So I have a Nginx running inside a docker container, I have a mysql running on localhost, I want to connect to the MySql from within my Nginx. The MySql is running on localhost and not exposing a port to the outside world, so its bound on localhost, not bound on the ip address of the machine.
Is there any way to connect to this MySql or any other program on localhost from within this docker container?
This question is different from "How to get the IP address of the docker host from inside a docker container" due to the fact that the IP address of the docker host could be the public IP or the private IP in the network which may or may not be reachable from within the docker container (I mean public IP if hosted at AWS or something). Even if you have the IP address of the docker host it does not mean you can connect to docker host from within the container given that IP address as your Docker network may be overlay, host, bridge, macvlan, none etc which restricts the reachability of that IP address.
This question is related to
nginx
docker
reverse-proxy
docker-networking
The answer is
The CGroups and Namespaces are playing major role in the Container Ecosystem.
Namespace provide a layer of isolation. Each container runs in a separate namespace and its access is limited to that namespace. The Cgroups controls the resource utilization of each container, whereas Namespace controls what a process can see and access the respective resource.
Here is the basic understanding of the solution approach you could follow,
Use Network Namespace
When a container spawns out of image, a network interface is defined and create. This gives the container unique IP address and interface.
$ docker run -it alpine ifconfig
By changing the namespace to host, cotainers networks does not remain isolated to its interface, the process will have access to host machines network interface.
$ docker run -it --net=host alpine ifconfig
If the process listens on ports, they'll be listened on the host interface and mapped to the container.
Use PID Namespace By changing the Pid namespace allows a container to interact with other process beyond its normal scope.
This container will run in its own namespace.
$ docker run -it alpine ps aux
By changing the namespace to the host, the container can also see all the other processes running on the system.
$ docker run -it --pid=host alpine ps aux
Sharing Namespace
This is a bad practice to do this in production because you are breaking out of the container security model which might open up for vulnerabilities, and easy access to eavesdropper. This is only for debugging tools and understating the loopholes in container security.
The first container is nginx server. This will create a new network and process namespace. This container will bind itself to port 80 of newly created network interface.
$ docker run -d --name http nginx:alpine
Another container can now reuse this namespace,
$ docker run --net=container:http mohan08p/curl curl -s localhost
Also, this container can see the interface with the processes in a shared container.
$ docker run --pid=container:http alpine ps aux
This will allow you give more privileges to containers without changing or restarting the application. In the similar way you can connect to mysql on host, run and debug your application. But, its not recommend to go by this way. Hope it helps.
I solved it by creating a user in MySQL for the container's ip:
$ sudo mysql<br>
mysql> create user 'username'@'172.17.0.2' identified by 'password';<br>
Query OK, 0 rows affected (0.00 sec)
mysql> grant all privileges on database_name.* to 'username'@'172.17.0.2' with grant option;<br>
Query OK, 0 rows affected (0.00 sec)
$ sudo vim /etc/mysql/mysql.conf.d/mysqld.cnf
<br>bind-address = 172.17.0.1
$ sudo systemctl restart mysql.service
Then on container: jdbc:mysql://<b>172.17.0.1</b>:3306/database_name
if you use docker-compose, maybe it can work:
iptables -I INPUT ! -i eth0 -p tcp --dport 8001 -j ACCEPT
the eth0 is your network interface that connect internet, and 8081 the host server port
the best way for iptables rule is iptables TRACE
Until host.docker.internal is working for every platform, you can use my container acting as a NAT gateway without any manual setup:
For macOS and Windows
Docker v 18.03 and above (since March 21st 2018)
Use your internal IP address or connect to the special DNS name host.docker.internal which will resolve to the internal IP address used by the host.
Linux support pending https://github.com/docker/for-linux/issues/264
MacOS with earlier versions of Docker
Docker for Mac v 17.12 to v 18.02
Same as above but use docker.for.mac.host.internal instead.
Docker for Mac v 17.06 to v 17.11
Same as above but use docker.for.mac.localhost instead.
