Determine project root from a running node js application

Question

Is there a better way than process cwd   to determine the root directory of a running node js process  Something like the equivalent of Rails root  but for Node js  I m looking for something that is as predictable and reliable as possible

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I ve found this works consistently for me  even when the application is invoked from a sub-folder  as it can be with some test frameworks  like Mocha   process mainModule paths 0  split  node modules   0  slice 0  -1     Why it works   At runtime node creates a registry of the full paths of all loaded files  The modules are loaded first  and thus at the top of this registry  By selecting the first element of the registry and returning the path before the  node modules  directory we are able to determine the root of the application   It s just one line of code  but for simplicity s sake  my sake   I black boxed it into an NPM module   https   www npmjs com package node-root pddivine  Enjoy

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A technique that I ve found useful when using express is to add the following to app js before any of your other routes are set     set rootPath app use function req  res  next      req rootPath     dirname    next         app use   myroute   myRoute     No need to use globals and you have the path of the root directory as a property of the request object   This works if your app js is in the root of your project which  by default  it is

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There is an INIT CWD property on process env   This is what I m currently working with in my project   const  INIT CWD    process env     process env INIT CWD  const paths   require    INIT CWD  config paths      Good Luck

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I know this one is already too late   But we can fetch root URL by two methods  1st method  var path   require  path    path dirname require main filename     2nd method  var path   require  path    path dirname process mainModule filename     Reference Link - https   gist github com geekiam e2e3e0325abd9023d3a3

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path dirname process mainModule filename

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It work for me   process env PWD

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Preamble This is a very old question but it seems to still hit the nerve in 2020 as in 2012  I ve checked all of the other answers and could not find a technique  note that this has its limitations  but all of the others are not applicable in every situation as well   GIT   child process If you are using GIT as your version control system  the problem of determining the project root can be reduced to  which I would consider the proper root of the project - after all  you would want your VCS to have the fullest visibility scope possible    retrieve repository root path  Since you have to run a CLI command to do that  we will need to spawn a child process  Additionally  as project root is highly unlikely to change mid-runtime  we can use the synchronous version of the child process module APIs at startup  I found spawnSync   to be the most suitable for the job  As for the actual command to run  git worktree  with a --porcelain option for ease of parsing  is all we need to retrieve the absolute root path  In the sample  I opted to return an array of paths because there might be more than one worktree  although they are likely to have common paths  just to be sure  Note that as we utilize a CLI command  shell option should be set to true  security shouldn t be an issue as there is no untrusted input   Approach comparison and fallbacks Understanding that a situation where VCS can be inaccessible is possible  I ve included a couple of fallbacks after analyzing docs and other answers  To sum up  the solutions proposed boil down to  excluding third-party modules  amp  package-specific       Solution                   Advantage                 Main Problem                         ------------------------   -----------------------   --------------------------------        filename                points to module file     relative to module                      dirname                 points to module dir      same as    filename                   node modules  tree walk   nearly guaranteed root    complex tree walking if nested        path resolve              root if CWD is root       same as  process cwd                  process argv 1            same as    filename       same as    filename                   process env INIT CWD      points to  npm run  dir   requires  npm     CLI launch          process env PWD           points to current dir     relative to  is the  launch dir       process cwd               same as  env PWD           process chdir path   at runtime      require main filename     root if      module       fails on  require d modules          From the comparison table above  the most universal are two approaches   require main filename as an easy way to get root if require main     module is met node modules tree walk proposed recently uses another assumption    if the directory of the module has node modules dir inside  it is likely to be the root  For the main app  it will get the app root and for the module - its project root  Fallback 1  Tree walk My implementation uses a more lax approach by stopping once a target directory is found as for a given module its root is its project root  One can chain the calls or extend it to make search depth configurable          summary gets root by walking up node modules     param  import  quot fs quot    fs     param  import  quot path quot    pt     const getRootFromNodeModules    fs  pt    gt                   param  string   startPath          returns  string                 startPath     dirname    gt               avoid loop if reached root path         if  startPath     pt parse startPath  root                return  startPath                      const isRoot   fs existsSync pt join startPath   quot node modules quot              if  isRoot                return  startPath                      return getRootFromNodeModules fs  pt  pt dirname startPath            Fallback 2  Main module The second implementation is trivial         summary gets app entry point if run directly     param  import  quot path quot    pt     const getAppEntryPoint    pt    gt                   returns  string                     gt             const   main     require           const   filename     main           return main     module                pt parse filename  dir                            Implementation I would suggest use the tree walker as fallback because it is more versatile  const   spawnSync     require  quot child process quot    const pt   require  path    const fs   require  quot fs quot             summary returns worktree root path s      param  function   string      fallback      returns  string        const getProjectRoot    fallback    gt         const   error  stdout     spawnSync           git worktree list --porcelain                         encoding   quot utf8 quot               shell  true                       if   stdout            console warn  Could not use GIT to find root  n n  error             return fallback   fallback                    return stdout          split  quot  n quot            map line   gt                const  key  value    line split   s                       return key      quot worktree quot    value    quot  quot                       filter Boolean        Disadvantages The most obvious is having GIT installed and initialized which might be undesirable   implausible  side note  having GIT installed on production servers is not uncommon  nor is it unsafe  though   Can be mediated by fallbacks as described above  Notes  A couple of ideas for further extension of approach 1    introduce config as a function parameter export the function to make it a module check if GIT is installed and   or initialized  References  git worktree reference spawnSync reference require main reference path dirname   reference

