpec.InfraContainerSpec = specgen.NewSpecGenerator(imageName, false)
 		podSpec.InfraContainerSpec.RawImageName = rawImageName
+		podSpec.InfraContainerSpec.BaseHostsFile = podSpec.PodNetworkConfig.HostsFile
 		podSpec.InfraContainerSpec.NetworkOptions = podSpec.NetworkOptions
 		podSpec.InfraContainerSpec.RestartPolicy = podSpec.RestartPolicy
 		err = specgenutil.FillOutSpecGen(podSpec.InfraContainerSpec, &infraOptions, []string{})

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

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

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.

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

libpod/container_config.go

@@ -290,11 +290,10 @@ type ContainerNetworkConfig struct {
 	// bind-mounted inside the container.
 	// Conflicts with HostAdd.
 	UseImageHosts bool
-	// BaseHostsFile is the path to a hosts file, the entries from this file
-	// are added to the containers hosts file. As special value "image" is
-	// allowed which uses the /etc/hosts file from within the image and "none"
-	// which uses no base file at all. If it is empty we should default
-	// to the base_hosts_file configuration in containers.conf.
+	// BaseHostsFile is the 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
+	// special flags `image` or `none`.
+	// If it is empty it defaults to the base_hosts_file configuration in containers.conf.
 	BaseHostsFile string `json:"baseHostsFile,omitempty"`
 	// Hosts to add in container
 	// Will be appended to host's host file

libpod/container_inspect.go

@@ -543,6 +543,8 @@ func (c *Container) generateInspectContainerHostConfig(ctrSpec *spec.Spec, named
 	hostConfig.GroupAdd = make([]string, 0, len(c.config.Groups))
 	hostConfig.GroupAdd = append(hostConfig.GroupAdd, c.config.Groups...)
 
+	hostConfig.HostsFile = c.config.BaseHostsFile
+
 	if ctrSpec.Process != nil {
 		if ctrSpec.Process.OOMScoreAdj != nil {
 			hostConfig.OomScoreAdj = *ctrSpec.Process.OOMScoreAdj

libpod/define/container_inspect.go

@@ -443,6 +443,8 @@ type InspectContainerHostConfig struct {
 	// ExtraHosts contains hosts that will be added to the container's
 	// /etc/hosts.
 	ExtraHosts []string `json:"ExtraHosts"`
+	// HostsFile is the base file to create the `/etc/hosts` file inside the container.
+	HostsFile string `json:"HostsFile"`
 	// GroupAdd contains groups that the user inside the container will be
 	// added to.
 	GroupAdd []string `json:"GroupAdd"`

libpod/define/pod_inspect.go

@@ -124,6 +124,9 @@ type InspectPodInfraConfig struct {
 	// HostAdd adds a number of hosts to the infra container's resolv.conf
 	// which will be shared with the rest of the pod.
 	HostAdd []string
+	// HostsFile is the base file to create the `/etc/hosts` file inside the infra container
+	// which will be shared with the rest of the pod.
+	HostsFile string
 	// Networks is a list of networks the pod will join.
 	Networks []string
 	// NetworkOptions are additional options for each network

libpod/pod_api.go

@@ -709,6 +709,9 @@ func (p *Pod) Inspect() (*define.InspectPodData, error) {
 			infraConfig.HostAdd = make([]string, 0, len(infra.config.HostAdd))
 			infraConfig.HostAdd = append(infraConfig.HostAdd, infra.config.HostAdd...)
 		}
+		if len(infra.config.BaseHostsFile) > 0 {
+			infraConfig.HostsFile = infra.config.BaseHostsFile
+		}
 
 		networks, err := infra.networks()
 		if err != nil {

pkg/domain/entities/pods.go

@@ -368,6 +368,7 @@ func ToPodSpecGen(s specgen.PodSpecGenerator, p *PodCreateOptions) (*specgen.Pod
 		s.DNSOption = p.Net.DNSOptions
 		s.NoManageHosts = p.Net.NoHosts
 		s.HostAdd = p.Net.AddHosts
+		s.HostsFile = p.Net.HostsFile
 	}
 
 	// Cgroup

pkg/domain/entities/types.go

@@ -55,6 +55,7 @@ type NetOptions struct {
 	DNSOptions         []string                           `json:"dns_option,omitempty"`
 	DNSSearch          []string                           `json:"dns_search,omitempty"`
 	DNSServers         []net.IP                           `json:"dns_server,omitempty"`
+	HostsFile          string                             `json:"hosts_file,omitempty"`
 	Network            specgen.Namespace                  `json:"netns,omitempty"`
 	NoHosts            bool                               `json:"no_manage_hosts,omitempty"`
 	PublishPorts       []types.PortMapping                `json:"portmappings,omitempty"`

pkg/specgen/generate/pod_create.go

@@ -243,6 +243,9 @@ func MapSpec(p *specgen.PodSpecGenerator) (*specgen.SpecGenerator, error) {
 	if len(p.HostAdd) > 0 {
 		spec.HostAdd = p.HostAdd
 	}
+	if len(p.HostsFile) > 0 {
+		spec.BaseHostsFile = p.HostsFile
+	}
 	if len(p.DNSServer) > 0 {
 		var dnsServers []net.IP
 		dnsServers = append(dnsServers, p.DNSServer...)

