Basic Usage

Once it is set up and running, Tangelo’s basic usage is relatively straightforward. This chapter explains how Tangelo serves web content, a best practices guide for organizing your content, and how to use HTTP authentication to protect your content.

Serving Web Content

Tangelo’s most basic purpose is to serve web content. Once Tangelo is running, it will serve content it finds in several places.

User home directories. If you visit a URL whose first path component begins with a tilde (“~”), such as http://localhost:8080/~spock, Tangelo will attempt to serve content from the tangelo_html directory of user spock‘s home directory. On a Linux system, this might be the directory /home/spock/tangelo_html.

Web root directory. Visiting other URLs (that do not begin with a tilde) will cause Tangelo to serve content out of the web root directory, which is set in the Tangelo configuration file, or by the -r (or --root) flag when Tangelo is launched (see Setup and Administration). For example, if the web root directory is set to /srv/tangelo/root, visiting http://localhost:8080/ would serve content from that directory, and visiting http://localhost:8080/foobar would serve content from /srv/tangelo/root/foobar, etc.

Plugin content directories. The URLs rooted at http://localhost:8080/plugin refer to web content served by any active Tangelo plugins. As such, files in plugin subdirectory of the web root directory will not be served by Tangelo. For information about how Tangelo plugins work, see Tangelo Plugins.

The foregoing examples demonstrate how Tangelo associates URLs to directories and files in the filesystem. URLs referencing particular files will cause Tangelo to serve that file immediately. URLs referencing a directory behave according to the following cascade of rules:

  1. If the directory contains a file named index.html, that file will be served.
  2. Otherwise, if the directory contains a file named index.htm, that file will be served.
  3. Otherwise, Tangelo will generate a directory listing for that directory and serve that. This listing will include hyperlinks to the files contained therein.

Furthermore, any URL referring to a Python script, but lacking the final .py, names a web service; such URLs do not serve static content, but rather run the referred Python script and serve the results (see Tangelo Web Services).

The following table summarizes Tangelo’s URL types:

URL type Example Behavior
Home directory http://localhost:8080/~troi/schedule.html serve /home/troi/tangelo_html/schedule.html
Web root http://localhost:8080/holodeck3/status.html serve /srv/tangelo/root/holodeck3/status.html
Indexed directory http://localhost:8080/tenforward serve /srv/tangelo/root/tenforward/index.html
Unindexed directory http://localhost:8080/warpdrive serve directory listing for /srv/tangelo/root/warpdrive
Web service http://localhost:8080/lcars/lookup serve result of executing run() function of /srv/tangelo/lcars/lookup.py
Plugin http://localhost:8080/plugin/foobar/... serve content from foobar plugin

HTTP Authentication

Tangelo supports HTTP Digest Authentication to password protect web directories. The process to protect a directory is as follows:

  1. Go to the directory you wish to protect:

    cd ~laforge/tangelo_html/DilithiumChamberStats
    

    The idea is, this directory (which is accessible on the web as http://localhost:8080/~laforge/DilithiumChamberStats) contains sensitive information, and should be restricted to just certain people who have a password.

  2. Create a file there called .htaccess and make it look like the following example, customizing it to fit your needs:

    AuthType digest
    AuthRealm USS Enterprise NCC-1701-D
    AuthPasswordFile /home/laforge/secret/dilithiumpw.txt
    

    This file requestes digest authnetication on the directory, sets the authentication realm to be the string “USS Enterprise NCC-1701-D”, and specifies that the acceptable usernames and passwords will be found in the file /home/laforge/secret/dilithiumpw.txt.

    Currently, the only supported authentication type is digest. The realm will be displayed to the user when prompted for a username and password.

  3. Create the password file, using the tangelo-passwd program (see tangelo-passwd):

    $ tangelo-passwd -c ~laforge/secret/dilithiumpw.txt "USS Enterprise NCC-1701-D" picard
    Enter password for picard@USS Enterprise NCC-1701-D: <type password here>
    Re-enter password: <retype password here>
    

    This will create a new password file. If you inspect the file, you will see a user picard associated with an md5 hash of the password that was entered. You can add more users by repeating the command without the -c flag, and changing the username.

    At this point, the directory is password protected - when you visit the page, you will be prompted for a username and password, and access to the page will be restricted until you provide valid ones.