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Simple  require  path   resolve

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if you want to determine project root from a running node js application you can simply just too   process mainModule path

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Try path  makeLong  some filename on root js     example   cons path   require  path    console log path  makeLong  some filename on root js      That will return full path from root of your node application  same position of package json

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Make it sexy    const users   require           database users        what you have    OR const users   require   db users        no matter how deep you are const products   require   database products        alias or pathing from root directory     Three simple steps to solve the issue of ugly path    Install the package  npm install sexy-require --save Include require  sexy-require   once on the top of your main application file   require  sexy-require    const routers   require   routers    const api   require   api         Optional step  Path configuration can be defined in  paths file on root directory of your project    db    server database  api-v1    server api legacy  api-v2    server api v2

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There are several ways to approach this  each with their own pros and cons  require main filename From http   nodejs org api modules html   When a file is run directly from Node  require main is set to its module  That means that you can determine whether a file has been run directly by testing require main     module Because module provides a filename property  normally equivalent to   filename   the entry point of the current application can be obtained by checking require main filename   So if you want the base directory for your app  you can do  var path   require  path    var appDir   path dirname require main filename    Pros  amp  Cons This will work great most of the time  but if you re running your app with a launcher like pm2 or running mocha tests  this method will fail  global X Node has a a global namespace object called global     anything that you attach to this object will be available everywhere in your app   So  in your index js  or app js or whatever your main app file is named   you can just define a global variable     index js var path   require  path    global appRoot   path resolve   dirname       lib moduleA component1 js require appRoot     lib moduleB component2 js     Pros  amp  Cons Works consistently but you have to rely on a global variable  which means that you can t easily reuse components etc  process cwd   This returns the current working directory   Not reliable at all  as it s entirely dependent on what directory the process was launched from    cd  home demo    mkdir subdir   echo  quot console log process cwd     quot   gt  subdir demo js   node subdir demo js  home demo   cd subdir   node demo js  home demo subdir  app-root-path To address this issue  I ve created a node module called app-root-path   Usage is simple  var appRoot   require  app-root-path    var myModule   require appRoot     lib my-module js     The app-root-path module uses several different techniques to determine the root path of the app  taking into account globally installed modules  for example  if your app is running in  var www  but the module is installed in    nvm v0 x x lib node     It won t work 100  of the time  but it s going to work in most common scenarios  Pros  amp  Cons Works without configuration in most circumstances   Also provides some nice additional convenience methods  see project page    The biggest con is that it won t work if   You re using a launcher  like pm2 AND  the module isn t installed inside your app s node modules directory  for example  if you installed it globally   You can get around this by either setting a APP ROOT PATH environmental variable  or by calling  setPath   on the module  but in that case  you re probably better off using the global method  NODE PATH environmental variable If you re looking for a way to determine the root path of the current app  one of the above solutions is likely to work best for you   If  on the other hand  you re trying to solve the problem of loading app modules reliably  I highly recommend looking into the NODE PATH environmental variable  Node s Modules system looks for modules in a variety of locations   One of these locations is wherever process env NODE PATH points  If you set this environmental variable  then you can require modules with the standard module loader without any other changes  For example  if you set NODE PATH to  var www lib  the the following would work just fine  require  module2 component js         looks for  var www lib module2 component js  A great way to do this is using npm   quot scripts quot          quot start quot    quot NODE PATH   node app js quot     Now you can start your app with npm start and you re golden   I combine this with my enforce-node-path module  which prevents accidentally loading the app without NODE PATH set  For even more control over enforcing environmental variables  see checkenv  One gotcha  NODE PATH must be set outside of the node app   You cannot do something like process env NODE PATH   path resolve   dirname  because the module loader caches the list of directories it will search before your app runs   added 4 6 16  Another really promising module that attempts to solve this problem is wavy

