github.com/kim0/docker@v0.6.2-0.20161130212042-4addda3f07e7/docs/extend/plugins_authorization.md

github.com/kim0/docker@v0.6.2-0.20161130212042-4addda3f07e7/docs/extend/plugins_authorization.md (about)

1 ---
2 title: "Access authorization plugin"
3 description: "How to create authorization plugins to manage access control to your Docker daemon."
4 keywords: ["security, authorization, authentication, docker, documentation, plugin, extend"]
5 aliases: ["/engine/extend/authorization/"]
6 ---
7
8 
16
17 # Create an authorization plugin
18
19 This document describes the Docker Engine plugins generally available in Docker
20 Engine. To view information on plugins managed by Docker Engine currently in
21 experimental status, refer to [Docker Engine plugin system](index.md).
22
23 Docker's out-of-the-box authorization model is all or nothing. Any user with
24 permission to access the Docker daemon can run any Docker client command. The
25 same is true for callers using Docker's remote API to contact the daemon. If you
26 require greater access control, you can create authorization plugins and add
27 them to your Docker daemon configuration. Using an authorization plugin, a
28 Docker administrator can configure granular access policies for managing access
29 to Docker daemon.
30
31 Anyone with the appropriate skills can develop an authorization plugin. These
32 skills, at their most basic, are knowledge of Docker, understanding of REST, and
33 sound programming knowledge. This document describes the architecture, state,
34 and methods information available to an authorization plugin developer.
35
36 ## Basic principles
37
38 Docker's [plugin infrastructure](plugin_api.md) enables
39 extending Docker by loading, removing and communicating with
40 third-party components using a generic API. The access authorization subsystem
41 was built using this mechanism.
42
43 Using this subsystem, you don't need to rebuild the Docker daemon to add an
44 authorization plugin. You can add a plugin to an installed Docker daemon. You do
45 need to restart the Docker daemon to add a new plugin.
46
47 An authorization plugin approves or denies requests to the Docker daemon based
48 on both the current authentication context and the command context. The
49 authentication context contains all user details and the authentication method.
50 The command context contains all the relevant request data.
51
52 Authorization plugins must follow the rules described in [Docker Plugin API](plugin_api.md).
53 Each plugin must reside within directories described under the
54 [Plugin discovery](plugin_api.md#plugin-discovery) section.
55
56 **Note**: the abbreviations `AuthZ` and `AuthN` mean authorization and authentication
57 respectively.
58
59 ## Default user authorization mechanism
60
61 If TLS is enabled in the [Docker daemon](https://docs.docker.com/engine/security/https/), the default user authorization flow extracts the user details from the certificate subject name.
62 That is, the `User` field is set to the client certificate subject common name, and the `AuthenticationMethod` field is set to `TLS`.
63
64 ## Basic architecture
65
66 You are responsible for registering your plugin as part of the Docker daemon
67 startup. You can install multiple plugins and chain them together. This chain
68 can be ordered. Each request to the daemon passes in order through the chain.
69 Only when all the plugins grant access to the resource, is the access granted.
70
71 When an HTTP request is made to the Docker daemon through the CLI or via the
72 remote API, the authentication subsystem passes the request to the installed
73 authentication plugin(s). The request contains the user (caller) and command
74 context. The plugin is responsible for deciding whether to allow or deny the
75 request.
76
77 The sequence diagrams below depict an allow and deny authorization flow:
78
79 ![Authorization Allow flow](images/authz_allow.png)
80
81 ![Authorization Deny flow](images/authz_deny.png)
82
83 Each request sent to the plugin includes the authenticated user, the HTTP
84 headers, and the request/response body. Only the user name and the
85 authentication method used are passed to the plugin. Most importantly, no user
86 credentials or tokens are passed. Finally, not all request/response bodies
87 are sent to the authorization plugin. Only those request/response bodies where
88 the `Content-Type` is either `text/*` or `application/json` are sent.
89
90 For commands that can potentially hijack the HTTP connection (`HTTP
91 Upgrade`), such as `exec`, the authorization plugin is only called for the
92 initial HTTP requests. Once the plugin approves the command, authorization is
93 not applied to the rest of the flow. Specifically, the streaming data is not
94 passed to the authorization plugins. For commands that return chunked HTTP
95 response, such as `logs` and `events`, only the HTTP request is sent to the
96 authorization plugins.
97
98 During request/response processing, some authorization flows might
99 need to do additional queries to the Docker daemon. To complete such flows,
100 plugins can call the daemon API similar to a regular user. To enable these
101 additional queries, the plugin must provide the means for an administrator to
102 configure proper authentication and security policies.
103
104 ## Docker client flows
105
106 To enable and configure the authorization plugin, the plugin developer must
107 support the Docker client interactions detailed in this section.
108
109 ### Setting up Docker daemon
110
111 Enable the authorization plugin with a dedicated command line flag in the
112 `--authorization-plugin=PLUGIN_ID` format. The flag supplies a `PLUGIN_ID`
113 value. This value can be the plugin’s socket or a path to a specification file.
114 Authorization plugins can be loaded without restarting the daemon. Refer
115 to the [`dockerd` documentation](../reference/commandline/dockerd.md#configuration-reloading) for more information.
