'Allow docker container to connect to a local/host postgres database
I've recently been playing around with Docker and QGIS and have installed a container following the instructions in this tutorial.
Everything works great, although I am unable to connect to a localhost postgres database that contains all my GIS data. I figure this is because my postgres database is not configured to accept remote connections and have been editing the postgres conf files to allow remote connections using the instructions in this article.
I'm still getting an error message when I try and connect to my database running QGIS in Docker: could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections to port 5433?
The postgres server is running, and I've edited my pg_hba.conf file to allow connections from a range of IP addresses (172.17.0.0/32). I had previously queried the IP address of the docker container using docker ps and although the IP address changes, it has so far always been in the range 172.17.0.x
Any ideas why I can't connect to this database? Probably something very simple I imagine!
I'm running Ubuntu 14.04; Postgres 9.3
Solution 1:[1]
Simple Solution
The newest version of docker (18.03) offers a built in port forwarding solution. Inside your docker container simply have the db host set to host.docker.internal. This will be forwarded to the host the docker container is running on.
Documentation for this is here: https://docs.docker.com/docker-for-mac/networking/#i-want-to-connect-from-a-container-to-a-service-on-the-host
Solution 2:[2]
Docker for Mac solution
17.06 onwards
Thanks to @Birchlabs' comment, now it is tons easier with this special Mac-only DNS name available:
docker run -e DB_PORT=5432 -e DB_HOST=docker.for.mac.host.internal
From 17.12.0-cd-mac46, docker.for.mac.host.internal should be used instead of docker.for.mac.localhost. See release note for details.
Older version
@helmbert's answer well explains the issue. But Docker for Mac does not expose the bridge network, so I had to do this trick to workaround the limitation:
$ sudo ifconfig lo0 alias 10.200.10.1/24
Open /usr/local/var/postgres/pg_hba.conf and add this line:
host all all 10.200.10.1/24 trust
Open /usr/local/var/postgres/postgresql.conf and edit change listen_addresses:
listen_addresses = '*'
Reload service and launch your container:
$ PGDATA=/usr/local/var/postgres pg_ctl reload
$ docker run -e DB_PORT=5432 -e DB_HOST=10.200.10.1 my_app
What this workaround does is basically same with @helmbert's answer, but uses an IP address that is attached to lo0 instead of docker0 network interface.
Solution 3:[3]
Simple solution
Just add --network=host to docker run. That's all!
This way container will use the host's network, so localhost and 127.0.0.1 will point to the host (by default they point to a container). Example:
docker run -d --network=host \
-e "DB_DBNAME=your_db" \
-e "DB_PORT=5432" \
-e "DB_USER=your_db_user" \
-e "DB_PASS=your_db_password" \
-e "DB_HOST=127.0.0.1" \
--name foobar foo/bar
Solution 4:[4]
The solution posted here does not work for me. Therefore, I am posting this answer to help someone facing similar issue.
Note: This solution works for Windows 10 as well, please check comment below.
OS: Ubuntu 18
PostgreSQL: 9.5 (Hosted on Ubuntu)
Docker: Server Application (which connects to PostgreSQL)
I am using docker-compose.yml to build application.
STEP 1: Please add host.docker.internal:<docker0 IP>
version: '3'
services:
bank-server:
...
depends_on:
....
restart: on-failure
ports:
- 9090:9090
extra_hosts:
- "host.docker.internal:172.17.0.1"
To find IP of docker i.e. 172.17.0.1 (in my case) you can use:
$> ifconfig docker0
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 172.17.0.1 netmask 255.255.0.0 broadcast 172.17.255.255
OR
$> ip a
1: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
STEP 2: In postgresql.conf, change listen_addresses to listen_addresses = '*'
STEP 3: In pg_hba.conf, add this line
host all all 0.0.0.0/0 md5
STEP 4: Now restart postgresql service using, sudo service postgresql restart
STEP 5: Please use host.docker.internal hostname to connect database from Server Application.
Ex: jdbc:postgresql://host.docker.internal:5432/bankDB
Enjoy!!
Solution 5:[5]
To set up something simple that allows a Postgresql connection from the docker container to my localhost I used this in postgresql.conf:
listen_addresses = '*'
And added this pg_hba.conf:
host all all 172.17.0.0/16 password
Then do a restart. My client from the docker container (which was at 172.17.0.2) could then connect to Postgresql running on my localhost using host:password, database, username and password.
Solution 6:[6]
for docker-compose you can try just add
network_mode: "host"
example :
version: '2'
services:
feedx:
build: web
ports:
- "127.0.0.1:8000:8000"
network_mode: "host"
Solution 7:[7]
you can pass --network=host during docker run command to access localhost inside container.
Ex:
docker run --network=host docker-image-name:latest
In case you want to pass env variables with localhost use --env-file paramater to access environment variables inside container.
