Responder CLI

Responder installs a command line program responder. Use it to launch a Responder application from a file or module, either located on a local or remote filesystem, or object store.

Launch Module Entrypoint

For loading a Responder application from a Python module, you will refer to its API() instance using a Python entry point object reference that points to a Python object. It is either in the form importable.module, or importable.module:object.attr.

A basic invocation command to launch a Responder application:

responder run acme.app

The command above assumes a Python package acme including an app module acme/app.py that includes an attribute api that refers to a responder.API instance, reflecting the typical layout of a standard Responder application.

Loading a Responder application using an entrypoint specification will inherit the capacities of Python’s import system, as implemented by importlib.

Launch Local File

Acquire a minimal example single-file application, helloworld.py [1], to your local filesystem, giving you the chance to edit it, and launch the Responder HTTP service.

wget https://github.com/kennethreitz/responder/raw/refs/heads/main/examples/helloworld.py
responder run helloworld.py

Note

To validate the example application, invoke a HTTP request, for example using curl, HTTPie, or your favourite browser at hand.

http http://127.0.0.1:5042/Hello

The response is no surprise.

HTTP/1.1 200 OK
content-length: 13
content-type: text/plain
date: Sat, 26 Oct 2024 13:16:55 GMT
encoding: utf-8
server: uvicorn

Hello, world!

[1]

The Responder application helloworld.py implements a basic echo handler.

Launch Remote File

You can also launch a single-file application where its Python file is stored on a remote location.

Responder supports all filesystem adapters compatible with fsspec, and installs the adapters for Azure Blob Storage (az), Google Cloud Storage (gs), GitHub, HTTP, and AWS S3 by default.

# Works 1:1.
responder run https://github.com/kennethreitz/responder/raw/refs/heads/main/examples/helloworld.py
responder run github://kennethreitz:responder@/examples/helloworld.py

If you need access other kinds of remote targets, see the list of fsspec-supported filesystems and protocols. The next section enumerates a few synthetic examples. The corresponding storage buckets do not even exist, so don’t expect those commands to work.

# Azure Blob Storage, Google Cloud Storage, and AWS S3.
responder run az://kennethreitz-assets/responder/examples/helloworld.py
responder run gs://kennethreitz-assets/responder/examples/helloworld.py
responder run s3://kennethreitz-assets/responder/examples/helloworld.py

# Hadoop Distributed File System (hdfs), SSH File Transfer Protocol (sftp),
# Common Internet File System (smb), Web-based Distributed Authoring and
# Versioning (webdav).
responder run hdfs://kennethreitz-assets/responder/examples/helloworld.py
responder run sftp://user@host/kennethreitz/responder/examples/helloworld.py
responder run smb://workgroup;user:password@server:port/responder/examples/helloworld.py
responder run webdav+https://user:password@server:port/responder/examples/helloworld.py

Tip

In order to install support for all filesystem types supported by fsspec, run:

uv pip install 'fsspec[full]'

When using uv, this concludes within an acceptable time of approx. 25 seconds. If you need to be more selectively instead of using full, choose from one or multiple of the available fsspec extras, which are:

abfs, arrow, dask, dropbox, fuse, gcs, git, github, hdfs, http, oci, s3, sftp, smb, ssh.

Launch with Non-Standard Instance Name

By default, Responder will acquire an responder.API instance using the symbol name api from the specified Python module.

If your main application file uses a different name than api, please append the designated symbol name to the launch target address.

It works like this for module entrypoints and local files:

responder run acme.app:service
responder run /path/to/acme/app.py:service

It works like this for URLs:

responder run http://app.server.local/path/to/acme/app.py#service

Within your app.py, the instance would have been defined to use the service symbol name instead of api, like this:

service = responder.API()

Build JavaScript Application

The build subcommand invokes npm run build, optionally accepting a target directory. By default, it uses the current working directory, where it expects a regular NPM package.json file.

responder build

When specifying a target directory, Responder will change to that directory beforehand.

responder build /path/to/project