vchouhan / cfenv

Groom your app’s Cloud Foundry environment

Groom your app’s Cloud Foundry environment with cfenv.

Use cfenv to pick a Cloud Foundry environment for your application and reduce the number of logins and targeting that you do.

Powerful in development. Specify your app's Cloud Foundry environment once, in a single file. Changing directrories changes your Cloud Foundry environment.

One thing well. cfenv is concerned solely with switching Cloud Foundry environments. It's simple and predictable. A plugin architecture lets you tailor it to suit your needs.

Special Thanks

Without rbenv this project would not exist. rbenv provided to be amazingly high quality and amenable to the modifications that make cfenv possible. I cannot recommend rbenv enough if you're a Ruby developer and it's a model for a well written project for everyone else. Finally, thanks to Dan Mikusa for the inspiration to create this project.

Table of Contents

• How It Works
  • Understanding PATH
  • Understanding Shims
  • Choosing the Cloud Foundry Environment
  • Locating the Cloud Foundry Environment
• Installation
  • Basic GitHub Checkout
    • Upgrading
  • Homebrew on Mac OS X
  • How cfenv hooks into your shell
  • Creating Cloud Foundry Environments
  • Destroying Cloud Foundry Environments
• Command Reference
  • cfenv local
  • cfenv global
  • cfenv shell
  • cfenv environments
  • cfenv environment
  • cfenv rehash
  • cfenv which
  • cfenv whence
• Development
  • Version History
  • License

How It Works

At a high level, cfenv intercepts the cf command using a shim executable injected into your PATH, determines which Cloud Foundry environment has been specified by your application, and passes your commands along after setting CF_HOME to the appropriate location.

Understanding PATH

When you run a command like cf, your operating system searches through a list of directories to find an executable file with that name. This list of directories lives in an environment variable called PATH, with each directory in the list separated by a colon:

/usr/local/bin:/usr/bin:/bin

Directories in PATH are searched from left to right, so a matching executable in a directory at the beginning of the list takes precedence over another one at the end. In this example, the /usr/local/bin directory will be searched first, then /usr/bin, then /bin.

Understanding Shims

cfenv works by inserting a directory of shims at the front of your PATH:

~/.cfenv/shims:/usr/local/bin:/usr/bin:/bin

Through a process called rehashing, cfenv maintains a cf shim in that directory.

The shim is a lightweight executables that simply passes your command along to cfenv. So with cfenv installed, when you run, cf, your operating system will do the following:

• Search your PATH for an executable file named cf
• Find the cfenv shim named cf at the beginning of your PATH
• Run the shim named cf, which in turn passes the command along to cfenv

Choosing the Cloud Foundry Environment

When you execute the shim, cfenv determines which Cloud Foundry environment to use by reading it from the following sources, in this order:

1. The CFENV_ENVIRONMENT environment variable, if specified. You can use the cfenv shell command to set this environment variable in your current shell session.

2. The first .cf-environment file found by searching the directory of the script you are executing and each of its parent directories until reaching the root of your filesystem.

3. The first .cf-environment file found by searching the current working directory and each of its parent directories until reaching the root of your filesystem. You can modify the .cf-environment file in the current working directory with the cfenv local command.

4. The global ~/.cfenv/environment file. You can modify this file using the cfenv global command. If the global environment file is not present, cfenv assumes you want to use the "system" Cloud Foundry environment—i.e. whatever environment would be used if `cfenv weren't in your path.

Locating the Cloud Foundry Environment

Once cfenv has determined which Cloud Foundry environment your application has specified, it passes the prepends the corresponding CF_HOME environment variable to the command.

Each Cloud Foundry environment is installed into its own directory under ~/.cfenv/environments. For example, you might have these environments installed:

• ~/.cfenv/environments/development/
• ~/.cfenv/environments/testing/
• ~/.cfenv/environments/production/

Environment names to cfenv are simply the names of the directories in ~/.cfenv/environments.

Installation

If you're on Mac OS X, consider installing with Homebrew.

Basic GitHub Checkout

This will get you going with the latest version of cfenv and make it easy to fork and contribute any changes back upstream.

1. Check out cfenv into ~/.cfenv.

   $ git clone https://github.com/nebhale/cfenv.git ~/.cfenv

2. Add ~/.cfenv/bin to your $PATH for access to the cfenv command-line utility.

   $ echo 'export PATH="$HOME/.cfenv/bin:$PATH"' >> ~/.bash_profile

   Ubuntu Desktop note: Modify your ~/.bashrc instead of ~/.bash_profile.

   Zsh note: Modify your ~/.zshrc file instead of ~/.bash_profile.

3. Add cfenv init to your shell to enable shims and autocompletion.

   $ echo 'eval "$(cfenv init -)"' >> ~/.bash_profile

   Same as in previous step, use ~/.bashrc on Ubuntu, or ~/.zshrc for Zsh.

4. Restart your shell so that PATH changes take effect. (Opening a new terminal tab will usually do it.) Now check if cfenv was set up:

   $ type cfenv
   #=> "cfenv is a function"

5. (Optional) Install cf-build, which provides the cfenv create command that simplifies the process of creating new Cloud Foundry environments.

Upgrading

If you've installed cfenv manually using git, you can upgrade your installation to the cutting-edge version at any time.

