自定义 openstack REST API (newton)

外部访问 openstack  都是通过 REST API 的方式，比如 获取一个image 的详细信息 /v2/images/{image_id} ,有关 API 的信息参考 api文档 .

我是基于devstack newton 版本进行编写的，步骤如下

1.创建一个python文件叫documents.py

2.documents.py 中有一个类 继承 extensions.ExtensionDescriptor 这个类，并且覆盖name,alias,namespace,update这个四个属性，并且实现get_resources这个方法

class Documents(extensions.ExtensionDescriptor):
    name = "documents"
    alias = "os-documents"
    namespace = "www.doc.com"
    update = "2017-8-23T00:00:00+00:00"
    
    def get_resources(self):
        resources = [extensions.ResourceExtension("os-documents",DocumentsController())]
        return resources

3.创建一个实现你请求的类，比如你想获取一个image的详细信息，实现的具体方法在这里实现。大家注意  Documents 类中实现的get_resources(self) 方法，这个方法会引用现在创建的类，从而获取想要 的数据。这里为了方便，不去数据库中查询数据，而用一个集合代替

　　　　3.1声明一个集合，里边存储documents 的数据

　　　　　　

documents={"documents":[{"id":"1001","name":"docs1"},
                        {"id":"1002","name":"docs2"},
                        {"id":"1003","name":"docs3"}
                        ]}

　　　　3.2创建一个类，名字叫做DocumentsController

　　　　3.3 在DocumentsController创建一个index方法，这个方法就会自动处理获取所有信息的请求 

　

    def index(self,req):
        '''
        get v2/{tenant_id}/os-documents
        '''
        return  documents

　　3.4在DocumentsController创建一个show方法，这个方法就会自动处理获取指定条目请求

    def show(self,req,id):
        '''
         get v2/{tenant_id}/os-documents/{id}
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] ==id:
                document = docu
        if docu == None:
            raise webob.exc.HTTPNotFound(explanation="documents not found")
        else:
            return document

　　3.5在DocumentsController创建一个create方法，这个处理创建一个条目的请求

　

    def create(self,req,body):
        '''
        post v2/{tenant_id}/os-documents
        '''
        try:
            documents["documents"].append(body["document"])
        except:
            raise webob.exc.HTTPBadRequest(explanation="document invaild")
        return body["document"]
  

　　3.6在DocumentsController创建一个update方法，这个处理更新一个条目的请求

    def update(self,req,body,id):
        '''
        put v2/{tenant_id}/os-documents/{id}
        
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] == id:
                documents["documents"].remove(docu)
                documents["documents"].append(body["document"])
                document = body["document"]
        
        if document == None:
            webob.exc.HTTPNotFound(explanation="document not found")
        
        else:
            return document

　　3.7 在DocumentsController创建一个delete方法，这个处理删除一个条目的请求

    def delete(self,req,id):
        '''
        delete v2/{tenant_id}/os-documents/{id}
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] == id:
                document = docu
                documents["documents"].remove(docu)
                return webob.Response(status_int = 202)
            
        if document == None:
            raise webob.exc.HTTPNotFound(explanation="document not found")
        

完整代码如下：

import webob
from webob  import exc
from nova import exception
from nova.api.openstack import extensions
from docutils.nodes import document
from _ast import alias
from argparse import Namespace

documents={"documents":[{"id":"1001","name":"docs1"},
                        {"id":"1002","name":"docs2"},
                        {"id":"1003","name":"docs3"}
                        ]}

class DocumentsController():
    def index(self,req):
        '''
        get v2/{tenant_id}/os-documents
        '''
        return  documents
    
    def show(self,req,id):
        '''
         get v2/{tenant_id}/os-documents/{id}
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] ==id:
                document = docu
        if docu == None:
            raise webob.exc.HTTPNotFound(explanation="documents not found")
        else:
            return document
        
        
    def create(self,req,body):
        '''
        post v2/{tenant_id}/os-documents
        '''
        try:
            documents["documents"].append(body["document"])
        except:
            raise webob.exc.HTTPBadRequest(explanation="document invaild")
        return body["document"]
    
    def update(self,req,body,id):
        '''
        put v2/{tenant_id}/os-documents/{id}
        
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] == id:
                documents["documents"].remove(docu)
                documents["documents"].append(body["document"])
                document = body["document"]
        
        if document == None:
            webob.exc.HTTPNotFound(explanation="document not found")
        
        else:
            return document
        
    def delete(self,req,id):
        '''
        delete v2/{tenant_id}/os-documents/{id}
        '''
        document = None
        for docu in documents["documents"]:
            if docu["id"] == id:
                document = docu
                documents["documents"].remove(docu)
                return webob.Response(status_int = 202)
            
        if document == None:
            raise webob.exc.HTTPNotFound(explanation="document not found")
        
        
        

class Documents(extensions.ExtensionDescriptor):
    name = "documents"
    alias = "os-documents"
    namespace = "www.doc.com"
    update = "2017-8-23T00:00:00+00:00"
    
    def get_resources(self):
        resources = [extensions.ResourceExtension("os-documents",DocumentsController())]
        return resources

将这个文件放到 nova/api/openstack/compute      目录下，重启nova 尝试方法一下 v2/{tenant_id}/os-documents

参考文档  WritingRequestExtensions