Theia API Documentation v1.65.0
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    Developing

    This file contains tips to help you take (and understand) your first steps in the world of Theia development. Are you in a hurry? See the Quick Start.

    How to build Theia and the example applications

    Theia is a framework to build IDEs, so you can't really "run" Theia itself. However, you can run the example applications included in its repository. One is a browser-based IDE and the other is the Electron-based equivalent.

    The following instructions are for Linux and macOS.

    For Windows instructions click here.

    • Node.js >= 20 and < 24.
      • If you are interested in Theia's VS Code Extension support then you should use a Node version at least compatible with the one included in the version of Electron used by VS Code.
    • git (If you would like to use the Git-extension too, you will need to have git version 2.11.0 or higher.)
    • Python3 is required for the build due to node-gyp

    Some additional tools and libraries are needed depending on your platform:

    • Linux

      • make
      • gcc (or another compiling toolchain)
      • pkg-config
      • build-essential: sudo apt-get install build-essential
      • native-keymap native node module dependencies:
        • Debian-based: sudo apt-get install libx11-dev libxkbfile-dev
        • Red Hat-based: sudo yum install libX11-devel.x86_64 libxkbfile-devel.x86_64 # or .i686
        • FreeBSD: sudo pkg install libX11
      • keytar native node module dependencies (reference):
        • Debian/Ubuntu: sudo apt-get install libsecret-1-dev
        • Red Hat-based: sudo yum install libsecret-devel
        • Arch Linux: sudo pacman -S libsecret
        • Alpine: apk add libsecret-dev
    • Linux/MacOS

      • nvm is recommended to easily switch between Node.js versions.
    • Windows

      • We recommend using scoop. The detailed steps are here.

    To build and run the browser example:

    git clone https://github.com/eclipse-theia/theia \
    && cd theia \
    && npm install \
    && npm run build:browser \
    && npm run download:plugins \
    && npm run start:browser

    Start your browser on http://localhost:3000.

    To build and run the Electron example:

    git clone https://github.com/eclipse-theia/theia \
    && cd theia \
    && npm install \
    && npm run build:electron \
    && npm run download:plugins \
    && npm run start:electron

    You can download plugins to use with the examples applications by running:

    npm run download:plugins
    

    To run the browser example using SSL use:

    git clone https://github.com/eclipse-theia/theia \
    && cd theia \
    && npm install \
    && npm run download:plugins \
    && npm run build:browser \
    && npm run start:browser --ssl --cert /path/to/cert.crt --certkey /path/to/certkey.key

    Start your browser on https://localhost:3000.

    Gitpod is a Theia-based IDE for GitHub. You can start by prefixing any GitHub URL in the Theia repository with gitpod.io/#:

    npm run start:browser ../.. --hostname 0.0.0.0
    
    git clone https://github.com/eclipse-theia/theia
    

    The directory containing the Theia repository will now be referred to as $THEIA, so if you want to copy-paste the examples, you can set the THEIA variable in your shell:

    THEIA=$PWD/theia
    

    Theia repository has multiple folders:

    • packages folder contains runtime packages, as the core package and extensions to it
    • dev-packages folder contains devtime packages
      • @theia/cli is a command line tool to manage Theia applications
      • @theia/ext-scripts is a command line tool to share scripts between Theia runtime packages
    • examples folder contains example applications, both Electron-based and browser-based
    • doc folder provides documentation about how Theia works
    • scripts folder contains JavaScript scripts used by npm scripts when installing
    • the root folder lists dev dependencies and wires everything together with Lerna

    You can download dependencies and build TypeScript packages using:

    npm install
    npm run compile

    These commands download dependencies, links and builds all TypeScript packages.

    To build the example applications:

    npm run build:browser
    npm run build:browser-only
    npm run build:electron

    # build all example applications at once:
    npm run build:applications

    To learn more and understand precisely what's going on, please look at scripts in package.json.

    npm run all
    

    This will install dependencies, link and build TypeScript packages, lint, and build the example applications.

    Dependencies must be installed before running this command.

    npm run compile
    

    Linting takes a lot of time, this is a limitation from ESLint. We always lint in the GitHub Workflows, but if you want to lint locally you have to do it manually:

    npm run lint # lint TypeScript sources
    

    Note that npm run all does linting.

    From the root:

    npx lerna run compile --scope @theia/core
    

    From the package:

    npm run compile
    

    We can start the application from the examples/browser directory with:

    npm run start
    

    This command starts the backend application listening on port 3000. The frontend application should be available on http://localhost:3000.

