I am new to Docker.
I have an image containing a yii framework. both front and back end are containing yii framework.
here is my docker-compose.yml file:
version: '2'
services:
frontend:
build: ./dockerfile-frontend
container_name: erp2_frontend
links:
- backend
environment:
ENABLE_ENV_FILE: 1
ENABLE_LOCALCONF: 1
API_TOKEN: "4022dfde02359429d905066e557245c760f68f5c"
ports:
- "8080:80"
backend:
build: ./dockerfile-backend
container_name: erp2_backend
environment:
ENABLE_ENV_FILE: 1
Now I want to connect my backend image to the mssql server which is outside the docker network. Now, the server contains the mssql server are connected to the local network of my host container. My host container is ubuntu-linux. How can I connect the backend to the mssql server ? is that possible?
thanks for reply.
I don't see a network configuration in your docker-compose file which means that the default bridge network will be used.
You can go ahead and simply specify the external mssql IP and port and your container would be able to communication with mssql. Although you can't initiate a connection from the outside as you have not exposed and mapped any port in backend service.
Related
When all are run standalone outside of docker it works with no problem when core attempts to do a get from cerner. However, doing the same when all are dockerized as below I get:
Get http://cerner:8602/api/v1/patient/search: dial TCP 192.168.240.4:8602: connect: connection refused. The .4 is the IP of the cerner container and .2 is the IP of the core container
Cerner is the name of the container being called from core. If I change the name to the ip-address of the host server and use the ports, it works fine also. It just does not allow container to container using the containers DNS or IP. I have attempted with and without the private network and get the same thing.
The containers are all scratch go.
version: '3.7'
services: caConnector:
image: vertisoft/ca_connector:latest
ports:
- "8601:7001"
env_file:
- .env.ca_connector
networks:
- core-net
fhir:
image: vertisoft/fhir_connector:latest
container_name: cerner
ports:
- "8602:7002"
env_file:
- .env.fhir_connector
networks:
- core-net
core:
image: vertisoft/core:latest
ports:
- "8600:7000"
env_file:
- .env.core
networks:
- core-net
networks: core-net:
driver: bridge
You should call the container service with containerPort, not with hostPort in service to service communication. in your case, it should be 7000 to 7002 for any container to connect using container name.
Get http://cerner:8602/api/v1/patient/search: dial TCP
192.168.240.4:8602: connect: connection refused.
As in the error, it tries to attempt connection using publish port.
For example
version: "3"
services:
web:
build: .
ports:
- "8000:8000"
db:
image: postgres
ports:
- "8001:5432"
When you run docker-compose up, the following happens:
A network called myapp_default is created.
A container is created
using web’s configuration. It joins the network myapp_default under
the name web. A container is created using db’s configuration. It
joins the network myapp_default under the name db.
In v2.1+, overlay
networks are always attachable
Each container can now look up the hostname web or db and get back the
appropriate container’s IP address. For example, web’s application
code could connect to the URL postgres://db:5432 and start using the
Postgres database.
It is important to note the distinction between HOST_PORT and CONTAINER_PORT. In the above example, for db, the HOST_PORT is 8001 and the container port is 5432 (postgres default). Networked service-to-service communication use the CONTAINER_PORT. When HOST_PORT is defined, the service is accessible outside the swarm as well.
Within the web container, your connection string to db would look like postgres://db:5432, and from the host machine, the connection string would look like postgres://{DOCKER_IP}:8001.
compose-networking
I have two different projects running on different docker containsers. Below the two YML files:
FILE webserver-api/docker-compose.yml
version: "3.1"
services:
webserver:
image: nginx:alpine
container_name: webserver-api
working_dir: /application
volumes:
- .:/application
- ./docker/nginx/nginx.conf:/etc/nginx/conf.d/default.conf
ports:
- "8005:80"
FILE client-app/docker-compose.yml
version: '3'
services:
web:
container_name: client-app
build:
context: ./
dockerfile: deploy/web.docker
volumes:
- ./:/var/www
ports:
- "8010:80"
links:
- app
app: [...]
database: [...]
From the client-app I would like to call the webserver-api.
When I'm trying to consume the API from webserver-api I'm getting the message "cURL error connection refused" or timeout error.
For example
$response = file_get_contents('http:/localhost:8005/api/test');
I tried also to replace the localhost with the IP of the webserver-api container like this:
$response = file_get_contents('http://172.25.0.2:8005/api/test');
But still I get a timeout connection error.
Which is the correct URL of the server container to call form the client container? Or how to set the host URL?
Thanks a lot for the help and time.
You need create a network first. Then use this network for both your client and server docker compose. Otherwise the network is isolated.
Another approach is expose the port of server to localhost and connect to localhost from client side.
As per the docker-compose documentation
By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.
So ideally if your service are interdependent you should put them in a single compose file. In that case you could have accessed your service directly by name and container port
http://webserver/api/test
But since they are in separate compose file, you can access the service via host mapped port
$response = file_get_contents('http://localhost:8005/api/test');
it should also work.
To debug you can check
If port binding to 8005 is happening on your host.
The endpoint specified is correct and accessible from host.
Finally I figured it out.
By default docker creates a network called (in my case) webserver-api_default where webserver-api is the name of the folder that contains the YML file [projectname]_default.
On the client-app/docker-compose.yml of the client I had to specify which network to join:
version: '3'
networks:
default:
external:
name: webserver-api_default
web:
container_name: client-app
build:
context: ./
dockerfile: deploy/web.docker
volumes:
- ./:/var/www
ports:
- "8010:80"
links:
- app
app: [...]
database: [...]