Docker for Mac 17.05 and below
To access host machine from the docker container you must attach an IP alias to your network interface. You can bind whichever IP you want, just make sure you're not using it to anything else.
sudo ifconfig lo0 alias 123.123.123.123/24
Then make sure that you server is listening to the IP mentioned above or 0.0.0.0. If it's listening on localhost 127.0.0.1 it will not accept the connection.
Then just point your docker container to this IP and you can access the host machine!
To test you can run something like curl -X GET 123.123.123.123:3000 inside the container.
The alias will reset on every reboot so create a start-up script if necessary.
Solution and more documentation here: https://docs.docker.com/docker-for-mac/networking/#use-cases-and-workarounds
I disagree with the answer from Thomasleveil.
Making mysql bind to 172.17.42.1 will prevent other programs using the database on the host to reach it. This will only work if all your database users are dockerized.
Making mysql bind to 0.0.0.0 will open the db to outside world, which is not only a very bad thing to do, but also contrary to what the original question author wants to do. He explicitly says "The MySql is running on localhost and not exposing a port to the outside world, so its bound on localhost"
To answer the comment from ivant
"Why not bind mysql to docker0 as well?"
This is not possible. The mysql/mariadb documentation explicitly says it is not possible to bind to several interfaces. You can only bind to 0, 1, or all interfaces.
As a conclusion, I have NOT found any way to reach the (localhost only) database on the host from a docker container. That definitely seems like a very very common pattern, but I don't know how to do it.
Simplest solution for Mac OSX
Just use the IP address of your Mac. On the Mac run this to get the IP address and use it from within the container:
$ ifconfig | grep 'inet 192'| awk '{ print $2}'
As long as the server running locally on your Mac or in another docker container is listening to 0.0.0.0, the docker container will be able to reach out at that address.
If you just want to access another docker container that is listening on 0.0.0.0 you can use 172.17.0.1
To make everything work, you need to create a config for your server (caddy, nginx) where the main domain will be "docker.for.mac.localhost". For this replace in baseURL "http://localhost/api" on "http://docker.for.mac.localhost/api"
docker-compose.yml
backend:
restart: always
image: backend
build:
dockerfile: backend.Dockerfile
context: .
environment:
# add django setting.py os.getenv("var") to bd config and ALLOWED_HOSTS CORS_ORIGIN_WHITELIST
DJANGO_ALLOWED_PROTOCOL: http
DJANGO_ALLOWED_HOSTS: docker.for.mac.localhost
POSTGRES_PASSWORD: 123456
POSTGRES_USER: user
POSTGRES_DB: bd_name
WAITDB: "1"
volumes:
- backend_static:/app/static
- backend_media:/app/media
depends_on:
- db
frontend:
restart: always
build:
dockerfile: frontend.Dockerfile
context: .
image: frontend
environment:
# replace baseURL for axios
API_URL: http://docker.for.mac.localhost/b/api
API_URL_BROWSER: http://docker.for.mac.localhost/b/api
NUXT_HOST: 0.0.0.0
depends_on:
- backend
caddy:
image: abiosoft/caddy
restart: always
volumes:
- $HOME/.caddy:/root/.caddy
- ./Caddyfile.local:/etc/Caddyfile
- backend_static:/static
- backend_media:/media
ports:
- 80:80
depends_on:
- frontend
- backend
- db
Caddyfile.local
http://docker.for.mac.localhost {
proxy /b backend:5000 {
header_upstream Host {host}
header_upstream X-Real-IP {remote}
header_upstream X-Forwarded-For {remote}
header_upstream X-Forwarded-Port {server_port}
header_upstream X-Forwarded-Proto {scheme}
}
proxy / frontend:3000 {
header_upstream Host {host}
header_upstream X-Real-IP {remote}
header_upstream X-Forwarded-For {remote}
header_upstream X-Forwarded-Port {server_port}
header_upstream X-Forwarded-Proto {scheme}
}
root /
log stdout
errors stdout
gzip
}
http://docker.for.mac.localhost/static {
root /static
}
http://docker.for.mac.localhost/media {
root /media
}
django settings.py
ALLOWED_HOSTS = [os.getenv("DJANGO_ALLOWED_HOSTS")]
CORS_ORIGIN_WHITELIST = [f'{os.getenv("DJANGO_ALLOWED_PROTOCOL")}://{os.getenv("DJANGO_ALLOWED_HOSTS")}']
DATABASES = {
"default": {
"ENGINE": "django.db.backends.postgresql_psycopg2",
"NAME": os.getenv("POSTGRES_DB"),
"USER": os.getenv("POSTGRES_USER"),
"PASSWORD": os.getenv("POSTGRES_PASSWORD"),
"HOST": "db",
"PORT": "5432",
}
}
nuxt.config.js (the baseURL variable will override API_URL of environment)
axios: {
baseURL: 'http://127.0.0.1:8000/b/api'
},
You can get the host ip using alpine image
docker run --rm alpine ip route | awk 'NR==1 {print $3}'
This would be more consistent as you're always using alpine to run the command.
