Description

Fig is a utility for configuring environments and managing dependencies across a team of developers.

An "environment" in fig is a set of environment variables. A "package" is a collection of files, along with some metadata describing which environment variables should be modified when the package is included. For instance, each dependency may prepend its corresponding jar to CLASSPATH. The metadata may also list that package's lower-level Fig package dependencies.

Fig recursively builds an environment consisting of package dependencies (typically specified via command-line options or a package.fig file), each of which as noted above may have its own dependencies, and optionally executes a shell command in that environment. The caller's environment is not affected.

Developers can use package.fig 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, ensuring that all developers on a team are using the same environments.

Packages exist in two places: a "local" repository cache in the user's home directory--also called the fig-home--and a "remote" repository on a shared server. Fig will automatically download packages from the remote repository and install them in the fig-home as needed. Fig does not contact the remote repository unless it needs to. The fig-home is $HOME/.fighome, but may be changed by setting the $FIG_HOME environment variable.

Fig is similar to a lot of other package/dependency-management 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 cross platform and project-oriented.

Usage

Fig recognizes the following options:

Flags

-?, -h, --help                   display this help text
-v, --version                    Print fig version
-g, --get VARIABLE               print value of environment variable VARIABLE
    --list-local, --list         list packages in $FIG_HOME
    --list-configs               list configurations
    --list-dependencies          list package dependencies, recursively
    --list-variables             list all variables defined/used by package and its dependencies
    --list-remote                list packages in remote repo
    --list-tree                  for listings, output a tree instead of a list
    --list-all-configs           for listings, follow all configurations of the base package
    --clean                      remove package from $FIG_HOME
    --publish                    install package in $FIG_HOME and in remote repo
    --publish-local              install package only in $FIG_HOME
-c, --config CONFIG              apply configuration CONFIG, default is "default"
    --file FILE                  read fig file FILE. Use '-' for stdin. See also --no-file
    --no-file                    ignore package.fig file in current directory
-p, --append VARIABLE=VALUE      append (actually, prepend) VALUE to environment variable VARIABLE, delimited by separator
-i, --include DESCRIPTOR         include package/version:config specified in DESCRIPTOR (with any variable prepends) in environment
-s, --set VARIABLE=VALUE         set environment variable VARIABLE to VALUE
    --archive PATH               include PATH archive in package (when using --publish)
    --resource PATH              include PATH resource in package (when using --publish)
-u, --update                     check remote repo for updates and download to $FIG_HOME as necessary
-m, --update-if-missing          check remote repo for updates only if package missing from $FIG_HOME
-l, --login                      login to remote repo as a non-anonymous user
    --force                      force-overwrite existing version of a package to the remote repo
    --figrc PATH                 add PATH to configuration used for Fig
    --no-figrc                   ignore ~/.figrc
    --log-config PATH            use PATH file as configuration for Log4r
    --log-level LEVEL            set logging level to LEVEL
                                   (off, fatal, error, warn, info, debug, all)
    --                           end of fig options; anything after this is used as a command to run

Some of these options may also be expressed as statements in a package.fig file. For instance, --append, --archive, --resource, include.

One point of frequent confusion revolves around which statements are concerned with publishing packages, and which are for downloading packages and otherwise modifying the Fig environment. The same Fig file can contain both publish (e.g., append, resource) and download (e.g., include) statements, but you may not want to use the same dependency file for both publishing a package and specifying that same package's dependencies, since for example its "build-time" dependencies may differ from its "include-time" dependencies. Multiple config sections may be helpful in organizing these concerns.

Environment Variables Influencing Fig's Behavior

FIG_FTP_THREADS     Optional - Size of FTP session pool. Defaults to 16.
FIG_HOME            Optional - Location of local repo cache. Defaults to $HOME/.fighome.
FIG_REMOTE_LOGIN    Required for --login, unless $HOME/.netrc is configured.
FIG_REMOTE_URL      Require for operations involving the remote repository.
FIG_REMOTE_USER     Required for --login, unless $HOME/.netrc is configured.

