When I start MySQL :
docker run --rm -d -e MYSQL_ROOT_PASSWORD=root -p 3306:3306 -v /Docker/data/matos/mysql:/var/lib/mysql mysql:5.7
And start PHPMyAdmin :
docker run --rm -d -e PMA_HOST=172.17.0.1 phpmyadmin/phpmyadmin:latest
PMA cannot connect to the DB server.
When I try with PMA_HOST=172.17.0.2 (which is the address assigned to the MySQL container), it works.
But :
as MySQL container publishes its 3306 port, I think it should be reachable on 172.17.0.1:3306.
I don't want to use the 172.17.0.2 address because the MySQL container can be assigned another address whenever it restarts
Am I wrong ?
(I know I can handle this with docker-compose, but prefer managing my containers one by one).
(My MySQL container is successfully telnetable from my laptop with telnet 172.17.0.1 3306).
(My docker version : Docker version 20.10.3, build 48d30b5).
Thanks for your help.
Create a new docker network and start both containers with the network
docker network create my-network
docker run --rm -d --network my-network -e MYSQL_ROOT_PASSWORD=root -p 3306:3306 -v /Docker/data/matos/mysql:/var/lib/mysql --name mysql mysql:5.7
docker run --rm -d --network my-network -e PMA_HOST=mysql phpmyadmin/phpmyadmin:latest
Notice in the command that I've given the mysql container a name 'mysql' and used it as the address for phpmyadmin
Just found out the problem.
My ufw was active on my laptop, and did not allow explicitly port 3306.
I managed to communicate between PMA container and MySQL, using 172.17.0.1, either by disabling ufw or adding a rule to explicitly accept port 3306.
Thanks #kidustiliksew for your quick reply, and the opportunity you gave me to test user-defined networks.
maybe it's a good idea to use docker-compose.
Create a docker-compose.yml file and inside declare two services, one web and the other db, then you can reference them through their service names (web, db)
ex: PMA_HOST=db
Related
I am running Mongo DB image with following command:
docker run -d -p 27017:27017 -e MONGO_INITDB_ROOT_USERNAME=test -e MONGO_INITDB_ROOT_PASSWORD=password --name=testdb mongo
This created container and I'm able to connect to this from robo3T.
Now I ran mongo-express image with following command and trying to above DB:
docker run -d -p 8081:8081 -e ME_CONFIG_MONGODB_ADMINUSERNAME=test -e ME_CONFIG_MONGODB_ADMINPASSWORD=password -e ME_CONFIG_MONGODB_SERVER=testdb --name=mongo-ex mongo-express
But I'm getting following error:
UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [testb:27017] on first connect [Error: getaddrinfo ENOTFOUND testb
If I'm creating a custom bridge network and running these two images in that container it's working.
My question is: As the default network is bridge network, and these containers are creating in default bridge network, why are they not able to communicate? Why is it working with custom bridge network?
There are two kinds of "bridge network"; if you don't have a docker run --net option then you get the "default" bridge network which is pretty limited. You almost always want to docker network create a "user-defined" bridge network, which has the standard Docker networking features.
# Use modern Docker networking
docker network create myapp
docker run -d --net myapp ... --name testdb mongo
docker run -d --net myapp ... -e ME_CONFIG_MONGODB_SERVER=testdb mongo-express
# Because both containers are on the same --net, the first
# container's --name is usable as a host name from the second
The "default" bridge network that you get without --net by default forbids inter-container communication, and you need a special --link option to make the connection. This is considered obsolete, and the Docker documentation page describing links notes that links "may eventually be removed".
# Use obsolete Docker networking; may stop working at some point
docker run -d ... --name testdb mongo
docker run -d ... -e ME_CONFIG_MONGODB_SERVER=testdb --link testdb mongo-express
# Containers can only connect to each other by name if they use --link
On modern Docker setups you really shouldn't use --link or the equivalent Compose links: option. Prefer to use the more modern docker network create form. If you're using Compose, note that Compose creates a network named default but this is a "user-defined bridge"; in most cases you don't need any networks: options at all to get reasonable inter-container networking.
I am trying to make a portable solution to having my application container connect to a postgres container. By 'portable' I mean that I can give the user two docker run commands, one for each container, and they will always work together.
I have a postgres docker container running on my local PC, and I run it like this,
docker run -p 5432:5432 -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11
and I am able to access it from a python flask app, using the address 127.0.0.1:5432.
I put the python app in a docker container as well, and I am having trouble connecting to the postgres container.
Address 127.0.0.1:5432 does not work.
Address 172.17.0.2:5432 DOES work (172.17.0.2 is the address of the docker container running postgres). However I consider this not portable because I can't guarantee what the postgres container IP will be.
I am aware of the --add-host flag, but it is also asking for the host-ip, which I want to be the localhost (127.0.0.1). Despite several hits on --add-host I wasn't able to get that to work so that the final docker run commands can be the same on any computer they are run on.
I also tried this: docker container port accessed from another container
My situation is that the postgres and myApp will be containers running on the same computer. I would prefer a non-Docker compose solution.
The comment from Truong had me try that approach (again) and I got it working. Here are my steps in case it helps out another. The crux of the problem was needing one container to address another container in a way that was static (didn't change). Using user defined network was the answer, because you can name a container, and thus reference that container IP by that name.
My steps,
docker network create mynet
docker run --net mynet --name mydb -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11
Now the IP address of the postgres database is mydb, and all the ports of this container are exposed to any other container running in this network.
Now add the front end app,
docker run --net mynet -ti -p 80:80 -v mydockerhubaccount/myapp
Well, the set up is simple, there should be two containers: one of them for the mysql database and the other one for web application.
What I do to run the containers,
the first one for database and the second for the app:
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d mysql
docker run -p 8081:8081 myrepo/myapp
The application tries to connect to database using localhost:3306, but as I found out the issue is that each container has its own localhost.
One of the solution I found was to add the same network for containers using --net and the docker commands happend to be like the following:
docker network create my-network
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d
--net my-network mysql
docker run --net my-network -p 8081:8081 myrepo/myapp
Though, the web application still is not able to connect to the database. What am I doing wrong and what is the proper flow to connect application to database when they are both inside containers?
You could use the name of the container (i.e. mysql-container) to connect to mysql. Example:
Run the mysql container:
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d --net my-network mysql
Connect from another container using the mysql client:
docker run --net my-network -it mysql mysql -u root -p db -h mysql-container
In your application you should replace in the database URL, whatever IP you have with mysql-container.
Well, after additional research, I successfully managed to connect to the database.
The approach I used is the following:
On my host I grabbed the IP address of the docker itself but not the specific container:
sudo ip addr show | grep docker0
The IP address of the docker0 I added to the database connection URL inside my application and thus application managed to connect to the database (note: with this flow I don't add the --net keyword when start container)
What definitely strange is that even adding shared network like --net=my-nework for both the container didn't work. Moreover I did try to use --net=host to share the host network with container's one, still it was unsuccessful. If there's any who can explain why it couldn't work, please - share your knowledge.
I am trying to have my application connect to the Sql Server Express DB, both which are containerized.
When i run my app container in in a separate VM to the db, it connects and all is good.
However if the app container is running on the same VM as the DB container, it cannot connect.
I've tried setting the network mode to host and still nothing.
I got a very simple setup as part of my hands on learning.
Diagram of setup below.
Model A: Vm to VM - Connection Works
Model B: Internal VM - Cannot Connect thus App fails
I been reading up on docker a bit (running simple docker setup) to try and figure out the problem but no luck so far.
I've also used docker-compose to try and help still no luck.
Edit 1:
Commands used.
SQL Server: as per docker hub instructions
docker run --restart always -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=RANDOMPASS01!' -e 'MSSQL_PID=Express' -p 1433:1433 -d mcr.microsoft.com/mssql/server:2017-latest-ubuntu
AppA
This by itself works fine in Model A
docker run -p 5000:80 -d appa:0.1
I've also tried
docker run -p 5000:80 --network host -d appa:01
For what I see that you're doing it (starting your app container with net=host) should be working without issues as long as you are using localhost for connecting to the db.
If this is just for testing in your local machine I would suggest start both containers within their own docker network and access the db by container name, you can do it manually or use docker-compose to do it.
Example with docker-compose:
version: '3'
services:
db:
image: mcr.microsoft.com/mssql/server:2017-latest-ubuntu
ports:
- 1433:1433
environment:
- MSSQL_PID=Express
- SA_PASSWORD=RANDOMPASS01!
- ACCEPT_EULA=Y
restart: always
app:
# You can use this to tell docker-compose to build the image of you app
# or use a prebuilt image like the db service is using
image: appa:0.1
ports:
- 5000:80
Put this in a file called docker-compose.yml and start it with:
docker-compose up
This will create two containers in the same network, this will provide you as well with a DNS record for each container with the name of the provided service in the docker-compose file, so instead of using an IP or localhost you use "db" or "app".
More info for docker-compose: https://docs.docker.com/compose/overview/
The manual way:
docker network create mynetwork
Run the containers within the network:
docker run -p 5000:80 -d --net=mynetwork --name app appa:0.1
docker run --restart always -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=RANDOMPASS01!' -e 'MSSQL_PID=Express' -p 1433:1433 --net=mynetwork --name db -d mcr.microsoft.com/mssql/server:2017-latest-ubuntu
In the same way as using docker-compose you can access the db by using the "db" dns record that docker creates based on the name of the container.
The aforementioned DNS records are only resolvable within the containers.
More info on user-defined networks: https://docs.docker.com/network/bridge/
Ok, I am pretty new to Docker world. So this might be a very basic question.
I have a container running in Docker, which is running RabbitMQ. Let's say the name of this container is "Rabbit-container".
RabbitMQ container was started with this command:
docker run -d -t -i --name rmq -p 5672:5672 rabbitmq:3-management
Python script command with 2 args:
python ~/Documents/myscripts/migrate_data.py amqp://rabbit:5672/ ~/Documents/queue/
Now, I am running a Python script from my host machine, which is creating some messages. I want to send these messages to my "Rabbit-container". Hence I want to connect to this container from my host machine (Mac OSX).
Is this even possible? If yes, how?
Please let me know if more details are needed.
So, I solved it by simply mapping the RMQ listening port to host OS:
docker run -d -t -i --name rmq -p 15672:15672 -p 5672:5672 rabbitmq:3-management
I previously had only -p 15672:15672 in my command. This is mapping the Admin UI from Docker container to my host OS. I added -p 5672:5672, which mapped RabbitMQ listening port from Docker container to host OS.
If you're running this container in your local OSX system then you should find your default docker-machine ip address by running:
docker-machine ip default
Then you can change your python script to point to that address and mapped port on <your_docker_machine_ip>:5672.
That happens because docker runs in a virtualization engine on OSX and Windows, so when you map a port to the host, you're actually mapping it to the virtual machine.
You'd need to run the container with port 5672 exposed, perhaps 15672 as well if you want WebUI, and 5671 if you use SSL, or any other port for which you add tcp listener in rabbitmq.
It would be also easier if you had a specific IP and a host name for the rabbitmq container. To do this, you'd need to create your own docker network
docker network create --subnet=172.18.0.0/16 mynet123
After that start the container like so
docker run -d --net mynet123--ip 172.18.0.11 --hostname rmq1 --name rmq_container_name -p 15673:15672 rabbitmq:3-management
note that with rabbitmq:3-management image the port 5672 is (well, was when I used it) already exposed so no need to do that. --name is for container name, and --hostname obviously for host name.
So now, from your host you can connect to rmq1 rabbitmq server.
You said that you have never used docker-machine before, so i assume you are using the Docker Beta for Mac (you should see the docker-icon in the menu bar at the top).
Your docker run command for rabbit is correct. If you now want to connect to rabbit, you have two options:
Wrap your python script in a new container and link it to rabbit:
docker run -it --rm --name migration --link rmq:rabbit -v ~/Documents/myscripts:/app -w /app python:3 python migrate_data.py
Note that we have to link rmq:rabbit, because you name your container rmq but use rabbit in the script.
Execute your python script on your host machine and use localhost:5672
python ~/Documents/myscripts/migrate_data.py amqp://localhost:5672/ ~/Documents/queue/