I am new to Docker.
I was trying to dockerize a simple static website using nginx base image.
The applicatio runs fine on local server when i run.
docker run -d -P <container-name>
So, here the app runs on some random port on which i am able to see my app running.
while, when i try to specify port by using the following command:
docker run -d -p 5000:5000 --restart=always --name app mkd63/leo-electricals
The page at localhost:5000 shows site cant be reached.
My Dockerfile is:
FROM nginx:alpine
COPY . /usr/share/nginx/html
EXPOSE 5000
By default, the nginx image listens on port 80 inside the container.
Publishing a port creates a port forward from the host into the container. This doesn't modify what port the application is listening on inside the container, so if you forward to an unused port, you won't connect to anything.
Exposing a port in the Dockerfile is documentation by the image creator to those running the image, but doesn't modify container networking or have any control over what the application running inside the container is doing. With docker, the -P flag uses that documentation to publish every exposed port.
To map port 5000 on the host to nginx listening on port 80 inside the container, use:
docker run -d -p 5000:80 --restart=always --name app mkd63/leo-electric
Related
I am trying to run jenkins container. I used "docker run --restart always --name myjenkins -p 8080:80 jenkins" but cannot access jenkins at http://localhost:8080 on browser. If I use docker run --restart always --name myjenkins -p 8080:8080 jenkins, I can access the jenkins url.
Thanks in advance
Without Docker
Each application must use a different port.
You can access to your application using directly its ports (if are available of course):
APP_A : 192.168.4.5:8080
APP_B : 10.10.10.15:8081
APP_C : www.app.com:8082
With Docker
Applications could use any port because each one "is a different world"
You can not access to your docker applications using its internal ports:
APP_A : 192.168.4.5:8080
APP_B : 10.10.10.15:8080
APP_C : www.app.com:8080
Because for instance, 8080 of APP_B is only visible inside APP_B container. No body can access to this applications.
In order to access to your docker applications, You must explicitly establish a relationship between:
Linux host ports <-> inside containers ports.
To do that you could use -p parameter
docker run -d -p 8080:8080 APP_A ...
docker run -d -p 8081:8080 APP_B ...
docker run -d -p 8082:8080 APP_C ...
After this you could access to your docker applications using its new ports :
APP_A : 192.168.4.5:8080
APP_B : 10.10.10.15:8081
APP_C : www.app.com:8082
Also a common error when docker-compose & docker network are used is use localhost instead ip when a docker app needs to connect to another docker app. As you can see you need to use ip or domain + external port instead localhost:8080
what is the difference between publishing 8080:80 and 8080:8080 in a docker run?
With 8080:80 you expect that your application uses or start with the 80 internal port inside container.
With 8080:8080 you expect that your application uses or start with the 8080 internal port inside container.
You just need to research what is the internal container port used by your jenkins and put it in docker run -p ...
8080:80 refers that in the container you are using port 80 and you are forwarding that port to host machine's 8080 port. So you are running Jenkins on port 80 inside your container wherever in scenario 2 you are running Jenkins on port 8080 inside the container and exposing it over the same port on host machine.
For example if I am running mysql in container I may use 8080:3306 so mysql would be running on port 3306 but exposed on 8080 of host machine but if choose it to be 8080:80 for mysql it may not work because as per the code of mysql it binds itself on port 3306 not port 80. Same is the scenario in your case of Jenkins too.
When you say 8080:80, it means any request coming on port 8080 will be forwarded to service running on port 80 inside your docker container.
Similarly 8080:8080 means any request coming for port 8080 will be forwarded to service running on port 8080 inside your container
You can also think of it as -
Port for Outside World: Actual Port of service in container
Hope this helps
The syntax looks like below. More details about -p flag.
docker run -p [ip-on-host:]port-on-host:port-in-container image-name
In your case, -p 8080:80 means leading all traffic to port 80 in container. If you check port status on host by netstat -lntp|grep 8080, there is a process managed by docker-proxy who is listening on port 8080 on host machine. It would manage all traffic routing between port 8080 on host and port 80 in container.
In my workplace docker is running behind firewall, only the port that is meant to serve webpage is excluded by rule.
