docker build a custom image from docker-compose.yml - docker

Question

I have a setup where I have a Dockerfile and a docker-compose.yml.
Dockerfile:
# syntax=docker/dockerfile:1
FROM php:7.4
COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer
RUN docker-php-ext-install mysqli pdo pdo_mysql
RUN apt-get -y update
RUN apt-get -y install git
COPY . .
RUN composer install
YML file:
version: '3.8'
services:
foo_db:
image: mysql:5.7
environment:
- MYSQL_ROOT_PASSWORD=foo
- MYSQL_DATABASE=foo
foo_app:
image: foo_php
platform: linux/x86_64
restart: unless-stopped
ports:
- 8000:8000
links:
- foo_db
environment:
- DB_CONNECTION=mysql
- DB_HOST=foo_db
- DB_PORT=3306
- DB_PASSWORD=foo
command: sh -c "php artisan serve --host=0.0.0.0 --port=8000"
foo_phpmyadmin:
image: phpmyadmin
links:
- foo_db
environment:
PMA_HOST: foo_db
PMA_PORT: 3306
PMA_ARBITRARY: 1
PMA_USER: root
PMA_PASSWORD: foo
restart: always
ports:
- 8081:80
In order to set this up on a new workstation the steps I am taking are first running:
docker build -t foo_php .
As I understand it this runs the commands in the Dockerfile and creates a new image called foo_php.
Once that is done I am running docker compose up.
Question:
How can I tell docker that I would like my foo_app image to be automatically built, so that I can skip the step of first building the image. Ideally I would have one command similar to docker compose up that I could call each time I want to launch my containers. The first time it would build the images it needs including this custom image of mine described in the Dockerfile, and subsequent times calling it would just run these images. Does a method to achieve this exist?

Answer 1

You can ask docker compose to build the image every time:
docker compose up --build
But you need to also instruct docker compose on what to build:
foo_app:
image: foo_php
build:
context: .
where context points to the folder containing your Dockerfile