Ex:
docker run --network=host --env-file .env-file-name docker-image-name:latest
Note: pass the parameters before docker image name otherwise parameters will not work. (I faced this, so heads up!)
Solution 8:[8]
In Ubuntu:
First You have to check that is the Docker Database port is Available in your system by following command -
sudo iptables -L -n
Sample OUTPUT:
Chain DOCKER (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 172.17.0.2 tcp dpt:3306
ACCEPT tcp -- 0.0.0.0/0 172.17.0.3 tcp dpt:80
ACCEPT tcp -- 0.0.0.0/0 172.17.0.3 tcp dpt:22
Here 3306 is used as Docker Database Port on 172.17.0.2 IP, If this port is not available Run the following command -
sudo iptables -A INPUT -p tcp --dport 3306 -j ACCEPT
Now, You can easily access the Docker Database from your local system by following configuration
host: 172.17.0.2
adapter: mysql
database: DATABASE_NAME
port: 3307
username: DATABASE_USER
password: DATABASE_PASSWORD
encoding: utf8
In CentOS:
First You have to check that is the Docker Database port is Available in your firewall by following command -
sudo firewall-cmd --list-all
Sample OUTPUT:
target: default
icmp-block-inversion: no
interfaces: eno79841677
sources:
services: dhcpv6-client ssh
**ports: 3307/tcp**
protocols:
masquerade: no
forward-ports:
sourceports:
icmp-blocks:
rich rules:
Here 3307 is used as Docker Database Port on 172.17.0.2 IP, If this port is not available Run the following command -
sudo firewall-cmd --zone=public --add-port=3307/tcp
In server, You can add the port permanently
sudo firewall-cmd --permanent --add-port=3307/tcp
sudo firewall-cmd --reload
Now, You can easily access the Docker Database from your local system by the above configuration.
Solution 9:[9]
You can add multiple listening address for better security.
listen_addresses = 'localhost,172.17.0.1'
Adding listen_addresses = '*' isn't a good option, which is very dangerous and expose your postgresql database to the wild west.
Solution 10:[10]
Just in case, above solutions don't work for anyone. Use below statement to connect from docker to host postgres (on mac):
psql --host docker.for.mac.host.internal -U postgres
Solution 11:[11]
One more thing needed for my setup was to add
172.17.0.1 localhost
to /etc/hosts
so that Docker would point to 172.17.0.1 as the DB hostname, and not rely on a changing outer ip to find the DB. Hope this helps someone else with this issue!
Solution 12:[12]
Let me try explain what i did.
Postgresql
First of all I did the configuration needed to make sure my Postgres Database was accepting connections from outside.
open pg_hba.conf and add in the end the following line:
host all all 0.0.0.0/0 md5
open postgresql.conf and look for listen_addresses and modify there like this:
listen_addresses = '*'
Make sure the line above is not commented with a #
-> Restart your database
OBS: This is not the recommended configuration for a production environment
Next, I looked for my host’s ip. I was using localhosts ip 127.0.0.1, but the container doesn’t see it, so the Connection Refused message in question shows up when running the container. After a long search in web about this, I read that the container sees the internal ip from your local network (That one your router attributes to every device that connects to it, i’m not talking about the IP that gives you access to the internet). That said, i opened a terminal and did the following:
Look for local network ip
Open a terminal or CMD
(MacOS/Linux)
$ ifconfig
(Windows)
$ ipconfig
This command will show your network configuration information. And looks like this:
en4:
ether d0:37:45:da:1b:6e
inet6 fe80::188d:ddbe:9796:8411%en4 prefixlen 64 secured scopeid 0x7
inet 192.168.0.103 netmask 0xffffff00 broadcast 192.168.0.255
nd6 options=201<PERFORMNUD,DAD>
media: autoselect (100baseTX <full-duplex>)
status: active
Look for the one that is active.
In my case, my local network ip was 192.168.0.103
With this done, I ran the container.
Docker
Run the container with the --add-host parameter, like this:
$ docker run --add-host=aNameForYourDataBaseHost:yourLocalNetWorkIp --name containerName -di -p HostsportToBind:containerPort imageNameOrId
In my case I did:
$ docker run --add-host=db:192.168.0.103 --name myCon -di -p 8000:8000 myImage
I’m using Django, so the 8000 port is the default.
Django Application
The configuration to access the database was:
In settings.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql',
'NAME': ‘myDataBaseName',
'USER': ‘username',
'PASSWORD': '123456',
'HOST': '192.168.0.103',
'PORT': 5432,
}
}
References
About -p flag:
Connect using network port mapping
About docker run:
Docker run documentation
Interesting article: Docker Tip #35: Connect to a Database Running on Your Docker Host
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow