Added the /fs/cat/ api

api/fs.go

@@ -139,6 +139,37 @@ func (a *AllocFS) ReadAt(alloc *Allocation, path string, offset int64, limit int
 	return resp.Body, nil, nil
 }
 
+// Cat is used to read contents of a file at the given path in an allocation
+// directory
+func (a *AllocFS) Cat(alloc *Allocation, path string, q *QueryOptions) (io.Reader, *QueryMeta, error) {
+	node, _, err := a.client.Nodes().Info(alloc.NodeID, &QueryOptions{})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if node.HTTPAddr == "" {
+		return nil, nil, fmt.Errorf("http addr of the node where alloc %q is running is not advertised", alloc.ID)
+	}
+	u := &url.URL{
+		Scheme: "http",
+		Host:   node.HTTPAddr,
+		Path:   fmt.Sprintf("/v1/client/fs/cat/%s", alloc.ID),
+	}
+	v := url.Values{}
+	v.Set("path", path)
+	u.RawQuery = v.Encode()
+	req := &http.Request{
+		Method: "GET",
+		URL:    u,
+	}
+	c := http.Client{}
+	resp, err := c.Do(req)
+	if err != nil {
+		return nil, nil, err
+	}
+	return resp.Body, nil, nil
+}
+
 func (a *AllocFS) getErrorMsg(resp *http.Response) error {
 	if errMsg, err := ioutil.ReadAll(resp.Body); err == nil {
 		return fmt.Errorf(string(errMsg))

command/agent/fs_endpoint.go

@@ -27,6 +27,8 @@ func (s *HTTPServer) FsRequest(resp http.ResponseWriter, req *http.Request) (int
 		return s.FileStatRequest(resp, req)
 	case strings.HasPrefix(path, "readat/"):
 		return s.FileReadAtRequest(resp, req)
+	case strings.HasPrefix(path, "cat/"):
+		return s.FileCatRequest(resp, req)
 	default:
 		return nil, CodedError(404, ErrInvalidMethod)
 	}
@@ -94,3 +96,33 @@ func (s *HTTPServer) FileReadAtRequest(resp http.ResponseWriter, req *http.Reque
 	io.Copy(resp, r)
 	return nil, nil
 }
+
+func (s *HTTPServer) FileCatRequest(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	var allocID, path string
+	var err error
+
+	q := req.URL.Query()
+
+	if allocID = strings.TrimPrefix(req.URL.Path, "/v1/client/fs/cat/"); allocID == "" {
+		return nil, allocIDNotPresentErr
+	}
+	if path = q.Get("path"); path == "" {
+		return nil, fileNameNotPresentErr
+	}
+	fs, err := s.agent.client.GetAllocFS(allocID)
+	if err != nil {
+		return nil, err
+	}
+
+	fileInfo, err := fs.Stat(path)
+	if err != nil {
+		return nil, err
+	}
+	if fileInfo.IsDir {
+		return nil, fmt.Errorf("file %q is a directory")
+	}
+
+	r, err := fs.ReadAt(path, int64(0), fileInfo.Size)
+	io.Copy(resp, r)
+	return nil, nil
+}

command/fs_cat.go

@@ -130,21 +130,9 @@ nomad alloc-status %s`, allocID, allocID)
 		f.Ui.Error(msg)
 		return 0
 	}
-	// Stat the file to find it's size
-	file, _, err := client.AllocFS().Stat(alloc, path, nil)
-	if err != nil {
-		f.Ui.Error(err.Error())
-		return 1
-	}
-	if file.IsDir {
-		f.Ui.Error(fmt.Sprintf("The file %q is a directory", file.Name))
-		return 1
-	}
 
 	// Get the contents of the file
-	offset := 0
-	limit := file.Size
-	r, _, err := client.AllocFS().ReadAt(alloc, path, int64(offset), limit, nil)
+	r, _, err := client.AllocFS().Cat(alloc, path, nil)
 	if err != nil {
 		f.Ui.Error(fmt.Sprintf("Error reading file: %v", err))
 		return 1