Setup and Administration¶
While the Quick Start instructions will get you exploring the Tangelo examples in just two commands, Tangelo has a rich set of configuration options that can be used to administer Tangelo effectively. This page will discuss configuration and deployment strategies, including suggestions for best practices.
Configuring and Launching Tangelo¶
The simplest way to launch a Tangelo server is to use this command:
(This command causes Tangelo to begin serving content out of the current directory on the default port, 8080.)
Tangelo’s runtime behaviors are specified via configuration file and command line options. Tangelo configuration files are YAML files representing a key-value store (“associative array” in YAML jargon) at the top level. Each options is specified as a key-value pair: the line starts with the name of the key, then a colon followed by a space, and then the value.
The example configuration found at
/usr/share/tangelo/conf/tangelo.local.conf reads something like the
hostname: 0.0.0.0 port: 8080
This minimal configuration file specifies that Tangelo should listen on all
interfaces for connections on port 8080. By contrast,
looks like this:
hostname: 0.0.0.0 port: 80 user: nobody group: nobody
This configuration file is meant for the case when Tangelo is to be installed as
a system-level service. It will run on port 80 (the standard port for an HTTP
server) and, though it will need to be started with superuser privileges, it
will drop those privleges to run as user
nobody in group
prevent damage to the system should the process be, e.g., hijacked by an
To run Tangelo using a particular configuration file,
tangelo can be invoked
tangelo -c ~/myconfig.yaml
When the flag is omitted, Tangelo will use default values for all configuration options (see Configuration Options below).
Finally, all configuration options can also be specified on the command line. This has the effect of overriding whatever value may be set in the specified configuration file. This can be useful for, e.g., using a single configuration file for multiple Tangelo instances, but varying the port number.
The following table shows what fields can be included in the configuration file, what they mean, and their default values if left unspecified.
|hostname||The hostname interface on which to listen for connections||
|port||The port number on which to listen for connections||
|root||The path to the directory to be served by Tangelo as the web root||
|drop-privileges||Whether to drop privileges when started as the superuser||
|sessions||Whether to enable server-side session tracking||
|user||The user account to drop privileges to||
|group||The user group to drop privileges to||
|access-auth||Whether to protect directories containing a
|key||The path to the SSL key||
|cert||The path to the SSL certificate||
|plugins||A list of plugins to load (see Plugin Configuration)||
|||This is to say, Tangelo serves from the directory in which it was invoked by default.|
|||(1, 2) Your Unix system may already have a user named “nobody” which has the least possible level of permissions. The theory is that system daemons can be run as this user, limiting the damage a rogue process can do. However, if multiple daemons are run this way, any rogue daemon can theoretically gain control of the others. Therefore, the recommendation is to create a new user named “tangelo”, that also has minimal permissions, but is only used to run Tangelo in privilege drop mode.|
|||(1, 2) You must also specify both key and cert to serve content over https.|
|||(1, 2, 3) That is to say, the option is simply unset by default, the equivalent of not mentioning the option at all in a configuration file.|
|||This option can only appear in the configuration file; there is no command line equivalent.|
Administering a Tangelo Installation¶
Administering Tangelo on a particular system requires making some decisions about how Tangelo ought to behave, then implementing those decisions in a configuration file.
For example, as the system administrator you might create a directory on the web
server machine at
/srv/tangelo which would serve as the web root, containing
the website front page and supporting materials.
You should then prepare a plugin configuration file that, at the very least, activates the Tangelo plugin:
enabled: true path: /usr/share/tangelo/plugins/tangelo
This file can be saved to
It remains to configure Tangelo itself. The hostname should reflect the desired external identity of the Tangelo server - perhaps excelsior.starfleet.mil. As this is a “global” deployment, we want to listen on port 80 for connections. Since we will need to start Tangelo as root (to gain access to the low-numbered ports), we should also specify a user and group to drop privileges to: these can be the specially created user and group tangelo.
The corresponding configuration file might look like this:
# Network options. hostname: excelsior.starfleet.mil port: 80 # Privilege drop options. user: tangelo group: tangelo # Runtime resources. root: /srv/tangelo
This file should be saved to
/etc/tangelo.conf, and then Tangelo can be
launched with a command like
tangelo -c /etc/tangelo.conf (running the
sudo may be necessary to allow for port 80 to be bound).
A Note on Version Numbers¶
Tangelo uses semantic versioning for its version numbers, meaning that each release’s version number establishes a promise about the levels of functionality and backwards compatibility present in that release. Tangelo’s version numbers come in two forms: x.y and x.y.z. x is a major version number, y is a minor version number, and z is a patch level.
Following the semantic versioning approach, major versions represent a stable API for the software as a whole. If the major version number is incremented, it means you can expect a discontinuity in backwards compatibility. That is to say, a setup that works for, e.g., version 1.3 will work for versions 1.4, 1.5, and 1.10, but should not be expected to work with version 2.0.
The minor versions indicate new features or functionality added to the previous version. So, version 1.1 can be expected to contain some feature not found in version 1.0, but backwards compatibility is ensured.
The patch level is incremented when a bug fix or other correction to the software occurs.
Major version 0 is special: essentially, there are no guarantees about compatibility in the 0.y series. The stability of APIs and behaviors begins with version 1.0.
In addition to the standard semantic versioning practices, Tangelo also tags the current version number with “dev” in the Git repository, resulting in version numbers like “1.1dev” for the Tangelo package that is built from source. The release protocol deletes this tag from the version number before uploading a package to the Python Package Index.