Add Meta models support for AWS Bedrock LLM (#764)

* Update aws_bedrock.rb

* Revert "Update aws_bedrock.rb"

This reverts commit 34ac330.

* Add Aws Bedrock Meta support

* Update complete.json

* Fix bedrock renaming of response

* Fix specs

lib/langchain/llm/aws_bedrock.rb

@@ -48,7 +48,7 @@ class AwsBedrock < Base
 
     attr_reader :client, :defaults
 
-    SUPPORTED_COMPLETION_PROVIDERS = %i[anthropic cohere ai21].freeze
+    SUPPORTED_COMPLETION_PROVIDERS = %i[anthropic ai21 cohere meta].freeze
     SUPPORTED_CHAT_COMPLETION_PROVIDERS = %i[anthropic].freeze
     SUPPORTED_EMBEDDING_PROVIDERS = %i[amazon].freeze
 
@@ -209,6 +209,8 @@ def compose_parameters(params)
         compose_parameters_cohere params
       elsif completion_provider == :ai21
         compose_parameters_ai21 params
+      elsif completion_provider == :meta
+        compose_parameters_meta params
       end
     end
 
@@ -219,6 +221,8 @@ def parse_response(response)
         Langchain::LLM::CohereResponse.new(JSON.parse(response.body.string))
       elsif completion_provider == :ai21
         Langchain::LLM::AI21Response.new(JSON.parse(response.body.string, symbolize_names: true))
+      elsif completion_provider == :meta
+        Langchain::LLM::AwsBedrockMetaResponse.new(JSON.parse(response.body.string))
       end
     end
 
@@ -282,6 +286,16 @@ def compose_parameters_ai21(params)
       }
     end
 
+    def compose_parameters_meta(params)
+      default_params = @defaults.merge(params)
+
+      {
+        temperature: default_params[:temperature],
+        top_p: default_params[:top_p],
+        max_gen_len: default_params[:max_tokens_to_sample]
+      }
+    end
+
     def response_from_chunks(chunks)
       raw_response = {}
 

lib/langchain/llm/response/aws_bedrock_meta_response.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Langchain::LLM
+  class AwsBedrockMetaResponse < BaseResponse
+    def completion
+      completions.first
+    end
+
+    def completions
+      [raw_response.dig("generation")]
+    end
+
+    def stop_reason
+      raw_response.dig("stop_reason")
+    end
+
+    def prompt_tokens
+      raw_response.dig("prompt_token_count").to_i
+    end
+
+    def completion_tokens
+      raw_response.dig("generation_token_count").to_i
+    end
+
+    def total_tokens
+      prompt_tokens + completion_tokens
+    end
+  end
+end

spec/fixtures/llm/aws_bedrock_meta/complete.json

@@ -0,0 +1,6 @@
+{
+  "generation": "The sky has no definitive",
+  "prompt_token_count": 792,
+  "generation_token_count": 300,
+  "stop_reason": "length"
+}

spec/langchain/llm/response/aws_bedrock_meta_response_spec.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+RSpec.describe Langchain::LLM::AwsBedrockMetaResponse do
+  let(:raw_chat_completions_response) {
+    JSON.parse File.read("spec/fixtures/llm/aws_bedrock_meta/complete.json")
+  }
+
+  subject { described_class.new(raw_chat_completions_response) }
+
+  describe "#complete" do
+    it "returns completion" do
+      expect(subject.completion).to eq("The sky has no definitive")
+    end
+  end
+end