Fix Docker API compatibility with network alias (#17167)

* Add BaseHostsFile to container configuration
* Do not copy /etc/hosts file from host when creating a container using Docker API

Signed-off-by: Gavin Lam <gavin.oss@tutamail.com>

libpod/container_config.go

@@ -291,6 +291,12 @@ 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 string `json:"baseHostsFile,omitempty"`
 	// Hosts to add in container
 	// Will be appended to host's host file
 	HostAdd []string `json:"hostsAdd,omitempty"`

libpod/container_internal_common.go

@@ -2267,7 +2267,14 @@ func (c *Container) addHosts() error {
 	if err != nil {
 		return fmt.Errorf("failed to get container ip host entries: %w", err)
 	}
-	baseHostFile, err := etchosts.GetBaseHostFile(c.runtime.config.Containers.BaseHostsFile, c.state.Mountpoint)
+
+	// Consider container level BaseHostsFile configuration first.
+	// If it is empty, fallback to containers.conf level configuration.
+	baseHostsFileConf := c.config.BaseHostsFile
+	if baseHostsFileConf == "" {
+		baseHostsFileConf = c.runtime.config.Containers.BaseHostsFile
+	}
+	baseHostFile, err := etchosts.GetBaseHostFile(baseHostsFileConf, c.state.Mountpoint)
 	if err != nil {
 		return err
 	}

libpod/options.go

@@ -2373,6 +2373,19 @@ func WithGroupEntry(groupEntry string) CtrCreateOption {
 	}
 }
 
+// WithBaseHostsFile sets the option to copy /etc/hosts file.
+func WithBaseHostsFile(baseHostsFile string) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+
+		ctr.config.BaseHostsFile = baseHostsFile
+
+		return nil
+	}
+}
+
 // WithMountAllDevices sets the option to mount all of a privileged container's
 // host devices
 func WithMountAllDevices() CtrCreateOption {