Class: Langfuse::ApiClient

Inherits:
Object
  • Object
show all
Defined in:
lib/langfuse/api_client.rb

Overview

HTTP client for Langfuse API

Handles authentication, connection management, and HTTP requests to the Langfuse REST API.

Examples:

api_client = Langfuse::ApiClient.new(
  public_key: "pk_...",
  secret_key: "sk_...",
  base_url: "https://cloud.langfuse.com",
  timeout: 5,
  logger: Logger.new($stdout)
)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(public_key:, secret_key:, base_url:, timeout: 5, logger: nil, cache: nil) ⇒ ApiClient

Initialize a new API client

Parameters:

  • public_key (String) —

    Langfuse public API key

  • secret_key (String) —

    Langfuse secret API key

  • base_url (String) —

    Base URL for Langfuse API

  • timeout (Integer) (defaults to: 5) —

    HTTP request timeout in seconds

  • logger (Logger) (defaults to: nil) —

    Logger instance for debugging

  • cache (PromptCache, RailsCacheAdapter, nil) (defaults to: nil) —

    Optional cache for prompt responses



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# File 'lib/langfuse/api_client.rb', line 52

def initialize(public_key:, secret_key:, base_url:, timeout: 5, logger: nil, cache: nil)
  @public_key = public_key
  @secret_key = secret_key
  @base_url = base_url
  @timeout = timeout
  @logger = logger || Logger.new($stdout, level: Logger::WARN)
  @cache = cache
end

Instance Attribute Details

#base_url ⇒ String (readonly)

Returns Base URL for Langfuse API.

Returns:

  • (String) —

    Base URL for Langfuse API



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# File 'lib/langfuse/api_client.rb', line 32

def base_url
  @base_url
end

#cache ⇒ PromptCache, ... (readonly)

Returns Optional cache for prompt responses.

Returns:



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# File 'lib/langfuse/api_client.rb', line 41

def cache
  @cache
end

#logger ⇒ Logger (readonly)

Returns Logger instance for debugging.

Returns:

  • (Logger) —

    Logger instance for debugging



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# File 'lib/langfuse/api_client.rb', line 38

def logger
  @logger
end

#public_key ⇒ String (readonly)

Returns Langfuse public API key.

Returns:

  • (String) —

    Langfuse public API key



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# File 'lib/langfuse/api_client.rb', line 26

def public_key
  @public_key
end

#secret_key ⇒ String (readonly)

Returns Langfuse secret API key.

Returns:

  • (String) —

    Langfuse secret API key



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# File 'lib/langfuse/api_client.rb', line 29

def secret_key
  @secret_key
end

#timeout ⇒ Integer (readonly)

Returns HTTP request timeout in seconds.

Returns:

  • (Integer) —

    HTTP request timeout in seconds



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# File 'lib/langfuse/api_client.rb', line 35

def timeout
  @timeout
end

Instance Method Details

#connection(timeout: nil) ⇒ Faraday::Connection

Get a Faraday connection

Parameters:

  • timeout (Integer, nil) (defaults to: nil) —

    Optional custom timeout for this connection

Returns:

  • (Faraday::Connection) 


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# File 'lib/langfuse/api_client.rb', line 65

def connection(timeout: nil)
  if timeout
    # Create dedicated connection for custom timeout
    # to avoid mutating shared connection
    build_connection(timeout: timeout)
  else
    @connection ||= build_connection
  end
end

#create_dataset(name:, description: nil, metadata: nil) ⇒ Hash

Create a new dataset

Examples:

data = api_client.create_dataset(name: "my-dataset", description: "QA evaluation set")

Parameters:

  • name (String) —

    Dataset name (required)

  • description (String, nil) (defaults to: nil) —

    Optional description

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata hash

Returns:

  • (Hash) —

    The created dataset data

Raises:



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# File 'lib/langfuse/api_client.rb', line 337

def create_dataset(name:, description: nil, metadata: nil)
  with_faraday_error_handling do
    payload = { name: name, description: description, metadata: metadata }.compact

    response = connection.post("/api/public/v2/datasets", payload)
    handle_response(response)
  end
end

#create_dataset_item(dataset_name:, input: nil, expected_output: nil, metadata: nil, id: nil, source_trace_id: nil, source_observation_id: nil, status: nil) ⇒ Hash

Create a new dataset item (or upsert if id is provided)

rubocop:disable Metrics/ParameterLists

Examples:

data = api_client.create_dataset_item(
  dataset_name: "my-dataset",
  input: { query: "What is Ruby?" },
  expected_output: { answer: "A programming language" }
)

Parameters:

  • dataset_name (String) —

    Name of the dataset (required)

  • input (Object, nil) (defaults to: nil) —

    Input data for the item

  • expected_output (Object, nil) (defaults to: nil) —

    Expected output for evaluation

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata

  • id (String, nil) (defaults to: nil) —

    Optional ID for upsert behavior

  • source_trace_id (String, nil) (defaults to: nil) —

    Link to source trace

  • source_observation_id (String, nil) (defaults to: nil) —

    Link to source observation

  • status (Symbol, nil) (defaults to: nil) —

    Item status (:active or :archived)

Returns:

  • (Hash) —

    The created dataset item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 367

def create_dataset_item(dataset_name:, input: nil, expected_output: nil,
                        metadata: nil, id: nil, source_trace_id: nil,
                        source_observation_id: nil, status: nil)
  with_faraday_error_handling do
    payload = build_dataset_item_payload(
      dataset_name: dataset_name, input: input, expected_output: expected_output,
      metadata: metadata, id: id, source_trace_id: source_trace_id,
      source_observation_id: source_observation_id, status: status
    )

    response = connection.post("/api/public/dataset-items", payload)
    handle_response(response)
  end
end

#create_dataset_run_item(dataset_item_id:, run_name:, trace_id: nil, observation_id: nil, metadata: nil, run_description: nil) ⇒ Hash

Create a dataset run item (link a trace to a dataset item within a run)

Examples:

api_client.create_dataset_run_item(dataset_item_id: "item-123", run_name: "eval-v1", trace_id: "trace-abc")

Parameters:

  • dataset_item_id (String) —

    Dataset item ID (required)

  • run_name (String) —

    Run name (required)

  • trace_id (String, nil) (defaults to: nil) —

    Trace ID to link

  • observation_id (String, nil) (defaults to: nil) —

    Observation ID to link

  • metadata (Hash, nil) (defaults to: nil) —

    Optional metadata

  • run_description (String, nil) (defaults to: nil) —

    Optional run description

Returns:

  • (Hash) —

    The created dataset run item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 249

def create_dataset_run_item(dataset_item_id:, run_name:, trace_id: nil,
                            observation_id: nil, metadata: nil, run_description: nil)
  with_faraday_error_handling do
    payload = { datasetItemId: dataset_item_id, runName: run_name }
    payload[:traceId] = trace_id if trace_id
    payload[:observationId] = observation_id if observation_id
    payload[:metadata] = metadata if metadata
    payload[:runDescription] = run_description if run_description

    response = connection.post("/api/public/dataset-run-items", payload)
    handle_response(response)
  end
end

#create_prompt(name:, prompt:, type:, config: {}, labels: [], tags: [], commit_message: nil) ⇒ Hash

Create a new prompt (or new version if prompt with same name exists)

rubocop:disable Metrics/ParameterLists

Examples:

Create a text prompt

api_client.create_prompt(
  name: "greeting",
  prompt: "Hello {{name}}!",
  type: "text",
  labels: ["production"]
)

Parameters:

  • name (String) —

    The prompt name

  • prompt (String, Array<Hash>) —

    The prompt content

  • type (String) —

    Prompt type (“text” or “chat”)

  • config (Hash) (defaults to: {}) —

    Optional configuration (model params, etc.)

  • labels (Array<String>) (defaults to: []) —

    Optional labels (e.g., [“production”])

  • tags (Array<String>) (defaults to: []) —

    Optional tags

  • commit_message (String, nil) (defaults to: nil) —

    Optional commit message

Returns:

  • (Hash) —

    The created prompt data

Raises:



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# File 'lib/langfuse/api_client.rb', line 147

def create_prompt(name:, prompt:, type:, config: {}, labels: [], tags: [], commit_message: nil)
  with_faraday_error_handling do
    path = "/api/public/v2/prompts"
    payload = {
      name: name,
      prompt: prompt,
      type: type,
      config: config,
      labels: labels,
      tags: tags
    }
    payload[:commitMessage] = commit_message if commit_message

    response = connection.post(path, payload)
    handle_response(response)
  end
end

#delete_dataset_item(id) ⇒ Hash

Note:

404 responses are treated as success to keep DELETE idempotent across retries

Delete a dataset item by ID

Examples:

api_client.delete_dataset_item("item-uuid-123")

Parameters:

  • id (String) —

    Dataset item ID

Returns:

  • (Hash) —

    The response body

Raises:



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# File 'lib/langfuse/api_client.rb', line 450

def delete_dataset_item(id)
  encoded_id = URI.encode_uri_component(id)
  response = connection.delete("/api/public/dataset-items/#{encoded_id}")
  handle_delete_dataset_item_response(response, id)
rescue Faraday::RetriableResponse => e
  logger.error("Faraday error: Retries exhausted - #{e.response.status}")
  handle_delete_dataset_item_response(e.response, id)
rescue Faraday::Error => e
  logger.error("Faraday error: #{e.message}")
  raise ApiError, "HTTP request failed: #{e.message}"
end

#get_dataset(name) ⇒ Hash

Fetch a dataset by name

Examples:

data = api_client.get_dataset("my-dataset")

Parameters:

  • name (String) —

    Dataset name (supports folder paths like “evaluation/qa-dataset”)

Returns:

  • (Hash) —

    The dataset data

Raises:



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# File 'lib/langfuse/api_client.rb', line 318

def get_dataset(name)
  with_faraday_error_handling do
    encoded_name = URI.encode_uri_component(name)
    response = connection.get("/api/public/v2/datasets/#{encoded_name}")
    handle_response(response)
  end
end

#get_dataset_item(id) ⇒ Hash

Fetch a dataset item by ID

Examples:

data = api_client.get_dataset_item("item-uuid-123")

Parameters:

  • id (String) —

    Dataset item ID

Returns:

  • (Hash) —

    The dataset item data

Raises:



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# File 'lib/langfuse/api_client.rb', line 393

def get_dataset_item(id)
  with_faraday_error_handling do
    encoded_id = URI.encode_uri_component(id)
    response = connection.get("/api/public/dataset-items/#{encoded_id}")
    handle_response(response)
  end
end

#get_projects ⇒ Hash

Fetch projects accessible with the current API keys

Examples:

data = api_client.get_projects
project_id = data["data"][0]["id"]

Returns:

  • (Hash) —

    The parsed response body containing project data

Raises:



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# File 'lib/langfuse/api_client.rb', line 272

def get_projects # rubocop:disable Naming/AccessorMethodName
  with_faraday_error_handling do
    response = connection.get("/api/public/projects")
    handle_response(response)
  end
end

#get_prompt(name, version: nil, label: nil) ⇒ Hash

Fetch a prompt from the Langfuse API

Checks cache first if caching is enabled. On cache miss, fetches from API and stores in cache. When using Rails.cache backend, uses distributed lock to prevent cache stampedes.

Parameters:

  • name (String) —

    The name of the prompt

  • version (Integer, nil) (defaults to: nil) —

    Optional specific version number

  • label (String, nil) (defaults to: nil) —

    Optional label (e.g., “production”, “latest”)

Returns:

  • (Hash) —

    The prompt data

Raises:

  • (ArgumentError) —

    if both version and label are provided

  • (NotFoundError) —

    if the prompt is not found

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors



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# File 'lib/langfuse/api_client.rb', line 117

def get_prompt(name, version: nil, label: nil)
  raise ArgumentError, "Cannot specify both version and label" if version && label
  return fetch_prompt_from_api(name, version: version, label: label) if cache.nil?

  cache_key = PromptCache.build_key(name, version: version, label: label)
  fetch_with_appropriate_caching_strategy(cache_key, name, version, label)
end

#list_dataset_items(dataset_name:, page: nil, limit: nil, source_trace_id: nil, source_observation_id: nil) ⇒ Array<Hash>

List items in a dataset with optional filters

Examples:

items = api_client.list_dataset_items(dataset_name: "my-dataset", limit: 50)

Parameters:

  • dataset_name (String) —

    Name of the dataset (required)

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page

  • source_trace_id (String, nil) (defaults to: nil) —

    Filter by source trace ID

  • source_observation_id (String, nil) (defaults to: nil) —

    Filter by source observation ID

Returns:

  • (Array<Hash>) —

    Array of dataset item hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 414

def list_dataset_items(dataset_name:, page: nil, limit: nil,
                       source_trace_id: nil, source_observation_id: nil)
  result = list_dataset_items_paginated(
    dataset_name: dataset_name, page: page, limit: limit,
    source_trace_id: source_trace_id, source_observation_id: source_observation_id
  )
  result["data"] || []
end

#list_dataset_items_paginated(dataset_name:, page: nil, limit: nil, source_trace_id: nil, source_observation_id: nil) ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Full paginated response including “meta” for internal pagination use

Returns:

  • (Hash) —

    Full response hash with “data” array and “meta” pagination info



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# File 'lib/langfuse/api_client.rb', line 427

def list_dataset_items_paginated(dataset_name:, page: nil, limit: nil,
                                 source_trace_id: nil, source_observation_id: nil)
  with_faraday_error_handling do
    params = build_dataset_items_params(
      dataset_name: dataset_name, page: page, limit: limit,
      source_trace_id: source_trace_id, source_observation_id: source_observation_id
    )

    response = connection.get("/api/public/dataset-items", params)
    handle_response(response)
  end
end

