How can I modify php.ini using Railway Nixpacks?

I need to increase the upload_max_filesize directive in php.ini to allow images over 2MB to upload to my Laravel site, which is deployed in Railway using Nixpacks.

I've already tried to include some init_set('upload_max_filesize', '100M') in my routes, including this directive in the nginx.conf, and adding the environment variable PHP_INI_UPLOAD_MAX_FILESIZE in Railway. None of these solutions worked.

How can I modify the php.ini while using Nixpacks in Railway?

Solution

Although I could not find any solution to do this using Nixpacks, I finally ended up adding a Dockerfile in the root folder of the project to do the deployment with docker. If Railways detects a Dockerfile in the root folder, it automatically executes the deployment using it.

Here the Dockerfile I used which is working fine with a Laravel app:

FROM php:8.1-apache

# Arguments defined in docker-compose.yml
ARG user
ARG uid

# Install system dependencies
RUN apt-get update && apt-get install -y \
    git \
    curl \
    libpng-dev \
    libonig-dev \
    libxml2-dev \
    zip \
    unzip

# Clear cache
RUN apt-get clean && rm -rf /var/lib/apt/lists/*

# Install PHP extensions
RUN docker-php-ext-install pdo_mysql mbstring exif pcntl bcmath gd

# Get latest Composer
COPY --from=composer:latest /usr/bin/composer /usr/bin/composer

# Set up node and npm

RUN curl -sL https://deb.nodesource.com/setup_18.x | bash
RUN apt-get update && apt-get -y install nodejs 

# Set working directory
WORKDIR /var/www

RUN apt-get update && apt-get install -y \
        libfreetype6-dev \
        libjpeg62-turbo-dev \
        libpng-dev \
    && docker-php-ext-configure gd --with-freetype --with-jpeg \
    && docker-php-ext-install -j$(nproc) gd

WORKDIR /var/www/html
COPY . .

#Modify php.ini setings

RUN touch /usr/local/etc/php/conf.d/uploads.ini \
    && echo "upload_max_filesize = 10M;" >> /usr/local/etc/php/conf.d/uploads.ini

#Serve the application

RUN composer install
RUN npm install
CMD php artisan migrate --force && php artisan storage:link && php artisan serve --host=0.0.0.0 --port=$PORT