Similar to Mariano's answer you can use same command to set an environment variable
DOCKER_HOST=$(docker run --rm alpine ip route | awk 'NR==1 {print $3}') docker-compose up
Try this:
version: '3.5'
services:
yourservice-here:
container_name: container_name
ports:
- "4000:4000"
extra_hosts: # <---- here
- localhost:192.168.1.202
- or-vitualhost.local:192.168.1.202
To get 192.168.1.202, uses ifconfig
This worked for me. Hope this help!
Here is my solution : it works for my case
set local mysql server to public access by comment
#bind-address = 127.0.0.1in /etc/mysql/mysql.conf.drestart mysql server
sudo /etc/init.d/mysql restartrun the following command to open user root access any host
mysql -uroot -proot GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT OPTION; FLUSH PRIVILEGES;create sh script : run_docker.sh
#!bin/bash
HOSTIP=`ip -4 addr show scope global dev eth0 | grep inet | awk '{print \$2}' | cut -d / -f 1`
docker run -it -d --name web-app \
--add-host=local:${HOSTIP} \
-p 8080:8080 \
-e DATABASE_HOST=${HOSTIP} \
-e DATABASE_PORT=3306 \
-e DATABASE_NAME=demo \
-e DATABASE_USER=root \
-e DATABASE_PASSWORD=root \
sopheamak/springboot_docker_mysql
run with docker-composer
version: '2.1'
services:
tomcatwar: extra_hosts: - "local:10.1.2.232" image: sopheamak/springboot_docker_mysql
ports: - 8080:8080 environment: - DATABASE_HOST=local - DATABASE_USER=root - DATABASE_PASSWORD=root - DATABASE_NAME=demo - DATABASE_PORT=3306
You can simply do ifconfig on host machine to check your host IP, then connect to the ip from within your container, works perfectly for me.
This worked for me on an NGINX/PHP-FPM stack without touching any code or networking where the app's just expecting to be able to connect to localhost
Mount mysqld.sock from the host to inside the container.
Find the location of the mysql.sock file on the host running mysql:
netstat -ln | awk '/mysql(.*)?\.sock/ { print $9 }'
Mount that file to where it's expected in the docker:
docker run -v /hostpath/to/mysqld.sock:/containerpath/to/mysqld.sock
Possible locations of mysqld.sock:
/tmp/mysqld.sock
/var/run/mysqld/mysqld.sock
/var/lib/mysql/mysql.sock
/Applications/MAMP/tmp/mysql/mysql.sock # if running via MAMP
Connect to the gateway address.
? docker network inspect bridge | grep Gateway
"Gateway": "172.17.0.1"
Make sure the process on the host is listening on this interface (i.e 172.17.0.1 in my machine). It works for me in linux.
? python -m http.server &> /dev/null &
[1] 149976
? docker run --rm python python -c "from urllib.request import urlopen;print(b'Directory listing for' in urlopen('http://172.17.0.1:8000').read())"
True
This is not an answer to the actual question. This is how I solved a similar problem. The solution comes totally from: Define Docker Container Networking so Containers can Communicate. Thanks to Nic Raboy
Leaving this here for others who might want to do REST calls between one container and another. Answers the question: what to use in place of localhost in a docker environment?
