The Trac Environment

Trac uses a directory structure and a database for storing project data. The directory is referred to as the environment.

Trac supports ​SQLite, ​PostgreSQL and ​MySQL databases. With PostgreSQL and MySQL you have to create the database before running trac-admin initenv.

Creating an Environment

A new Trac environment is created using the initenv command:

$ trac-admin /path/to/myproject initenv

trac-admin will ask you for the name of the project and the database connection string.

A base configuration can be specified using the --inherit or --config options. The --inherit option can be specified one or more times to utilize a global configuration. The options specified in a --config file will be used to override the defaults when initializing trac.ini. See below for an example of defining repositories in a configuration file.

Useful Tips

• Place your environment's directory on a filesystem which supports sub-second timestamps, as Trac monitors the timestamp of its configuration files and changes happening on a filesystem with too coarse-grained timestamp resolution may go undetected in Trac < 1.0.2. This is also true for the location of authentication files when using TracStandalone.

• The user under which the web server runs will require file system write permission to the environment directory and all the files inside. Please remember to set the appropriate permissions. The same applies to the source code repository, although the user under which Trac runs will only require write access to a Subversion repository created with the BDB file system; for other repository types, check the corresponding plugin's documentation.

• Non-ascii environment paths are not supported.

• TracPlugins located in a shared plugins directory that is defined in an inherited configuration are not enabled by default, in contrast to plugins in the environment plugins directory. Hence, if they need to create extra tables, for example, the tables will not be created during environment creation and you'll need to upgrade the environment. Alternatively you can avoid the need to upgrade the environment by explicitly enabling the plugin(s) in a configuration file using the --inherit or --config option. See TracAdmin#FullCommandReference for more information.

Caveat: don't confuse the Trac environment directory with the source code repository directory.

This is a common beginners' mistake. It happens that the structure for a Trac environment is loosely modeled after the Subversion repository directory structure, but those are two disjoint entities and they are not and must not be located at the same place.

Database Connection Strings

You will need to specify a database connection string at the time the environment is created. The default is SQLite, which is sufficient for most projects. The SQLite database file is stored in the environment directory, and can easily be backed up together with the rest of the environment.

Note that if the username or password of the connection string (if applicable) contains the :, / or @ characters, they need to be ​URL encoded.

$ python -c "import urllib; print urllib.quote('password@:/123', '')"
password%40%3A%2F123

SQLite Connection String

The connection string for an SQLite database is:

sqlite:db/trac.db

where db/trac.db is the path to the database file within the Trac environment.

PostgreSQL Connection String

The connection string for PostgreSQL is a bit more complex. For example, to connect to a PostgreSQL database named trac on localhost for user johndoe and password letmein, use:

postgres://johndoe:letmein@localhost/trac

If PostgreSQL is running on a non-standard port, for example 9342, use:

postgres://johndoe:letmein@localhost:9342/trac

On UNIX, you might want to select a UNIX socket for the transport, either the default socket as defined by the PGHOST environment variable:

postgres://user:password@/database

or a specific one:

postgres://user:password@/database?host=/path/to/socket/dir

See the ​PostgreSQL documentation for detailed instructions on how to administer ​PostgreSQL. Generally, the following is sufficient to create a database user named tracuser and a database named trac:

$ createuser -U postgres -E -P tracuser
$ createdb -U postgres -O tracuser -E UTF8 trac

When running createuser you will be prompted for the password for the tracuser. This new user will not be a superuser, will not be allowed to create other databases and will not be allowed to create other roles. These privileges are not needed to run a Trac instance. If no password is desired for the user, simply remove the -P and -E options from the createuser command. Also note that the database should be created as UTF8. LATIN1 encoding causes errors, because of Trac's use of unicode.

Under some default configurations (Debian), run the createuser and createdb scripts as the postgres user:

$ sudo su - postgres -c 'createuser -U postgres -S -D -R -E -P tracuser'
$ sudo su - postgres -c 'createdb -U postgres -O tracuser -E UTF8 trac'

Trac uses the public schema by default, but you can specify a different schema in the connection string:

postgres://user:pass@server/database?schema=yourschemaname

MySQL Connection String

The format of the MySQL connection string is similar to PostgreSQL, with the postgres scheme being replaced by mysql. For example, to connect to a MySQL database on localhost named trac for user johndoe with password letmein:

mysql://johndoe:letmein@localhost:3306/trac

Changing Database Backend

The TracAdmin convert_db command allows migrating between SQLite, MySQL and PostgreSQL databases.

convert_db <dburi> [new_env]

    Convert database

    Converts the database backend in the environment in which the command is
    run (in-place), or in a new copy of the environment. For an in-place
    conversion, the data is copied to the database specified in <dburi> and the
    [trac] database setting is changed to point to the new database. The new
    database must be empty, which for an SQLite database means the file should
    not exist. The data in the existing database is left unmodified.

    For a database conversion in a new copy of the environment, the environment
    in which the command is executed is copied and the [trac] database setting
    is changed in the new environment. The existing environment is left
    unmodified.

    Be sure to create a backup (see `hotcopy`) before converting the database,
    particularly when doing an in-place conversion.

Deleting a Trac Environment

The Trac environment can be deleted using standard filesystem utilities to delete the directory that was passed to the initenv command. For an environment using SQLite, this will also delete the SQLite database, which resides on-disk in the environment db directory. For an environment using PostgreSQL or MySQL, you will need to use the associated database utilities to delete the database.

Source Code Repository

A single environment can be connected to more than one repository. However, by default Trac is not connected to any source code repository, and the Browse Source navigation item will not be displayed. There are several ways to connect repositories to an environment, see TracRepositoryAdmin.

Repositories can be defined at the time of environment creation by specifying a configuration file to the initenv command using the --config or --inherit options. Cached repositories will be synchronized if the repository connector(s) are enabled. Example:

$ trac-admin $ENV initenv --config=config.ini
$ cat config.ini
[components]
tracopt.versioncontrol.* = enabled

[repositories]
.dir = /path/to/default/type/repos
repos1.type = git
repos1.dir = /path/to/git/repos
repos2.type = svn
repos2.dir = /path/to/svn/repos

Directory Structure

An environment consists of the following files and directories:

• README - Brief description of the environment.
• VERSION - Environment version identifier.
• files
  • attachments - Attachments to wiki pages and tickets.
• conf
  • trac.ini - Main configuration file.
• db
  • trac.db - The SQLite database, if you are using SQLite.
• htdocs - Directory containing web resources, which can be referenced in templates using the path /chrome/site/....
• log - Default directory for log files when file logging is enabled and a relative path is given.
• plugins - Environment-specific plugins.
• templates - Custom Genshi environment-specific templates.
  • site.html - Method to customize the site header, footer, and style.

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See also: TracAdmin, TracBackup, TracIni