I want nginx in a Docker container to host a simple static hello world html website. I want to simply start it with "docker run imagename". In order to do that I added the run parameters to the Dockerfile. The reason I want to do that is that I would like to host the application on Cloud Foundry in a next step. Unfortunately I get the following error when doing it like this.
Dockerfile
FROM nginx:alpine
COPY . /usr/share/nginx/html
EXPOSE 5000
CMD ["nginx -d -p 5000:5000"]
Error
Error starting userland proxy: Bind for 0.0.0.0:5000: unexpected error Permission denied.
From ::
https://docs.docker.com/engine/reference/builder/#expose
EXPOSE does not make the ports of the container accessible to the host. To do that, you must use either the -p flag to publish a range of ports or the -P flag to publish all of the exposed ports. You can expose one port number and publish it externally under another number
CMD ["nginx -d -p 5000:5000"]
You add your dockerfile
FROM nginx:alpine
its already starts nginx.
after you build from your dockerfile
you should use this on
docker run -d -p 5000:5000 <your_image>
Edit:
If you want to use docker port 80 -> machine port 5000
docker run -d -p 5000:80 <your_image>
Related
TL;DR: Why does an aspnet core app run on port 80 from within a Docker image, but 5000 outside a docker image.
Elaborate
I went through the aspnet core / docker tutorial found here:
https://learn.microsoft.com/en-us/dotnet/core/docker/building-net-docker-images
Half way through the page, I start the application with the following as prescribed:
dotnet run
Among other things, this prints this:
Now Listening on: http://localhost:5000
Great. That is what I expected. The next thing in the tutorial is to start the exact same application from within a Docker image.
docker build -t aspnetapp .
docker run -it --rm -p 5000:80 --name aspnetcore_sample aspnetapp
This results in
Now listening on: http://[::]:80
Wait. Wat? Why is the aspnet core app running on port 80? It was running on port 5000 when I ran it directly from the machine. There were no configuration file changes.
I suspect that it has something to do with the base docker images, but am not yet skilled enough in docker to track this down.
The microsoft/aspnetcore-build container builds on top of the
microsoft/aspnetcore container. The dockerhub page for that says:
A note on ports
This image sets the ASPNETCORE_URLS environment variable to http://+:80 which means that if you have not explicity set a URL in your application, via app.UseUrl in your Program.cs for example, then your application will be listening on port 80 inside the container.
So this is the container actively setting the port to 80. You can override it, if you want, by doing this in your Dockerfile:
ENV ASPNETCORE_URLS=http://+:5000
Also, it is worth noting that because of the docker command you are using, you will still be able to access the application at http://localhost:5000 whether you are running the application directly or in a container.
without dockerfile you can set any port out of the docker container. (.NET Core 3.1, .NET 5, .NET 6, .NET 7+) with docker args
docker run -it --rm -p 5000:80 -p 5001:443 -e ASPNETCORE_HTTPS_PORT=https://+:5001
-e ASPNETCORE_URLS=http://+:5000 --name aspnetcore_sample aspnetapp
more details:
https://github.com/dotnet/dotnet-docker/blob/17c1eec582e84ba9cbea5641cd9cc13fe1a41c39/samples/run-aspnetcore-https-development.md?plain=1#L85
https://github.com/dotnet/dotnet-docker/blob/5926a01d44bd47b6202ba71e30f9faa08fad1aec/samples/run-in-sdk-container.md?plain=1#L109
If you are using .NET Core 2.2 or higher, then you should to use another image: mcr.microsoft.com/dotnet/core/aspnet:2.2. In that case specifying ENV ASPNETCORE_URLS=http://+:5000 does not help. You still can force app to listen to port 5000 by using UseUrls("http://*:5000") in Programs.cs file.
Some links in other answers are for older versions, or no longer exist. The below applies to v6.
All the mcr.microsoft.com/dotnet/aspnet images are here. Suppose you are using the alpine version.
The aspnet image is based on the runtime image, as shown here.
The runtime image is based on the runtime-deps image, as shown here.
The runtime-deps image is based on the amd64/alpine image, as shown here (an older version, but with the same structure). And it sets ENV ASPNETCORE_URLS=http://+:80, as shown here, which means the container is listening on port 80.
Windows Networking Stack Limitation plays hard on Windows Docker Container.Reference Video
docker run -it --rm -p ${host_computer_port}:${container_port} --name ${container_name} ${image_name}
Example of the command:
docker run -it --rm -p 5000:8090 --name dockerwebapp9172020c dockerwebapp9172020
What is above command mean?
