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Java container cant connect to MYSQL container with docker-compose

I was given a multy-steps task and im stuck !!
im trying to connect my Java container to my MYSQL container,but im getting 503 ERROR
HTTP ERROR 503
Problem accessing /. Reason:
Service Unavailable
docker-compose file :
version: "3.3"
services:
lavagna:
build: .
ports:
- "8080:8080"
networks:
- back_net
depends_on:
- my_db
environment:
spring.datasource.url: "jdbc:mysql://my-db:3306/lavagna"
my_db:
image: mysql:5.7
ports:
- "3306:3306"
networks:
- back_net
volumes:
- $PWD/mysql:/var/lib/mysql
environment:
MYSQL_ROOT_PASSWORD: 123
MYSQL_USER: eyal
MYSQL_PASSWORD: 123
networks:
back_net:
driver: bridge
I got the JAVA src files,i just used maven localy to build it and use target for the Java Dockerfile
java app dockerfile :
FROM openjdk:8-jre-alpine
EXPOSE 8080
COPY ./target/. .
COPY ./entrypoint.sh .
ENV DB_DIALECT MYSQL
ENV DB_URL jdbc:mysql://localhost:3306/lavagna
ENV DB_USER "root"
ENV DB_PASS "123"
ENV SPRING_PROFILE dev
RUN apk update \
&& apk add ca-certificates \
&& update-ca-certificates && apk add openssl
RUN chmod 774 entrypoint.sh
ENTRYPOINT [ "./entrypoint.sh" ]

I think you need a combination of comments and answers given already. Your containers are on the same network, so it appears to boil down to configuration.
In your docker file update your DB_URL to:
ENV DB_URL jdbc:mysql://my_db:3306/lavagna
If you use localhost your container will loopback to itself, and never hit the network.
In your docker-compose yml file, you have a typo in the url, try updating to:
spring.datasource.url: "jdbc:mysql://my_db:3306/lavagna"
As an aside, using depends_on does not wait for the service to be ready. It simply dictates start order as the documentation states:
There are several things to be aware of when using depends_on:
depends_on does not wait for db and redis to be “ready” before starting web - only until they have been started. If you need to wait for a service to be ready...

Unable to link two Docker containers on a custom bridge network on Windows

I want two Docker containers to be able to communicate with each other on a Windows machine running Docker Toolbox. I am able to link the containers using the --link option; however, if I try to run the containers on a custom bridge network that I created, the containers are unable to communicate with each other :
Here are the steps I followed :
docker network create web-application-mysql-network
docker run --detach --env MYSQL_ROOT_PASSWORD=somepassword--env MYSQL_USER=some-user --env MYSQL_PASSWORD=pass --env MYSQL_DATABASE=mydb --name mysql --publish 3306:3306 --network=web-application-mysql-network mysql:5.7
docker run -p 8080:8080 -d --network=web-application-mysql-network myrepo/mywebapp:0.0.1-SNAPSHOT
The image in the last command above contains the Tomcat web server Docker image as the base image and a "WAR" (web archive file) that will be hosted in Tomcat. When I check the logs for the container started by the last command, I can see the following errors :
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
I am able to link the two containers without any issues if I used the --link option instead of running them on my custom bridge network.
Additional info : I am using localhost in my web app code for the MySQL URL. This seemed to work fine when using --link
What configuration/command parameters am I missing to make this work?

When you're using the network, you should use the container name you want to connect to in the URL. In other words, you have to use mysql in mywebapp to reach the DB.
I'd suggest you take a check to docker-compose since it allows you to avoid the manual creation of the network.
Here's an example:
version: "3"
services:
mysql:
image: mysql:5.7
env_file:
- db.env
environment:
MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
MYSQL_USER: ${MYSQL_USER:-user}
MYSQL_PASSWORD: ${MYSQL_PASSWORD}
MYSQL_DATABASE: "mydb"
volumes:
- dbdata:/var/lib/mysql
mywebapp:
image: myrepo/mywebapp:${TAG_VERSION:-0.0.1-SNAPSHOT}
build:
context: ./mywebapp_location
dockerfile: Dockerfile
ports:
- "8080:8080"
volumes:
dbdata:
db.env:
MYSQL_ROOT_PASSWORD=mysql_root_password
MYSQL_USER=the_user
MYSQL_PASSWORD=the_user_password
To build you can simply execute:
docker-compose build
and to start simply:
docker-compose up
for the rest you can use the normal docker commands.