    If you rebuild native Node.js packages for Electron then rollback these changes before starting the browser example by running from the root directory:

    npm run rebuild:browser
    
    npm start:electron
    

    Rebuilds everything: TypeScript and example applications.

    npm run build
    

    To rebuild everything each time a change is detected run:

    npm run watch
    

    To rebuild each time a change is detected in frontend or backend you can run:

    # either
    npm run watch:browser

    # or
    npm run watch:electron

    You can use npx to watch a single package:

    npx lerna run watch --scope @theia/package-name
    

    Once you have built all TypeScript packages once, making a single change and recompiling should be rather quick.

    Given this, you can efficiently watch the whole monorepo using TypeScript build mode and have it quickly compiled.

    See Watch the core and extension packages.

    In this mode, TypeScript only compiles what changed along with its dependents.

    Let assume you have to work for instance in the @theia/navigator extension. But you might have to apply changes in any of its upstream dependencies such as @theia/filesystem or @theia/core, you can either do npm run watch which could be super expensive, as it watches all the packages. Or you can do npx run watch @theia/navigator and npx run watch @theia/filesystem and npx run watch @theia/core in three individual shells. Or you can do the following single-liner:

    npx lerna run watch --scope @theia/navigator --include-filtered-dependencies --parallel
    
    • Open the debug view and run the Launch Browser Backend configuration.
    • Start the backend by using npm run start.
    • In a browser: Open http://localhost:3000/ and use the dev tools for debugging.
    • Open the debug view and run the Launch Browser Frontend configuration.
    • Open the debug view and run the Launch Browser Backend configuration.
    • Then run the Launch Browser Frontend configuration.
    • Open the debug view and run the Launch Electron Backend configuration.
    • Start the Electron backend
      • Either open the debug view and run the Launch Electron Backend configuration
      • Or use npm run start.
    • Attach to the Electron Frontend
      • Either open the debug view and run the Attach to Electron Frontend configuration
      • Or in Electron: Help -> Toggle Electron Developer Tools.
    • Open the debug view and run the Launch Electron Backend & Frontend configuration.
    • Pass --${server-name}-inspect arg to the backend server.
    • Attach the debugger to the logged port.

    In order to look up server-name run the backend server with --log-level=debug flag to enable logging of IPC servers instantiation. You should be able to see message of [${server-name}: ${server-PID}]: IPC started format, like [nsfw-watcher: 37557] IPC started.

    • Pass --hosted-plugin-inspect=9339 arg to the backend server from the command line.
      • Instead, you can run Launch Browser Backend launch configuration which is already pre-configured.
    • Open the debug view and run the Attach to Plugin Host launch configuration.
      • It connects to the plugin host if at least one extension is detected, otherwise it timeouts after 60s.
      • If you want to debug the activation then enable stopOnEntry flag.
    • Open the browser page.

    click for base article

    The following launch configuration is meant to be used when the Theia project is opened as the main project in VS Code, the following launch configuration is added inside .vscode/launch.json.

    • The source repository of your plugin is expected under your ${workspaceFolder}/plugins folder
    • You can start the frontend from URL: http://localhost:3030
    • It's suggested to update your frontend launch configuration URL to open your favorite target project in a second launch

    Launch configuration template that will start the backend process, and then attempt to connect on port 9339 to debug the plugin-host sub-process:

    {
    "name": "Launch VS Code extension as Theia plugin",
    "type": "node",
    "request": "launch",
    "port": 9339,
    "timeout": 100000,
    "args": [
    "${workspaceFolder}/examples/browser/src-gen/backend/main.js",
    "${workspaceFolder}",
    "--port=3030",
    "--hosted-plugin-inspect=9339", // spawn the plugin-host in debug mode
    "--plugins=local-dir:${workspaceFolder}/plugins"
    ],
    "stopOnEntry": false,
    "sourceMaps": true,
    "outFiles": [
    "${workspaceFolder}/**/*.js"
    ],
    "internalConsoleOptions": "openOnSessionStart",
    "outputCapture": "std"
    }

    Enable source maps in the plugin's tsconfig.json

    {
    "compilerOptions": {
    "sourceMap": true
    }
    }

    If Webpack is used you should bundle in development mode in the package.json scripts to avoid minification:

    webpack --mode development
    

    As well as enabling source map output in the webpack.config.js

    module.exports = {
    devtool: 'source-map'
    }

    If you get errors while building like:

    (parent folders)/index.d.ts: error TS2300: Duplicate identifier
    

    You can fix it by modifying your tsconfig.json:

    {
    "compilerOptions": {
    "typeRoots": ["./node_modules/@types"]
    }
    }
    • Use Chrome devtools to profile both the frontend and backend (Node.js).
      • For Node.js: open chrome://inspect, click the configure button and ensure target host and port are listed.
    • Learn how to get and understand CPU measurements: https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/
    • Learn how to get and understand Memory measurements: https://developers.google.com/web/tools/chrome-devtools/memory-problems/
    • Before taking the memory snapshot always collect garbage.
    • Make sure that Chrome extensions don't distort measurements by disabling them.
      • For frontend: React extension is leaking components.
    • Make measurements before and after improvements to provide them as evidence on a pull request.
      • Also document how to reproduce improved measurements in How to test section of a pull request description.
    • If objects don't have a proper class, i.e. plain JSON, then find one of them in the first snapshot and check that it is garbage collected in the diff between snapshots.
    • In Browser: open the devtools.
    • In Electron: Help -> Toggle Electron Developer Tools.
        npm run test
    

    By default, this will generate the code coverage for the tests in an HTML format, which can be easily viewed with your browser (Chrome/Firefox/Edge/Safari etc.) by opening packages/<package name>/coverage/index.html.

    • Install scoop.
    • Install nvm with scoop: scoop install nvm.
    • Install Node.js with nvm: nvm install lts, then use it: nvm use lts. You can list all available Node.js versions with nvm list available if you want to pick another version.
    • If you need to install windows-build-tools, see Installing Windows Build Tools.
    • If you run into problems with installing the required build tools, the node-gyp documentation offers a useful guide how to install the dependencies manually. The versions required for building Theia are:
    • If you have multiple versions of either python or Visual Studio installed, or if the tool is not found, you may adjust the version used as described here

    Clone, build and run Theia. Using Git Bash as administrator:

    git clone https://github.com/eclipse-theia/theia.git \
    && cd theia \
    && npm install \
    && npm run build:browser \
    && npm run start:browser

    If you do not have Git Bash installed on your system, get one, or use scoop: scoop install git.

    • Previously, windows-build-tools is required to build Native Nodes modules on Windows. The npm package is now deprecated because NodeJS installer can now install all the required tools that it needs, including Windows Build Tools.
    • In case you need to install the tool manually, run PowerShell as Administrator and copy paste the following: npm --add-python-to-path install --global --production windows-build-tools.

    First make sure that you follow the steps given in the docs correctly.

    The start command will start a watcher on many files in the theia directory. To avoid ENOSPC errors, increase your default inotify watches.

    It can be done like so:

    echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
    

    If you see LINK : fatal error LNK1104: cannot open file 'C:\\Users\\path\\to\\node.lib' [C:\path\to\theia\node_modules\drivelist\build\drivelist.vcxproj], then set the Visual Studio version manually with npm config set msvs_version 2017 --global.

    If you are facing with EPERM: operation not permitted or permission denied errors while building, testing or running the application then;

    • You don't have write access to the installation directory.
    • Try to run your command line (PowerShell, GitBash, Cygwin or whatever you are using) as an administrator.
    • The permissions in the NPM cache might get corrupted. Please try to run npm cache clean to fix them.
    • If you experience issues such as Error: EBUSY: resource busy or locked, rename, try to disable (or uninstall) your anti-malware software. See here.
    • Still having issues on Windows? File a [bug]. We are working on Linux or OS X operating systems. Hence, we are more than happy to receive any Windows-related feedbacks, bug reports.

    If you're still struggling with the build, but you use Windows 10, then you can enable the Windows Subsystem for Linux and you can get a Linux distro for free.

    You need to have the Xcode command line tools installed in order to build and run Theia. You can install the tools by running

    xcode-select --install
    

    If you already have Xcode installed, but you see the xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance error, you need to run the following command to fix it: sudo xcode-select --switch /Library/Developer/CommandLineTools.

    The solution is the same if you have updated to 10.14 (Mojave) and you can see the gyp: No Xcode or CLT version detected! error. More details here.

    When trying to install with root privileges, you might encounter errors such as cannot run in wd.

    Several options are available to you:

    • Install without root privileges
    • Use the --unsafe-perm flag: npm install --unsafe-perm