Your machine Port (5000) is mapped to container Port (8090). It does not mean that application running in container listening on PORT: 8090. See docker file below on how to map container port to application port.
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-nanoserver-1903 AS base
WORKDIR /app
EXPOSE 8090
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-nanoserver-1903 AS build
WORKDIR /src
COPY ["DockerWebApp/DockerWebApp.csproj", "DockerWebApp/"]
RUN dotnet restore "DockerWebApp/DockerWebApp.csproj"
COPY . .
WORKDIR "/src/DockerWebApp"
RUN dotnet build "DockerWebApp.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "DockerWebApp.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENV ASPNETCORE_URLS http://*:8090
ENTRYPOINT ["dotnet", "DockerWebApp.dll"]
Testing
Windows Networking Stack Limitation will not allow to run following command directly.
http://localhost:5000
Let's get on with first workaround.
Workaround-1 Directly hit Container. (Below command in PowerShell or Command Prompt)
ps c:/>docker inspect f31e8add55af
Find IP Address of a container from "NETWORKS" node at very end and run command in browser.
http://{container IP}:8090
Workaroud-2 From Windows Host
Let's find Your Machine IP address first.
c:\>ipconfig
Once you find your Machine IP, run following command.
http://{Your Machine IP}:5000
since 5000 is mapped to container port(8090) and asp.net core application is also listening to 8090 port within container.
Reference:Windows Containers and Docker: 101
I'm following Digital Ocean's tutorial on how to start a nginx docker container (Currently on Step 4). Currently this is their output:
$ docker run --name docker-nginx -p 80:80 -d nginx
d3ccb73a91985651ec61231bca9f9c716f0dec807e354a29eeef2144f883a01c
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b91f3ce26553 nginx "nginx -g 'daemon off" About a minute ago Up About a minute 0.0.0.0:80->80/tcp, 443/tcp docker-nginx
But when I run it, this is my output (noticed the different IP of the container):
C:\>docker run --name docker-nginx -p 80:80 -d nginx
d3ccb73a91985651ec61231bca9f9c716f0dec807e354a29eeef2144f883a01c
C:\>docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d3ccb73a9198 nginx "nginx -g 'daemon off" 14 hours ago Up 2 seconds 10.0.75.2:80->80/tcp, 443/tcp docker-nginx
Why does this happen? And how can I get the same results as Digital Ocean's? (Getting the server to start on localhost)
Edit: I'm using Docker for windows (recently released) which apparently runs native using Hyper-V. My output for docker-machine ls is this:
C:\>docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
C:\>
But when I run it, this is my output (noticed the different IP of the
container)
Since this a Windows machine, I assume that you're using Docker Toolbox Docker for Windows. 10.0.75.2 is the IP of the boot2docker virtual machine.
If you are using Windows or Mac OS, you will need some form of virtualization in
order to run Docker. The IP you just saw is the IP of that lightweight virtual machine.
And how can I get the same results as Digital Ocean's? (Getting the
server to start on localhost)
Use a Linux distribution! Also you can enable Expose container ports on localhost in Docker For Windows Settings:
Despite you created the containers in your local machine. These are actually running on a different machine (a virtual machine)
First, check what is the IP of your docker machine (the virtual machine)
$docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM
default * virtualbox Running tcp://192.168.99.100
Then run curl command (or open a browser) to view the default web site on your nginx web server inside the container
curl http://192.168.99.100:80
if you are using a virtual machine on windows:
docker-machine ip default
https://docs.docker.com/machine/concepts/
When I ran this command for the first time: docker run -d -p 80:80 --name docker-tutorial docker101tutorial
I got this error:
docker: Error response from daemon: Conflict. The container name
"/docker-tutorial" is already in use by container "LONG_CONTAINER_ID".
You have to remove (or rename) that container to be able to reuse that
name.
so, I tried to remove this container using: docker rm -f LONG_CONTAINER_ID
then I did: docker run -d -p 3080:80 --name docker-tutorial docker101tutorial
note 3080:80 instead of 80:80... Had I run this from the docker desktop, I would see this default option below:
I have a frontend-only web application hosted in Docker. The backend already exists but it has "custom IP" address, so I had to update my local /etc/hosts file to access it. So, from my local machine I am able to access the backend API without problem.
But the problem is that Docker somehow can not resolve this "custom IP", even when the host in written in the container (image?) /etc/hosts file.
