sys-dependencies

Manage system dependencies the npm way

sys-dependencies is a simple utility written in pure bash to install and update system dependencies defined in a package.json file, in a similar way to npm.
It is designed to integrate smoothly with npm scripts, or to be used independently as a shell command.
Rather than hosting and distributing packages, the purpose of sys-dependencies is to provide a standard way to declare dependencies managed by various package managers.

Contents

• Installation
  • Npm package
  • Install script
  • Source code
  • Verifying and debugging
• Updating
  • Npm package
  • Shell script
• Usage
  • Declaring system dependencies
  • Installing packages
  • Updating packages
• Internal modules
  • Package managers
  • Node
  • Python
  • Git repositories
  • Config files
  • Parameters
  • Core modules
• Build your own modules
  • Module name and location
  • Module structure
    • Package.json
    • Package.bash
• License

Installation

sys-dependencies can be installed in three different ways: as a npm package, using a helper script or by cloning this repo. The way you decide to install it depends on your intended usage:

• If you plan to integrate sys-dependencies as part of your npm scripts, or nest it as a npm command within your package, you should install it as a npm package
• If you need to use sys-dependencies separately from npm (e.g. if your goal is to install npm itself), and be able to access it across your system and not just within a particular package, you should install it as a shell command either using the install script or by manually cloning the repo

Npm package

To install sys-dependencies as a npm dependency, simply run the following:

npm install --save-dev sys-dependencies

sys-dependencies will be available to use in your npm scripts using the spm command (see Usage).

Install script

To use the install script, you can either download it and run it manually, or use the following command:

curl -sLo- https://raw.githubusercontent.com/romainv/sys-dependencies/master/install.bash | bash

This requires that curl be installed as well as git, as the install script will clone sys-dependencies' repository to ~/.spm. It will also install sys-dependencies' own dependencies and add a few lines in your ~/.bashrc file to make the spm command available in your shell.
To customize the installation directory, you can set the SPM_DIR env variable to your chosen location: export SPM_DIR=~/custom-location && curl -sLo- <install_script_url> | bash.

Source code

This way to install sys-dependencies is essentially equivalent to executing the install script, so you can refer to it for more details. The steps are as follows:

git clone https://github.com/romainv/sys-dependencies.git ~/.spm
~/.spm/spm update spm
source ~/.bashrc

This obviously requires that git be installed. Other dependencies will be installed automatically by sys-dependencies itself.

Verifying and debugging

To verify that the installation succeeded, run:

command -v spm

This should output spm if the installation was successful. Please note that which spm will not work, since spm is a sourced shell function, not an executable binary. If you get spm: command not found, try to restart your shell or run the following:

source ~/.bash

This should make the spm command available in the current shell.

Updating

Npm package

To update sys-dependencies if it was installed as a npm package, use npm's default commands to manage dependencies versions:

npm update sys-dependencies

To upgrade to the latest version in case there was a major version change:

npm install sys-dependencies@latest

Shell script

To update the shell command, simply use the following:

spm update spm

Usage

sys-dependencies provides the spm command to manage dependencies. For basic usage instructions, run spm help to display the available commands and arguments.
Below we detail how to define your system dependencies, install and update them.

Declaring system dependencies

The typical way to use sys-dependencies is by declaring the modules that your package depends on in it's package.json file (if you don't have one, simply create a new file at the root of your repository). Similar to how you'd declare your node dependencies, you can declare your system dependencies as follows:

{
  "sysDependencies": {
    "<module-id>": "<module-version>"
  }
}

In the above:

• <module-id> can be in two formats: <module-name> or <module-type>/<module-name> (see the modules section below)
• <module-version> defines the version to install, similar to how npm defines them. To not set a specific version but use the latest available, you can use *

OS-specific dependencies
If you want to declare dependencies which are specific to a particular OS, you can nest them under the identifier of this OS as follows:

{
  "sysDependencies": {
    "<OS-ID>": {
      "<module-id>": "<module-version>"
    }
  }
}

To get the list of OS identifiers, check the getOS function.

Installing packages

The basic usage to install dependencies defined in package.json is:

spm install

This will look for your current repository's package.json and install the dependencies defined under sysDependencies (see previous section).

If you installed sys-dependencies as a npm package, you will typically want to execute it after installing the npm dependencies. In the scripts section of your package.json, add the following:

{
  "scripts": {
    "postinstall": "spm install"
  }
}

To install a specific package (not necessarily declared in package.json), simply specify its name:

spm install <package>

Updating packages

You can update your dependencies using:

spm update

or to update a specific package:

spm update <package>

Internal modules

sys-dependencies bundles a few modules which aim at specifying dependencies using your system's package managers. It also provides a few utilities to manage the installation of config files and the input of parameters.

Package managers

You can specify dependencies for the following package managers, provided they are compatible with your operating system:

• apt/<package> to use apt
• brew/<package> to use brew
• gem/<package> to use gem
• pip/<package> to use pip
• snap/<package> to use snap
• to declare local npm dependencies, declare them as usual under the dependencies section of your package.json.
• to declare global npm dependencies, you can use npm/<package> under the sysDependencies section of your package.json.

Node

You can install node and npm on your system by using the node module: spm install node. This will install nvm which is used to manage node's installation and updates. To specify which version to install, you can either place a .nvmrc file at the root of your repo (see instructions), or use one of the following strategies in the sysDependencies section of your package.json:

• "node/<branch>": "*" to install the latest version of the specified <branch> (e.g. erbium)
• "node": "10.10.0" to install a specific version
  See also nvm usage and sys-dependencies' node module for more details.

