Django + ElasticSearch + Docker - Connection Timeout no matter what hostname I use - django

Question

I'm having issues connecting with my Elasticsearch container since day 1.
First I was using elasticsearch as the hostname, then I've tried the container name web_elasticsearch_1, and finally I'd set a Static IP address to the container and passed it in my configuration file.
PYPI packages:
django==3.2.9
elasticsearch==7.15.1
elasticsearch-dsl==7.4.0
docker-compose.yml
version: "3.3"
services:
web:
build:
context: .
dockerfile: local/Dockerfile
image: project32439/python
command: python manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- "8000:8000"
env_file:
- local/python.env
depends_on:
- elasticsearch
elasticsearch:
image: elasticsearch:7.10.1
environment:
- xpack.security.enabled=false
- discovery.type=single-node
networks:
default:
ipv4_address: 172.18.0.10
settings.py
# Elasticsearch
ELASTICSEARCH_HOST = "172.18.0.10"
ELASTICSEARCH_PORT = 9200
service.py
from django.conf import settings
from elasticsearch import Elasticsearch, RequestsHttpConnection
es = Elasticsearch(
hosts=[{"host": settings.ELASTICSEARCH_HOST, "port": settings.ELASTICSEARCH_PORT}],
use_ssl=False,
verify_certs=False,
connection_class=RequestsHttpConnection,
)
traceback
HTTPConnectionPool(host='172.18.0.10', port=9200): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<urllib3.connection.HTTPConnection object at 0x7f1973ebd6d0>, 'Connection to 172.18.0.10 timed out. (connect timeout=5)'))

Answer 1

By default Docker Compose uses a bridge network to provision inter-container communication. You can read more about this network at the Debian Wiki.
What matters for you, is that by default Docker Compose creates a hostname that equals the service name in the docker-compose.yml file. So update your file:
version: "3.3"
services:
web:
build:
context: .
dockerfile: local/Dockerfile
image: project32439/python
command: python manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- "8000:8000"
env_file:
- local/python.env
depends_on:
- elasticsearch
elasticsearch:
image: elasticsearch:7.10.1
environment:
- xpack.security.enabled=false
- discovery.type=single-node
And now you can connect with elasticsearch:9200 instead of 172.18.0.10 from your web container. For more info see this article.