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.
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 learning docker and during my project, i can't enter the mongo db with this command:
mongo -u "username" -p "mypassword"
It throws me this error:
bash: mongo: command not found
I am not sure what the issue is. I have installed the community edition of mongo db and i also tried different terminals but i can't enter the db.
Any suggestions?
Thanks in advance!
I assume, you did the following: Create docker-compose.yml as you wrote before. Start docker compose up. This will start a container on your system, having mongodb installed in it. It will not affect your "normal" system outside this container. (You can imagine it as kind of a virtual machine, though it is not really the same.) So, if you did not install mongodb on your local host system as well, the error you encounter is quite explicable.
If you want to access the mongodb running within the container, you have two possibilities:
1. From outside the container (which is the more common use case)
You will have to install mongo on your regular PC (or anywhere you want to access your db from) as well. Then you would issue mongo 127.0.0.1:3000. The 3000 is important as your docker-compose.yml says, mongo is listening on port 3000. Note that you might have to get your network configuration adapted before this works, especially from other PCs, where 127.0.0.1 won't be correct.
2. From within the container
Once your container is started, you can also execute a command inside it, like this: docker exec -it ${container_id} /bin/bash. You'll have to find out the container's ID beforehand, using something like docker-compose ps -q. This will start a bash shell inside the container and "connect" you to it. (If there's no /bin/bash installed in the container, this will not work. Try e. g. /bin/sh instead.) Now your terminal will be inside the container and just be able to use the commands present there. So, to get back to your local PC, don't forget to issue exit.
Conclusion
IMHO, the crucial point is, that the physical PC you are working in front of and the container running inside it are almost completely different systems, connected only by the docker daemon and some virtual network access. You'll have to keep that in mind and decide what you want to do/run inside the container and what to do outside, on the host.
Here is a little further reference that might help you. And this answer is about how to find out your container ID in an automated way. (Assuming that you are running just that one container!)
I had never used PostgreSQL nor Docker before. I set up an already developed project that uses these two technologies in order to modify it.
To get the project running on my Linux (Pop!_OS 20.04) machine I was given these instructions (sorry if this is irrelevant but I don't know what is important and what is not to state my problem):
Installed Docker CE and Docker Compose.
Cloned the project with git and ran the commands git submodule init and git submodule update.
Initialized the container with: docker-compose up -d
Generated the application configuration file: ./init.sh
After all of that the app was available at http://localhost:8080/app/ and I got inside the project's directory the following subdirectories:
And inside dbdata:
Now I need to modify the DB and there's where the difficulty arose since I don't know how to set up the connection with PostgreSQL inside Docker.
In a project without Docker which uses MySQL I would
Create the local project's database "dbname".
Import the project's DB: mysql -u username -ppassword dbname < /path/to/dbdata.sql
Connect a DB client (DBeaver in my case) to the local DB and perform the necessary modifications.
In an endeavour to do something like that with PostgeSQL, I have read that I need to
Install and configure Ubuntu 20.04 serve.
Install PostgreSQL.
Configure Postgres “roles” to handle authentication and authorization.
Create a new Database.
And then what?
How can I set up the connection in order to be able to modify the DB from DBeaver and see the changes reflected on http://localhost:8080/app/ when Docker is involved?
Do I really need an Ubuntu server?
Do I need other program than psql to connect to Postgres from the command line?
I have found many articles related to the local setup of PostgreSQL with Docker but all of them address the topic from scratch, none of them talk about how to connect to the DB of an "old" project inside Docker. I hope someone here can give directions for a newbie on what to do or recommend an article explaining from scratch how to configure PostgreSQL and then connecting to a DB in Docker. Thanks in advance.
Edit:
Here's the output of docker ps
You have 2 options to get into known waters pretty fast:
Publish the postgres port on the docker host machine, install any postgres client you like on the host and connect to the database hosted in the container as you would have done this traditionally. You will use localhost:5433 to reach the DB. << Update: 5433 is the port where the postgres container is published on you host, according to the screenshot.
Another option is to add another service in your docker-compose file to host the client itself in a container.
Here's a minimal example in which I am launching two containers: the postgres and an adminer that is exposed on the host machine on port 9999.
version: '3'
services:
db:
image: postgres
restart: always
environment:
POSTGRES_PASSWORD: example
adminer:
image: adminer
restart: always
ports:
- 9999:8080
then I can access the adminer at localhost:9999 (password is example):
Once I'm connected to my postgres through adminer, I can import and execute any SQL query I need:
A kind advice is to have a thorough lecture to understand how the data is persisted in a Docker context. Performance and security are also topics that you might want to add under your belt as a novice in the field better sooner than later.
If you're running your PostgreSQL container inside your own machine you don't need anything else to connect using a database client. That's because to the host machine, all the containers are accessible using their own subnet.
That means that if you do this:
docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' 341164c5050f`
it will output a list of IPs that you can configure in your DBeaver to access the container instance directly.
If you're not fond of doing that (or you prefer to use cli) you can always use the psql inside the installation of the PostgreSQL container to achieve something like you described in mysql point nº2:
docker exec -i 341164c5050f bash -c 'psql -U $POSTGRES_USER' < /path/to/your/schema.sql
It's important to inform the -i, otherwise it'll not read the schema from the stdin. If you're looking for psql in the interactive mode, use -it instead.
Last but not least, you can always edit the docker-compose.yml file to export the port and connect to the instance using the public IP/loopback device.
I have started a new (.net core 3.0)project in Visual Studio, with Docker support (Windows)
I have added Docker support (right-click on project Add->Docker support) and in the same way added Docker compose support.
If I just Click "play-button" for Docker Compose, the project starts everything works well.
But when I run docker-compose up from the solution folder I get
Cannot start service testproj30: failed to create endpoint
testproj30_testproj30_1 on network nat: hnsCall failed in Win32: The
specified port already exists.
(I have closed my VS solution). If I remove the port mapping in docker-compose.override.yaml I dont get this error message. I have dont the most common tricks with restarting docker servce, hni service and so on. Nothing helps.
I dont want to depend on all VS-voodoo from the project file and God knows what other files that are involved.
I can run docker run -p 8080:80 443:443 without any port problems
I fixed a similar problem by removing some terminated container and then pruning networks.
List terminated container :
docker ps -a
Remove them (Cygwin syntax) :
docker rm $(docker ps -aq)
You will have error message for runnnig containers.
Clean your networks :
docker network prune
For myself, the main cause was the Docker killing process skiped the port releasing mechanism of my application.
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.