Fig is a utility for configuring environments and managing dependencies across a team of developers. You give it a list of packages and a shell command to run; it creates an environment that includes those packages, then executes the shell command in it (the caller's environment is not affected).
An "environment" in fig is just a set of environment variables. A "package" is a collection of files, plus some metadata describing what environment variables should be modified when the package is included.
Developers can use package files to specify the list of dependencies to use for different tasks. This file will typically be versioned along with the rest of the source files. This ensures that all developers on a team are using the same environemnts.
Packages exist in two places: a "local" repository in the user's home directory, and a "remote" repository on a server somewhere that is shared by a team. Fig will automatically download packages from the remote repository and install them in the local repository, when needed.
Fig is similar to a lot of other package/dependnency managment tools. In particular, it steals a lot of ideas from Apache Ivy and Debian APT. However, unlike Ivy, fig is meant to be lightweight (no XML, no JVM startup time), language agnostic (Java doesn't get preferential treatment), and work with executables as well as libraries. And unlike APT, fig is meant to be cross platform (Windows support is coming) and project-oriented.
Fig can be installed via rubygems. The gems are hosted at Gemcutter, so you'll need to set that up first:
$ gem install gemcutter
$ gem tumble
Fig also depends on a third-party library named, libarchive. Libarchive is easily available via most package management systems on Linux, FreeBSD, and OS X. Libarchive versions greater than 2.6.0 are preferred. If you are on Windows, the gem will install the libarchive binaries for you.
[Linux - Debian / Ubuntu]
apt-get libarchive-dev
[Linux - Red Hat / CentOS]
yum install libarchive-devel
[OS X - MacPorts]
port install libarchive
Then you can install fig:
$ gem install fig
Fig recognizes the following options (not all are implemented yet):
-d, --debug Print debug info
--force Download/install packages from remote repository, even if up-to-date
-u, --update Download/install packages from remote repository, if out-of-date
-n, --no Automatically answer "n" for any prompt (batch mode)
-y, --yes Automatically answer "y" for any prompt (batch mode)
The following otpions modify the environment generated by fig:
-i, --include DESCRIPTOR Include package in environment (recursive)
-p, --append VAR=VALUE Append value to environment variable using platform-specific separator
-s, --set VAR=VALUE Set environment variable
The following commands will be run in the environment created by fig:
-b, --bash Print bash commands so user's environment can be updated (usually used with 'eval')
-g, --get VARIABLE Get value of environment variable
-x, --execute DESCRIPTOR Execute command associated with specified configuration
-- COMMAND [ARGS...] Execute arbitrary shell command
Fig also supports the following options, which don't require a fig environment. Any modifiers will be ignored:
-?, -h, --help Display this help text
--publish Upload package to the remote repository (also installs in local repository)
--publish-local Install package in local repository only
--list List the packages installed in local repository
Fig lets you configure environments three different ways:
- From the command line
- From a "package.fig" file in the current directory
- From packages included indirectly via one of the previous two methods
So to get started, let's trying defining an environment variable via the command line and executing a command in the newenvironment. We'll set the "GREETING" variable to "Hello", then run a command that uses that variable:
$ fig -s GREETING=Hello -- echo "\$GREETING, World"
Hello, World
Note that you need to put a slash before the dollar sign, otherwise the shell will evaluate the environment variable before it ever gets to fig.
Also note that when running fig, the original environment isn't affected:
$ echo $GREETING
<nothing>
Fig also lets you append environment variables, using the system-specified path separator (e.g. colon on unix, semicolon on windows). This is useful for adding directories to the PATH, LD_LIBRARY_PATH, CLASSPATH, etc. For example, let's create a "bin" directory, add a shell script to it, then include it in the PATH:
$ mkdir bin
$ echo "echo \$GREETING, World" > bin/hello
$ chmod +x bin/hello
$ fig -s GREETING=Hello -p PATH=bin -- hello
Hello, World
You can also specify environment modifiers in files. Fig looks for a file called "package.fig" in the current directory, and automatically processes it. So we can implement the previous example by creating a "package.fig" file that looks like:
config default
set GREETING=Hello
append PATH=@/bin
end
The '@' symbol represents the directory that the "package.fig" file is in (this example would still work if we just used "bin", but later on when we publish our project to the shared repository we'll definitely need the '@'). Then we can just run:
$ fig -- hello
Hello, World
A single fig file can have multiple configurations:
config default
set GREETING=Hello
append PATH=@/bin
end
config french
set GREETING=Bonjour
append PATH=@/bin
end
Configurations other than "default" can be specified using the "-c" option:
$ fig -c french -- hello
Bonjour, World
Now let's say we want to share our little script with the rest of the team by bundling it into a package. The first thing we need to do is specify the location of the remote repository by defining the FIG_REMOTE_URL environment variable. If you just want to play around with fig, you can have it point to localhost:
$ export FIG_REMOTE_URL=ssh://localhostpwd/remote
Before we publish our package, we'll need to tell fig which files we want to include. We do this by using the "resource" statement in our "package.fig" file:
resource bin/hello
config default...
Now we can share the package with the rest of the team by using the "--publish" option:
$ fig --publish hello/1.0.0
The "hello/1.0.0" string represents the name of the package and the version number. Once the package has been published, we can include it in other environments by using the "-i" or "--include" option (I'm going to move the "package.fig" file out of the way first, so that fig doesn't automatically process it.):
$ mv package.fig package.bak
$ fig -u -i hello/1.0.0 -- hello
...downloading files...
Hello, World
The "-u" (or "--update") option tells fig to check the remote repository for packages if they aren't already installed locally (fig will never make any network connections unless this option is specified). Once the packages are downloaded, we can run the same command without the "-u" option:
$ fig -i hello/1.0.0 -- hello
Hello, World
Also, when including a package, you can specify a particular configuration by appending it to the package name using a colon:
$ fig -i hello/1.0.0:french -- hello
Bonjour, World
By default, the resources associated with a package live in the fig home directory, which defaults to "~/.fighome". This doesn't always play nicely with IDE's however, so fig gives you a way to copy resources from the repository to the current directory. To do this you add "retrieve" statements to your "package.fig" file.
For example, let's create a package that contains a library for the "foo" programming language. First we'll define a "package.fig" file:
config default
append FOOPATH=lib/hello.foo
end
Then:
$ mkdir lib
$ echo "print 'hello'" > lib/hello.foo
$ fig --publish hello-lib/3.2.1
Now we'll move to a different directory (or delete the current "package.fig" file) and create a new "package.fig" file:
retrieve FOOPATH->lib/[package]
config default
include hello-lib/3.2.1
end
When we do an update, all resources in the FOOPATH will be copied into the lib directory, into a subdirectory that matches the package name:
$ fig -u
...downloading...
...retrieving...
$ cat lib/hello-lib/hello.foo
print 'hello'
#fig on irc.freenode.net
Copyright (c) 2009 Matthew Foemmel. See LICENSE for details.