And from the client container I have to make the call to the URL:
$response = file_get_contents('http://webserver-api:8005/api/test');
Where webserver-api is the name of the server container and not the name of the network.
https://docs.docker.com/compose/networking/
I am new to docker and I am trying to dockerize this application I have written in Golang. It is a simple web server that interacts with rabbitmq and mongodb
It takes the creadentials form a toml file and loads it into a config struct before starting the application server on port 3000. These are the credentials
mongo_server = "localhost"
database = "collect_db"
rabbitmq_server = "amqp://guest:guest#localhost:5672/"
If it can't connect to these urls it fails with an error. Following is my docker-compose.yml
version: '3'
services:
rabbitmq:
image: rabbitmq
ports:
- 5672:5672
mongodb:
image: mongo
ports:
- 27017:27017
web:
build: .
image: palash2504/collect
container_name: collect_service
ports:
- 3000:3000
depends_on:
- rabbitmq
- mongodb
links: [rabbitmq, mongodb]
But it fails to connect with rabbitmq on the url used for local development i.e. amqp://guest:guest#localhost:5672/
I realise that the rabbitmq container might be running on some different address other than the one provided in the config file.
I would like to know the correct way for setting any env credentials to be able to connect my app to rabbitmq.
Also what approach would be best to change my application code for initializing connections to external services? I was thinking about ditching the config.toml file and using os.Getenv and os.Setenv to get the urls for connections.
Localhost addresses are resolved, well, locally. They thus will not work inside containers, since they will look for a local address (i.e. inside the container).
Services can access each other by using service names as an address. So in the web container you can target mongodb for example.
You might give this a shot:
mongo_server = mongodb
database = "collect_db"
rabbitmq_server = "amqp://guest:guest#rabbitmq/"
It is advisable to set service target environment variables in the compose file itself:
#docker-compose.yml
#...other stuff...
web:
#...other stuff...
environment:
RABBITMQ_SERVER: rabbitmq
MONGO_SERVER: mongodb
depends_on:
- rabbitmq
- mongodb
This gives you a single place to make adjustments to the configuration.
As a side note, to me it seems that links: [rabbitmq, mongodb] can be removed. And I would advise not to alter the container name (remove container_name: collect_service unless it is necessary)
Unable to connect to containers running on separate docker hosts
I've got 2 docker Tomcat containers running on 2 different Ubuntu vm's. System-A has a webservice running and System-B has a db. I haven't been able to figure out how to connect the application running on system-A to the db running on system-B. When I run the database on system-A, the application(which is also running on system-A) can connect to the database. I'm using docker-compose to setup the network(which works fine when both containers are running on the same VM). I've execd into etc/hosts file in the application container on system-A and I think whats missing is the ip address of System-B.
services:
db:
image: mydb
hostname: mydbName
ports:
- "8012: 8012"
networks:
data:
aliases:
- mydbName
api:
image: myApi
hostname: myApiName
ports:
- "8810: 8810"
networks:
data:
networks:
data:
You would configure this exactly the same way you would as if Docker wasn't involved: configure the Tomcat instance with the DNS name or IP address of the other server. You would need to make sure the service is published outside of Docker space using a ports: directive.
On server-a.example.com you could run this docker-compose.yml file:
version: '3'
services:
api:
image: myApi
ports:
- "8810:8810"
env:
DATABASE_URL: "http://server-b.example.com:8012"
And on server-b.example.com:
version: '3'
services:
db:
image: mydb
ports:
- "8012:8012"
In principle it would be possible to set up an overlay network connecting the two hosts, but this is a significantly more complicated setup.
(You definitely don't want to use docker exec to modify /etc/hosts in a container: you'll have to repeat this step every time you delete and recreate the container, and manually maintaining hosts files is tedious and error-prone, particularly if you're moving containers between hosts. Consul could work as a service-discovery system that provides a DNS service.)
I have 2 .net core apps running in docker (one is a web api, the other is a web app consuming the web api):
I can't seem to communicate with the api via the web app, but I can access the api by going directly to it in my browser at http://localhost:44389
I have an environment variable in my web app that has that same info, but it can't get to it.
If I were to specify the deployed version of my API on azure, it's able to communicate with that address. Seems like the problem is the containers talking to each other.
I read that creating a bridge should fix that problem but it doesn't seem to. What am I doing wrong?
Here is my docker compose file:
version: '3.4'
services:
rc.api:
image: ${DOCKER_REGISTRY}rcapi
build:
context: .
dockerfile: rc.Api/Dockerfile
ports:
- "44389:80"
rc.web:
image: ${DOCKER_REGISTRY}rcweb
build:
context: .
dockerfile: rc.Web/Dockerfile
environment:
- api_endpoint=http://localhost:44389
depends_on:
- rc.api
networks:
my-net:
driver: bridge
docker-compose automatically creates a network between your containers. As your containers are in the same network you would be able to connect between containers using aliases. docker-compose creates an alias with the container name and the container IP. So in your case docker-compose should look like
version: '3.4'
services:
rc.api:
image: ${DOCKER_REGISTRY}rcapi
build:
context: .
dockerfile: rc.Api/Dockerfile
ports:
- "44389:80"
rc.web:
image: ${DOCKER_REGISTRY}rcweb
build:
context: .
dockerfile: rc.Web/Dockerfile
environment:
- api_endpoint=http://rc.api
depends_on:
- rc.api
networks:
my-net:
driver: bridge
As in rc.api opens port 80 in its container, therefore rc.web can access to 80 port with http://rc.api:80 or http://rc.api (without port since HTTP port is default 80)
You need to call http://rc.api because you have two containers and the API containers localhost is different from the web apps container localhost.
The convention is each service can be resolved by its name specified in the docker-compose.yml.
Thus you can call the API on internal Port 80 instead of exposing it on a particular port.