docker-compose - PHP instance seems not to communicate with db service

Question

I'm developing a project based on the Github template dunglas/symfony-docker to which I want to add a mysql database..

It seems that my docker-compose.yml file is incorrectly configured because the communication between PHP and mysql is malfunctioning. Indeed when I try to perform a symfony migration, doctrine returns me the following error

An exception occurred in the driver: SQLSTATE[HY000] [2002] No such file or directory

When I inspect the PHP logs I notice that PHP is waiting after the database

php_1 | Still waiting for db to be ready... Or maybe the db is not reachable.

my docker-compose.yml look like :

version: "3.4"

services:
  php:
    build:
      context: .
      target: symfony_php
      args:
        SYMFONY_VERSION: ${SYMFONY_VERSION:-}
        SKELETON: ${SKELETON:-symfony/skeleton}
        STABILITY: ${STABILITY:-stable}
    restart: unless-stopped
    volumes:
      - php_socket:/var/run/php
    healthcheck:
      interval: 10s
      timeout: 3s
      retries: 3
      start_period: 30s
    environment:
      # Run "composer require symfony/orm-pack" to install and configure Doctrine ORM
      #DATABASE_URL: postgresql://${POSTGRES_USER:-symfony}:${POSTGRES_PASSWORD:-ChangeMe}@database:5432/${POSTGRES_DB:-app}?serverVersion=${POSTGRES_VERSION:-13}
      DATABASE_URL: mysql://wijo:wijo@localhost:3306/wijo"
      # Run "composer require symfony/mercure-bundle" to install and configure the Mercure integration
      MERCURE_URL: ${CADDY_MERCURE_URL:-http://caddy/.well-known/mercure}
      MERCURE_PUBLIC_URL: https://${SERVER_NAME:-localhost}/.well-known/mercure
      MERCURE_JWT_SECRET: ${CADDY_MERCURE_JWT_SECRET:-!ChangeMe!}

  caddy:
    build:
      context: .
      target: symfony_caddy
    depends_on:
      - php
    environment:
      SERVER_NAME: ${SERVER_NAME:-localhost, caddy:80}
      MERCURE_PUBLISHER_JWT_KEY: ${CADDY_MERCURE_JWT_SECRET:-!ChangeMe!}
      MERCURE_SUBSCRIBER_JWT_KEY: ${CADDY_MERCURE_JWT_SECRET:-!ChangeMe!}
    restart: unless-stopped
    volumes:
      - php_socket:/var/run/php
      - caddy_data:/data
      - caddy_config:/config
    ports:
      # HTTP
      - target: 80
        published: ${HTTP_PORT:-80}
        protocol: tcp
      # HTTPS
      - target: 443
        published: ${HTTPS_PORT:-443}
        protocol: tcp
      # HTTP/3
      - target: 443
        published: ${HTTP3_PORT:-443}
        protocol: udp

# Mercure is installed as a Caddy module, prevent the Flex recipe from installing another service
###> symfony/mercure-bundle ###
###< symfony/mercure-bundle ###
  db:
    image: mysql
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: 'wijo'
      MYSQL_USER: 'wijo'
      MYSQL_PASSWORD: 'wijo'
      MYSQL_DATABASE: 'wijo'
    volumes:
      - db-data:/var/lib/mysql
      - ./docker/db/data:/var/lib/mysql

  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080

volumes:
  php_socket:
  caddy_data:
  caddy_config:
###> symfony/mercure-bundle ###
###< symfony/mercure-bundle ###

###> doctrine/doctrine-bundle ###
  db-data:
###< doctrine/doctrine-bundle ###

dockerFile

# the different stages of this Dockerfile are meant to be built into separate images
# https://docs.docker.com/develop/develop-images/multistage-build/#stop-at-a-specific-build-stage
# https://docs.docker.com/compose/compose-file/#target


# https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact
ARG PHP_VERSION=8.1
ARG CADDY_VERSION=2

# "php" stage
FROM php:${PHP_VERSION}-fpm-alpine AS symfony_php

# persistent / runtime deps
RUN apk add --no-cache \
        acl \
        fcgi \
        file \
        gettext \
        git \
        gnu-libiconv \
    ;

# install gnu-libiconv and set LD_PRELOAD env to make iconv work fully on Alpine image.
# see https://github.com/docker-library/php/issues/240#issuecomment-763112749
ENV LD_PRELOAD /usr/lib/preloadable_libiconv.so

