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cloudflare_workersai.ts
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cloudflare_workersai.ts
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import {
SimpleChatModel,
type BaseChatModelParams,
} from "@langchain/core/language_models/chat_models";
import type { BaseLanguageModelCallOptions } from "@langchain/core/language_models/base";
import {
AIMessageChunk,
BaseMessage,
ChatMessage,
} from "@langchain/core/messages";
import { ChatGenerationChunk } from "@langchain/core/outputs";
import { getEnvironmentVariable } from "@langchain/core/utils/env";
import { CallbackManagerForLLMRun } from "@langchain/core/callbacks/manager";
import type { CloudflareWorkersAIInput } from "../llms/cloudflare_workersai.js";
import { convertEventStreamToIterableReadableDataStream } from "../utils/event_source_parse.js";
/**
* @deprecated Install and import from "@langchain/cloudflare" instead.
*
* An interface defining the options for a Cloudflare Workers AI call. It extends
* the BaseLanguageModelCallOptions interface.
*/
export interface ChatCloudflareWorkersAICallOptions
extends BaseLanguageModelCallOptions {}
/**
* @deprecated Install and import from "@langchain/cloudflare" instead.
*
* A class that enables calls to the Cloudflare Workers AI API to access large language
* models in a chat-like fashion. It extends the SimpleChatModel class and
* implements the CloudflareWorkersAIInput interface.
* @example
* ```typescript
* const model = new ChatCloudflareWorkersAI({
* model: "@cf/meta/llama-2-7b-chat-int8",
* cloudflareAccountId: process.env.CLOUDFLARE_ACCOUNT_ID,
* cloudflareApiToken: process.env.CLOUDFLARE_API_TOKEN
* });
*
* const response = await model.invoke([
* ["system", "You are a helpful assistant that translates English to German."],
* ["human", `Translate "I love programming".`]
* ]);
*
* console.log(response);
* ```
*/
export class ChatCloudflareWorkersAI
extends SimpleChatModel
implements CloudflareWorkersAIInput
{
static lc_name() {
return "ChatCloudflareWorkersAI";
}
lc_serializable = true;
model = "@cf/meta/llama-2-7b-chat-int8";
cloudflareAccountId?: string;
cloudflareApiToken?: string;
baseUrl: string;
streaming = false;
constructor(fields?: CloudflareWorkersAIInput & BaseChatModelParams) {
super(fields ?? {});
this.model = fields?.model ?? this.model;
this.streaming = fields?.streaming ?? this.streaming;
this.cloudflareAccountId =
fields?.cloudflareAccountId ??
getEnvironmentVariable("CLOUDFLARE_ACCOUNT_ID");
this.cloudflareApiToken =
fields?.cloudflareApiToken ??
getEnvironmentVariable("CLOUDFLARE_API_TOKEN");
this.baseUrl =
fields?.baseUrl ??
`https://api.cloudflare.com/client/v4/accounts/${this.cloudflareAccountId}/ai/run`;
if (this.baseUrl.endsWith("/")) {
this.baseUrl = this.baseUrl.slice(0, -1);
}
}
get lc_secrets(): { [key: string]: string } | undefined {
return {
cloudflareApiToken: "CLOUDFLARE_API_TOKEN",
};
}
_llmType() {
return "cloudflare";
}
/** Get the identifying parameters for this LLM. */
get identifyingParams() {
return { model: this.model };
}
/**
* Get the parameters used to invoke the model
*/
invocationParams(_options?: this["ParsedCallOptions"]) {
return {
model: this.model,
};
}
_combineLLMOutput() {
return {};
}
/**
* Method to validate the environment.
*/
validateEnvironment() {
if (!this.cloudflareAccountId) {
throw new Error(
`No Cloudflare account ID found. Please provide it when instantiating the CloudflareWorkersAI class, or set it as "CLOUDFLARE_ACCOUNT_ID" in your environment variables.`
);
}
if (!this.cloudflareApiToken) {
throw new Error(
`No Cloudflare API key found. Please provide it when instantiating the CloudflareWorkersAI class, or set it as "CLOUDFLARE_API_KEY" in your environment variables.`
);
}
}
async _request(
messages: BaseMessage[],
options: this["ParsedCallOptions"],
stream?: boolean
) {
this.validateEnvironment();
const url = `${this.baseUrl}/${this.model}`;
const headers = {
Authorization: `Bearer ${this.cloudflareApiToken}`,
"Content-Type": "application/json",
};
const formattedMessages = this._formatMessages(messages);
const data = { messages: formattedMessages, stream };
return this.caller.call(async () => {
const response = await fetch(url, {
method: "POST",
headers,
body: JSON.stringify(data),
signal: options.signal,
});
if (!response.ok) {
const error = new Error(
`Cloudflare LLM call failed with status code ${response.status}`
);
// eslint-disable-next-line @typescript-eslint/no-explicit-any
(error as any).response = response;
throw error;
}
return response;
});
}
async *_streamResponseChunks(
messages: BaseMessage[],
options: this["ParsedCallOptions"],
runManager?: CallbackManagerForLLMRun
): AsyncGenerator<ChatGenerationChunk> {
const response = await this._request(messages, options, true);
if (!response.body) {
throw new Error("Empty response from Cloudflare. Please try again.");
}
const stream = convertEventStreamToIterableReadableDataStream(
response.body
);
for await (const chunk of stream) {
if (chunk !== "[DONE]") {
const parsedChunk = JSON.parse(chunk);
const generationChunk = new ChatGenerationChunk({
message: new AIMessageChunk({ content: parsedChunk.response }),
text: parsedChunk.response,
});
yield generationChunk;
// eslint-disable-next-line no-void
void runManager?.handleLLMNewToken(generationChunk.text ?? "");
}
}
}
protected _formatMessages(
messages: BaseMessage[]
): { role: string; content: string }[] {
const formattedMessages = messages.map((message) => {
let role;
if (message._getType() === "human") {
role = "user";
} else if (message._getType() === "ai") {
role = "assistant";
} else if (message._getType() === "system") {
role = "system";
} else if (ChatMessage.isInstance(message)) {
role = message.role;
} else {
console.warn(
`Unsupported message type passed to Cloudflare: "${message._getType()}"`
);
role = "user";
}
if (typeof message.content !== "string") {
throw new Error(
"ChatCloudflareWorkersAI currently does not support non-string message content."
);
}
return {
role,
content: message.content,
};
});
return formattedMessages;
}
/** @ignore */
async _call(
messages: BaseMessage[],
options: this["ParsedCallOptions"],
runManager?: CallbackManagerForLLMRun
): Promise<string> {
if (!this.streaming) {
const response = await this._request(messages, options);
const responseData = await response.json();
return responseData.result.response;
} else {
const stream = this._streamResponseChunks(messages, options, runManager);
let finalResult: ChatGenerationChunk | undefined;
for await (const chunk of stream) {
if (finalResult === undefined) {
finalResult = chunk;
} else {
finalResult = finalResult.concat(chunk);
}
}
const messageContent = finalResult?.message.content;
if (messageContent && typeof messageContent !== "string") {
throw new Error(
"Non-string output for ChatCloudflareWorkersAI is currently not supported."
);
}
return messageContent ?? "";
}
}
}