13 KiB
table of contents
- check dependencies
- name and config
- schema and check
- choose phase to run
- implement the logic
- write test case
- register public API
- register control API
check dependencies
if you have dependencies on external libraries, check the dependent items. if your plugin needs to use shared memory, it needs to declare in bin/apisix, for example :
lua_shared_dict plugin-limit-req 10m;
lua_shared_dict plugin-limit-count 10m;
lua_shared_dict prometheus-metrics 10m;
lua_shared_dict plugin-limit-conn 10m;
lua_shared_dict upstream-healthcheck 10m;
lua_shared_dict worker-events 10m;
# for openid-connect plugin
lua_shared_dict discovery 1m; # cache for discovery metadata documents
lua_shared_dict jwks 1m; # cache for JWKs
lua_shared_dict introspection 10m; # cache for JWT verification results
The plugin itself provides the init method. It is convenient for plugins to perform some initialization after the plugin is loaded.
Note : if the dependency of some plugin needs to be initialized when Nginx start, you may need to add logic to the initialization method "http_init" in the file apisix.lua, And you may need to add some processing on generated part of Nginx configuration file in bin/apisix file. but it is easy to have an impact on the overall situation according to the existing plugin mechanism, we do not recommend this unless you have a complete grasp of the code.
name and config
Determine the name and priority of the plugin, and add to conf/config-default.yaml. For example, for the example-plugin plugin, you need to specify the plugin name in the code (the name is the unique identifier of the plugin and cannot be duplicate), you can see the code in file "apisix/plugins/example-plugin.lua" :
local plugin_name = "example-plugin"
local _M = {
version = 0.1,
priority = 0,
name = plugin_name,
schema = schema,
metadata_schema = metadata_schema,
}
Note : The priority of the new plugin cannot be the same as the priority of any existing plugin. In addition, plugins with a high priority value will be executed first in a given phase (see the definition of phase in choose-phase-to-run). For example, the priority of example-plugin is 0 and the priority of ip-restriction is 3000. Therefore, the ip-restriction plugin will be executed first, then the example-plugin plugin.
in the "conf/config-default.yaml" configuration file, the enabled plugins (all specified by plugin name) are listed.
plugins: # plugin list
- limit-req
- limit-count
- limit-conn
- key-auth
- prometheus
- node-status
- jwt-auth
- zipkin
- ip-restriction
- grpc-transcode
- serverless-pre-function
- serverless-post-function
- openid-connect
- proxy-rewrite
- redirect
...
Note : the order of the plugins is not related to the order of execution.
If your plugin has a new code directory of its own, you will need to modify the Makefile to create directory, such as:
$(INSTALL) -d $(INST_LUADIR)/apisix/plugins/skywalking
$(INSTALL) apisix/plugins/skywalking/*.lua $(INST_LUADIR)/apisix/plugins/skywalking/
schema and check
Write Json Schema descriptions and check functions. Similarly, take the example-plugin plugin as an example to see its configuration data :
"example-plugin" : {
"i": 1,
"s": "s",
"t": [1]
}
Let's look at its schema description :
local schema = {
type = "object",
properties = {
i = {type = "number", minimum = 0},
s = {type = "string"},
t = {type = "array", minItems = 1},
ip = {type = "string"},
port = {type = "integer"},
},
required = {"i"},
}
The schema defines a non-negative number i, a string s, a non-empty array of t, and ip / port. Only i is required.
At the same time, we need to implement the check_schema(conf) method to complete the specification verification.
function _M.check_schema(conf, schema_type)
return core.schema.check(schema, conf)
end
Note: the project has provided the public method "core.schema.check", which can be used directly to complete JSON verification.
In addition, if the plugin needs to use some metadata, we can define the plugin metadata_schema, and then we can dynamically manage these metadata through the admin api. Example:
local metadata_schema = {
type = "object",
properties = {
ikey = {type = "number", minimum = 0},
skey = {type = "string"},
},
required = {"ikey", "skey"},
additionalProperties = false,
}
local plugin_name = "example-plugin"
local _M = {
version = 0.1,
priority = 0, -- TODO: add a type field, may be a good idea
name = plugin_name,
schema = schema,
metadata_schema = metadata_schema,
}
You might have noticed the key-auth plugin has type = 'auth' in its definition.
When we set the type of plugin to auth, it means that this plugin is an authentication plugin.
An authentication plugin needs to choose a consumer after execution. For example, in key-auth plugin, it calls the consumer.attach_consumer to attach a consumer, which is chosen via the apikey header.
To interact with the consumer resource, this type of plugin needs to provide a consumer_schema to check the plugins configuration in the consumer.
