I have a problem with connecting to existing remote MSSQL database from inside of a docker container running in stack.
My application consists of three modules (backend, frontend and haproxy)
Backend module is written in Java (SpringBoot app) and it's also the one that needs to connect do remote MSSQL database (by remote I mean placed on different sever, separate of docker part).
I have the following docker compose file:
I start the stack by using following command:
docker stack deploy -c docker-compose.yml myapp
The result is, all containers are up and running, but spring app reports that connection to DB is timed out:
Server seems to be configured properly, I am able to access the host from container through telnet.
When running independently (even from docker container) backend app is able to connect to database with no problems, while stacked with docker-compose however it's unable to connect to the very same db.
I've also tried to provide db server IP instead of host name - no success.
Maybe setting up networks section in docker compose would do the trick?
UPDATE
Another thing you can do is to use host.docker.internal instead of the IP address of the database. This ONLY works on docker for windows or docker for mac.
Source: I want to connect from a container to a service on the host
OLD, only works when not in swarm mode
You need to specify that docker should use the same network as the host, you can do this in the following way:
version: '3'
services:
web-app:
build:
dockerfile: web-app/something
ports:
- 8080:8080
network_mode: "host"
Reference: Use host networking
It seems that the issue was caused by networks overlapping.
Adding network configured as show below, allowed either to connect to my remote database and keep my endpoints hidden:
networks:
backend:
ipam:
driver: default
config:
- subnet: 192.168.40.0/26
Related
i have macOS 11.5, docker desktop 4.10, microservices with spring boot.
I use docker-compose to allow me to start my microservices.
A portion of docker-compose:
authentication-server:
build: ./authentication-server
network_mode: "host"
image: authentication-server: 0.0.9
hostname: authentication-srv
ports:
- "4445:4445"
basically I need to communicate with the container, interrogating it from my pc using Postman, then a REST request.
Despite the nerwork_mode: "host" when I try to ping localhost: 4445 it tells me
"ping: cannot resolve localhost: 4445: Unknown host".
As well as trying the various container names:
"ping: cannot resolve authentication-srv: 4445: Unknown host"
"ping: cannot resolve authentication-server: 4445: Unknown host"
So my need is to communicate with a container created with docker-compose on my local pc. How can I solve? thank you
This question already has answers here:
From inside of a Docker container, how do I connect to the localhost of the machine?
(40 answers)
Closed 2 years ago.
I have a Spring app that connects to local Postgres db. It works fine.
I then created a Docker image from the Spring app. When running the container it throws a db connection error.
I have followed the solution suggested here, but still getting the same error.
[ERROR ] [task-1] c.z.h.p.HikariPool c.z.h.p.HikariPool.throwPoolInitializationException(HikariPool.java:593) – HikariPool-1 - Exception during pool initialization.
org.postgresql.util.PSQLException: Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:285)
at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:217)
at org.postgresql.Driver.makeConnection(Driver.java:458)
at org.postgresql.Driver.connect(Driver.java:260)
I have run the docker image in several ways with the same result.
docker run app-image
docker run --network=host app-image
Dockerfile:
FROM java:8-jdk-alpine
COPY ./build/libs/runtime-0.0.1-SNAPSHOT.jar /usr/app/
WORKDIR /usr/app
ENTRYPOINT ["java", "-jar", "runtime-0.0.1-SNAPSHOT.jar"]
# Expose standard tomcat port
EXPOSE 9888
postgresql.conf:
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
listen_addresses = '*'
pg_hba.conf
# TYPE DATABASE USER ADDRESS METHOD
host postgres postgres 0.0.0.0/0 trust
host postgres postgres 172.17.0.0/16 trust
The spring application tries to connect to localhost:5432. Since the host and each container are separate network entities (i.e., the host and each container has its own network address in the docker-internal network), the container tries to connect to the database running on it. Since there is not database running, the connection cannot be established.
To fix this issue, you need to get the IP address of the host machine within the docker-internal network (see, e.g., this article at devilbox) and use this address as database server for the spring application.
I would recommend to run the postgres in a docker container aswell. You can, for example, use the official postgres image from dockerhub. Then you can reference the postgres-container from within the spring-container by the postgres-container's name.
So I have created a java spring boot application which uses Keycloak for authenticating its users.
When I run keycloak from docker-compose I can sucesfully authenticate when running my application as a standalone jar file or when debugging. But when I put my spring boot application as a docker containers inside docker-compose. I cannot authenticate users anymore.
my error log from spring boot docker container:
springBootApp | 2019-12-19 13:16:41.498 ERROR 1 --- [nio-8081-exec-2] o.k.a.rotation.JWKPublicKeyLocator : Error when sending request to retrieve realm keys
springBootApp |
springBootApp | org.keycloak.adapters.HttpClientAdapterException: IO error
I though that the problem is with network. but all containers are running in the same virtual network. They are also also in same docker-compose file.
this is my keycloak part:
keycloak:
image: jboss/keycloak
ports:
- 18080:8080
volumes:
- ../keycloak:/opt/jboss/keycloak/imports
command:
- "-b 0.0.0.0 -Dkeycloak.import=/opt/jboss/keycloak/imports/realm-export.json"
environment:
- KEYCLOAK_USER=admin
- KEYCLOAK_PASSWORD=admin
my spring boot app
mySpringBootApp:
image: mySpringBootApp:master-1
environment:
- SPRING_PROFILES_ACTIVE=developmentTest
depends_on:
- jaeger
- keycloak
- db
ports:
- "8081:8081"
When I try to use
curl localhost:18080 from my host. I get the response.
when I try to use curl from springBootApp docker I get connection refused. So I assume that even though they are in the same network they don't see each other.
You have to keep in mind that your docker container is isolated from the host it is running on. localhost for your computer is different then localhost from inside the docker container.
You are using docker-compose and both services are in the same docker-compose.yaml configuration this means you can use the service name of a service to reach it from within another service that is in the same docker-compose file.
In your case the service you want to access is called keycloak and you have mapped its ports as 18080:8080 meaning that from your computer localhost 18080 accesses the port 8080 of this particular container.
In order to access this container (or service in a docker-compose context) you need to replace localhost by the name of your service.
In your case to curl the keycloak container from mySprngBootApp container you need to replace lcalhost by the name of the service so long story short: curl keycloak:18080
I would define network for your services in docker compose, like:
services:
app:
image: some-image
networks:
- my-network-name
networks:
my-network-name:
name: my-global-net
And you can be sure, that services are in the same network and speak via service's name with each other.
I have a docker swarm setup with services registered in an overlay network. Comunication between services is working fine however I get a "Connection refused" from one of my services that connects to an external DB. The service is a Java based application (spring boot).
The connection is defined with its IP (jdbc:mysql://192.168.130.141:3306/database?autoReconnect=true)
I have checked that I can ping the server from the container docker exec -it e093 ping 192.168.130.141 gives expected answer
I have rechecked (4 times) my credentials
I can connect to the DB from the host
Host is Ubuntu 16.04.4 LTS
I am running docker 18.03.0-ce and the exact error is
java.net.ConnectException: Connection refused (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_151]
I'll skip the full stack trace here.
Any help would be greatly appreciated
--EDIT--
Let me clarify that the database is a Galera cluster and the IP I try to connect to is the load balancer (HAProxy) in front of it. I know the setup works as I have other applications connecting to the cluster in this matter as well as the service itself (when not in a docker container).
So, as far as I can tell, my connection informations are correct but it doesn't connect from inside docker services.
Can you show your docker-compose.yml? In the ports you have to expose the port that you need to access.
ports:
- 3306:3306
You can install telnet to test if the port is open using this commands inside the container
docker container ls
docker exec -it conainerid bash
apt-get update
apt-get install telnet
I’m new to docker and I’m trying to connect my spring boot app running into my boot-example docker container to a mysql server running into my mymysql docker container on port 6603, both running on the same phisical machine.
The fact is: if I connect my spring-boot app to my mymysql docker container in order to communicate with the database, I get no errors and everything works fine.
When I move my spring boot application into my boot-example container and try to communicate (through Hibernate) to my mymysql container, then I get this error:
2018-02-05 09:58:38.912 ERROR 1 --- [ main] o.a.tomcat.jdbc.pool.ConnectionPool : Unable to create initial connections of pool.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: 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.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_111]
My spring boot application.properties are:
server.port=8083
spring.jpa.hibernate.ddl-auto=create-drop
spring.datasource.url=jdbc:mysql://localhost:6603/mydockerdb
spring.datasource.username=root
spring.datasource.password=mypassword
It works fine until my spring boot app runs in a docker container on port 8082, (after the docker image is correctly built):
docker run -it -p 8082:8083 boot-example
You cannot use localhost inside the container, it's the container itself. Hence, you will always get the connection refused error.
You can do below things -
Add your host machine IP in application.properties file of your spring boot application. (Not recommended since it breaks docker portability logic)
In case you want to use localhost, use --net=host while starting the container. (Not recommended for Production since no logical network layer exists)
Use --links for container communication with a DNS name. (deprecated/legacy)
Create a compose file & call your DB from spring boot app with the service name since they will be in same network & highly integrated with each other. (Recommended)
PS - Whenever you need to integrate multiple containers together, always go for docker-compose version 3+. Use docker run|build to understand the fundamentals & performing dry/test runs.
As #vivekyad4v suggested - the easiest way to achieve your desire, is to use docker-compose which has better container communication integration.
Docker-compose is a tool for managing single or multiple docker container/s. It uses single configuration file called docker-compose.yml.
For better information about docker-compose, please take a look at documentation and compose file reference
In my experience, it is good practice to follow SRP (single responsibility principle), thus - creating one container for your database and one for your application. Both of them are communicating using network you specify in your configuration.
Following example of docker-compose.yml might help you:
version: '2'
networks:
# your network name
somename:
driver: bridge
services:
# PHP server
php:
image: dalten/php5.6-apache
ports:
- 80:80
volumes:
- .application_path:/some/application/path
# your container network name defined at the beggining
networks:
- somename
# Mysql server for backend
mysql:
image: dalten/mysql:dev
ports:
- 3306:3306
# The /var/lib/mysql volume MUST be specified to achieve data persistence over container restart
volumes:
- ./mysql_data:/var/lib/mysql
environment:
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: backend
# your container network name defined at the beggining
networks:
- somename
Note: Communication between containers inside network can be achieved by calling the service name from inside container.
The connection parameters to MySQL container from PHP, would in this example be:
hostname: mysql
port: 3306
database: backend
user: root
password: root
As per above suggestion, Docker-compose is a way but if you don't want to go with compose/swarm mode.
Simply create your own network using docker network create myNet
Deploy your containers listening on a created network --network myNet
Change your spring.datasource.url to jdbc:mysql://mymysql:6603/mydockerdb
By using DNS resolution of docker demon, containers can discover each other and hence can communicate.
[DNS is not supported by default bridge. A user-defined network using bridge does.]
For more information: https://docs.docker.com/engine/userguide/networking/