Commands affected by environment variables

`--list-remote`

When using the --list-remote command against an FTP server, fig uses a pool of FTP sessions to improve performance. By default it opens 16 connections, but that number can be overridden by setting the FIG_FTP_THREADS environment variable.

`--login`

If the --login option is supplied, fig will look for credentials. If environment variables FIG_REMOTE_USER and/or FIG_REMOTE_PASSWORD are defined, fig will use them instead of prompting the user. If ~/.netrc exists, with an entry corresponding to the host parsed from FIG_REMOTE_URL, that entry will take precedence over FIG_REMOTE_USER and FIG_REMOTE_PASSWORD. If sufficient credentials are still not found, fig will prompt for whatever is still missing, and use the accumulated credentials to authenticate against the remote server. Even if both environment variables are defined, fig will only use them if --login is given.

Examples

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

Command Line

To get started, let's define an environment variable via the command line and execute a command in the new environment. 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

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

Fig Files

You can also specify environment modifiers in files. Fig looks for a file called "package.fig" in the current directory and automatically processes it.

This "package.fig" file implements the previous example:

config default
  set GREETING=Hello
  append PATH=@/bin
end

Then we can just run:

$ fig -- hello
Hello, World

NOTE: The '@' symbol in a given package.fig file (or in a published dependency's .fig file) represents the full path to that file's directory. The above 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 '@', since the project directories will live in the fig-home rather than under our current directory).

A single fig file may have multiple configurations:

config default
  set GREETING=Hello
  append PATH=@/bin
end

config french
  set GREETING=Bonjour
  append PATH=@/bin
end

Config Sections

Configurations other than "default" can be specified using the "-c" option:

$ fig -c french -- hello
Bonjour, World

The statements from one config section can be incorporated into another config section via an include statement:

config default
  include :spanish
end

config spanish
  set GREETING="Buenas Dias"
  append PATH=@/bin
end

Note that config statements cannot be nested within a fig file. I.e. the following is invalid:

config foo
  config bar
  end
end

Packages

Let's share our little script with the rest of the team by bundling it into a package and publishing it. First, point the FIG_REMOTE_URL environment variable to the remote repository. If you just want to play around with fig, you can have it point to a local directory:

$ export FIG_REMOTE_URL=file://$(pwd)/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

Once the package has been published, we can include it in other environments with the -i or --include option. (For the purpose of this example, let's first move the "package.fig" file out of the way, so that it doesn't confuse fig or us.) The "hello/1.0.0" string represents the name of the package and the version number.

$ 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

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

Retrieves

By default, the resources associated with a package live in the fig home directory, which defaults to "$HOME/.fighome". This doesn't always play nicely with IDE's however, so fig provides a "retrieve" statement to copy resources from the repository to the current directory.

For example, let's create a package that contains a library for the "foo" programming language. 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

Create a new "package.fig" file (first moving to a different directory or deleting the "package.fig" we just used for publishing):

retrieve FOOPATH->lib/[package]
config default
  include hello-lib/3.2.1
end

Upon a fig --update, each resource in FOOPATH will be copied into lib/[package], where [package] resolves to the resource's package name (minus the version).

 $ fig -u
 ...downloading...
 ...retrieving...
 $ cat lib/hello-lib/hello.foo
 print 'hello'

Package Statement Descriptions

`add`

Specifies a value to be appended to a PATH-like environment variable, e.g. CLASSPATH for Java. Does not include the delimiter within the variable, just the component value.

`append`

Synonym for add.

`archive`

Specifies an archive file (either a local path or a URL) that is supposed to be incorporated into the package. This is different from a resource in that the contents will be extracted as part of installation.

`command`

Specifies a default command to be run for a given config when no command is given on the command-line.

config default
  command echo Hello there.
end

Cannot be specified outside of a config statement. There may not be multiple commands within a given config.

