I am running a angular app on node server and in server.js I have specified app.listen(8084,localhost)..So when i run npm start in the docker container and try to -p 8084:8084 in docker run I was not able to get anything, even though the curl command inside my container curl localhost:8084 was giving me right result.
So i change the app.listen(8084) and the -p 8084:8084 started working..I am not sure why ?
When you open socket, you need to bind it to some interface in your system. There are predefined values:
0.0.0.0 - all interfaces, your service will be available from any interface
locahost, 127.0.0.1 - bind locally. That means service is NOT available from oustide -- this is your case.
You also can specify particular interface IP address to bind to it.
When you start your container, by default docker start default bridge network, so your container is being put into separate network and to access it, you need to allow incoming remote connections in container.
You bind your service to localhost into a container, so no communication is possible outside the container. localhost for your node server is not the same than localhost for your container.
Related
I have a docker container running in localhost:3000
Also, I have a node app running in localhost:8081
Now if I want to make post or get request from localhost:3000 to localhost:8001 its not working at all.
Now if run the service as a binary (not a docker file) on localhost:3000 the same API requests works.
How do I communicate if using docker?
Each container runs on it's own bridge network where localhost means the container itself.
To access the host, you can add the option --add-host=host.docker.internal:host-gateway to the docker run command. Then you can access the host using the host name host.docker.internal. I.e. if you have a REST service on the host, your URL would look something like http://host.docker.internal:8081/my/service/endpoint.
The name host.docker.internal is the common name to use for the host, but you can use any name you like.
You need docker version 20.10 for this to work.
Say, if I use this command inside a docker container.
/opt/lampp/bin/mysql -h localhost -u root -pThePassword
What would the localhost here refer to? The host machine's IP or the docker container's own IP?
From inside a container, localhost always refers to the current container. It never refers to another container, and it never refers to anything else running on your physical system that's not in the same container. It's not usually useful to make outbound connections to localhost or configure localhost as your database host.
From a shell on your host system, localhost could refer to daemons running on your system outside Docker, or to ports you've published with docker run -p options.
From a different system, localhost refers to the system it's called from.
In terms of IP addresses, localhost is always 127.0.0.1, and that IP address is special and is always localhost and behaves the same way as above.
If you want to make a connection to a container...
...from another container, the best way is to make sure they're on the same Docker network (you started them from the same Docker Compose YAML file; you did a docker network create and then did docker run --net ... on the same network) and use Docker's internal DNS service to refer to them by the container's --name or its name in the Docker Compose YAML file and the port number inside the container. Even if the target has a published port with a docker run -p option or Docker Compose ports: setting, use the second (container-internal) port number.
...from outside Docker space, make sure you started the container with a docker run -p or Docker Compose ports: option, and connect to the host's IP address or DNS name using the first port number from that option.
...from a terminal window or browser on the same physical host, not in a container, in this case and in this case only, localhost will work consistently.
Except:
If you started a container with --net host, localhost refers to the physical host, and you're in the "terminal window on the same physical host" scenario.
If you've gone out of your way to have multiple servers in the same container, you can use localhost to communicate between them.
If you're running in Kubernetes, and you have multiple containers in the same pod, you can use localhost to communicate between them. Between pods, you should set up a service in front of each pod/deployment, and use DNS names of the form service-name.namespace-name.svc.cluster.local.
Definitely, It will be your container, if you are running command in container.
/opt/lampp/bin/mysql -h localhost -u root -pThePassword
If you run this command inside container then it will try to connect mysql running inside container.
I am trying to put an application that listens to several ports inside a Docker image.
At the moment, I have one docker image with a Nginx server with the front-end and a Python app: the Nginx runs on the port 27019 and the app runs on 5984.
The index.html file listens to localhost:5984 but it seems like it only listens to it outside the container (on the localhost of my computer).
The only way I can make it work at the moment is by using the -p option twice in the docker run:
docker run -p 27019:27019 -p 5984:5984 app-test.
