HTTPower.Adapter.Tesla (HTTPower v0.23.0)

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Tesla adapter for HTTPower.

This adapter allows HTTPower to work with existing Tesla clients, enabling you to add HTTPower's production features (circuit breakers, rate limiting, retry logic, PCI logging) on top of your existing Tesla setup without rewriting your HTTP infrastructure.

Features

  • Works with any Tesla client configuration
  • Preserves Tesla middleware stack
  • Supports all Tesla adapters (Finch, Hackney, Mint, Gun, etc.)
  • Transparent pass-through of Tesla features

Configuration

The Tesla adapter requires a Tesla client to be passed in the options:

# Create your Tesla client
tesla_client = Tesla.client([
  Tesla.Middleware.BaseUrl.new("https://api.example.com"),
  Tesla.Middleware.JSON,
  Tesla.Middleware.Logger
])

# Use with HTTPower
client = HTTPower.new(
  adapter: {HTTPower.Adapter.Tesla, tesla_client}
)

HTTPower.get(client, "/users")

Testing

For testing, you can use Tesla's testing capabilities:

# Use Tesla.Mock for testing
Tesla.Mock.mock(fn
  %{method: :get, url: "https://api.example.com/users"} ->
    %Tesla.Env{status: 200, body: %{"users" => []}}
end)

Or use HTTPower's test mode blocking:

Application.put_env(:httpower, :test_mode, true)
# Requests will be blocked unless using a test adapter

Tesla Client Middleware

The Tesla adapter respects all middleware in your Tesla client:

  • Authentication middleware (Bearer, Basic, OAuth)
  • Retry middleware (note: disable if using HTTPower's retry)
  • Logging middleware
  • Custom middleware

Important: JSON Middleware

If your Tesla client includes Tesla.Middleware.JSON, you should remove it when wrapping with HTTPower. HTTPower handles JSON encoding/decoding via HTTPower.Codec, and having both active will cause double-decoding:

# Before (double-decoding risk)
Tesla.client([Tesla.Middleware.JSON])

# After (correct)
Tesla.client([])  # HTTPower handles JSON via json: option

Connection options are configured on the Tesla client, not per request

Unlike the Finch and Req adapters, this adapter does not forward the timeout, ssl_verify, or proxy request options to Tesla — Tesla configures those on the client itself (e.g. Tesla.Middleware.Timeout and the chosen Tesla adapter's transport/proxy options). Passing them to HTTPower.get/2 etc. with this adapter has no effect; configure them when you build the Tesla client instead.

Example

# Define Tesla client with middleware
defmodule MyApp.ApiClient do
  use Tesla

  plug Tesla.Middleware.BaseUrl, "https://api.example.com"
  plug Tesla.Middleware.JSON
  plug Tesla.Middleware.Headers, [{"authorization", "Bearer token"}]

  # Use Finch adapter
  adapter Tesla.Adapter.Finch, name: MyApp.Finch
end

# Wrap with HTTPower for production features
tesla_client = MyApp.ApiClient.client()

client = HTTPower.new(
  adapter: {HTTPower.Adapter.Tesla, tesla_client},
  circuit_breaker: [threshold: 5],  # Future feature
  rate_limit: [requests: 100, per: :second]  # Future feature
)

# Make requests - Tesla handles HTTP, HTTPower adds reliability
{:ok, response} = HTTPower.get(client, "/users")