feat: ai-proxy plugin

Makefile

@@ -374,6 +374,12 @@ install: runtime
 	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/utils
 	$(ENV_INSTALL) apisix/utils/*.lua $(ENV_INST_LUADIR)/apisix/utils/
 
+	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/plugins/ai-proxy
+	$(ENV_INSTALL) apisix/plugins/ai-proxy/*.lua $(ENV_INST_LUADIR)/apisix/plugins/ai-proxy
+
+	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/plugins/ai-proxy/drivers
+	$(ENV_INSTALL) apisix/plugins/ai-proxy/drivers/*.lua $(ENV_INST_LUADIR)/apisix/plugins/ai-proxy/drivers
+
 	$(ENV_INSTALL) bin/apisix $(ENV_INST_BINDIR)/apisix
 
 

apisix/cli/config.lua

@@ -219,6 +219,7 @@ local _M = {
     "proxy-rewrite",
     "workflow",
     "api-breaker",
+    "ai-proxy",
     "limit-conn",
     "limit-count",
     "limit-req",

apisix/core/request.lua

@@ -21,6 +21,7 @@
 
 local lfs = require("lfs")
 local log = require("apisix.core.log")
+local json = require("apisix.core.json")
 local io = require("apisix.core.io")
 local req_add_header
 if ngx.config.subsystem == "http" then
@@ -334,6 +335,21 @@ function _M.get_body(max_size, ctx)
 end
 
 
+function _M.get_json_request_body_table()
+    local body, err = _M.get_body()
+    if not body then
+        return nil, { message = "could not get body: " .. (err or "request body is empty") }
+    end
+
+    local body_tab, err = json.decode(body)
+    if not body_tab then
+        return nil, { message = "could not get parse JSON request body: " .. err }
+    end
+
+    return body_tab
+end
+
+
 function _M.get_scheme(ctx)
     if not ctx then
         ctx = ngx.ctx.api_ctx

apisix/plugins/ai-proxy.lua

@@ -0,0 +1,138 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+local core = require("apisix.core")
+local schema = require("apisix.plugins.ai-proxy.schema")
+local require = require
+local pcall = pcall
+local internal_server_error = ngx.HTTP_INTERNAL_SERVER_ERROR
+local bad_request = ngx.HTTP_BAD_REQUEST
+local ngx_req = ngx.req
+local ngx_print = ngx.print
+local ngx_flush = ngx.flush
+
+local plugin_name = "ai-proxy"
+local _M = {
+    version = 0.5,
+    priority = 999,
+    name = plugin_name,
+    schema = schema,
+}
+
+
+function _M.check_schema(conf)
+    local ai_driver = pcall(require, "apisix.plugins.ai-proxy.drivers." .. conf.model.provider)
+    if not ai_driver then
+        return false, "provider: " .. conf.model.provider .. " is not supported."
+    end
+    return core.schema.check(schema.plugin_schema, conf)
+end
+
+
+local CONTENT_TYPE_JSON = "application/json"
+
+
+local function keepalive_or_close(conf, httpc)
+    if conf.set_keepalive then
+        httpc:set_keepalive(10000, 100)
+        return
+    end
+    httpc:close()
+end
+
+
+function _M.access(conf, ctx)
+    local ct = core.request.header(ctx, "Content-Type") or CONTENT_TYPE_JSON
+    if not core.string.has_prefix(ct, CONTENT_TYPE_JSON) then
+        return bad_request, "unsupported content-type: " .. ct
+    end
+
+    local request_table, err = core.request.get_json_request_body_table()
+    if not request_table then
+        return bad_request, err
+    end
+
+    local ok, err = core.schema.check(schema.chat_request_schema, request_table)
+    if not ok then
+        return bad_request, "request format doesn't match schema: " .. err
+    end
+
+    if conf.model.name then
+        request_table.model = conf.model.name
+    end
+
+    if core.table.try_read_attr(conf, "model", "options", "stream") then
+        request_table.stream = true
+    end
+
+    local ai_driver = require("apisix.plugins.ai-proxy.drivers." .. conf.model.provider)
+    local res, err, httpc = ai_driver.request(conf, request_table, ctx)
+    if not res then
+        core.log.error("failed to send request to LLM service: ", err)
+        return internal_server_error
+    end
+
+    local body_reader = res.body_reader
+    if not body_reader then
+        core.log.error("LLM sent no response body")
+        return internal_server_error
+    end
+
+    if conf.passthrough then
+        ngx_req.init_body()
+        while true do
+            local chunk, err = body_reader() -- will read chunk by chunk
+            if err then
+                core.log.error("failed to read response chunk: ", err)
+                break
+            end
+            if not chunk then
+                break
+            end
+            ngx_req.append_body(chunk)
+        end
+        ngx_req.finish_body()
+        keepalive_or_close(conf, httpc)
+        return
+    end
+
+    if request_table.stream then
+        while true do
+            local chunk, err = body_reader() -- will read chunk by chunk
+            if err then
+                core.log.error("failed to read response chunk: ", err)
+                break
+            end
+            if not chunk then
+                break
+            end
+            ngx_print(chunk)
+            ngx_flush(true)
+        end
+        keepalive_or_close(conf, httpc)
+        return
+    else
+        local res_body, err = res:read_body()
+        if not res_body then
+            core.log.error("failed to read response body: ", err)
+            return internal_server_error
+        end
+        keepalive_or_close(conf, httpc)
+        return res.status, res_body
+    end
+end
+
+return _M

apisix/plugins/ai-proxy/drivers/openai.lua

@@ -0,0 +1,85 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+local _M = {}
+
+local core = require("apisix.core")
+local http = require("resty.http")
+local url  = require("socket.url")
+
+local pairs = pairs
+
+-- globals
+local DEFAULT_HOST = "api.openai.com"
+local DEFAULT_PORT = 443
+local DEFAULT_PATH = "/v1/chat/completions"
+
+
+function _M.request(conf, request_table, ctx)
+    local httpc, err = http.new()
+    if not httpc then
+        return nil, "failed to create http client to send request to LLM server: " .. err
+    end
+    httpc:set_timeout(conf.timeout)
+
+    local endpoint = core.table.try_read_attr(conf, "override", "endpoint")
+    local parsed_url
+    if endpoint then
+        parsed_url = url.parse(endpoint)
+    end
+
+    local ok, err = httpc:connect({
+        scheme = parsed_url.scheme or "https",
+        host = parsed_url.host or DEFAULT_HOST,
+        port = parsed_url.port or DEFAULT_PORT,
+        ssl_verify = conf.ssl_verify,
+        ssl_server_name = parsed_url.host or DEFAULT_HOST,
+        pool_size = conf.keepalive and conf.keepalive_pool,
+    })
+
+    if not ok then
+        return nil, "failed to connect to LLM server: " .. err
+    end
+
+    local path = (parsed_url.path or DEFAULT_PATH)
+
+    local headers = (conf.auth.header or {})
+    headers["Content-Type"] = "application/json"
+    local params = {
+        method = "POST",
+        headers = headers,
+        keepalive = conf.keepalive,
+        ssl_verify = conf.ssl_verify,
+        path = path,
+        query = conf.auth.query
+    }
+
+    if conf.model.options then
+        for opt, val in pairs(conf.model.options) do
+            request_table[opt] = val
+        end
+    end
+    params.body = core.json.encode(request_table)
+
+    local res, err = httpc:request(params)
+    if not res then
+        return nil, err
+    end
+
+    return res, nil, httpc
+end
+
+return _M