Doing so, I generate two localhost ports on my computer. If I don't put the -p 5984:5984 it doesn't work.
I plan on using more ports for the application, so I'd like to avoid adding -p xxx:xxx for each new port.
How can I make an application inside the container (in this case the index.html at 27019) listens to another port inside the same container, without having to publish both of them? Can it be generalized to more than two ports? The final objective would be to have a complete application running on a single port on a server/computer, while listening to several ports inside Docker container(s).
If you want to expose two virtual hosts on the same outgoing port then you need a proxy like for example https://github.com/jwilder/nginx-proxy .
It's not a good thing to put a lot of applications into one container, normally you should split that with one container per app, it's the way it should be used.
But if you absolutly want to use many apps into one container you can use proxy or write a dockerfile that will open your ports itself.
So, I'm trying to get Jenkins working inside of docker as an exercise to get experience using docker. I have a small linux server, running Ubuntu 14.04 in my house (computer I wasn't using for anything else), and have no issues getting the container to start up, and connect to Jenkins over my local network.
My issue comes in when I try to connect to it from outside of my local network. I have port 8080 forwarded to the serve with the container, and if I run a port checker it says the port is open. However, when I actually try and go to my-ip:8080, I will either get nothing if I started the container just with -p 8080:8080 or "Error: Invalid request or server failed. HTTP_Proxy" if I run it with -p 0.0.0.0:8080:8080.
I wanted to make sure it wasn't jenkins, so I tried getting just a simple hello world flask application to work, and had the exact same issue. Any recommendations? Do I need to add anything extra inside Ubuntu to get it to allow outside connections to go to my containers?
EDIT: I'm also just using the official Jenkins image from docker hub.
If you are running this:
docker run -p 8080:8080 jenkins
Then to connect to jenkins you will have to connect to (in essence you are doing port forwarding):
http://127.0.0.1:8080 or http://localhost:8080
If you are just running this:
docker run jenkins
You can connect to jenkins using the container's IP
http://<containers-ip>:8080
The Dockerfile when the Jenkins container is built already exposes port 8080
The Docker Site has a great amount of information on container networks.
https://docs.docker.com/articles/networking
"By default Docker containers can make connections to the outside world, but the outside world cannot connect to containers."
You will need to provide special options when invoking docker run in order for containers to accept incoming connections.
Use the -P or --publish-all=true|false for containers to accept incoming connections.
The below should allow you to access it from another network:
docker run -P -p 8080:8080 jenkins
if you can connect to Jenkins over local network from a machine different than the one docker is running on but not from outside your local network, then the problem is not docker. In this case the problem is what ever machine who is receiving outside connection (normally your router, modem or ...) does not know to which machine the outside request should be forwarded.
You have to make sure you are forwarding the proper port on your external IP to proper port on the machine which is running Docker. This can be normally done on your internet modem/router.
I'm having some troubles running Apache under Docker, and I wanted to ask for some directions. My current setup is the following : I have Docker 0.8 installed on an Ubuntu 12.04 server.
I want to run an Apache server under Docker, and bind it to a specific ip on the host, my intention being to run multiple Apache servers under Docker on the same hardware node each with it's one interface.
Now, I've been able to start the Apache server inside Docker, and have it run like a daemon (-D FOREGROUND, or under supervisord), and I've even been able to bind it to 0.0.0.0:$PORT and access it from the outside. But when I created multiple interfaces on the hardware node let's say 10.10.10.1, and 10.10.10.2, and tried to bind to -p 10.10.10.1:80:80, I'm not able to access 10.10.10.1:80 from the outside.
A little info about the network setup: I have my eth0 interface which has trunking out of which I create multiple vlans on which I want to put Docker instances (probably with a bridge on the eth0.$VLAN_NO, when I want to put more on the same vlan).
So basically, to reiterate, i have started a Docker container bound with -p 10.10.10.1:80:80, with an Apache inside Docker on port 80 and I can't access it (although binded on 0.0.0.0:80:80 works).