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I use this   For my module named mymodule  var BASE DIR     dirname replace        mymodule           1

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Old question  I know  however no question mention to use progress argv  The argv array includes a full pathname and filename  with or without  js extension  that was used as parameter to be executed by node  Because this also can contain flags  you must filter this   This is not an example you can directly use  because of using my own framework  but I think it gives you some idea how to do it  I also use a cache method to avoid that calling this function stress the system too much  especially when no extension is specified  and a file exist check is required   for example   node myfile   or  node myfile js   That s the reason I cache it  see also code below     function getRootFilePath             if   isDefined  oData SU ROOT FILE PATH                           var sExt   false               each  process argv  function  i  v                                     Skip invalid and provided command line options                 if    v  amp  amp  isValidString  v    amp  amp  v 0       -                                          sExt   getFileExt  v                         if    sExt      js         sExt         amp  amp  fileExists  v   js                                                      var a   uniformPath  v   split                                     Chop off last string  filename                         a a length-1                                   Cache it so we don t have to do it again                          oData SU ROOT FILE PATH a join                                     Found  skip loop                         return true                                                         true        lt -- true is  each in reverse order                    return oData SU ROOT FILE PATH

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dirname will give you the root directory  as long as you re in a file that s in the root directory      ProjectDirectory js  this file is in the project s root directory because you are putting it there   module exports          root             return   dirname            In some other file   const ProjectDirectory   require  path to ProjectDirectory    console log  Project root directory is   ProjectDirectory root

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At top of main file add   mainDir     dirname    Then use it in any file you need   console log  mainDir     mainDir      mainDir is defined globally  if you need it only in current file - use   dirname instead  main file is usually in root folder of the project and is named like main js  index js  gulpfile js

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1- create a file in the project root call it settings js  2- inside this file add this code  module exports         POST MAX SIZE   40     MB     UPLOAD MAX FILE SIZE  40    MB     PROJECT DIR     dirname      3- inside node modules create a new module name it  settings  and inside the module index js write this code   module exports   require        settings      4- and any time you want your project directory just use   var settings   require  settings    settings PROJECT DIR     in this way you will have all project directories relative to this file

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Just use    path resolve           output is your project root directory

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You can simply add the root directory path in the express app variable and get this path from the app  For this add app set  rootDirectory     dirname   in your index js or app js file  And use req app get  rootDirectory   for getting the root directory path in your code

