I have a flask application which is running as docker container. Flask application uses local mongodb. This docker container is not able to connect to local mongodb.
I have tried following option :
set --network="host" in docker run ... command
set MONGO_URI = "mongodb://host-ip-address:27017/model-service-sample",
set MONGO_URI = "mongodb://container-gateway-ip-address:27017/model-service-sample"
None of the above options worked.
Can anyone please suggest a way to accomplish this?
For MacOS you should use:
host.docker.internal or gateway.docker.internal
for connecting from a container to a service on the host.
refer : https://docs.docker.com/docker-for-mac/networking/#/known-limitations-use-cases-and-workarounds
Related
On a virtual machine I have 2 docker containers running with the names <postgres> and <system> that run on the network with name <network>. I can't change options in these containers. I have created a flask application that connects to a database and outputs the required information. To connect from local computer I use
conn = psycopg2.connect(
database="db", user='user1', password='user1_passwd'
host='<VM_ip>', port='<db_port>',
sslmode='require',
sslcert='./user1.crt',
sslkey='./user1.key')
and it worked great.
But, when I run my application on the same VM and specify
conn = psycopg2.connect(
database="db", user='user1', password='user1_passwd'
host='<postgres>.<network>', port='<db_port>',
sslmode='require',
sslcert='./user1.crt',
sslkey='./user1.key')
I get an error:
psycopg2.OperationalError: could not parse network address \"<postgres>.<network>\": Name or service not known.
Local connections are allowed in pg_hba, the problem is in connecting from the new container in VM.
Here are the settings of my new container:
version: '3'
services:
app:
container_name: app
restart: always
build: ./app
ports:
- "5000:5000"
command: gunicorn -w 1 -b 0.0.0.0:8000 wsgi:server
I tried to make the same connection as from the local computer, specifying the VM_ip, but that didn't help either.
I also tried to specify the <postgres> container ip instead of its name in the host=, but this also caused an error.
Do you know what could be the problem?
You need to create a network first which you will use to communicate between containers. You can do that by:
docker network create <example> #---> you can name it whatever you want
Then you need to connect both containers with the network that you made.
docker run -d --net example --name <postgres_container> <postgres_image>
docker run -d --net example --name <flask_container> <flask_image>
You can read more about the docker network in its documentation here:
https://docs.docker.com/network/
from what I can see you might be using the docker-compose file for the deployment of the services, you can add one more layer above the service layer for the network where you can define the network that is supposed to be used by the services that are deployed. The network that is defined needs also be mentioned in the service definition this lets the Internal DNS engine that docker-compose creates in the background discover all the services in the network with the help of the service name.
A Bridge network may be a good driver to be used here.
You can use the following links for a better understanding of networks in docker-compose.
https://docs.docker.com/compose/compose-file/compose-file-v3/#network
https://docs.docker.com/compose/compose-file/compose-file-v3/#networks
I am using the jupyter/scipy-notebook image and want to connect to a MongoDB that runs locally on MacOS (port-forwarded through K8). I cannot get this to work. I can connect from the docker to the host using "host.docker.internal" but cannot reach MongoDB.
I tried two different approaches
A. Using the network flag to avoid the issue entirely:
docker run --network="host" jupyter/scipy-notebook:b418b67c225b
Result: Cannot reach the notebook at all on localhost:8888
B. Running the image without the network flag and connect to "host.docker.internal" when using the MongoDB.
docker run -p 8888:8888 jupyter/scipy-notebook:b418b67c225b
client = MongoClient("mongodb://host.docker.internal:27017/?readPreference=primary&ssl=false")
db = client["foo"]
db.list_collection_names()
Result: Some kind of topology error:
ServerSelectionTimeoutError: Could not reach any servers in ........ [Errno -3] Temporary failure in name resolution')>]>
Any ideas?
I have built a docker image for a flask app I have with some html templates and after running my image I go to localhost:5000which takes me to the start page in my flask app . I press a register button to register a user using a flask endpoint but I get
pymongo.errors.ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused
Before going to localhost I run my mongodb image with sudo docker start mongodband the connection seems to hit this error whenever I have to search something in my monogdb database for the endpoint . Do I need a docker-compose.yml to connect and I cannot connect without one ?
This is how I connect to mongodb using pymongo
client = MongoClient('mongodb://localhost:27017/')
db = client['MovieFlixDB']
users = db['Users']
movies = db['Movies']
How I run my flask app :
if __name__ == '__main__':
app.run(debug=True, host='0.0.0.0', port=5000)
I would appreciate your help . Thank you in advance
To connect containers to each other you should use networks.