Here is the consumer configuration for key-auth plugin:
{
"username": "Joe",
"plugins": {
"key-auth": {
"key": "Joe's key"
}
}
}
It will be used when you try to create a Consumer
To validate the configuration, the plugin uses a schema like this:
local consumer_schema = {
type = "object",
additionalProperties = false,
properties = {
key = {type = "string"},
},
required = {"key"},
}
Note the difference between key-auth's check_schema(conf) method to example-plugin's:
-- key-auth
function _M.check_schema(conf, schema_type)
if schema_type == core.schema.TYPE_CONSUMER then
return core.schema.check(consumer_schema, conf)
else
return core.schema.check(schema, conf)
end
end
-- example-plugin
function _M.check_schema(conf, schema_type)
return core.schema.check(schema, conf)
end
choose phase to run
Determine which phase to run, generally access or rewrite. If you don't know the Openresty life cycle, it's recommended to know it in advance. For example key-auth is an authentication plugin, thus the authentication should be completed before forwarding the request to any upstream service. Therefore, the plugin must be executed in the rewrite phases. In APISIX, only the authentication logic can be run in the rewrite phase. Other logic needs to run before proxy should be in access phase.
The following code snippet shows how to implement any logic relevant to the plugin in the OpenResty log phase.
function _M.log(conf)
-- Implement logic here
end
Note : we can't invoke ngx.exit or core.respond.exit in rewrite phase and access phase. if need to exit, just return the status and body, the plugin engine will make the exit happen with the returned status and body. example
implement the logic
Write the logic of the plugin in the corresponding phase.
write test case
For functions, write and improve the test cases of various dimensions, do a comprehensive test for your plugin! The test cases of plugins are all in the "t/plugin" directory. You can go ahead to find out. APISIX uses test-nginx as the test framework. A test case (.t file) is usually divided into prologue and data parts by _data_. Here we will briefly introduce the data part, that is, the part of the real test case. For example, the key-auth plugin:
=== TEST 1: sanity
--- config
location /t {
content_by_lua_block {
local plugin = require("apisix.plugins.key-auth")
local ok, err = plugin.check_schema({key = 'test-key'}, core.schema.TYPE_CONSUMER)
if not ok then
ngx.say(err)
end
ngx.say("done")
}
}
--- request
GET /t
--- response_body
done
--- no_error_log
[error]
A test case consists of three parts :
- Program code : configuration content of Nginx location
- Input : http request information
- Output check : status, header, body, error log check
When we request /t, which config in the configuration file, the Nginx will call "content_by_lua_block" instruction to complete the Lua script, and finally return. The assertion of the use case is response_body return "done", "no_error_log" means to check the "error.log" of Nginx. There must be no ERROR level record. The log files for the unit test are located in the following folder: 't/servroot/logs'.
The above test case represents a simple scenario. Most scenarios will require multiple steps to validate. To do this, create multiple tests === TEST 1, === TEST 2, and so on. These tests will be executed sequentially, allowing you to break down scenarios into a sequence of atomic steps.
Additionally, there are some convenience testing endpoints which can be found here. For example, see proxy-rewrite. In test 42, the upstream uri is made to redirect /test?new_uri=hello to /hello (which always returns hello world). In test 43, the response body is confirmed to equal hello world, meaning the proxy-rewrite configuration added with test 42 worked correctly.
Refer the following document to setup the testing framework.
Attach the test-nginx execution process:
According to the path we configured in the makefile and some configuration items at the front of each .t file, the framework will assemble into a complete nginx.conf file. "t/servroot" is the working directory of Nginx and start the Nginx instance. according to the information provided by the test case, initiate the http request and check that the return items of HTTP include HTTP status, HTTP response header, HTTP response body and so on.
Register public API
A plugin can register API which exposes to the public. Take jwt-auth plugin as an example, this plugin registers GET /apisix/plugin/jwt/sign to allow client to sign its key:
local function gen_token()
...
end
function _M.api()
return {
{
methods = {"GET"},
uri = "/apisix/plugin/jwt/sign",
handler = gen_token,
}
}
end
Note that the public API is exposed to the public. You may need to use interceptors to protect it.
Register control API
If you only want to expose the API to the localhost or intranet, you can expose it via Control API.
Take a look at example-plugin plugin:
local function hello()
local args = ngx.req.get_uri_args()
if args["json"] then
return 200, {msg = "world"}
else
return 200, "world\n"
end
end
function _M.control_api()
return {
{
methods = {"GET"},
uris = {"/v1/plugin/example-plugin/hello"},
handler = hello,
}
}
end
If you don't change the default control API configuration, the plugin will be expose GET /v1/plugin/example-plugin/hello which can only be accessed via 127.0.0.1.