If using Nixpacks, you can override the start command with a Procfile at the root of your app. The runtime(s) will then initialize as soon as you start your application.

When multiple providers are defined, Railway will build your service with the language providers (in the order you defined) and ensure your binaries are ready to be called. This is useful if you have code that calls libraries that need to be built from another language within your repo. Within your Service's settings, under the Builds section, you can define within the multi-select box which Nixpacks language providers you would like to use for your builds. If there is a detected nixpacks.toml file, it is possible to define a build provider ahead of time like so: This determines which language provider to install packages and runtimes for. With Nixpacks, we analyze the app source directory and generate a build plan. This feature is only available to Priority Boarding members. Note, negations will only work if you include files in a preceding rule. Here are a few examples of common use-cases. For a root directory of /app, /app/**.js would be used as a pattern to match files in the new root. Note, if a Root Directory is provided, patterns still operate from /. When specified, any changes thatĭon't match the patterns will skip creating a new deployment. For example, a monorepo might want to only trigger builds if files areĬhanged in the /packages/backend directory. That can be used to trigger a new deployment based on what file paths haveĬhanged. Outside the root directory will not trigger a new build. When specified, all build and deployĬommands will operate within that root directory. The root directory defaults to / but can be changed for various use-cases like For those familiar with Nixpacks, this gets set as the -build-cmd argument during the Nixpacks build. If using the Nixpacks builder, you can customize the build command that is run.

Reach out on Discord or on the Nixpacks GitHub repo. If you have a language or feature that you want us to support, please don't hesitate to These include things likeįor a full list of these options, please view the Nixpacks docs. Nixpacks has a variety of options that can be configured with environment variables. Railway uses Nixpacks to build and deploy your code withĬurrently, we support the following languages out of the box.

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