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| 1 | +# Developing Node.js using Dev Containers |
| 2 | + |
| 3 | +Node.js publishes a [nightly image on DockerHub](https://hub.docker.com/r/nodejs/devcontainer) for |
| 4 | +[Dev Containers](https://containers.dev/) that can be used to spin up a |
| 5 | +development container that comes with pre-installed build dependencies and pre-genreated build cache. |
| 6 | + |
| 7 | +When you need to test a few changes in the main branch and do not need |
| 8 | +to change the V8 headers (which is rare), using the nightly image will allow you to compile your |
| 9 | +changes from a fresh checkout quickly without having to compile the entire codebase, especially V8, |
| 10 | +from scratch. |
| 11 | + |
| 12 | +The Dev Container also allows you to test your changes in a different operating system, and to test |
| 13 | +third-party code from bug reports safely with your work-in-progress Node.js branches in an isolated environment. |
| 14 | + |
| 15 | +There are many command line tools, IDEs and services that [support Dev Containers](https://containers.dev/supporting). |
| 16 | +Among them, [Visual Studio Code (VS Code)](https://code.visualstudio.com/) is a very popuplar option. |
| 17 | +This guide will walk you through the steps to set up a Dev Container for Node.js development using VS Code. |
| 18 | +You should be able to use the same [`nodejs/devcontainer:nightly` image](https://hub.docker.com/r/nodejs/devcontainer) |
| 19 | +in other tools and services using generally similar steps. |
| 20 | + |
| 21 | +## Prerequisites |
| 22 | + |
| 23 | +Before you begin, ensure you have the following installed on your machine: |
| 24 | + |
| 25 | +* [Docker](https://www.docker.com/get-started) |
| 26 | +* [Visual Studio Code](https://code.visualstudio.com/) |
| 27 | +* [Dev Containers extension for VS Code](https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.remote-containers) |
| 28 | + |
| 29 | +## Setting Up the Dev Container |
| 30 | + |
| 31 | +### 1. Clone the Node.js Repository |
| 32 | + |
| 33 | +If you haven't already, clone the Node.js repository to your local machine. |
| 34 | + |
| 35 | +```bash |
| 36 | +git clone https://github.com/nodejs/node.git |
| 37 | +``` |
| 38 | + |
| 39 | +Or follow [this guide](./pull-requests.md#setting-up-your-local-environment) if you are |
| 40 | +setting up the git repository to contribute changes as pull requests. |
| 41 | + |
| 42 | +### 2. Open the Repository in VS Code |
| 43 | + |
| 44 | +Launch VS Code and open the cloned Node.js repository. |
| 45 | + |
| 46 | +### 3. Start the Dev Container |
| 47 | + |
| 48 | +* Press `Ctrl+Shift+P` or `Cmd+Shift+P` to open the command palette. |
| 49 | +* Type `Dev Containers: Reopen in Container` and select it. |
| 50 | +* Select the appropriate Dev Container configuration from the drop down. The base configuration in this |
| 51 | + repository is `Node.js Dev Container` located in |
| 52 | + [`.devcontainer/base/devcontainer.json`](../../.devcontainer/base/devcontainer.json), which should be |
| 53 | + automatically detected by VS Code. |
| 54 | + |
| 55 | +### 4. Wait for the Container to Build |
| 56 | + |
| 57 | +VS Code will build the Dev Container based on the configuration file. This may take some time depending |
| 58 | +on your internet connection and system performance. |
| 59 | + |
| 60 | +After the Dev Container is built, it will start automatically. By default it will run `git restore-mtime` to |
| 61 | +restore the modification times of the files in the working directory, in order to keep the build cache valid, |
| 62 | +and you will see something like this in the terminal. |
| 63 | + |
| 64 | +```text |
| 65 | +Running the postCreateCommand from devcontainer.json... |
| 66 | +
|
| 67 | +[10136 ms] Start: Run in container: /bin/sh -c git restore-mtime |
| 68 | +``` |
| 69 | + |
| 70 | +This may take a few seconds. Wait until it finishes before you open a new terminal. |
| 71 | + |
| 72 | +### 5. Build your changes |
| 73 | + |
| 74 | +Once the Dev Container is running, you can open a terminal in VS Code and run the build commands. By default, |
| 75 | +your local repository is mounted inside a checkout in the Dev Container, so any changes you make will be reflected |
| 76 | +in the container environment. |
| 77 | + |
| 78 | +In the Dev Container, the necessary dependencies are already installed and Node.js has already been |
| 79 | +compiled, so a usable cache will exist. For better developer experience, the |
| 80 | +build tool used in the Dev Container is `ninja`, instead of `make`. See |
| 81 | +[Building Node.js with Ninja](./building-node-with-ninja.md) for more details on using `ninja` to build Node.js. |
| 82 | + |
| 83 | +```bash |
| 84 | +./configure --ninja |
| 85 | +ninja -C out/Release |
| 86 | +``` |
| 87 | + |
| 88 | +As long as your local checkout is not too different from the main branch in the nightly image, the build |
| 89 | +should be incremental and fast. |
| 90 | + |
| 91 | +### 6. Leaving the Container |
| 92 | + |
| 93 | +When you're done working in the Dev Container, open the command palette again and select |
| 94 | +`Dev Containers: Reopen Folder locally` to go back to your local development environment. |
| 95 | + |
| 96 | +## Customizing the Dev Container |
| 97 | + |
| 98 | +The default configuration is located in |
| 99 | +[`.devcontainer/base/devcontainer.json`](../../.devcontainer/base/devcontainer.json) which pairs with the |
| 100 | +official [Node.js Nightly Dev Container image](https://github.com/nodejs/devcontainer). |
| 101 | +This is tracked in version control. You can create a personal configuration by creating a new |
| 102 | +directory in `.devcontainer/` and adding a `devcontainer.json` file there (for example, |
| 103 | +`.devcontainer/local/devcontainer.json`), and configure VS Code to use it. |
| 104 | + |
| 105 | +## Rebuilding the Dev Container |
| 106 | + |
| 107 | +Docker will cache the already downloaded Dev Container images. If you wish to pull a new nightly image, you can do |
| 108 | +so by running the following command in the terminal on your host machine: |
| 109 | + |
| 110 | +```bash |
| 111 | +docker pull nodejs/devcontainer:nightly |
| 112 | +``` |
| 113 | + |
| 114 | +The default configuration creates a volume to cache the build outputs between Dev Container restarts. If you wish to |
| 115 | +clear the build cache, you can do so by deleting the volume named `node-devcontainer-cache`. |
| 116 | + |
| 117 | +```bash |
| 118 | +docker volume rm node-devcontainer-cache |
| 119 | +``` |
| 120 | + |
| 121 | +To rebuild the Dev Container in VS Code, open the command palette and select |
| 122 | +`Dev Containers: Rebuild and Reopen in Container`. |
| 123 | + |
| 124 | +## Further Reading |
| 125 | + |
| 126 | +* If you want to propose changes to the official Node.js Nightly Dev Container image, feedback is welcome at |
| 127 | + [nodejs/devcontainer](https://github.com/nodejs/devcontainer). There, you can find the Dockerfile and |
| 128 | + automated nightly workflows. |
| 129 | +* [Visual Studio Code Dev Containers Documentation](https://code.visualstudio.com/docs/remote/containers) |
| 130 | +* [GitHub's Introduction to Dev Containers](https://docs.github.com/en/codespaces/setting-up-your-project-for-codespaces/adding-a-dev-container-configuration/introduction-to-dev-containers) |
| 131 | +* [The Dev Containers Specification](https://containers.dev/implementors/spec/) |
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