First you create a network
docker network create my-network
Run mongodb specyfing the network.
docker container run -d --name mongodb -p 27017:27017 --network my-network mongodb:latest
Modify your app to connect to mongodb as host instead of localhost. Containers that are connected to a common network can talk to each other by using their names (DNS names) that can be automatically resolved to container IPs.
client = MongoClient('mongodb://mongodb:27017/')
You could also think about providing such deatils (db host, user, password) through environment variables and read them in your app.
Rebuild image with your app and run it
docker container run --name flask-app -d --network my-network my-flaskapp-image
You can read more about container networking in docker docs.
Do I need a docker-compose.yml to connect and I cannot connect without
one ?
If you use docker-compose, it will be easier and don't have to use too many commands to deploy. Look at this example (there are too many however you can refer random service).
Steps -
Build your docker-componse file [I have modified the one in the example of random service, removing rest] e.g.
version: '3.3'
services:
web-random:
build:
context: .
args:
requirements: ./flask-mongodb-example/requirements.txt
image: web-random-image
ports:
- "800:5000"
entrypoint: python ./flask-mongodb-example/random_demo.py
depends_on:
- mongo
mongo:
image: mongo:4.2-bionic
ports:
- "27017:27017"
Refer this example to update your mongo URL in your python code
Now, use the following command to compose and bring up the containers
docker-compose build
docker-compose up
Now, either browse your URL with browser or use the curl command
I am working on golang project, recently I read about docker and try to use docker with my app. I am using mongoDB for database.
Now problem is that, I am creating Dockerfile to install all packages and compile and run the go project.
I am running mongo data as locally, if I am running go program without docker it gives me output, but if I am using docker for same project (just installing dependencies with this and running project), it compile successfully but not gives any output, having error::
CreateSession: no reachable servers
my Dockerfile::
# Start from a Debian image with the latest version of Go installed
# and a workspace (GOPATH) configured at /go.
FROM golang
WORKDIR $GOPATH/src/myapp
# Copy the local package files to the container's workspace.
ADD . /go/src/myapp
#Install dependencies
RUN go get ./...
# Build the installation command inside the container.
RUN go install myapp
# Run the outyet command by default when the container starts.
ENTRYPOINT /go/bin/myapp
# Document that the service listens on port 8080.
EXPOSE 8080
EXPOSE 27017
When you run your application inside Docker, it's running in a virtual environment; It's just like another computer but everything is virtual, including the network.
To connect your container to the host, Docker gives it an special ip address and give this ip an url with the value host.docker.internal.
So, assuming that mongo is running with binding on every interface on the host machine, from the container it could be reached with the connection string:
mongodb://host.docker.internal:21017/database
Simplifying, Just use host.docker.internal as your mongodb hostname.
In your golang project, how do you specify connection to mongodb? localhost:27017?
If you are using localhost in your code, your docker container will be the localhost and since you don't have mongodb in the same container, you'll get the error.
If you are starting your docker with command line docker run ... add --network="host". If you are using docker-compose, add network_mode: "host"
Ideally you would setup mongodo in it's own container and connect them from your docker-compose.yml -- but that's not what you are asking for. So, I won't go into that.
In future questions, please include relevant Dockerfile, docker-compose.yml to the extent possible. It will help us give more specific answer.
I'm having docker container up and running by using the following command:
docker run -p 27017:27017 -d mongo
Docker Logs for reference.
Then I clone a github repo: https://github.com/springframeworkguru/spring-boot-mongodb.git
Import the project in IntelliJ IDE, build it and run.
SpringBoot App Error Logs here
Issue : I'm not able to connect to the mongo app running in the container from my SpringBoot application as I'm getting MongoSocketOpenException as shown in the logs.
Any help is appreciated?
Docker version 18.03.0-ce, build 0520e24302
OS: Windows 10
Docker for win has some problems with loopback interfaces.
https://blog.sixeyed.com/published-ports-on-windows-containers-dont-do-loopback/
Try run docker inspect and configure your application with the container address.
Problem: I was trying to configure SpringBoot Application to mongo container IP which I retrieved from mongo inspect <mongo_container> command which was incorrect.
Solution: Configured my application using docker IP retrieved by docker-machine <env> which resolved the problem.
Link to the post is here.