I have a docker container that is running on Windows currently and it is accessing database resources via the host name (e.g Desktop1, Desktop2, etc...). The docker container is using a bridge network that was created new for the purpose of the system.
What I notice on Windows is that I can ping or connect to those resources simply via the host name and I do not need to remember the IP address of the computer.
I also notice that this can also be done even if I don't have a DNS server running locally (I think?).
However, when I run the container on an Ubuntu host, I keep getting connection errors and timeouts.
I have tried to edit the /etc/hosts and /etc/hostname to include the proper host name of the PC and the fixed wired IP I am using.
I have also tried a test database on the same Ubuntu system but I cannot connect to it via its host name. At best, I am able to connect via something like Desktop1.local but it only solves 1 issue. The other responses I receive from the other systems on the network return only the hostname (e.g. http://Desktop2/api/..., ws://Desktop3/api/..., etc...).
I was wondering if there is a configuration I am missing to have the same functionality as Windows? Do I need to change my code to handle this kind of situations or do I need to do something else like on the OS level?
My command for creating the docker container is along these lines:
docker create -p 172.16.0.1:50000:80/tcp --env MongoDatabaseSettings__ConnectionString="mongodb://desktop1:27017/?uuidRepresentation=standard" --env ConnectionStrings__MySQLConnection="server=desktop2;database=DB;user=user;password=password" --name container1 registry.gitlab.com/group/image:latest
Contents of my /etc/hosts
127.0.0.1 localhost
172.16.0.1 desktop1
If it's me, maybe will try to build the reverse proxy server.
Step. 1
choose your server. (recommend Nginx)
Step. 2
Forward traffic
For example, if your ip of docker service is 192.168.1.2:8080, then you can make 127.0.0.1:80 to forward to it. (or any port you want)
Then you just need to access 127.0.0.1:80, the server will forward the traffic to service of docker.
I dont know is that you actually want to do.
oh, btw, if you still want to access via host name, just edit host file with root user. (make 127.0.0.1:80 a custom domain.
I dont know the reason of that why you can not setting the host file, but set 127.0.0.1 in host file is always working for me.
I'm using docker for building both UI and some backend microservices, and using Spring Zuul as the Proxy to pass Restful API calls from UI to the downstream microservices. My UI project needs to specify an IP address in the JS file before the build, and the Zuul project also needs to specify the IP addresses for the downstream microservices. So that after starting the containers, I can access my application using my docker machine IP http://192.168.10.1/myapp and the restful API calls in the browser network tab will be http://192.168.10.1/mymicroservices/getProduct, etc.
I can set all the IPs to my docker machine IP and build them without issues. However for my colleagues located in other countries, their docker machine IP will be different. How can I make docker use a specific IP, for example, 192.168.10.50, which I can set in the UI project and Zuul Proxy project, so that the docker IP will be the same for everyone, regardless of what their actual docker machine IP is?
What I've tried:
I've tried port forwarding in VirtualBox. It works for the UI, however the restful API calls failed.
I also tried the solution mentioned in this post:
Assign static IP to Docker container
However I can't access the services from the browser using the container IP address.
Do you have any better ideas? Thank you!
first of to clarify couple things,
If you are doin docker run ..... then you just starting container in your docker which is installed on the host machine. And there now way docker can change ip of your host machine. Thus if your other services are running somewhere else they will have to know something about docker host machine, ip or dns name.
so basically docker does runs on 127.0.0.1 if you are trying it on docker host machine, or on host machine IP if from outside of it. So docker don't need IP of host to start.
The other thing is if you are doing docker-composer up/start. Which means all services are in that docker compose file. In this case docker composer creates docker network for all containers in it. in this case you definitely can use fixed IPs for containers, though most often you don't need to because docker takes care of name resolution in that network.
if you are doing k8s way - then it is third way (production way), and it os another story.
if that is neither of above then please provide more info on how are you doing stuff.
EDIT - to:
if you are using docker composer and need to expose any of your containers to host machine you can do it through port mapping:
web:
image: some image here
ports:
- 8181:8080
left is the host machine port, right is container port
and then in browser on the host you can do request to localhost:8181
here is doc
https://docs.docker.com/compose/compose-file/#ports
I have a docker container that needs to access an network server on the LAN. This server is visible from the docker host machine and I can access it from within the container when I reference the IP address directly.