Python

To install python, simply use spm install python. This will install pyenv which is used to manage python's installation and updates.
To specify which version to install, place a .python-version file at the root of your repo. See pyenv usage and the python module for more details.

Git repositories

You can specify remote git repositories to clone and keep updated at a particular location on your system by using the repo module: "repo/<local-dir>": "<remote-url>".

Config files

To manipulate files, you can use the internal file module which works as follows:

{
  "sysDependencies": {
    "file/<target-file>": {
      "<action>": "<arguments>",
      "onUpdate": "<onUpdate-command>"
    }
  }
}

In the above sample:

• <target-file> is the path to the target file. It can contain a tilde ~ to refer to the $HOME folder. To point at your OS' rcfile, you can use <rcfile> (see decodeFilename for details)
• "<action>": "<arguments>" can be one of the following (see processConfigFile for details):
  • "copy": "<source-file>": to copy the <source-file> to the <target-file>. The <source-file> path can be relative to the current module's package.json
  • "addToFile": ["<line1>", <line2>", ...]: to append lines <line1>, <line2> etc. at the end of <target-file> (lines already existing in the <target-file> won't be duplicated)
  • "generate": "<command>": to generate the <target-file> by executing the supplied command
  • "link": "<source-file>": to create a symlink of the <source-file> to the <target-file>
  • "ini": { "<section>": { "<key>": "<value>" } }: generates the <target-file> as an INI file, where the <key>/<value> pairs nested in each <section> are provided in JSON format
• onUpdate is optional, and will be triggered if the target file was created or modified

Parameters

If you need dynamic env variables throughout the setup process, you can use the param module as follows:

{
  "sysDependencies": {
    "param/<PARAM_NAME>": "<value>"
  }
}

where:

• <PARAM_NAME> is the name of the parameter.
• <value> is a bash command that will output the value to use for this parameter. If you leave it empty, user will be prompted to enter the value manually
• If some parameters are sensitive and you don't want their values to be displayed, you can append an asterisk * at the end of the parameter name: <PARAM_NAME*> (e.g. "param/FOO*": "cat ~/.secret")

Parameters can be used in <arguments> of the file module. To use them, refer to them with a $ prefix like you would in bash: $PARAM_NAME. This also applies inside of <source-file>, where the references will be replaced by the parameter's <value>.
To use the parameters in your module's functions declared in package.bash, you can access them via the SPM_PARAMS associative array as follows: ${SPM_PARAMS[PARAM_NAME]}.

Core modules

sys-dependencies uses internal modules to manage its own dependencies. The system dependencies required to run spm are declared in the core module.
The spm module handles the installation of sys-dependencies on the host system and its own updates.

Build your own modules

To extend sys-dependencies' features, you can build your own modules locally and bundle them with your code.

Module name and location

Place your modules under a sys_modules folder at the root of your repo (next to where node typically creates its node_modules folder).
The folder name you choose will be your module's id (<module-id> in the below file tree).
A typical folder structure for a node project would look like this:

.
+-- node_modules
+-- sys_modules
|   +-- <module-id>
+-- package.json

When looking for modules, sys-dependencies will search upwards from the current working directory for the sys_modules/<module-id> folder. If it doesn't find one, it will look for internal modules. This way, you can easily override an internal module by simply placing one with the same name in a local sys_modules folder.

Module structure

A module consists of a required package.json file that will describe the module's name and its dependencies, and an optional package.bash that declares the bash functions used to manage the module.

.
+-- <module-id>
|   +-- package.json
|   +-- package.bash

Package.json

The package.json file contains two optional fields: name and sysDependencies. The former provides a more descriptive name than the module id, the latter describes the module's dependencies as explained in Declaring system dependencies.

{
  "name": "<module-name>",
  "sysDependencies": {
    "<module-id>": "<module-version>"
  }
}

Package.bash

The package.bash file is optional. If provided, it should declare the functions that will be used to manage the module's installation and updates.
For an overview of how each function is used, check the processModule function. For a live example, check spm's internal package.bash.

Each function will be passed two arguments: the first is the module's name, the second its dependency version, as in "<module-type>/<name>": "<version>".
Below is the list of functions that should be declared:

• checkInstall (required): it should return a boolean (true if module is installed), and not output anything to stdout or stderr as it would be interpreted as an error.
• runInstall (required): it should install the module and cause checkInstall to be truthy. The installation log can be output to stdout or stderr, and will be displayed if an error occurred.
• checkUpdates (required): it should return a boolean (true if an update is available), and not output anything to stdout or stderr as it would be interpreted as an error.
• runUpdates (required): it should update the module and cause checkUpdate to be falsy. The update log can be output to stdout or stderr, and will be displayed if an error occurred.
• getInstalledVersion (required): it should return the currently installed version of the module.
• getLatestVersion (required): it should return the latest version available for the module.
• preProcess (optional): it will be executed before any other function once the module is imported. You can use it to dynamically adjust the environment before processing the module, such as adding dependencies. If the function produced an output to stdout or stderr, it should return true, otherwise an exit code 2 so that sys-dependencies can properly display progress.
• postProcess (optional): it will be executed after all the other functions. You can use it to display information or further configuration after a module was installed or updated for instance. If the function produced an output to stdout or stderr, it should return true, otherwise an exit code 2 so that sys-dependencies can properly display progress.

License

sys-dependencies is MIT licensed