Connection refused on docker container

Question

I m new to Docker and trying to make a demo Rails app  I made a dockerfile that looks like this    FROM ruby 2 2 MAINTAINER marko codeship com    Install apt based dependencies required to run Rails as    well as RubyGems  As the Ruby image itself is based on a    Debian image  we use apt-get to install those  RUN apt-get update  amp  amp  apt-get install -y   build-essential   nodejs        Configure the main working directory  This is the base        directory used in any further RUN  COPY  and ENTRYPOINT        commands  RUN mkdir -p  app WORKDIR  app        Copy the Gemfile as well as the Gemfile lock and install        the RubyGems  This is a separate step so the dependencies        will be cached unless changes to one of those two files        are made  COPY Gemfile Gemfile lock    RUN gem install bundler  amp  amp  bundle install --jobs 20 --retry 5    Copy the main application  COPY         Expose port 8080 to the Docker host  so we can access it    from the outside  EXPOSE 8080    The main command to run when the container starts  Also    tell the Rails dev server to bind to all interfaces by    default  CMD   bundle    exec    rails    server    -b    0 0 0 0    -p    8080     I then built it like so    docker build -t demo      And call a command to start the server which does start the server on port 8080    Johns-MacBook-Pro demo johnkealy  docker run -it demo   gt  Booting WEBrick   gt  Rails 4 2 5 application starting in development on http   0 0 0 0 8080   gt  Run  rails server -h  for more startup options   gt  Ctrl-C to shutdown server  2016-04-23 16 50 34  INFO  WEBrick 1 3 1  2016-04-23 16 50 34  INFO  ruby 2 2 4  2015-12-16   x86 64-linux   2016-04-23 16 50 34  INFO  WEBrick  HTTPServer start  pid 1 port 8080   I then try to find the correct IP to navigate to    Johns-MacBook-Pro demo johnkealy  docker-machine ip default 192 168 99 100   I navigate to http   192 168 99 100 8080 and get the error This site can   t be reached 192 168 99 100 refused to connect   What could I be doing wrong

User · Answer

Command EXPOSE in your Dockerfile lets you bind container s port to some port on the host machine but it doesn t do anything else   When running container  to bind ports specify -p option   So let s say you expose port 5000  After building the image when you run the container  run docker run -p 5000 5000 name  This binds container s port 5000 to your laptop computers port 5000 and that portforwarding lets container to receive outside requests   This should do it

User · Answer

In Docker Quickstart Terminal run following command    docker-machine ip 192 168 99 100

User · Answer

In Windows  you also normally need to run command line as administrator   As standard-user   docker build -t myimage -f Dockerfile   Sending build context to Docker daemon  106 8MB Step 1 1   FROM mcr microsoft com dotnet core runtime 3 0 Get https   mcr microsoft com v2   dial tcp  lookup mcr microsoft com on    1  53  read udp    1  45540- gt    1  53  read    gt  gt  gt connection refused   But as an administrator   docker build -t myimage -f Dockerfile   Sending build context to Docker daemon  106 8MB Step 1 1   FROM mcr microsoft com dotnet core runtime 3 0 3 0  Pulling from dotnet core runtime 68ced04f60ab  Pull complete                                                                                             e936bd534ffb  Pull complete                                                                                             caf64655bcbb  Pull complete                                                                                             d1927dbcbcab  Pull complete                                                                                             Digest  sha256 e0c67764f530a9cad29a09816614c0129af8fe3bd550eeb4e44cdaddf8f5aa40 Status  Downloaded newer image for mcr microsoft com dotnet core runtime 3 0  --- gt  f059cd71a22a Successfully built f059cd71a22a Successfully tagged myimage latest

User · Answer

If you are using Docker toolkit on window 10 home you will need to access the webpage through docker-machine ip command  It is generally 192 168 99 100   It is assumed that you are running with publish command like below   docker run -it -p 8080 8080 demo   With Window 10 pro version you can access with localhost or corresponding loopback 127 0 0 1 8080 etc  Tomcat or whatever you wish   This is because you don t have a virtual box there and docker is running directly on Window Hyper V and loopback is directly accessible    Verify the hosts file in window for any digression  It should have  127 0 0 1 mapped to localhost

User · Answer

You need to publish the exposed ports by using the following options   -P  upper case  or --publish-all that will tell Docker to use random ports from your host and map them to the exposed container s ports   -p  lower case  or --publish    that will tell Docker to use ports you manually set and map them to the exposed container s ports   The second option is preferred because you already know which ports are mapped  If you use the first option then you will need to call docker inspect demo and check which random ports are being used from your host at the Ports section   Just run the following command   docker run -it -p 8080 8080 demo   After that your url will work

User · Answer

I had the same problem  I was using Docker Toolbox on Windows Home   Instead of localhost I had to use http   192 168 99 100 8080    You can get the correct IP address using the command   docker-machine ip   The above command returned 192 168 99 100 for me

[docker] Connection refused on docker container

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