Docker-compose ERR_NAME_NOT_RESOLVED (Java Spring + Angular)

I have a two simple images:
#Angular image
FROM node:12.2.0
WORKDIR /app
ENV PATH /app/node_modules/.bin:$PATH
COPY package.json /app/package.json
RUN npm install
RUN npm install -g #angular/cli#7.3.9
COPY . /app
CMD ng serve
&
# Java spring (REST) image
FROM openjdk:8-jdk-alpine
VOLUME /tmp
COPY ./target/api-0.0.1-SNAPSHOT.jar app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar", "app.jar"]
And my docker-compose:
version: '3'
services:
web_app_speech:
image: web_app_speech
restart: always
ports:
- "4300:4200"
depends_on:
- api_speech_docker
api_speech_docker:
image: api_speech_docker
ports:
- "8080:8080"
restart: always
$> docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
15c719d31861 web_app_speech "/bin/sh -c 'ng serv…" 9 minutes ago Up 9 minutes 0.0.0.0:4300->4200/tcp azure_web_app_speech_1
044fd15f07e4 api_speech_docker "java -Djava.securit…" 10 minutes ago Up 9 minutes 0.0.0.0:8080->8080/tcp azure_api_speech_docker_1
I can access my REST API from localhost:8080 and my web app from localhost:4300 without problem but when I try to perform a call from my web_app to my rest_api I have the following error:
OPTIONS http://api_speech_docker:8080/speech net::ERR_NAME_NOT_RESOLVED
I have no idea how to fix this, if you need more logs tell me !
Thanks for your help 🙏

To my understanding your REST API is being called from your browser which cannot resolve the docker service names. For different applications, I used the following solutions:
Use localhost: http://localhost:8080/speech
Works great for locally hosted projects
If hosting on the cloud, may cause other errors
or
Hit endpoint through public IP http://13.192.123.12:8080/speech
Only works if the IP address does not change
If hosting on the cloud, inbound traffic through port 8080 must be allowed as well

Docker disable restart on-failure

The following situation:
I have a Spring Boot Application
which runs in a Docker swarm
but fails to start because it was not properly configured (a property is missing).
It seems to me that the docker swarm always tries to restart the container, but always fails because of the missing property.
The restart makes no sense because docker will never be able to start the application unless I fix the missing property.
So currently the swarm ends in an endless loop.
Regarding this problem I already read:
The docker documentation: https://docs.docker.com/config/containers/start-containers-automatically/
and several StackOverflow posts: https://stackoverflow.com/search?q=Docker+restart
My "setup":
The dockerfile:
ARG nexus_docker_registry=mynexus.com:10099
FROM ${nexus_docker_registry}/openjdk:8-jdk-alpine
ADD myjar.jar myjar.jar
ENV JAVA_OPTS=""
ENTRYPOINT [ "java", "-jar", "/myjar.jar" ]
my YML-file to create the docker service:
---
- hosts: docker_manager
become: false
vars:
servicename: 'myservice'
imageurl: "mynexus.com:10099/myjar:{{version}}"
extraoptions:
- "--with-registry-auth"
- "--detach=true"
- "--log-driver gelf"
- "--log-opt 'gelf-address=udp://{{ groups['logstash'][0] }}:10001'"
- "--hostname 'myhost.com'"
- "--mount 'type=bind,source=/etc/localtime,destination=/etc/localtime:ro'"
- "--mount 'type=volume,source=mykeys,destination=/mykeys'"
- "--env 'spring.profiles.active=docker'"
- "--publish 8000:6666"
tasks:
- name: Include vault
include_vars: "myvault.yml"
- name: "delete service '{{ servicename }}'"
command: sudo docker service rm "{{ servicename }}"
args:
warn: false
ignore_errors: true
run_once: true
- name: "create service {{ servicename }}"
command: sudo docker service create {{ extraoptions | join( ' ' ) }} --name "{{ servicename }}" "{{ imageurl }}"
args:
warn: false
run_once: true
What I want to achieve is:
If the spring boot application is not able to start because of for example a BeanCreationException or something similar, then I don't want the docker service to restart endlessly.
If I restart the swarm etc. the docker service should restart automatically.
In the docker documentation is written:
If you manually stop a container, its restart policy is ignored until the Docker daemon restarts or the container is manually restarted. This is another attempt to prevent a restart loop.
So I guess that what I want to achieve is not possible with a restart policy.
Questions:
but maybe I can write something in my Dockerfile that I achieve my goals?
Or am I totally wrong here and misinterpret the documentation?
I am unfortunately not a docker expert and still learning to handle 'the swarm'.

There are 4 different restart policies in Docker:
no - Do not automatically restart the container. (the default)
on-failure - Restart the container if it exits due to an error, which manifests as a non-zero exit code.
always - Always restart the container if it stops
unless-stopped - Similar to always, except that when the container is stopped (manually or otherwise), it is not restarted even after Docker daemon restarts.
There is no way for docker to "detect" a type of error from an application and restart or not depending on that.
One way to achieve this is to use supervisord within your container and let that handle the restart depending of a list of exit codes that you define. But this means that your container will only restart when supervisord crashes, not when you application does and you'll have to change your code to return different exit codes on the errors that should be restarting and the ones that shouldn't.

Because it does not seem possible what I wanted to achieve, I read the documentation again (https://docs.docker.com/engine/reference/commandline/service_create/) and found the option --restart-max-attempts which will solve my problem with the endless loop.

You may want to try and implement the creation of a docker stack based on a docker-compose file.
In this scenario, as the compose v3 documentation indicates, you have full control over the service restart policy.
The next example won't allow restart:
version: "3.9"
services:
python:
image: my_user/my_repo:my_container
volumes:
- /home/python:/home
deploy:
restart_policy:
condition: none
You can adjust the restart_policy block with condition: [none | on-failure | any] and with max_attempts: [your_int]

Spring Boot + docker-compose + MySQL: Connection refused

I'm trying to set up a Spring Boot application that depends on a MySQL database called teste in docker-compose. After issuing docker-compose up, I'm getting:
Caused by: java.net.ConnectException: Connection refused (Connection refused)
I'm running on Linux Mint, my docker-compose version is 1.23.2, my Docker version is 18.09.0.
application.properties
# JPA PROPS
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy
spring.datasource.url=jdbc:mysql://db:3306/teste?useSSL=false&serverTimezone=UTC
spring.datasource.username=rafael
spring.datasource.password=password
spring.database.driverClassName =com.mysql.cj.jdbc.Driver
docker-compose.yml
version: '3.5'
services:
db:
image: mysql:latest
environment:
- MYSQL_ROOT_PASSWORD=rootpass
- MYSQL_DATABASE=teste
- MYSQL_USER=rafael
- MYSQL_PASSWORD=password
ports:
- 3306:3306
web:
image: spring-mysql
depends_on:
- db
links:
- db
ports:
- 8080:8080
environment:
- DATABASE_HOST=db
- DATABASE_USER=rafael
- DATABASE_NAME=teste
- DATABASE_PORT=3306
and the Dockerfile
FROM openjdk:8
ADD target/app.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

Docker compose always starts and stops containers in dependency order, or sequential order in the file if not given. But docker-compose does not guarantee that it will wait till the dependency container is running. You can refer here for further details. So the problem here is that your database is not ready when your spring-mysql container tries to access the database. So, the recommended solution is you could use wait-for-it.sh or similar script to wrap your spring-mysql app starting ENTRYPOINT.
As example if you use wait-for-it.sh your ENTRYPOINT in your Dockerfile should change to following after copying above script to your project root:
ENTRYPOINT ["./wait-for-it.sh", "db:3306", "--", "java", "-jar", "app.jar"]
And two other important thing to consider here is:
Do not use links they are deprecated you should use user-defined network instead. All services in docker-compose file will be in single user-defined network if you don't explicitly define any network. So you just have to remove the links from compose file.
You don't need to publish the port for docker container if you only use it inside the user-defined network.

I was facing the same issue and in case you do not want to use any custom scripts, this can easily be resolved using health checks along with depends on. A sample using these is as follows:
services:
mysql-db:
image: mysql
environment:
- MYSQL_ROOT_PASSWORD=vikas1234
- MYSQL_USER=vikas
ports:
- 3306:3306
restart: always
healthcheck:
test: [ "CMD", "mysqladmin" ,"ping", "-h", "localhost" ]
timeout: 20s
retries: 10
app:
image: shop-keeper
container_name: shop-keeper-app
build:
context: .
dockerfile: Dockerfile
ports:
- 8080:8080
depends_on:
mysql-db:
condition: service_healthy
environment:
SPRING_DATASOURCE_URL: jdbc:mysql://mysql-db:3306/shopkeeper?createDatabaseIfNotExist=true
SPRING_DATASOURCE_USERNAME: root
SPRING_DATASOURCE_PASSWORD: vikas1234

Your config looks nice, I would just recommend:
Remove links: db. It has no value in user-defined bridge networking
Remove port exposing for db unless you want to connect from outside docker-compose - all ports are exposed automatically inside user-defined bridge network.
I think the problem is that database container takes more time to start than web. depends_on just controls the order, but does not guarantee you database readiness. If possible, set several connection attempts or put socket-wait procedure in your web container.