$ cd ~/.cfenv
$ git pull

To use a specific release of cfenv, check out the corresponding tag:

$ cd ~/.cfenv
$ git fetch
$ git checkout v0.3.0

If you've installed via Homebrew, then upgrade via its brew command:

$ brew update
$ brew upgrade cfenv cf-build

Homebrew on Mac OS X

As an alternative to installation via GitHub checkout, you can install cfenv and cf-build using the Homebrew package manager on Mac OS X:

$ brew tap nebhale/personal
$ brew update
$ brew install cfenv cf-build

Afterwards you'll still need to add eval "$(cfenv init -)" to your profile as stated in the caveats. You'll only ever have to do this once.

How cfenv hooks into your shell

Skip this section unless you must know what every line in your shell profile is doing.

cfenv init is the only command that crosses the line of loading extra commands into your shell. Here's what cfenv init actually does:

1. Sets up your shims path. This is the only requirement for cfenv to function properly. You can do this by hand by prepending ~/.cfenv/shims to your $PATH.

2. Installs autocompletion. This is entirely optional but pretty useful. Sourcing ~/.cfenv/completions/cfenv.bash will set that up. There is also a ~/.cfenv/completions/cfenv.zsh for Zsh users.

3. Rehashes shims. From time to time you'll need to rebuild your shim files. Doing this automatically makes sure everything is up to date. You can always run cfenv rehash manually.

4. Installs the sh dispatcher. This bit is also optional, but allows cfenv and plugins to change variables in your current shell, making commands like cfenv shell possible. The sh dispatcher doesn't do anything crazy like override cd or hack your shell prompt, but if for some reason you need cfenv to be a real script rather than a shell function, you can safely skip it.

Run cfenv init - for yourself to see exactly what happens under the hood.

Creating Cloud Foundry Environments

The cfenv create command doesn't ship with cfenv out of the box, but is provided by the cf-build project. If you installed it either as part of GitHub checkout process outlined above or via Homebrew, you should be able to:

$ cfenv install development

Alternatively to the create command, you can create an environment manually as a subdirectory of ~/.cfenv/environments/. An entry in that directory can also be a symlink to a Cloud Foundry environment installed elsewhere on the filesystem. cfenv doesn't care; it will simply treat any entry in the environments/ directory as a separate Cloud Foundry environment.

Destroying Cloud Foundry Environments

As time goes on, Cloud Foundry environments you create will accumulate in your ~/.cfenv/environments directory.

To remove old Cloud Foundry environments, simply rm -rf the directory of the environment you want to remove. You can find the directory of a particular Cloud Foundry environment with the cfenv prefix command, e.g. cfenv prefix development.

The cf-build plugin provides an cfenv destroy command to automate the removal process.

Command Reference

Like git, the cfenv command delegates to subcommands based on its first argument. The most common subcommands are:

cfenv local

Sets a local application-specific Cloud Foundry environment by writing the environment name to a .cf-environment file in the current directory. This environment overrides the global environment, and can be overridden itself by setting the CFENV_ENVIRONMENT environment variable or with the cfenv shell command.

$ cfenv local development

When run without an environment name, cfenv local reports the currently configured local environment. You can also unset the local environment:

$ cfenv local --unset

cfenv global

Sets the global Cloud Foundry environment to be used in all shells by writing the environment name to the ~/.cfenv/environment file. This environment can be overridden by an application-specific .cf-environment file, or by setting the CFENV_ENVIRONMENT environment variable.

$ cfenv global test

The special environment name system tells cfenv to use the system Cloud Foundry environment.

When run without an environment name, cfenv global reports the currently configured global environment.

cfenv shell

Sets a shell-specific Cloud Foundry environment by setting the CFENV_ENVIRONMENT environment variable in your shell. This environment overrides application-specific environments and the global environment.

$ cfenv shell production

When run without an environment name, cfenv shell reports the current value of CFENV_ENVIRONMENT. You can also unset the shell environment:

$ cfenv shell --unset

Note that you'll need rbenv's shell integration enabled (step 3 of the installation instructions) in order to use this command. If you prefer not to use shell integration, you may simply set the CFENV_ENVIRONMENT variable yourself:

$ export CFENV_ENVIRONMENT=production

cgenv environments

Lists all Cloud Foundry environments known to cfenv, and shows an asterisk next to the currently active environment.

$ cfenv environments
  development
  test
* production (set by /Users/bhale/.cfenv/environment)

cfenv environment

Displays the currently active Cloud Foundry environment, along with information on how it was set.

$ cfenv environment
production (set by /Users/bhale/dev/sources/nebhale/build-monitor/.cf-environment)

cfenv rehash

Installs the cf shim.

$ cfenv rehash

cfenv which

Displays the full path to the executable that cfenv will invoke when you run the given command.

$ cfenv which cf
/Users/bhale/.cfenv/environments/test/bin/cf

cfenv whence

Lists all Cloud Foundry environments with the given command installed.

$ cfenv whence cf
development
test
production

Development

The cfenv source code is hosted on GitHub. It's clean, modular, and easy to understand, even if you're not a shell hacker.

Tests are executed using Bats:

$ bats test
$ bats test/<file>.bats

Please feel free to submit pull requests and file bugs on the issue tracker.

Version History

1.0.0 (June 2, 2014)

• Initial public release.

License

(The MIT license)

Copyright (c) 2013 Ben Hale

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.