pkg/specgen/pod_validate.go

@@ -58,6 +58,9 @@ func (p *PodSpecGenerator) Validate() error {
 		if len(p.HostAdd) > 0 {
 			return exclusivePodOptions("NoInfra", "HostAdd")
 		}
+		if len(p.HostsFile) > 0 {
+			return exclusivePodOptions("NoInfra", "HostsFile")
+		}
 		if p.NoManageResolvConf {
 			return exclusivePodOptions("NoInfra", "NoManageResolvConf")
 		}
@@ -79,8 +82,13 @@ func (p *PodSpecGenerator) Validate() error {
 			return exclusivePodOptions("NoManageResolvConf", "DNSOption")
 		}
 	}
-	if p.NoManageHosts && len(p.HostAdd) > 0 {
-		return exclusivePodOptions("NoManageHosts", "HostAdd")
+	if p.NoManageHosts {
+		if len(p.HostAdd) > 0 {
+			return exclusivePodOptions("NoManageHosts", "HostAdd")
+		}
+		if len(p.HostsFile) > 0 {
+			return exclusivePodOptions("NoManageHosts", "HostsFile")
+		}
 	}
 
 	return nil

pkg/specgen/podspecgen.go

@@ -170,6 +170,13 @@ type PodNetworkConfig struct {
 	// Conflicts with NoInfra=true and NoManageHosts.
 	// Optional.
 	HostAdd []string `json:"hostadd,omitempty"`
+	// HostsFile is the base file to create the `/etc/hosts` file inside the infra container.
+	// This must either be an absolute path to a file on the host system, or one of the
+	// special flags `image` or `none`.
+	// If it is empty it defaults to the base_hosts_file configuration in containers.conf.
+	// Conflicts with NoInfra=true and NoManageHosts.
+	// Optional.
+	HostsFile string `json:"hostsFile,omitempty"`
 	// NetworkOptions are additional options for each network
 	// Optional.
 	NetworkOptions map[string][]string `json:"network_options,omitempty"`

pkg/specgen/specgen.go

@@ -539,11 +539,10 @@ type ContainerNetworkConfig struct {
 	// Conflicts with HostAdd.
 	// Optional.
 	UseImageHosts *bool `json:"use_image_hosts,omitempty"`
-	// BaseHostsFile is the path to a hosts file, the entries from this file
-	// are added to the containers hosts file. As special value "image" is
-	// allowed which uses the /etc/hosts file from within the image and "none"
-	// which uses no base file at all. If it is empty we should default
-	// to the base_hosts_file configuration in containers.conf.
+	// BaseHostsFile is the 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
+	// special flags `image` or `none`.
+	// If it is empty it defaults to the base_hosts_file configuration in containers.conf.
 	// Optional.
 	BaseHostsFile string `json:"base_hosts_file,omitempty"`
 	// HostAdd is a set of hosts which will be added to the container's

pkg/specgenutil/specgen.go

@@ -587,6 +587,7 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *entities.ContainerCreateOptions
 
 	if c.Net != nil {
 		s.HostAdd = c.Net.AddHosts
+		s.BaseHostsFile = c.Net.HostsFile
 		s.UseImageResolvConf = &c.Net.UseImageResolvConf
 		s.DNSServers = c.Net.DNSServers
 		s.DNSSearch = c.Net.DNSSearch

test/e2e/common_test.go

@@ -663,14 +663,14 @@ func (p *PodmanTestIntegration) RunLsContainerInPod(name, pod string) (*PodmanSe
 
 // BuildImage uses podman build and buildah to build an image
 // called imageName based on a string dockerfile
-func (p *PodmanTestIntegration) BuildImage(dockerfile, imageName string, layers string) string {
-	return p.buildImage(dockerfile, imageName, layers, "")
+func (p *PodmanTestIntegration) BuildImage(dockerfile, imageName string, layers string, extraOptions ...string) string {
+	return p.buildImage(dockerfile, imageName, layers, "", extraOptions)
 }
 
 // BuildImageWithLabel uses podman build and buildah to build an image
 // called imageName based on a string dockerfile, adds desired label to paramset
-func (p *PodmanTestIntegration) BuildImageWithLabel(dockerfile, imageName string, layers string, label string) string {
-	return p.buildImage(dockerfile, imageName, layers, label)
+func (p *PodmanTestIntegration) BuildImageWithLabel(dockerfile, imageName string, layers string, label string, extraOptions ...string) string {
+	return p.buildImage(dockerfile, imageName, layers, label, extraOptions)
 }
 
