janus

janus

janus is a no-configuration, single binary file server.

Why janus?

In ancient Roman religion, Janus (/ˈdʒeɪnəs/ JAY-nəs; Latin: IANVS (Iānus), pronounced [ˈjaːnʊs]) is the god of gates, transitions, doorways, passages, frames and more. He is usually depicted as having two faces, since he looks to the future and to the past.

Therefore, it is the ideal name for a lightweight file server, which supports downloads and uploads.

Installation

go get -v github.com/abc-inc/janus

Simple Usage & Directory Listing

janus requires no configuration file. All options are set via command line flags and/or environment variables. A list of options can be displayed by invoking janus -h:

Usage:
  janus [OPTIONS]

Application Options:
  -b, --client-body-buffer-size= total number of kilobytes stored in memory (per upload) (default: 8)
  -d, --server-root=             root directory to serve (default: .) [$JANUS_SERVER_ROOT]
  -l, --listen=                  host address and port to bind to (default: :8080) [$JANUS_LISTEN]
  -p, --prefix=                  prefix for the HTTP URLs (default: /) [$JANUS_PREFIX]
  -u, --enable-upload            enable upload of files by adding "?upload" [$JANUS_ENABLE_UPLOAD]
  -v, --version                  print version information

Help Options:
  -h, --help           Show this help message

For example, the following command starts janus serving the current directory (and restricts access to localhost only):

janus -l localhost:8080

When accessing a file, janus will stream its content. Additionally, it supports directory listing e.g.,

curl http://localhost:8080/

outputs

<pre>
<a href=".gitignore">.gitignore</a>
<a href="LICENSE">LICENSE</a>
<a href="Makefile">Makefile</a>
<a href="NOTES.md">NOTES.md</a>
<a href="README.md">README.md</a>
<a href="go.mod">go.mod</a>
<a href="go.sum">go.sum</a>
<a href="main.go">main.go</a>
<a href="main_test.go">main_test.go</a>
</pre>

The listen argument also supports interface names in addition to IP addresses and hostnames. The following example starts janus listening on the IP of eth0 at port 8081:

janus -l eth0:8081
2020-11-01 12:34:56 INF Resolving IP for bind address IP=192.168.0.250 interface=eth0
2020-11-01 12:34:56 INF Starting server enable-upload=false listen=192.168.0.1:8081 prefix=/ server-root=.

Upload

For security reasons file upload is disabled by default. When enabled, janus accepts HTTP POST requests (multipart/form-data) and stores the file in the directory where the URL is pointing to.

The following example starts janus and configures it to take files sent to http://<HOST>:8080/files and saves them in the uploads directory.

janus -d uploads -p /files -u

Files can be uploaded via the built-in web interface by appending ?upload to a directory e.g., http://192.168.0.250:8080/files/images?upload, or by sending an HTTP POST request e.g.,

curl -F file=@logo.png http://localhost:8080/files/images/

The uploaded file will be saved as uploads/images/logo.png.

Alternatives

• https://github.com/syntaqx/serve

  janus is heavily inspired by serve, which is an excellent file server with more features such as Basic authentication and TLS.