I have two separate docker-compose.yml
files in two different folders:
~/front/docker-compose.yml
~/api/docker-compose.yml
How can I make sure that a container in front
can send requests to a container in api
?
I know that --default-gateway
option can be set using docker run
for an individual container, so that a specific IP address can be assigned to this container, but it seems that this option is not available when using docker-compose
.
Currently I end up doing a docker inspect my_api_container_id
and look at the gateway in the output. It works but the problem is that this IP is randomly attributed, so I can't rely on it.
Another form of this question might thus be:
But in the end what I'm looking after is:
This question is related to
networking
docker
docker-compose
version: '2'
services:
bot:
build: .
volumes:
- '.:/home/node'
- /home/node/node_modules
networks:
- my-rede
mem_limit: 100m
memswap_limit: 100m
cpu_quota: 25000
container_name: 236948199393329152_585042339404185600_bot
command: node index.js
environment:
NODE_ENV: production
networks:
my-rede:
external:
name: name_rede_externa
You can add a .env
file in all your projects containing COMPOSE_PROJECT_NAME=somename
.
COMPOSE_PROJECT_NAME overrides the prefix used to name resources, as such all your projects will use somename_default
as their network, making it possible for services to communicate with each other as they were in the same project.
NB: You'll get warnings for "orphaned" containers created from other projects.
UPDATE: As of docker-compose file version 3.5:
I came across a similar problem and I solved it by adding a small change in one of my docker-compose.yml project.
For instance, we have two API's scoring
and ner
. Scoring
API needs to send a request to the ner
API for processing the input request. In order to do that they both are supposed to share the same network.
Note: Every container has its own network which is automatically created at the time of running the app inside docker. For example ner API network will be created like ner_default
and scoring API network will be named as scoring default
. This solution will work for version: '3'.
As in the above scenario, my scoring API wants to communicate with ner API then I will add the following lines. This means Whenever I create the container for ner API then it automatically added to the scoring_default network.
networks:
default:
external:
name: scoring_default
version: '3'
services:
ner:
container_name: "ner_api"
build: .
...
networks:
default:
external:
name: scoring_default
version: '3'
services:
api:
build: .
...
We can see this how the above containers are now a part of the same network called scoring_default
using the command:
docker inspect scoring_default
{
"Name": "scoring_default",
....
"Containers": {
"14a6...28bf": {
"Name": "ner_api",
"EndpointID": "83b7...d6291",
"MacAddress": "0....",
"IPv4Address": "0.0....",
"IPv6Address": ""
},
"7b32...90d1": {
"Name": "scoring_api",
"EndpointID": "311...280d",
"MacAddress": "0.....3",
"IPv4Address": "1...0",
"IPv6Address": ""
},
...
}
For using another docker-compose network you just do these(to share networks between docker-compose):
- Run the first docker-compose project by
up -d
- Find the network name of the first docker-compose by:
docker network ls
(It contains the name of the root directory project)- Then use that name by this structure at below in the second docker-compose file.
second docker-compose.yml
version: '3'
services:
service-on-second-compose: # Define any names that you want.
.
.
.
networks:
- <put it here(the network name that comes from "docker network ls")>
networks:
- <put it here(the network name that comes from "docker network ls")>:
external: true
If you are
Connection refused
while trying to communicate between two containersAnd you want to
api_a
communicate to api_b
(or vice versa) without the same "docker network" (example below)
you can use "host" of the second container as IP of your computer and port that is mapped from inside Docker container. You can obtain IP of your computer with this script (from: Finding local IP addresses using Python's stdlib):
import socket
def get_ip():
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
# doesn't even have to be reachable
s.connect(('10.255.255.255', 1))
IP = s.getsockname()[0]
except:
IP = '127.0.0.1'
finally:
s.close()
return IP
Example:
project_api_a/docker-compose.yml
:
networks:
app-tier:
driver: bridge
services:
api:
container_name: api_a
image: api_a:latest
depends_on:
- postgresql
networks:
- app-tier
inside api_a
container you are running Django app:
manage.py runserver 0.0.0.0:8000
and second docker-compose.yml from other project:
project_api_b/docker-compose-yml
:
networks:
app-tier:
driver: bridge
services:
api:
container_name: api_b
image: api_b:latest
depends_on:
- postgresql
networks:
- app-tier
inside api_b
container you are running Django app:
manage.py runserver 0.0.0.0:8001
And trying to connect from container api_a
to api_b
then URL of api_b
container will be:
http://<get_ip_from_script_above>:8001/
It can be especially valuable if you are using even more than two(three or more) docker-compose projects and it's hard to provide common network for all of it - it's good workaround and solution
I would ensure all containers are docker-compose
'd to the same network by composing them together at the same time, using:
docker compose --file ~/front/docker-compose.yml --file ~/api/docker-compose.yml up -d
The previous posts information is correct, but it does not have details on how to link containers, which should be connected as "external_links".