`config`

A grouping of statements that specifies what is to be done. There must either be a configuration named "default" or you will always have to specify a configuration on the command-line.

May not be nested. If you wish to incorporate the effects of one configuration into another, use an include statement.

`include`

Can be used in two ways: to affect configurations and to declare package dependencies.

Pull one configuration into another

You can get the effects of one configuration in another by using the name of the other configuration preceded by a colon:

config a
  include :b
end

config b
  ...
end

Declare a package dependency

States that one package should be installed prior to the current one; can specify a version.

config default
  include somepackage/1.2.3
end

Dependency version conflicts can be resolved by using override clauses.

Say you've got a "base-dependency" package. Then, in the package.fig for "middle-dependency-a" you have

config default
  include base-dependency/1.2.3
end

And in the package.fig for "middle-dependency-b" you have

config default
  include base-dependency/3.2.1
end

Finally, in the package.fig for the package you're working on you've got

config default
  include middle-dependency-a
  include middle-dependency-b
end

This will produce a conflicting requirement on "base-dependency". Resolve this by either matching the version of one dependency to another:

config default
  include middle-dependency-a override base-dependency/3.2.1
  include middle-dependency-b
end

Or specify the same version to both:

config default
  include middle-dependency-a override base-dependency/2.2.2
  include middle-dependency-b override base-dependency/2.2.2
end

Multiple override clauses can be specified in a single include statement.

`path`

Synonym for add.

`resource`

Specifies a file (either a local path or a URL) that is supposed to be incorporated into the package. This is different from an archive in that the contents will not be extracted as part of installation.

`retrieve`

Gives the installation location for a dependency.

`set`

Gives the value of an environment variable. Unlike add/append/path, this is the complete, final value.

Querying Fig Net Effects

If you've got a long chain of dependencies of packages, it can be challenging to figure out the full effects of it. There are a number of commands for just figuring out what things are coming from.

`--list-dependencies`

By itself, this will give you the total set of packages you're pulling in.

For example, if you have package A which depends upon packages B and C which both depend upon package D, running

fig --list-dependencies A/1.2.3

will give you

B/2.3.4
C/3.4.5
D/4.5.6

If there are no dependencies and stdout is connected to a terminal you'll get:

fig --list-dependencies package-with-no-dependencies/1.2.3

<no dependencies>

However, if stdout is not connected to a terminal:

fig --list-dependencies package-with-no-dependencies/1.2.3 | cat

[no output]

`--list-tree`

If you additionally specify --list-tree, you'll get a nested dependency tree:

fig --list-dependencies --list-tree A/1.2.3

A/1.2.3
    B/2.3.4
        D/4.5.6
    C/3.4.5
        D/4.5.6

If you don't specify a package descriptor, but you've got a package.fig file in the current directory with the same dependencies as package A above, you'll get

fig --list-dependencies --list-tree

<unpublished>
    B/2.3.4
        D/4.5.6
    C/3.4.5
        D/4.5.6

`--list-all-configs`

This will follow all of the dependencies using all the configurations in the package descriptor or the package.fig file. This will not follow all configurations in all depended upon packages, only the ones reachable by one of the configurations in the starting package.

Installation and Development

Installation

gem install fig

NOTE: When installing Fig on Windows you must first have installed the Development Kit available from http://rubyinstaller.org/downloads. Instructions for installation of the Development Kit are available at https://github.com/oneclick/rubyinstaller/wiki/Development-Kit.

Building the gem

rake build

Building a gem for ruby 1.8.7 on Windows

You can no longer use the rakefile to produce this specific gem. You will need to create a fig.gemspec file manually. Use the list of gem dependencies found in the rakefile as a guide. There are two specific gems that need to be depended on: json v 1.4.2 and libarchive-static-ruby186. Also, the spec.files should specificly list all the source files, pathed from the base directory of the project.

Community

#fig on irc.freenode.net

Fig Mailing List