Connections

These arguments choose the socket. They are client defaults, and a request can override them.

Local address

interface is the local side of the connection. Pass a network interface (eth0), an IP address, or a more specific form: if!eth0 for the interface, host!192.0.2.10 for the address, ifhost!eth0!192.0.2.10 for both. A hostname here waits on DNS, so pass a name or an address. On Windows, use an IP address. Interface names are ignored there.

ip_version is "any", "4", or "6". It limits which addresses of a hostname may be used, including when a pooled connection is reused. A URL that is already a numeric address is used as written.

async with Client(interface="eth0", ip_version="4") as client:
    await client.get("https://example.com", interface="")  # this call does not bind

Binding to an address the machine does not have raises InterfaceFailedError.

Proxy

proxy_url is per request. http://user:pass@proxy:8080 is enough for proxy authentication.

no_proxy is the list of hosts that skip the proxy. Separate them with commas. example.com also matches www.example.com, and it does not match example.com.org. A network such as 192.168.0.0/16 matches every address in it. * skips the proxy for every host.

async with Client(no_proxy="localhost,127.0.0.1") as client:
    await client.get("https://example.com", proxy_url="http://proxy:8080")
    await client.get("http://127.0.0.1:8080", proxy_url="http://proxy:8080")  # direct

Leave no_proxy as None and RedC honors the no_proxy or NO_PROXY environment variable, when one is set. "" ignores that variable and sends every host through the proxy.

Unix sockets

unix_socket connects to a filesystem socket instead of the host in the URL. The URL still supplies the request path and the Host header. A proxy is not used for that transfer.

async with Client(unix_socket="/var/run/docker.sock") as client:
    info = await client.get("http://localhost/v1.41/info")

unix_socket="" on a request goes back to TCP. The path limit is 107 bytes on Linux.

What may be requested

A request can use http, https, or file. A redirect can use http or https only. Anything else is rejected.