LangfusePromptProvider

This docs was updated at: 2026-02-23

com.paragon.prompts.LangfusePromptProvider  ·  Class

Implements PromptProvider

---

A PromptProvider that retrieves prompts from the Langfuse API.

This provider fetches prompts from Langfuse's prompt management service, supporting versioned prompts, labels, and both text and chat prompt types. It includes automatic retry with exponential backoff for transient failures.

Usage Example

// Create provider with builder
PromptProvider provider = LangfusePromptProvider.builder()
    .httpClient(new OkHttpClient())
    .publicKey("pk-lf-xxx")
    .secretKey("sk-lf-xxx")
    .build();
// Retrieve a prompt
Prompt prompt = provider.providePrompt("my-prompt-name");
// Retrieve a specific version
Prompt prompt = provider.providePrompt("my-prompt", Map.of("version", "2"));
// Retrieve by label
Prompt prompt = provider.providePrompt("my-prompt", Map.of("label", "staging"));

Supported Filters

• version - Retrieve a specific prompt version (integer)
• label - Retrieve prompt by label (e.g., "production", "staging")

Since: 1.0

Fields

DEFAULT_BASE_URL

public static final String DEFAULT_BASE_URL = "https://cloud.langfuse.com"

Default Langfuse cloud API base URL.

Methods

builder

public static @NonNull Builder builder()

Creates a new builder for LangfusePromptProvider.

Returns

a new builder instance

---

baseUrl

public @NonNull String baseUrl()

Returns the base URL for the Langfuse API.

Returns

the base URL

---

retryPolicy

public @NonNull RetryPolicy retryPolicy()

Returns the retry policy used by this provider.

Returns

the retry policy

---

httpClient

public @NonNull Builder httpClient(@NonNull OkHttpClient httpClient)

Sets the HTTP client to use for API requests.

Parameters

Name	Description
httpClient	the OkHttp client

Returns

this builder

---

publicKey

public @NonNull Builder publicKey(@NonNull String publicKey)

Sets the Langfuse public key.

Parameters

Name	Description
publicKey	the public API key

Returns

this builder

---

secretKey

public @NonNull Builder secretKey(@NonNull String secretKey)

Sets the Langfuse secret key.

Parameters

Name	Description
secretKey	the secret API key

Returns

this builder

---

baseUrl

public @NonNull Builder baseUrl(@NonNull String baseUrl)

Sets the Langfuse API base URL.

Defaults to LangfusePromptProvider#DEFAULT_BASE_URL.

Parameters

Name	Description
baseUrl	the base URL

Returns

this builder

---

retryPolicy

public @NonNull Builder retryPolicy(@NonNull RetryPolicy retryPolicy)

Sets the retry policy for handling transient failures.

Defaults to RetryPolicy.defaults().

Parameters

Name	Description
retryPolicy	the retry policy

Returns

this builder

---

objectMapper

public @NonNull Builder objectMapper(@NonNull ObjectMapper objectMapper)

Sets a custom ObjectMapper for JSON deserialization.

Parameters

Name	Description
objectMapper	the ObjectMapper

Returns

this builder

---

fromEnv

public @NonNull Builder fromEnv()

Creates a provider using environment variables.

Reads LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY, and optionally LANGFUSE_HOST.

Returns

this builder with environment configuration

---

build

public @NonNull LangfusePromptProvider build()

Builds the LangfusePromptProvider.

Returns

a new LangfusePromptProvider

Throws

Type	Condition
NullPointerException	if httpClient, publicKey, or secretKey is not set