 // PodmanPID execs podman and returns its PID
@@ -1299,7 +1299,7 @@ func (s *PodmanSessionIntegration) jq(jqCommand string) (string, error) {
 	return strings.TrimRight(out.String(), "\n"), err
 }
 
-func (p *PodmanTestIntegration) buildImage(dockerfile, imageName string, layers string, label string) string {
+func (p *PodmanTestIntegration) buildImage(dockerfile, imageName string, layers string, label string, extraOptions []string) string {
 	dockerfilePath := filepath.Join(p.TempDir, "Dockerfile-"+stringid.GenerateRandomID())
 	err := os.WriteFile(dockerfilePath, []byte(dockerfile), 0755)
 	Expect(err).ToNot(HaveOccurred())
@@ -1310,6 +1310,9 @@ func (p *PodmanTestIntegration) buildImage(dockerfile, imageName string, layers
 	if len(imageName) > 0 {
 		cmd = append(cmd, []string{"-t", imageName}...)
 	}
+	if len(extraOptions) > 0 {
+		cmd = append(cmd, extraOptions...)
+	}
 	cmd = append(cmd, p.TempDir)
 	session := p.Podman(cmd)
 	session.Wait(240)

test/e2e/containers_conf_test.go

@@ -21,7 +21,9 @@ import (
 var _ = Describe("Verify podman containers.conf usage", func() {
 
 	BeforeEach(func() {
-		os.Setenv("CONTAINERS_CONF", "config/containers.conf")
+		confPath, err := filepath.Abs("config/containers.conf")
+		Expect(err).ToNot(HaveOccurred())
+		os.Setenv("CONTAINERS_CONF", confPath)
 		if IsRemote() {
 			podmanTest.RestartRemoteService()
 		}
@@ -463,6 +465,79 @@ 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()
+			}
+
+			dockerfile := strings.Join([]string{
+				`FROM quay.io/libpod/alpine:latest`,
+				`RUN echo '56.78.12.34 image.example.com' > /etc/hosts`,
+			}, "\n")
+			podmanTest.BuildImage(dockerfile, "foobar.com/hosts_test:latest", "false", "--no-hosts")
+
+			session = podmanTest.Podman([]string{"run", "--name", "hosts_test", "--hostname", "hosts_test.dev", "--rm", "foobar.com/hosts_test:latest", "cat", "/etc/hosts"})
+			session.WaitWithDefaultTimeout()
+			Expect(session).Should(ExitCleanly())
+		})
+
+		Describe("base_hosts_file=path", func() {
+			BeforeEach(func() {
+				hostsPath := filepath.Join(podmanTest.TempDir, "hosts")
+				err := os.WriteFile(hostsPath, []byte("12.34.56.78 file.example.com"), 0755)
+				Expect(err).ToNot(HaveOccurred())
+				baseHostsFile = hostsPath
+			})
+
+			It("should use the hosts file from the file path", func() {
+				Expect(session.OutputToString()).ToNot(ContainSubstring("56.78.12.34 image.example.com"))
+				Expect(session.OutputToString()).To(ContainSubstring("12.34.56.78 file.example.com"))
+				Expect(session.OutputToString()).To(ContainSubstring("127.0.0.1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("::1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("host.containers.internal host.docker.internal"))
+				Expect(session.OutputToString()).To(ContainSubstring("hosts_test.dev hosts_test"))
+			})
+		})
+
+		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("56.78.12.34 image.example.com"))
+				Expect(session.OutputToString()).ToNot(ContainSubstring("12.34.56.78 file.example.com"))
+				Expect(session.OutputToString()).To(ContainSubstring("127.0.0.1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("::1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("host.containers.internal host.docker.internal"))
+				Expect(session.OutputToString()).To(ContainSubstring("hosts_test.dev hosts_test"))
+			})
+		})
+
+		Describe("base_hosts_file=none", func() {
+			BeforeEach(func() {
+				baseHostsFile = "none"
+			})
+
+			It("should not use any hosts files", func() {
+				Expect(session.OutputToString()).ToNot(ContainSubstring("56.78.12.34 image.example.com"))
+				Expect(session.OutputToString()).ToNot(ContainSubstring("12.34.56.78 file.example.com"))
+				Expect(session.OutputToString()).To(ContainSubstring("127.0.0.1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("::1 localhost"))
+				Expect(session.OutputToString()).To(ContainSubstring("host.containers.internal host.docker.internal"))
+				Expect(session.OutputToString()).To(ContainSubstring("hosts_test.dev hosts_test"))
+			})
+		})
+	})
+
 	It("seccomp profile path", func() {
 		configPath := filepath.Join(podmanTest.TempDir, "containers.conf")
 		os.Setenv("CONTAINERS_CONF", configPath)