nodus-http

Outbound HTTP client with circuit breaker, retry, and OTel trace propagation.

Wraps httpx with optional circuit-breaker protection, configurable retry logic, and trace ID header injection. All integrations are constructor-injected — no globals or module-level configuration.

Status: v0.1.0 — prepared, not yet published.

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Install

pip install nodus-http

# With circuit breaker:
pip install "nodus-http[circuit-breaker]"

# With OTel trace propagation:
pip install "nodus-http[otel]"

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What it provides

Component	Purpose
HttpClient	httpx wrapper with circuit breaker, retry, and trace headers
HttpResponse	Normalised response: status_code, headers, body, json(), ok
RetryConfig	Retry settings: max attempts, retryable status codes, backoff
inject_trace_headers	Add X-Trace-ID to a headers dict via callback

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Quick start

from nodus_http import HttpClient

client = HttpClient(base_url="https://api.example.com", timeout=10.0)
response = client.get("/users/123")

if response.ok:
    data = response.json()

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HttpClient

from nodus_http import HttpClient, RetryConfig
from nodus_circuit_breaker import CircuitBreaker

client = HttpClient(
    base_url="https://api.example.com",
    timeout=10.0,
    default_headers={"Authorization": "Bearer my-token"},
    retry_config=RetryConfig(
        max_attempts=3,
        retryable_status_codes={429, 502, 503, 504},
        backoff_ms=200,
        exponential=True,
    ),
    circuit_breaker=CircuitBreaker("api.example.com", failure_threshold=5),
    get_trace_id_fn=lambda: my_context.trace_id,  # optional
)

# Sync
response = client.get("/path")
response = client.post("/path", json={"key": "value"})
response = client.put("/path", json={...})
response = client.delete("/path")
response = client.request("PATCH", "/path", json={...})

# Async
response = await client.get_async("/path")
response = await client.post_async("/path", json={...})

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HttpResponse

response.ok           # True if 2xx
response.status_code  # int
response.headers      # dict
response.body         # bytes
response.json()       # parsed JSON (dict | list | ...)
response.text         # decoded string

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RetryConfig

from nodus_http import RetryConfig

config = RetryConfig(
    max_attempts=3,
    retryable_status_codes={429, 502, 503, 504},
    backoff_ms=100,
    exponential=True,   # doubles each attempt: 100ms, 200ms, 400ms
)

Retries fire on network errors and on responses with a retryable status code. Non-retryable errors (4xx except those in retryable_status_codes) are not retried.

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Trace header injection

from nodus_http import inject_trace_headers

headers = {"Content-Type": "application/json"}
headers = inject_trace_headers(headers, get_trace_id_fn=lambda: "trace-abc")
# headers now includes "X-Trace-ID": "trace-abc"

Pass get_trace_id_fn to HttpClient to inject the trace ID automatically on every request.

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Circuit breaker

Pass any object with a .call(fn) method as circuit_breaker. The nodus-circuit-breaker package provides a compatible CircuitBreaker:

pip install "nodus-http[circuit-breaker]"

from nodus_circuit_breaker import CircuitBreaker

cb = CircuitBreaker("my-api", failure_threshold=3, recovery_timeout_secs=30)
client = HttpClient("https://api.example.com", circuit_breaker=cb)

When the circuit is open, client.get(...) raises CircuitOpenError.

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Design

• httpx required. All other integrations (circuit breaker, retry, trace) are injected and optional.
• No globals. All configuration is per-HttpClient instance.
• Normalised response. HttpResponse wraps httpx responses with a consistent interface regardless of sync/async path.

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Development

pip install -e ".[dev]"
pytest tests/ -q

Tests use respx for request mocking.

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License

MIT — see LICENSE.