Merge pull request containers#2747 from mheon/dns_none

Add --dns=none

cmd/podman/common.go

@@ -388,6 +388,10 @@ func getCreateFlags(c *cliconfig.PodmanCommand) {
 		"network", getDefaultNetwork(),
 		"Connect a container to a network",
 	)
+	createFlags.Bool(
+		"no-hosts", false,
+		"Do not create /etc/hosts within the container, instead use the version from the image",
+	)
 	createFlags.Bool(
 		"oom-kill-disable", false,
 		"Disable OOM Killer",

cmd/podman/shared/create.go

@@ -357,6 +357,10 @@ func ParseCreateOpts(ctx context.Context, c *cliconfig.PodmanCommand, runtime *l
 		return nil, errors.Errorf("--cpu-quota and --cpus cannot be set together")
 	}
 
+	if c.Bool("no-hosts") && c.Flag("add-host").Changed {
+		return nil, errors.Errorf("--no-hosts and --add-host cannot be set together")
+	}
+
 	// EXPOSED PORTS
 	var portBindings map[nat.Port][]nat.PortBinding
 	if data != nil {
@@ -646,6 +650,7 @@ func ParseCreateOpts(ctx context.Context, c *cliconfig.PodmanCommand, runtime *l
 		GroupAdd:    c.StringSlice("group-add"),
 		Hostname:    c.String("hostname"),
 		HostAdd:     c.StringSlice("add-host"),
+		NoHosts:     c.Bool("no-hosts"),
 		IDMappings:  idmappings,
 		Image:       imageName,
 		ImageID:     imageID,

completions/bash/podman

@@ -1727,6 +1727,7 @@ _podman_container_run() {
 		--memory-reservation
 		--name
 		--network
+		--no-hosts
 		--oom-score-adj
 		--pid
 		--pids-limit

docs/podman-create.1.md

@@ -204,6 +204,9 @@ configuration passed to the container. Typically this is necessary when the
 host DNS configuration is invalid for the container (e.g., 127.0.0.1). When this
 is the case the **--dns** flags is necessary for every run.
 
+The special value **none** can be specified to disable creation of **/etc/resolv.conf** in the container by Podman.
+The **/etc/resolv.conf** file in the image will be used without changes.
+
 **--dns-option**=[]
 
 Set custom DNS options
@@ -457,6 +460,13 @@ Set the Network mode for the container
 
 Not implemented
 
+**--no-hosts**=*true*|*false*
+
+Do not create /etc/hosts for the container.
+By default, Podman will manage /etc/hosts, adding the container's own IP address and any hosts from **--add-host**.
+**--no-hosts** disables this, and the image's **/etc/host** will be preserved unmodified.
+This option conflicts with **--add-host**.
+
 **--oom-kill-disable**=*true*|*false*
 
 Whether to disable OOM Killer for the container or not.

docs/podman-run.1.md

@@ -210,6 +210,9 @@ configuration passed to the container. Typically this is necessary when the
 host DNS configuration is invalid for the container (e.g., 127.0.0.1). When this
 is the case the **--dns** flags is necessary for every run.
 
+The special value **none** can be specified to disable creation of **/etc/resolv.conf** in the container by Podman.
+The **/etc/resolv.conf** file in the image will be used without changes.
+
 **--dns-option**=[]
 
 Set custom DNS options
@@ -441,6 +444,13 @@ Set the Network mode for the container:
 
 Not implemented
 
+**--no-hosts**=*true*|*false*
+
+Do not create /etc/hosts for the container.
+By default, Podman will manage /etc/hosts, adding the container's own IP address and any hosts from **--add-host**.
+**--no-hosts** disables this, and the image's **/etc/host** will be preserved unmodified.
+This option conflicts with **--add-host**.
+
 **--oom-kill-disable**=*true*|*false*
 
 Whether to disable OOM Killer for the container or not.

