Call to undefined function mysqli_connect()

LexXy :

In this code must be an error due to empty arguments in the mysqli_connect function. But browser display different error. As I know mysqli_connect function installed by default. Where is the problem or my mistake? How I can fix it?

Dockerfile

FROM php:fpm

# Update system core
RUN apt update -y && apt upgrade -y

# Start PHP-FPM
CMD ["php-fpm"]

index.php

<?php mysqli_connect('', '', '', '', '', ''); ?>

Error in browser:

Fatal error: Uncaught Error: Call to undefined function mysqli_connect() in /var/www/index.php:3 Stack trace: #0 {main} thrown in /var/www/index.php on line 3

Dmitry :

In Dockerfile you need add mysqli extension:

FROM php:7.3-fpm

# Update system core

RUN apt update && apt install -y \
        libfreetype6-dev \
        libjpeg62-turbo-dev \
        libpng-dev libxml2-dev libcurl4-gnutls-dev


RUN docker-php-ext-install -j$(nproc) mysqli \
    && docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ \
    && docker-php-ext-install -j$(nproc) gd

# Start PHP-FPM
CMD ["php-fpm"]