#list_datasets(page: nil, limit: nil) ⇒ Array<Hash>

List all datasets in the project

Examples:

datasets = api_client.list_datasets(page: 1, limit: 10)

Parameters:

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page

Returns:

  • (Array<Hash>) —

    Array of dataset metadata hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 298

def list_datasets(page: nil, limit: nil)
  with_faraday_error_handling do
    params = { page: page, limit: limit }.compact

    response = connection.get("/api/public/v2/datasets", params)
    result = handle_response(response)
    result["data"] || []
  end
end

#list_prompts(page: nil, limit: nil) ⇒ Array<Hash>

List all prompts in the Langfuse project

Fetches a list of all prompt names available in your project. Note: This returns metadata only, not full prompt content.

Examples:

prompts = api_client.list_prompts
prompts.each do |prompt|
  puts "#{prompt['name']} (v#{prompt['version']})"
end

Parameters:

  • page (Integer, nil) (defaults to: nil) —

    Optional page number for pagination

  • limit (Integer, nil) (defaults to: nil) —

    Optional limit per page (default: API default)

Returns:

  • (Array<Hash>) —

    Array of prompt metadata hashes

Raises:



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# File 'lib/langfuse/api_client.rb', line 91

def list_prompts(page: nil, limit: nil)
  with_faraday_error_handling do
    params = { page: page, limit: limit }.compact

    response = connection.get("/api/public/v2/prompts", params)
    result = handle_response(response)

    # API returns { data: [...], meta: {...} }
    result["data"] || []
  end
end

#send_batch(events) ⇒ void

This method returns an undefined value.

Send a batch of events to the Langfuse ingestion API

Sends events (scores, traces, observations) to the ingestion endpoint. Retries transient errors (429, 503, 504, network errors) with exponential backoff. Batch operations are idempotent (events have unique IDs), so retries are safe.

Examples:

events = [
  {
    id: SecureRandom.uuid,
    type: "score-create",
    timestamp: Time.now.iso8601,
    body: { name: "quality", value: 0.85, trace_id: "abc123..." }
  }
]
api_client.send_batch(events)

Parameters:

  • events (Array<Hash>) —

    Array of event hashes to send

Raises:

  • (ArgumentError) —

    if events is not an Array or is empty

  • (UnauthorizedError) —

    if authentication fails

  • (ApiError) —

    for other API errors after retries exhausted



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# File 'lib/langfuse/api_client.rb', line 217

def send_batch(events)
  raise ArgumentError, "events must be an array" unless events.is_a?(Array)
  raise ArgumentError, "events array cannot be empty" if events.empty?

  path = "/api/public/ingestion"
  payload = { batch: events }

  response = connection.post(path, payload)
  handle_batch_response(response)
rescue Faraday::RetriableResponse => e
  # Retry middleware exhausted all retries - handle the final response
  logger.error("Langfuse batch send failed: Retries exhausted - #{e.response.status}")
  handle_batch_response(e.response)
rescue Faraday::Error => e
  logger.error("Langfuse batch send failed: #{e.message}")
  raise ApiError, "Batch send failed: #{e.message}"
end

#shutdown ⇒ void

This method returns an undefined value.

Shut down the API client and release resources

Shuts down the cache if it supports shutdown (e.g., SWR thread pool).



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# File 'lib/langfuse/api_client.rb', line 284

def shutdown
  cache.shutdown if cache.respond_to?(:shutdown)
end

#update_prompt(name:, version:, labels:) ⇒ Hash

Update labels for an existing prompt version

Examples:

Promote a prompt to production

api_client.update_prompt(
  name: "greeting",
  version: 2,
  labels: ["production"]
)

Parameters:

  • name (String) —

    The prompt name

  • version (Integer) —

    The version number to update

  • labels (Array<String>) —

    New labels (replaces existing). Required.

Returns:

  • (Hash) —

    The updated prompt data

Raises:



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# File 'lib/langfuse/api_client.rb', line 183

def update_prompt(name:, version:, labels:)
  raise ArgumentError, "labels must be an array" unless labels.is_a?(Array)

  with_faraday_error_handling do
    path = "/api/public/v2/prompts/#{URI.encode_uri_component(name)}/versions/#{version}"
    payload = { newLabels: labels }

    response = connection.patch(path, payload)
    handle_response(response)
  end
end