Get how your network looks like docker network ls
Create a new network docker network create -d my-net
Start the first container docker run -d -p 5000:5000 --network="my-net" --name "first_container" <MyImage1:v0.1>
Check out network settings for first container docker inspect first_container. "Networks": should have 'my-net'
Start the second container docker run -d -p 6000:6000 --network="my-net" --name "second_container" <MyImage2:v0.1>
Check out network settings for second container docker inspect second_container. "Networks": should have 'my-net'
ssh into your second container docker exec -it second_container sh or docker exec -it second_container bash.
Inside of the second container, you can ping the first container by ping first_container. Also, your code calls such as http://localhost:5000 can be replaced by http://first_container:5000
Several solutions come to mind:
- Move your dependencies into containers first
- Make your other services externally accessible and connect to them with that external IP
- Run your containers without network isolation
- Avoid connecting over the network, use a socket that is mounted as a volume instead
The reason this doesn't work out of the box is that containers run with their own network namespace by default. That means localhost (or 127.0.0.1 pointing to the loopback interface) is unique per container. Connecting to this will connect to the container itself, and not services running outside of docker or inside of a different docker container.
Option 1: If your dependency can be moved into a container, I would do this first. It makes your application stack portable as others try to run your container on their own environment. And you can still publish the port on your host where other services that have not been migrated can still reach it. You can even publish the port to the localhost interface on your docker host to avoid it being externally accessible with a syntax like: -p 127.0.0.1:3306:3306 for the published port.
Option 2: There are a variety of ways to detect the host IP address from inside of the container, but each have a limited number of scenarios where they work (e.g. requiring Docker for Mac). The most portable option is to inject your host IP into the container with something like an environment variable or configuration file, e.g.:
docker run --rm -e "HOST_IP=$(ip route get 1 | sed -n 's/^.*src \([0-9.]*\) .*$/\1/p')" ...
This does require that your service is listening on that external interface, which could be a security concern. For other methods to get the host IP address from inside of the container, see this post.
Slightly less portable is to use host.docker.internal. This works in current versions of Docker for Windows and Docker for Mac. And in 20.10, the capability has been added to Docker for Linux when you pass a special host entry with:
docker run --add-host host.docker.internal:host-gateway ...
The host-gateway is a special value added in Docker 20.10 that automatically expands to a host IP. For more details see this PR.
Option 3: Running without network isolation, i.e. running with --net host, means your application is running on the host network namespace. This is less isolation for the container, and it means you cannot access other containers over a shared docker network with DNS (instead, you need to use published ports to access other containerized applications). But for applications that need to access other services on the host that are only listening on 127.0.0.1 on the host, this can be the easiest option.
Option 4: Various services also allow access over a filesystem based socket. This socket can be mounted into the container as a bind mounted volume, allowing you to access the host service without going over the network. For access to the docker engine, you often see examples of mounting /var/run/docker.sock into the container (giving that container root access to the host). With mysql, you can try something like -v /var/run/mysqld/mysqld.sock:/var/run/mysqld/mysql.sock and then connect to localhost which mysql converts to using the socket.
Solution for Windows 10
Docker Community Edition 17.06.0-ce-win18 2017-06-28 (stable)
You can use DNS name of the host docker.for.win.localhost, to resolve to the internal IP. (Warning some sources mentioned windows but it should be win)
Overview
I needed to do something similar, that is connect from my Docker container to my localhost, which was running the Azure Storage Emulator and CosmosDB Emulator.
The Azure Storage Emulator by default listens on 127.0.0.1, while you can change the IP its bound too, I was looking for a solution that would work with default settings.
This also works for connecting from my Docker container to SQL Server and IIS, both running locally on my host with default port settings.