Hope this example make more clear to you:
Suppose you have app1/docker-compose.yml, with two services (svc11 and svc12), and app2/docker-compose.yml with two more services (svc21 and svc22) and suppose you need to connect in a crossed fashion:
svc11 needs to connect to svc22's container
So the configuration should be like this:
this is app1/docker-compose.yml:
version: '2'
services:
svc11:
container_name: container11
[..]
networks:
- default # this network
- app2_default # external network
external_links:
- container22:container22
[..]
svc12:
container_name: container12
[..]
networks:
default: # this network (app1)
driver: bridge
app2_default: # external network (app2)
external: true
this is app2/docker-compose.yml:
version: '2'
services:
svc21:
container_name: container21
[..]
networks:
- default # this network (app2)
- app1_default # external network (app1)
external_links:
- container11:container11
[..]
svc22:
container_name: container22
[..]
networks:
default: # this network (app2)
driver: bridge
app1_default: # external network (app1)
external: true
UPDATE: As of compose file version 3.5:
This now works:
version: "3.5"
services:
proxy:
image: hello-world
ports:
- "80:80"
networks:
- proxynet
networks:
proxynet:
name: custom_network
docker-compose up -d
will join a network called 'custom_network'. If it doesn't exist, it will be created!
root@ubuntu-s-1vcpu-1gb-tor1-01:~# docker-compose up -d
Creating network "custom_network" with the default driver
Creating root_proxy_1 ... done
Now, you can do this:
version: "2"
services:
web:
image: hello-world
networks:
- my-proxy-net
networks:
my-proxy-net:
external:
name: custom_network
This will create a container that will be on the external network.
I can't find any reference in the docs yet but it works!
Since Compose 1.18 (spec 3.5), you can just override the default network using your own custom name for all Compose YAML files you need. It is as simple as appending the following to them:
networks:
default:
name: my-app
The above assumes you have
version
set to3.5
(or above if they don't deprecate it in 4+).
Other answers have pointed the same; this is a simplified summary.
Another option is just running up the first module with the 'docker-compose' check the ip related with the module, and connect the second module with the previous net like external, and pointing the internal ip
example app1 - new-network created in the service lines, mark as external: true at the bottom app2 - indicate the "new-network" created by app1 when goes up, mark as external: true at the bottom, and set in the config to connect, the ip that app1 have in this net.
With this, you should be able to talk with each other
*this way is just for local-test focus, in order to don't do an over complex configuration ** I know is very 'patch way' but works for me and I think is so simple some other can take advantage of this
Just a small adittion to @johnharris85's great answer,
when you are running a docker compose file, a "default
" network is created
so you can just add it to the other compose file as an external network:
# front/docker-compose.yml
version: '2'
services:
front_service:
...
...
# api/docker-compose.yml
version: '2'
services:
api_service:
...
networks:
- front_default
networks:
front_default:
external: true
For me this approach was more suited because I did not own the first docker-compose file and wanted to communicate with it.
All containers from api
can join the front
default network with following config:
# api/docker-compose.yml
...
networks:
default:
external:
name: front_default
See docker compose guide: using a pre existing network (see at the bottom)
Source: Stackoverflow.com