The container starts but website does not open for same port.
If I host the website from machine running container using python -m SimpleHTTPServer it works.
docker container run --restart=always -p 8081: 8082 -it vue-js-app: latest
From the Docker documentation:
Publish or expose port (-p, --expose)
$ docker run -p 127.0.0.1:80:8080/tcp ubuntu bash
This binds port 8080 of the container to TCP port 80 on 127.0.0.1 of
the host machine. You can also specify udp and sctp ports. The Docker
User Guide explains in detail how to manipulate ports in Docker.
$ docker run --expose 80 ubuntu bash
This exposes port 80 of the container without publishing the port to
the host system’s interfaces.
And, from the Docker User Guide:
You also saw how you can bind a container’s ports to a specific port
using the -p flag. Here port 80 of the host is mapped to port 5000 of
the container:
$ docker run -d -p 80:5000 training/webapp python app.py
So, as an example of how to expose the ports you can use:
docker container run --restart always -p 8081:8082 -it vue-js-app:latest
I have a two HTTP servers on my host machine; one listening on 8080, the other listening on 8081. The 8080 is a webapp, and the 8081 is an API.
I also have a Docker container that should connect to the webapp on 8080 using an automated tool, and that webapp should make HTTP requests to the API that's on 8081.
Here is a visual representation of what I want:
Host machine HTTP 8080
⇩ ⇖
⇧ Docker container
Host machine HTTP 8081
The problem I'm having is that the Docker container cannot connect to the website on the host machines 8080. I'm not sure why, because I set the --network=host flag, so shouldn't it be using the host machines network?
This is my Docker image:
## Redacted irrelevant stuff...
EXPOSE 8080 8081
This is how run the container:
docker run -d -p 8080:8080 -p 8081:8081 --network=host --name=app app
Any ideas what's wrong with my setup?
So you have two services running directly on the machine and you want to deploy a Docker container that should connect to one of those services.
In that case, you shouldn't map those port to the container and you shouldn't expose those ports in the Dockerfile as those ports are not for the container.
Remove the Expose ports from the Dockerfile
Start the container using docker run -d --network=host --name=app app. The container should be able to access the services using localhost:8080.
I have apache installed inside a running ubuntu:14.04 container. How to access this in the browser of the host machine? The address showing inside the container is, 172.17.0.2. Please help.
By default, the apache httpd image exposes the port 80
docker run -it --rm --name my-apache-app -v "$PWD":/usr/local/apache2/htdocs/ httpd:2.4
So http://localhost should be enough.
In your case, make sure:
the httpd is actually running (docker exec -it <yourContainer> bash: ps -eaf),
you have mapped the port you are running Apache in your container to the host (-p 80:80 for instance).
By default, the apache image exposes the port 80, but you need config this in run command (-p):
docker run -d -p 80:80 httpd
The first number is port of Docker Host and the second one is port of container. This configuration will map all connections to port tcp 80 of docker host to the same port of container.
After that you can access your application in your browser, using 127.0.0.1, localhost or other IP Address of your interface.
I have found a similar thread, but failed to get it to work. So, the use case is
I start a container on my Linux host
docker run -i -t --privileged -p 8080:2375 mattgruter/doubledocker
When in that container, I want to start another one with GAE SDK devserver running.
At that, I need to access a running app from the host system browser.
When I start a container in the container as
docker run -i -t -p 2375:8080 image/name
I get an error saying that 2375 port is in use. I start the app, and can curl 0.0.0.0:8080 when inside both containers (when using another port 8080:8080 for example) but cannot preview the app from the host system, since lohalhost:8080 listens to 2375 port in the first container, and that port cannot be used when launching the second container.
I'm able to do that using the image jpetazzo/dind. The test I have done and worked (as an example):
From my host machine I run the container with docker installed:
docker run --privileged -t -i --rm -e LOG=file -p 18080:8080
jpetazzo/dind
Then inside the container I've pulled nginx image and run it with
docker run -d -p 8080:80 nginx
And from the host environment I can browse the nginx welcome page with http://localhost:18080
With the image you were using (mattgruter/doubledocker) I have some problem running it (something related to log attach).