116
117 ```bash
118 $ dockerd --authorization-plugin=plugin1 --authorization-plugin=plugin2,...
119 ```
120
121 Docker's authorization subsystem supports multiple `--authorization-plugin` parameters.
122
123 ### Calling authorized command (allow)
124
125 ```bash
126 $ docker pull centos
127 ...
128 f1b10cd84249: Pull complete
129 ...
130 ```
131
132 ### Calling unauthorized command (deny)
133
134 ```bash
135 $ docker pull centos
136 ...
137 docker: Error response from daemon: authorization denied by plugin PLUGIN_NAME: volumes are not allowed.
138 ```
139
140 ### Error from plugins
141
142 ```bash
143 $ docker pull centos
144 ...
145 docker: Error response from daemon: plugin PLUGIN_NAME failed with error: AuthZPlugin.AuthZReq: Cannot connect to the Docker daemon. Is the docker daemon running on this host?.
146 ```
147
148 ## API schema and implementation
149
150 In addition to Docker's standard plugin registration method, each plugin
151 should implement the following two methods:
152
153 * `/AuthZPlugin.AuthZReq` This authorize request method is called before the Docker daemon processes the client request.
154
155 * `/AuthZPlugin.AuthZRes` This authorize response method is called before the response is returned from Docker daemon to the client.
156
157 #### /AuthZPlugin.AuthZReq
158
159 **Request**:
160
161 ```json
162 {
163 "User": "The user identification",
164 "UserAuthNMethod": "The authentication method used",
165 "RequestMethod": "The HTTP method",
166 "RequestURI": "The HTTP request URI",
167 "RequestBody": "Byte array containing the raw HTTP request body",
168 "RequestHeader": "Byte array containing the raw HTTP request header as a map[string][]string "
169 }
170 ```
171
172 **Response**:
173
174 ```json
175 {
176 "Allow": "Determined whether the user is allowed or not",
177 "Msg": "The authorization message",
178 "Err": "The error message if things go wrong"
179 }
180 ```
181 #### /AuthZPlugin.AuthZRes
182
183 **Request**:
184
185 ```json
186 {
187 "User": "The user identification",
188 "UserAuthNMethod": "The authentication method used",
189 "RequestMethod": "The HTTP method",
190 "RequestURI": "The HTTP request URI",
191 "RequestBody": "Byte array containing the raw HTTP request body",
192 "RequestHeader": "Byte array containing the raw HTTP request header as a map[string][]string",
193 "ResponseBody": "Byte array containing the raw HTTP response body",
194 "ResponseHeader": "Byte array containing the raw HTTP response header as a map[string][]string",
195 "ResponseStatusCode":"Response status code"
196 }
197 ```
198
199 **Response**:
200
201 ```json
202 {
203 "Allow": "Determined whether the user is allowed or not",
204 "Msg": "The authorization message",
205 "Err": "The error message if things go wrong"
206 }
207 ```
208
209 ### Request authorization
210
211 Each plugin must support two request authorization messages formats, one from the daemon to the plugin and then from the plugin to the daemon. The tables below detail the content expected in each message.
212
213 #### Daemon -> Plugin
214
215 Name | Type | Description
216 -----------------------|-------------------|-------------------------------------------------------
217 User | string | The user identification
218 Authentication method | string | The authentication method used
219 Request method | enum | The HTTP method (GET/DELETE/POST)
220 Request URI | string | The HTTP request URI including API version (e.g., v.1.17/containers/json)
221 Request headers | map[string]string | Request headers as key value pairs (without the authorization header)
222 Request body | []byte | Raw request body
223
224
225 #### Plugin -> Daemon
226
227 Name | Type | Description
228 --------|--------|----------------------------------------------------------------------------------
229 Allow | bool | Boolean value indicating whether the request is allowed or denied
230 Msg | string | Authorization message (will be returned to the client in case the access is denied)
231 Err | string | Error message (will be returned to the client in case the plugin encounter an error. The string value supplied may appear in logs, so should not include confidential information)
232
233 ### Response authorization
234
235 The plugin must support two authorization messages formats, one from the daemon to the plugin and then from the plugin to the daemon. The tables below detail the content expected in each message.
236
237 #### Daemon -> Plugin
238
239
240 Name | Type | Description
241 ----------------------- |------------------ |----------------------------------------------------
242 User | string | The user identification
243 Authentication method | string | The authentication method used
244 Request method | string | The HTTP method (GET/DELETE/POST)
245 Request URI | string | The HTTP request URI including API version (e.g., v.1.17/containers/json)
246 Request headers | map[string]string | Request headers as key value pairs (without the authorization header)
247 Request body | []byte | Raw request body
248 Response status code | int | Status code from the docker daemon
249 Response headers | map[string]string | Response headers as key value pairs
250 Response body | []byte | Raw docker daemon response body
251
252
253 #### Plugin -> Daemon
254
255 Name | Type | Description
256 --------|--------|----------------------------------------------------------------------------------
257 Allow | bool | Boolean value indicating whether the response is allowed or denied
258 Msg | string | Authorization message (will be returned to the client in case the access is denied)
259 Err | string | Error message (will be returned to the client in case the plugin encounter an error. The string value supplied may appear in logs, so should not include confidential information)