Refactor saving OCI spec to disk into separate function

It will be needed for restarting containers

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #462
Approved by: baude

libpod/container.go

@@ -94,8 +94,6 @@ func (ns LinuxNS) String() string {
 type Container struct {
 	config *ContainerConfig
 
-	runningSpec *spec.Spec
-
 	state *containerState
 
 	// Locked indicates that a container has been locked as part of a

libpod/container_api.go

@@ -1,11 +1,9 @@
 package libpod
 
 import (
-	"encoding/json"
 	"io/ioutil"
 	"os"
 	gosignal "os/signal"
-	"path/filepath"
 	"strconv"
 	"time"
 
@@ -63,22 +61,6 @@ func (c *Container) Init() (err error) {
 		}
 	}()
 
-	// If the OCI spec already exists, we need to replace it
-	// Cannot guarantee some things, e.g. network namespaces, have the same
-	// paths
-	jsonPath := filepath.Join(c.bundlePath(), "config.json")
-	if _, err := os.Stat(jsonPath); err != nil {
-		if !os.IsNotExist(err) {
-			return errors.Wrapf(err, "error doing stat on container %s spec", c.ID())
-		}
-		// The spec does not exist, we're fine
-	} else {
-		// The spec exists, need to remove it
-		if err := os.Remove(jsonPath); err != nil {
-			return errors.Wrapf(err, "error replacing runtime spec for container %s", c.ID())
-		}
-	}
-
 	// Copy /etc/resolv.conf to the container's rundir
 	runDirResolv, err := c.generateResolvConf()
 	if err != nil {
@@ -101,20 +83,11 @@ func (c *Container) Init() (err error) {
 	if err != nil {
 		return err
 	}
-	c.runningSpec = spec
 
 	// Save the OCI spec to disk
-	fileJSON, err := json.Marshal(c.runningSpec)
+	if err := c.saveSpec(spec); err != nil {
-	if err != nil {
+		return err
-		return errors.Wrapf(err, "error exporting runtime spec for container %s to JSON", c.ID())
 	}
-	if err := ioutil.WriteFile(jsonPath, fileJSON, 0644); err != nil {
-		return errors.Wrapf(err, "error writing runtime spec JSON to file for container %s", c.ID())
-	}
-
-	logrus.Debugf("Created OCI spec for container %s at %s", c.ID(), jsonPath)
-
-	c.state.ConfigPath = jsonPath
 
 	// With the spec complete, do an OCI create
 	if err := c.runtime.ociRuntime.createContainer(c, c.config.CgroupParent); err != nil {

libpod/container_internal.go

@@ -1,6 +1,7 @@
 package libpod
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -730,3 +731,36 @@ func (c *Container) addImageVolumes(g *generate.Generator) error {
 	}
 	return nil
 }
+
+// Save OCI spec to disk, replacing any existing specs for the container
+func (c *Container) saveSpec(spec *spec.Spec) error {
+	// If the OCI spec already exists, we need to replace it
+	// Cannot guarantee some things, e.g. network namespaces, have the same
+	// paths
+	jsonPath := filepath.Join(c.bundlePath(), "config.json")
+	if _, err := os.Stat(jsonPath); err != nil {
+		if !os.IsNotExist(err) {
+			return errors.Wrapf(err, "error doing stat on container %s spec", c.ID())
+		}
+		// The spec does not exist, we're fine
+	} else {
+		// The spec exists, need to remove it
+		if err := os.Remove(jsonPath); err != nil {
+			return errors.Wrapf(err, "error replacing runtime spec for container %s", c.ID())
+		}
+	}
+
+	fileJSON, err := json.Marshal(spec)
+	if err != nil {
+		return errors.Wrapf(err, "error exporting runtime spec for container %s to JSON", c.ID())
+	}
+	if err := ioutil.WriteFile(jsonPath, fileJSON, 0644); err != nil {
+		return errors.Wrapf(err, "error writing runtime spec JSON for container %s to disk", c.ID())
+	}
+
+	logrus.Debugf("Created OCI spec for container %s at %s", c.ID(), jsonPath)
+
+	c.state.ConfigPath = jsonPath
+
+	return nil
+}