When the Docker container starts up I see this error
$ docker run media-saturn:dev
2016/05/11 07:26:46 [emerg] 1#1: host not found in upstream "my-server-address.com" in /etc/nginx/sites/ms.dev.my-company.com:36
nginx: [emerg] host not found in upstream "my-server-address.com" in /etc/nginx/sites/ms.dev.my-company.com:36
I update the /etc/hosts file via command in Dockerfile, like this
# install wget
RUN apt-get update \
&& apt-get install -y wget \
&& rm -rf /var/lib/apt/lists/*
# The trick is to add the hostname on the same line as you use it, otherwise the hosts file will get reset, since every RUN command starts a new intermediate container
# it has to be https otherwise authentification is required
RUN echo "123.45.123.45 my-server-address.com" >> /etc/hosts && wget https://my-server-address.com
When I ssh into the machine to check the current content of /etc/hosts, the line "123.45.123.45 my-server-address.com" is indeed there.
Can anyone help me out with this? I am Docker newbee.
I have solved this. There are two things at play.
One is how it works locally and the other is how it works in Docker Cloud.
Local workflow
cd into root of project, where Dockerfile is located
build image: docker build -t media-saturn:dev .
run the builded image: docker run -it --add-host="my-server-address.com:123.45.123.45" -p 80:80 media-saturn:dev
Docker cloud workflow
Add extra_host directive to your Stackfile, like this
and then click Redeploy in Docker cloud, so that changes take effect
extra_hosts:
'my-server-address.com:123.45.123.45'
Optimization tip
ignore as many folders as possible to speed up process of sending data to docker deamon
add .dockerignore file
typically you want to add folders like node_modelues, bower_modules and tmp
in my case the tmp contained about 1.3GB of small files, so ignoring it sped up the process significantly
Using Jason Wilder's NGINX-Proxy, is it possible to tie two or more sets of virtual hosts to individual ports on just one container?
What I'm thinking:
# start the reverse proxy
docker run -d -p 80:80 -v /var/run/docker.sock:/tmp/docker.sock jwilder/nginx-proxy
# start a first container for http://tutum.test.local
docker run -d -e "VIRTUAL_HOST=tutum.test.local" -e "VIRTUAL_HOST=tutum.school.nationwide" -p 80:80 -p 3000:3000 tutum/hello-world
Where the first virtual host could be linked to a socket running on port 3000 in the code, and the second virtual host could be linked to the 8080 port and handle regular API calls.
Is that possible or would I be better served to just break the socket off into a separate docker container?
After further examining the code I realized this is not currently supported. The best method I've found is to break the sockets and API into different containers.
After spending way too long trying to access my node server running from a docker container within a boot2docker instance I realised the issue came down to a difference between expose and docker run -p.
In my Dockerfile I had EXPOSE 3001, and I could not access this via my host machine.
After running "docker run -p 3001:3001 myappinst myapp" I was able to access the port.
Up until now I thought "docker run -p 3001:3001" was essentially the same as EXPOSE 3001 in the dockerfile.
I noticed however, when running docker ps
I get the following for "EXPOSE":
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
16341e2b9968 housemation-crawler:latest "npm start" 2 minutes ago Up 2 minutes 3001/tcp housemation-crawler-inst
(note: 3001/tcp)
vs the below with docker run -p 3001:3001
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
0b14f736033c housemation-crawler:latest "npm start" 8 seconds ago Up 2 seconds 0.0.0.0:3001->3001/tcp housemation-crawler-inst
(0.0.0.0:3001->3001/tcp)
Looks like the latter is doing some kind of port forwarding, whereas the former is just opening up the port? Would that be right?
If I wanted to access a non forwarded exposed port how would I go about doing so? Also, if I wanted to have port forwarding within the dockerfile, what would be the correct syntax?
Your assumptions about how EXPOSE in Dockerfile and -p option in docker run are right. As you can read in Docker on line documentation:
EXPOSE <port> [<port>...]
The EXPOSE instructions informs Docker that the container will listen
on the specified network ports at runtime. Docker uses this
information to interconnect containers using links (see the Docker
User Guide) and to determine which ports to expose to the host when
using the -P flag. Note: EXPOSE doesn't define which ports can be
exposed to the host or make ports accessible from the host by default.
To expose ports to the host, at runtime, use the -p flag or the -P
flag.
So the EXPOSE instruction in Dockerfile will indicate Docker which ports have to map to host if you run the container with the -P flag; but the local ports mapped are not deterministic and are chosen by Docker at run time. Apart from this, Docker will use the ports in EXPOSE to export information as environmental variables in linked containers.
If you want to set the local port mapped, you have to use the -p option in docker run.