I doing a hack similar to above posts of get the local IP to map to a alias name (DNS) in the container. The major problem is to get dynamically with a simple script that works both in Linux and OSX the host IP address. I did this script that works in both environments (even in Linux distribution with "$LANG" != "en_*" configured):
ifconfig | grep -E "([0-9]{1,3}\.){3}[0-9]{1,3}" | grep -v 127.0.0.1 | awk '{ print $2 }' | cut -f2 -d: | head -n1
So, using Docker Compose, the full configuration will be:
Startup script (docker-run.sh):
export DOCKERHOST=$(ifconfig | grep -E "([0-9]{1,3}\.){3}[0-9]{1,3}" | grep -v 127.0.0.1 | awk '{ print $2 }' | cut -f2 -d: | head -n1)
docker-compose -f docker-compose.yml up
docker-compose.yml:
myapp:
build: .
ports:
- "80:80"
extra_hosts:
- "dockerhost:$DOCKERHOST"
Then change http://localhost to http://dockerhost in your code.
For a more advance guide of how to customize the DOCKERHOST script, take a look at this post with a explanation of how it works.
Solution for Linux (kernel >=3.6).
Ok, your localhost server has default docker interface docker0 with ip address 172.17.0.1. Your container started with default network settings --net="bridge".
- Enable route_localnet for docker0 interface:
$ sysctl -w net.ipv4.conf.docker0.route_localnet=1 - Add this rules to iptables:
$ iptables -t nat -I PREROUTING -i docker0 -d 172.17.0.1 -p tcp --dport 3306 -j DNAT --to 127.0.0.1:3306
$ iptables -t filter -I INPUT -i docker0 -d 127.0.0.1 -p tcp --dport 3306 -j ACCEPT - Create mysql user with access from '%' that mean - from anyone, excluding localhost:
CREATE USER 'user'@'%' IDENTIFIED BY 'password'; - Change in your script the mysql-server address to 172.17.0.1
From the kernel documentation:
route_localnet - BOOLEAN: Do not consider loopback addresses as martian source or destination while routing. This enables the use of 127/8 for local routing purposes (default FALSE).
using
host.docker.internal
instead of
localhost
works flawlessly for me.
First see this answer for the options that you have to fix this problem. But if you use docker-compose you can add network_mode: host to your service and then use 127.0.0.1 to connect to the local host. This is just one of the options described in the answer above. Below you can find how I modified docker-compose.yml from https://github.com/geerlingguy/php-apache-container.git:
---
version: "3"
services:
php-apache:
+ network_mode: host
image: geerlingguy/php-apache:latest
container_name: php-apache
...
+ indicates the line I added.
[Additional info] This has also worked in version 2.2. and "host" or just 'host' are both worked in docker-compose.
---
version: "2.2"
services:
php-apache:
+ network_mode: "host"
or
+ network_mode: host
...
None of the answers worked for me when using Docker Toolbox on Windows 10 Home, but 10.0.2.2 did, since it uses VirtualBox which exposes the host to the VM on this address.
Very simple and quick, check your host IP with ifconfig (linux) or ipconfig (windows) and then create a
docker-compose.yml
version: '3' # specify docker-compose version
services:
nginx:
build: ./ # specify the directory of the Dockerfile
ports:
- "8080:80" # specify port mapping
extra_hosts:
- "dockerhost:<yourIP>"
This way, your container will be able to access your host. When accessing your DB, remember to use the name you specified before, in this case "dockerhost" and the port of your host in which the DB is running
For Linux, where you cannot change the interface the localhost service binds to
There are two problems we need to solve
- Getting the IP of the host
- Making our localhost service available to Docker
The first problem can be solved using qoomon's docker-host image, as given by other answers.
You will need to add this container to the same bridge network as your other container so that you can access it. Open a terminal inside your container and ensure that you can ping dockerhost.
bash-5.0# ping dockerhost
PING dockerhost (172.20.0.2): 56 data bytes
64 bytes from 172.20.0.2: seq=0 ttl=64 time=0.523 ms
Now, the harder problem, making the service accessible to docker.
