I'm currently working with Docker, I use mongo image for my DB container. For persistent storage, I mounted host machine's directory(e.g. /var/docker/data/db) to container(e.g. /data/db).
By now, whenever I wanted to run mongo shell and connect to my db I was doing these things:
Attach to running MongoDB container using docker exec -it <container> bash
Run mongo shell inside the container
Do some job
But I think it'll be much better if I could run mongod separately on the host machine, not in the container, and then connect to it even when the container is not running.
So is it possible to doing so? If I run two mongod process on the same directory(files), will there be an file access conflict?
If someone did similar kind of work, share me your experience please. Thanks.
Related
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'm trying to docker-containerize PostgreSQL server and this container will have many other applications as well. The need is that, PostgreSQL server data should be mapped to the host volume so that when container is stopped, we won't lose the data. Also that, the next time when we start the container, the same directory can be mapped again and postgres can use the old data. Below is the DOCKERFILE. Note that I'm using ubuntu 22.04 on the host.
FROM ubuntu:22.04
ENV DEBIAN_FRONTEND noninteractive
RUN apt install -y postgresql
ENTRYPOINT ["tail", "-f", "/dev/null"]
Docker image is built using the command
docker build -t pg_test .
and the container is run using the command
docker run --name test -v /home/me/data:/var/lib/postgresql/14/main pg_test
'/home/me/data' is the host directory which is empty where I want to map the postgres server data. '/var/lib/postgresql/14/main' is the directory inside the docker container where the postgres is supposed to store the data.
Once the docker container starts, I enter the docker container using the command
docker exec -it test bash
and once I'm inside, I'm trying to start the PostgreSQL service. But PostgreSQL fails to start as there is no data in '/var/lib/postgresql/14/main' directory. I understand that since I have mapped an empty host directory to '/var/lib/postgresql/14/main' directory, postgres doesn't have the files required to start.
I understand that I'm doing it the wrong way, but I couldn't find a way around it. Can anyone please help me to do this the right way, if there is one?
Any help would be appreciable.
You should use the postgres docker image, it will set up the db for you when you start the container, you can find instructions on https://hub.docker.com/_/postgres
If you must use a custom image, you will need to initialize the db yourself, usually by running initdb or whatever your system provides.
But really you should use the appropriate docker image, and if you need more services you start them in their own container and connect them to the postgres one
I have created the karaf dockerfile from scratch and it works with my application. Now, the postgreSQL and the MongoDB containers need to be running on the same network as the karaf container for the final step. Essentially, what i have so far is three separate dockerfiles. And what i need is for them to be able to communicate with each other. How do i approach this?
Use docker network ls command firstly, it will show the networks exist in the machine.
Then run your MongoDB container and set --net param.
docker run --net karaf_default mongo
The mongo and karaf will be in the same network now. (you can check doc of --link)
I have installed mongodb on a docker container together with openssh on ubuntu 14.04. The container is running with ssh but when I ssh into the container I get the following error when trying to start mongod.
root#430f9502ba2d:~# service mongod start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service mongod start
Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start mongod
Also start mongod does not affect anything.
Tried looking at this also Mongo daemon doesn't run by service mongod start without it helping.
mongod --config /your/path/to/mongod.conf doesn't seem to work also, just locks up.
The error below is standard as of course there is no mongod server running.
root#430f9502ba2d:/# mongo
MongoDB shell version: 2.6.9
connecting to: test
2015-05-07T20:49:56.213+0000 warning: Failed to connect to 127.0.0.1:27017, reason: errno:111 Connection refused
2015-05-07T20:49:56.214+0000 Error: couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connection attempt failed at src/mongo/shell/mongo.js:146
exception: connect failed
The problem here is your approach. Docker does not have an init system like you are used to on traditional systems. What docker does is replace PID 1 with the process you specify in the CMD or ENTRYPOINT Dockerfile commands. For now, ignore ENTRYPOINT, because it replaces what your CMD is run with (normally, it's /bin/sh -c). You need to instruct docker to start your mongod service in your Dockerfile with the CMD command, like:
CMD usr/bin/mongod
And when you run your container, mongod will be your PID 1. Now, you're probably wondering at this point "But what about my SSH server?" and the answer is: Don't run an SSH server on your docker containers. There are some use cases where running an SSH server is okay, but almost all of the "normal" reasons (debug, C&C, etc) are nullified with the "best practice" for getting a shell on your container:
docker exec -it myContainer /bin/bash
This will drop you into a shell on your running container. The recommendation here for managing configuration and changes in your docker container is to use something like Ansible. However, remember that docker containers are ephemeral, and you shouldn't be restarting services and changing configuration state on them. If you need a config change, change the Dockerfile or config data, and then start a new container. Good luck! Here is a little more information on Dockerizing MongoDB, but keep in mind that the method described there alters the ENTRYPOINT in the Dockerfile, which is a little more involved and requires a better understanding of what's going on in Dockerfiles.
This is really helpful. I was trying to make old Ansible playbooks work with Docker by creating several blank containers and let Ansible do the rest.
It works through command
mongod --dbpath /var/lib/mongodb --smallfiles
Today I was researching and trying docker, and with the most of things I was impressed. There are still some questions for me about docker.
Can anyone more experienced than me with Docker tell me what is the best way to login to postgres container (run bash), in order to view some postgres configuration files, view postgres logs, log into postgres shell, execute pg_dump for example, etc. etc..., and everything this while postgres process is running.
I see that people usually run one process per container, and with this approach I am not sure what is the best way to do mentioned actions on container which runs postgres?
Any advices?
Thanks!
You can usually get a shell like this:
docker exec -it some-node bash
The canonical docker way would be not to log in to the running db container, but instead do docker logs or link other containers to do maintenance tasks (e.g. docker run -it --rm --link <my-pg-container>:pg <my-pg-image> pgsql --host pg etc..