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Finding the root path of an electron app could get tricky  Because the root path is different for the main process and renderer under different conditions such as production  development and packaged conditions   I have written a npm package electron-root-path to capture the root path of an electron app     npm install electron-root-path  or     yarn add electron-root-path      Import ES6 way import   rootPath   from  electron-root-path       Import ES2015 way const rootPath   require  electron-root-path   rootPath      e g     read a file in the root const location   path join rootPath   package json    const pkgInfo   fs readFileSync location    encoding   utf8

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This will step down the directory tree until it contains a node modules directory  which usually indicates your project root   const fs   require  fs   const path   require  path    function getProjectRoot currentDir     dirname split path sep       if   currentDir length        throw Error  Could not find project root          const nodeModulesPath   currentDir concat   node modules    join path sep    if  fs existsSync nodeModulesPath   amp  amp   currentDir includes  node modules          return currentDir join path sep        return this getProjectRoot currentDir slice 0  -1       It also makes sure that there is no node modules in the returned path  as that means that it is contained in a nested package install

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Add this somewhere towards the start of your main app file  e g  app js    global   basedir     dirname    This sets a global variable that will always be equivalent to your app s base dir  Use it just like any other variable   const yourModule   require   basedir     path to module js      Simple

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This will do    path join    process argv 1  split          slice 0  -1

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Maybe you can try traversing upwards from   filename until you find a package json  and decide that s the main directory your current file belongs to

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Actually  i find the perhaps trivial solution also to most robust  you simply place the following file at the root directory of your project  root-path js which has the following code   import   as path from  path  const projectRootPath   path resolve   dirname  export const rootPath   projectRootPath

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As simple as add this line to your module in root  usually it is app js  global   basedir     dirname    Then  basedir will be accessiable to all your modules

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the easiest way to get the global root  assuming you use NPM to run your node js app  npm start   etc   var appRoot   process env PWD    If you want to cross-verify the above  Say you want to cross-check process env PWD with the settings of you node js application  if you want some runtime tests to check the validity of process env PWD  you can cross-check it with this code  that I wrote which seems to work well   You can cross-check the name of the last folder in appRoot with the npm package name in your package json file  for example       var path   require  path         var globalRoot     dirname     you may have to do some substring processing if the first script you run is not in the project root  since   dirname refers to the directory that the file is in for which   dirname is called in          compare the last directory in the globalRoot path to the name of the project in your package json file     var folders   globalRoot split path sep       var packageName   folders folders length-1       var pwd   process env PWD      var npmPackageName   process env npm package name      if packageName     npmPackageName           throw new Error  Failed check for runtime string equality between globalRoot-bottommost directory and npm package name               if globalRoot     pwd           throw new Error  Failed check for runtime string equality between globalRoot and process env PWD             you can also use this NPM module  require  app-root-path   which works very well for this purpose

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process mainModule is deprecated since v 14 0 0  When referring to the answer  please use require main  the rest still holds    process mainModule paths    filter p   gt   p includes  node modules       shift     Get all paths in main modules and filter out those with  node modules   then get the first of remaining path list  Unexpected behavior will not throw error  just an undefined   Works well for me  even when calling ie   mocha

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All these  root dirs  mostly need to resolve some virtual path to a real pile path  so may be you should look at path resolve   var path  require  path    var filePath   path resolve  our virtual path ext

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Create a function in app js    Function to get the app root folder    var appRootFolder   function dir level       var arr   dir split            arr splice arr length - level level       var rootFolder   arr join            return rootFolder        view engine setup app set  views   path join appRootFolder   dirname 1   views

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dirname isn t a global  it s local to the current module so each file has its own local  different value   If you want the root directory of the running process  you probably do want to use process cwd     If you want predictability and reliability  then you probably need to make it a requirement of your application that a certain environment variable is set  Your app looks for MY APP HOME  Or whatever  and if it s there  and the application exists in that directory then all is well  If it is undefined or the directory doesn t contain your application then it should exit with an error prompting the user to create the variable  It could be set as a part of an install process   You can read environment variables in node with something like process env MY ENV VARIABLE

[node.js] Determine project root from a running node.js application

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