ARG APCU_VERSION=5.1.21
RUN set -eux; \
    apk add --no-cache --virtual .build-deps \
        $PHPIZE_DEPS \
        icu-dev \
        libzip-dev \
        zlib-dev \
    ; \
    \
    docker-php-ext-configure zip; \
    docker-php-ext-install -j$(nproc) \
        intl \
        zip \
    ; \
    pecl install \
        apcu-${APCU_VERSION} \
    ; \
    pecl clear-cache; \
    docker-php-ext-enable \
        apcu \
        opcache \
    ; \
    \
    runDeps="$( \
        scanelf --needed --nobanner --format '%n#p' --recursive /usr/local/lib/php/extensions \
            | tr ',' '\n' \
            | sort -u \
            | awk 'system("[ -e /usr/local/lib/" $1 " ]") == 0 { next } { print "so:" $1 }' \
    )"; \
    apk add --no-cache --virtual .phpexts-rundeps $runDeps; \
    \
    apk del .build-deps

COPY docker/php/docker-healthcheck.sh /usr/local/bin/docker-healthcheck
RUN chmod +x /usr/local/bin/docker-healthcheck

HEALTHCHECK --interval=10s --timeout=3s --retries=3 CMD ["docker-healthcheck"]

RUN ln -s $PHP_INI_DIR/php.ini-production $PHP_INI_DIR/php.ini
COPY docker/php/conf.d/symfony.prod.ini $PHP_INI_DIR/conf.d/symfony.ini

COPY docker/php/php-fpm.d/zz-docker.conf /usr/local/etc/php-fpm.d/zz-docker.conf

COPY docker/php/docker-entrypoint.sh /usr/local/bin/docker-entrypoint
RUN chmod +x /usr/local/bin/docker-entrypoint

VOLUME /var/run/php

COPY --from=composer:latest /usr/bin/composer /usr/bin/composer

# https://getcomposer.org/doc/03-cli.md#composer-allow-superuser
ENV COMPOSER_ALLOW_SUPERUSER=1

ENV PATH="${PATH}:/root/.composer/vendor/bin"

WORKDIR /srv/app

# Allow to choose skeleton
ARG SKELETON="symfony/skeleton"
ENV SKELETON ${SKELETON}

# Allow to use development versions of Symfony
ARG STABILITY="stable"
ENV STABILITY ${STABILITY}

# Allow to select skeleton version
ARG SYMFONY_VERSION=""
ENV SYMFONY_VERSION ${SYMFONY_VERSION}

# Download the Symfony skeleton and leverage Docker cache layers
RUN composer create-project "${SKELETON} ${SYMFONY_VERSION}" . --stability=$STABILITY --prefer-dist --no-dev --no-progress --no-interaction; \
    composer clear-cache

###> recipes ###
###> doctrine/doctrine-bundle ###
RUN apk add --no-cache --virtual .pgsql-deps postgresql-dev; \
    docker-php-ext-install -j$(nproc) pdo_pgsql; \
    apk add --no-cache --virtual .pgsql-rundeps so:libpq.so.5; \
    apk del .pgsql-deps
###< doctrine/doctrine-bundle ###
###< recipes ###

COPY . .

RUN set -eux; \
    mkdir -p var/cache var/log; \
    composer install --prefer-dist --no-dev --no-progress --no-scripts --no-interaction; \
    composer dump-autoload --classmap-authoritative --no-dev; \
    composer symfony:dump-env prod; \
    composer run-script --no-dev post-install-cmd; \
    chmod +x bin/console; sync
VOLUME /srv/app/var

ENTRYPOINT ["docker-entrypoint"]
CMD ["php-fpm"]

FROM caddy:${CADDY_VERSION}-builder-alpine AS symfony_caddy_builder

RUN xcaddy build \
    --with github.com/dunglas/mercure \
    --with github.com/dunglas/mercure/caddy \
    --with github.com/dunglas/vulcain \
    --with github.com/dunglas/vulcain/caddy

FROM caddy:${CADDY_VERSION} AS symfony_caddy

WORKDIR /srv/app

COPY --from=dunglas/mercure:v0.11 /srv/public /srv/mercure-assets/
COPY --from=symfony_caddy_builder /usr/bin/caddy /usr/bin/caddy
COPY --from=symfony_php /srv/app/public public/
COPY docker/caddy/Caddyfile /etc/caddy/Caddyfile

my database url DATABASE_URL="mysql://wijo:wijo@localhost:3306/wijo"

Any clues to the issue?

Answer 1

localhost in a container means the container itself. You want to talk to your database container, so you should use it's service name and your database URL should be

DATABASE_URL="mysql://wijo:wijo@db:3306/wijo"