Introduce Sandbox entity

- Maps 1 to 1 with container's networking stack
- It holds container's specific nw options which
  before were incorrectly owned by Endpoint.
- Sandbox creation no longer coupled with Endpoint Join,
  sandbox and endpoint have now separate lifecycle.
- LeaveAll naturally replaced by Sandbox.Delete
- some pkg and file renaming in order to have clear
  mapping between structure name and entity ("sandbox")
- Revisited hosts and resolv.conf handling
- Removed from JoinInfo interface capability of setting hosts and resolv.conf paths
- Changed etchosts.Build() to first write the search domains and then the nameservers

Signed-off-by: Alessandro Boch <aboch@docker.com>

libnetwork/resolvconf/resolvconf.go

@@ -168,20 +168,25 @@ func GetSearchDomains(resolvConf []byte) []string {
 // Build writes a configuration file to path containing a "nameserver" entry
 // for every element in dns, and a "search" entry for every element in
 // dnsSearch.
-func Build(path string, dns, dnsSearch []string) error {
+func Build(path string, dns, dnsSearch []string) (string, error) {
 	content := bytes.NewBuffer(nil)
-	for _, dns := range dns {
-		if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil {
-			return err
-		}
-	}
 	if len(dnsSearch) > 0 {
 		if searchString := strings.Join(dnsSearch, " "); strings.Trim(searchString, " ") != "." {
 			if _, err := content.WriteString("search " + searchString + "\n"); err != nil {
-				return err
+				return "", err
 			}
 		}
 	}
+	for _, dns := range dns {
+		if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil {
+			return "", err
+		}
+	}
 
-	return ioutil.WriteFile(path, content.Bytes(), 0644)
+	hash, err := ioutils.HashData(bytes.NewReader(content.Bytes()))
+	if err != nil {
+		return "", err
+	}
+
+	return hash, ioutil.WriteFile(path, content.Bytes(), 0644)
 }

libnetwork/resolvconf/resolvconf_test.go

@@ -119,7 +119,7 @@ func TestBuild(t *testing.T) {
 	}
 	defer os.Remove(file.Name())
 
-	err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"})
+	_, err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -129,7 +129,7 @@ func TestBuild(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if expected := "nameserver ns1\nnameserver ns2\nnameserver ns3\nsearch search1\n"; !bytes.Contains(content, []byte(expected)) {
+	if expected := "search search1\nnameserver ns1\nnameserver ns2\nnameserver ns3\n"; !bytes.Contains(content, []byte(expected)) {
 		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
 	}
 }
@@ -141,7 +141,7 @@ func TestBuildWithZeroLengthDomainSearch(t *testing.T) {
 	}
 	defer os.Remove(file.Name())
 
-	err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"."})
+	_, err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"."})
 	if err != nil {
 		t.Fatal(err)
 	}