We can use telnet to check if we can access a port on the host (you may need to install this).
The problem is that our container will only be able to access services that bind to all interfaces, such as SSH:
bash-5.0# telnet dockerhost 22
SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
But services bound only to localhost will be inaccessible:
bash-5.0# telnet dockerhost 1025
telnet: can't connect to remote host (172.20.0.2): Connection refused
The proper solution here would be to bind the service to dockers bridge network. However, this answer assumes that it is not possible for you to change this. So we will instead use iptables.
First, we need to find the name of the bridge network that docker is using with ifconfig. If you are using an unnamed bridge, this will just be docker0. However, if you are using a named network you will have a bridge starting with br- that docker will be using instead. Mine is br-5cd80298d6f4.
Once we have the name of this bridge, we need to allow routing from this bridge to localhost. This is disabled by default for security reasons:
sysctl -w net.ipv4.conf.<bridge_name>.route_localnet=1
Now to set up our iptables rule. Since our container can only access ports on the docker bridge network, we are going to pretend that our service is actually bound to a port on this network.
To do this, we will forward all requests to <docker_bridge>:port to localhost:port
iptables -t nat -A PREROUTING -p tcp -i <docker_bridge_name> --dport <service_port> -j DNAT --to-destination 127.0.0.1:<service_port>
For example, for my service on port 1025
iptables -t nat -A PREROUTING -p tcp -i br-5cd80298d6f4 --dport 1025 -j DNAT --to-destination 127.0.0.1:1025
You should now be able to access your service from the container:
bash-5.0# telnet dockerhost 1025
220 127.0.0.1 ESMTP Service Ready
For those on Windows, assuming you're using the bridge network driver, you'll want to specifically bind MySQL to the ip address of the hyper-v network interface.
This is done via the configuration file under the normally hidden C:\ProgramData\MySQL folder.
Binding to 0.0.0.0 will not work. The address needed is shown in the docker configuration as well, and in my case was 10.0.75.1.
For Windows Machine :-
Run the below command to Expose docker port randomly during build time
$docker run -d --name MyWebServer -P mediawiki
In the above container list you can see the port assigned as 32768. Try accessing
localhost:32768
You can see the mediawiki page
The way I do it is pass the host IP as environment variable to container. Container then access the host by that variable.
For windows,
I have changed the database url in spring configuration: spring.datasource.url=jdbc:postgresql://host.docker.internal:5432/apidb
Then build the image and run. It worked for me.
Edit: I ended up prototyping out the concept on GitHub. Check out: https://github.com/sivabudh/system-in-a-box
First, my answer is geared towards 2 groups of people: those who use a Mac, and those who use Linux.
The host network mode doesn't work on a Mac. You have to use an IP alias, see: https://stackoverflow.com/a/43541681/2713729
What is a host network mode? See: https://docs.docker.com/engine/reference/run/#/network-settings
Secondly, for those of you who are using Linux (my direct experience was with Ubuntu 14.04 LTS and I'm upgrading to 16.04 LTS in production soon), yes, you can make the service running inside a Docker container connect to localhost services running on the Docker host (eg. your laptop).
How?
The key is when you run the Docker container, you have to run it with the host mode. The command looks like this:
docker run --network="host" -id <Docker image ID>
When you do an ifconfig (you will need to apt-get install net-tools your container for ifconfig to be callable) inside your container, you will see that the network interfaces are the same as the one on Docker host (eg. your laptop).
It's important to note that I'm a Mac user, but I run Ubuntu under Parallels, so using a Mac is not a disadvantage. ;-)
And this is how you connect NGINX container to the MySQL running on a localhost.
You need to know the gateway! My solution with local server was to expose it under 0.0.0.0:8000, then run docker with subnet and run container like:
docker network create --subnet=172.35.0.0/16 --gateway 172.35.0.1 SUBNET35
docker run -d -p 4444:4444 --net SUBNET35 <container-you-want-run-place-here>
So, now you can access your loopback through http://172.35.0.1:8000
Source: Stackoverflow.com