libpod/container.go

@@ -293,6 +293,10 @@ type ContainerConfig struct {
 	// namespace
 	// These are not used unless CreateNetNS is true
 	PortMappings []ocicni.PortMapping `json:"portMappings,omitempty"`
+	// UseImageResolvConf indicates that resolv.conf should not be
+	// bind-mounted inside the container.
+	// Conflicts with DNSServer, DNSSearch, DNSOption.
+	UseImageResolvConf bool
 	// DNS servers to use in container resolv.conf
 	// Will override servers in host resolv if set
 	DNSServer []net.IP `json:"dnsServer,omitempty"`
@@ -302,6 +306,10 @@ type ContainerConfig struct {
 	// DNS options to be set in container resolv.conf
 	// With override options in host resolv if set
 	DNSOption []string `json:"dnsOption,omitempty"`
+	// UseImageHosts indicates that /etc/hosts should not be
+	// bind-mounted inside the container.
+	// Conflicts with HostAdd.
+	UseImageHosts bool
 	// Hosts to add in container
 	// Will be appended to host's host file
 	HostAdd []string `json:"hostsAdd,omitempty"`

libpod/container_internal_linux.go

@@ -703,10 +703,11 @@ func (c *Container) makeBindMounts() error {
 			}
 		}
 
-		if c.config.NetNsCtr != "" {
-			// We share a net namespace
+		if c.config.NetNsCtr != "" && (!c.config.UseImageResolvConf || !c.config.UseImageHosts) {
+			// We share a net namespace.
 			// We want /etc/resolv.conf and /etc/hosts from the
-			// other container
+			// other container. Unless we're not creating both of
+			// them.
 			depCtr, err := c.runtime.state.Container(c.config.NetNsCtr)
 			if err != nil {
 				return errors.Wrapf(err, "error fetching dependency %s of container %s", c.config.NetNsCtr, c.ID())
@@ -718,53 +719,65 @@ func (c *Container) makeBindMounts() error {
 				return errors.Wrapf(err, "error fetching bind mounts from dependency %s of container %s", depCtr.ID(), c.ID())
 			}
 
-			// The other container may not have a resolv.conf or /etc/hosts
-			// If it doesn't, don't copy them
-			resolvPath, exists := bindMounts["/etc/resolv.conf"]
-			if exists {
-				c.state.BindMounts["/etc/resolv.conf"] = resolvPath
+			if !c.config.UseImageResolvConf {
+				// The other container may not have a resolv.conf or /etc/hosts
+				// If it doesn't, don't copy them
+				resolvPath, exists := bindMounts["/etc/resolv.conf"]
+				if exists {
+					c.state.BindMounts["/etc/resolv.conf"] = resolvPath
+				}
 			}
 
-			// check if dependency container has an /etc/hosts file
-			hostsPath, exists := bindMounts["/etc/hosts"]
-			if !exists {
-				return errors.Errorf("error finding hosts file of dependency container %s for container %s", depCtr.ID(), c.ID())
-			}
+			if !c.config.UseImageHosts {
+				// check if dependency container has an /etc/hosts file
+				hostsPath, exists := bindMounts["/etc/hosts"]
+				if !exists {
+					return errors.Errorf("error finding hosts file of dependency container %s for container %s", depCtr.ID(), c.ID())
+				}
 
-			depCtr.lock.Lock()
-			// generate a hosts file for the dependency container,
-			// based on either its old hosts file, or the default,
-			// and add the relevant information from the new container (hosts and IP)
-			hostsPath, err = depCtr.appendHosts(hostsPath, c)
+				depCtr.lock.Lock()
+				// generate a hosts file for the dependency container,
+				// based on either its old hosts file, or the default,
+				// and add the relevant information from the new container (hosts and IP)
+				hostsPath, err = depCtr.appendHosts(hostsPath, c)
 
-			if err != nil {
+				if err != nil {
+					depCtr.lock.Unlock()
+					return errors.Wrapf(err, "error creating hosts file for container %s which depends on container %s", c.ID(), depCtr.ID())
+				}
 				depCtr.lock.Unlock()
-				return errors.Wrapf(err, "error creating hosts file for container %s which depends on container %s", c.ID(), depCtr.ID())
-			}
-			depCtr.lock.Unlock()
 
-			// finally, save it in the new container
-			c.state.BindMounts["/etc/hosts"] = hostsPath
+				// finally, save it in the new container
+				c.state.BindMounts["/etc/hosts"] = hostsPath
+			}
 		} else {
-			newResolv, err := c.generateResolvConf()
-			if err != nil {
-				return errors.Wrapf(err, "error creating resolv.conf for container %s", c.ID())
+			if !c.config.UseImageResolvConf {
+				newResolv, err := c.generateResolvConf()
+				if err != nil {
+					return errors.Wrapf(err, "error creating resolv.conf for container %s", c.ID())
+				}
+				c.state.BindMounts["/etc/resolv.conf"] = newResolv
 			}
-			c.state.BindMounts["/etc/resolv.conf"] = newResolv
 
-			newHosts, err := c.generateHosts("/etc/hosts")
-			if err != nil {
-				return errors.Wrapf(err, "error creating hosts file for container %s", c.ID())
+			if !c.config.UseImageHosts {
+				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
 			}
-			c.state.BindMounts["/etc/hosts"] = newHosts
 		}
 
-		if err := label.Relabel(c.state.BindMounts["/etc/hosts"], c.config.MountLabel, true); err != nil {
-			return err
+		if c.state.BindMounts["/etc/hosts"] != "" {
+			if err := label.Relabel(c.state.BindMounts["/etc/hosts"], c.config.MountLabel, true); err != nil {
+				return err
+			}
 		}
 
-		if err := label.Relabel(c.state.BindMounts["/etc/resolv.conf"], c.config.MountLabel, true); err != nil {
-			return err
+		if c.state.BindMounts["/etc/resolv.conf"] != "" {
+			if err := label.Relabel(c.state.BindMounts["/etc/resolv.conf"], c.config.MountLabel, true); err != nil {
+				return err
+			}
 		}
 	}
 

libpod/options.go

@@ -997,6 +997,9 @@ func WithDNSSearch(searchDomains []string) CtrCreateOption {
 		if ctr.valid {
 			return ErrCtrFinalized
 		}
+		if ctr.config.UseImageResolvConf {
+			return errors.Wrapf(ErrInvalidArg, "cannot add DNS search domains if container will not create /etc/resolv.conf")
+		}
 		ctr.config.DNSSearch = searchDomains
 		return nil
 	}
@@ -1008,6 +1011,9 @@ func WithDNS(dnsServers []string) CtrCreateOption {
 		if ctr.valid {
 			return ErrCtrFinalized
 		}
+		if ctr.config.UseImageResolvConf {
+			return errors.Wrapf(ErrInvalidArg, "cannot add DNS servers if container will not create /etc/resolv.conf")
+		}
 		var dns []net.IP
 		for _, i := range dnsServers {
 			result := net.ParseIP(i)
@@ -1027,6 +1033,9 @@ func WithDNSOption(dnsOptions []string) CtrCreateOption {
 		if ctr.valid {
 			return ErrCtrFinalized
 		}
+		if ctr.config.UseImageResolvConf {
+			return errors.Wrapf(ErrInvalidArg, "cannot add DNS options if container will not create /etc/resolv.conf")
+		}
 		ctr.config.DNSOption = dnsOptions
 		return nil
 	}
@@ -1038,6 +1047,11 @@ func WithHosts(hosts []string) CtrCreateOption {
 		if ctr.valid {
 			return ErrCtrFinalized
 		}
+
+		if ctr.config.UseImageHosts {
+			return errors.Wrapf(ErrInvalidArg, "cannot add hosts if container will not create /etc/hosts")
+		}
+
 		ctr.config.HostAdd = hosts
 		return nil
 	}
@@ -1184,6 +1198,44 @@ func WithCtrNamespace(ns string) CtrCreateOption {
 	}
 }
 
+// WithUseImageResolvConf tells the container not to bind-mount resolv.conf in.
+// This conflicts with other DNS-related options.
+func WithUseImageResolvConf() CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return ErrCtrFinalized
+		}
+
+		if len(ctr.config.DNSServer) != 0 ||
+			len(ctr.config.DNSSearch) != 0 ||
+			len(ctr.config.DNSOption) != 0 {
+			return errors.Wrapf(ErrInvalidArg, "not creating resolv.conf conflicts with DNS options")
+		}
+
+		ctr.config.UseImageResolvConf = true
+
+		return nil
+	}
+}
+
+// WithUseImageHosts tells the container not to bind-mount /etc/hosts in.
+// This conflicts with WithHosts().
+func WithUseImageHosts() CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return ErrCtrFinalized
+		}
+
+		if len(ctr.config.HostAdd) != 0 {
+			return errors.Wrapf(ErrInvalidArg, "not creating /etc/hosts conflicts with adding to the hosts file")
+		}
+
+		ctr.config.UseImageHosts = true
+
+		return nil
+	}
+}
+
 // withIsInfra sets the container to be an infra container. This means the container will be sometimes hidden
 // and expected to be the first container in the pod.
 func withIsInfra() CtrCreateOption {

pkg/spec/createconfig.go

@@ -88,6 +88,7 @@ type CreateConfig struct {
 	ExposedPorts       map[nat.Port]struct{}
 	GroupAdd           []string // group-add
 	HealthCheck        *manifest.Schema2HealthConfig
+	NoHosts            bool
 	HostAdd            []string //add-host
 	Hostname           string   //hostname
 	Image              string
@@ -505,12 +506,19 @@ func (c *CreateConfig) GetContainerCreateOptions(runtime *libpod.Runtime, pod *l
 		options = append(options, libpod.WithDNSSearch(c.DNSSearch))
 	}
 	if len(c.DNSServers) > 0 {
-		options = append(options, libpod.WithDNS(c.DNSServers))
+		if len(c.DNSServers) == 1 && strings.ToLower(c.DNSServers[0]) == "none" {
+			options = append(options, libpod.WithUseImageResolvConf())
+		} else {
+			options = append(options, libpod.WithDNS(c.DNSServers))
+		}
 	}
 	if len(c.DNSOpt) > 0 {
 		options = append(options, libpod.WithDNSOption(c.DNSOpt))
 	}
-	if len(c.HostAdd) > 0 {
+	if c.NoHosts {
+		options = append(options, libpod.WithUseImageHosts())
+	}
+	if len(c.HostAdd) > 0 && !c.NoHosts {
 		options = append(options, libpod.WithHosts(c.HostAdd))
 	}
 	logPath := getLoggingPath(c.LogDriverOpt)

test/e2e/run_test.go

@@ -749,13 +749,19 @@ USER mail`
 
 	It("podman run with bad healthcheck timeout", func() {
 		session := podmanTest.Podman([]string{"run", "-dt", "--healthcheck-cmd", "foo", "--healthcheck-timeout", "0s", ALPINE, "top"})
-		session.Wait()
+		session.WaitWithDefaultTimeout()
 		Expect(session.ExitCode()).ToNot(Equal(0))
 	})
 
 	It("podman run with bad healthcheck start-period", func() {
 		session := podmanTest.Podman([]string{"run", "-dt", "--healthcheck-cmd", "foo", "--healthcheck-start-period", "-1s", ALPINE, "top"})
-		session.Wait()
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).ToNot(Equal(0))
+	})
+
+	It("podman run with --add-host and --no-hosts fails", func() {
+		session := podmanTest.Podman([]string{"run", "-dt", "--add-host", "test1:127.0.0.1", "--no-hosts", ALPINE, "top"})
+		session.WaitWithDefaultTimeout()
 		Expect(session.ExitCode()).ToNot(Equal(0))
 	})
 })