However I need to be able to specify a url and port (e.g http://myserver:8080) rather than an IP address, which the docker container cannot resolve.
How can I configure the container to resolve this? ideally using the docker hosts dns. I have looked at many of the docs, but not being a DNS expert, it doesn't seem straightforward.
UPDATE:
I have tried this, which seems to work, but does this have any downsides or unintended consequences?
--network host
Thanks,
The rigth way to do this is to configure the docker daemon dns as specified under daemon-dns-options.
Using the host network is not recommended as it has some downsides https://docs.docker.com/network/host/
I'm trying to make a docker machine available to my Windows by a host name. After creating it like
docker-machine create -d virtualbox mymachine
and setting up a docker container that exposes the port 80, how can I give that docker machine a host name such that I can enter "http://mymachine/" into my browser to load the website? When I change "mymachine" to the actual IP address then it works.
There is an answer to this question but I would like to achieve it without an entry in the hosts file. Is that possible?
You might want to refer to docker documentaion:
https://docs.docker.com/engine/userguide/networking/#exposing-and-publishing-ports
You expose ports using the EXPOSE keyword in the Dockerfile or the
--expose flag to docker run. Exposing ports is a way of documenting which ports are used, but does not actually map or open any ports.
Exposing ports is optional.
You publish ports using the --publish or --publish-all flag to docker
run. This tells Docker which ports to open on the container’s network
interface. When a port is published, it is mapped to an available
high-order port (higher than 30000) on the host machine, unless you
specify the port to map to on the host machine at runtime. You cannot
specify the port to map to on the host machine when you build the
image (in the Dockerfile), because there is no way to guarantee that
the port will be available on the host machine where you run the
image.
I also suggest reviewing the -P flag as it differs from the -p one.
Also i suggest you try "Kitematic" for Windows or Mac, https://kitematic.com/ . It's much simpler (but dont forget to commit after any changes!)
Now concerning the network in your company, it has nothing to do with docker, as long as you're using docker locally on your computer it wont matter what configuration your company set. Even you dont have to change any VM network config in order to expose things to your local host, all comes by default if you're using Vbox ( adapter 1 ==> NAT & adapter 2 ==> host only )
hope this is what you're looking for
If the goal is to keep it as simple as possible for multiple developers, localhost will be your best bet. As long as the ports you're exposing and publishing are available on host, you can just use http://localhost in the browser. If it's a port other than 80/443, just append it like http://localhost:8080.
If you really don't want to go the /etc/hosts or localhost route, you could also purchase a domain and have it route to 127.0.0.1. This article lays out the details a little bit more.
Example:
dave-mbp:~ dave$ traceroute yoogle.com
traceroute to yoogle.com (127.0.0.1), 64 hops max, 52 byte packets
1 localhost (127.0.0.1) 0.742 ms 0.056 ms 0.046 ms
Alternatively, if you don't want to purchase your own domain and all developers are on the same network and you are able to control DHCP/DNS, you can setup your own DNS server to include a private route back to 127.0.0.1. Similar concept to the Public DNS option, but a little more brittle since you might allow your devs to work remote, outside of a controlled network.
Connecting by hostname requires that you go through hostname to IP resolution. That's handled by the hosts file and falls back to DNS. This all happens before you ever touch the docker container, and docker machine itself does not have any external hooks to go out and configure your hosts file or DNS servers.
With newer versions of Docker on windows, you run containers with HyperV and networking automatically maps ports to localhost so you can connect to http://localhost. This won't work with docker-machine since it's spinning up virtualbox VM's without the localhost mapping.
If you don't want to configure your hosts file, DNS, and can't use a newer version of docker, you're left with connecting by IP. What you can do is use a free wildcard DNS service like http://xip.io/ that maps any name you want, along with your IP address, back to that same IP address. This lets you use things like a hostname based reverse proxy to connect to multiple containers inside of docker behind the same port.
One last option is to run your docker host VM with a static IP. Docker-machine doesn't support this directly yet, so you can either rely on luck to keep the same IP from a given range, or use another tool like Vagrant to spin up the docker host VM with a static IP on the laptop. Once you have a static IP, you can modify the host file once, create a DNS entry for every dev, or use the same xip.io URL, to access the containers each time.
If you're on a machine with Multicasting DNS (that's Bonjour on a Mac), then the approach that's worked for me is to fire up an Avahi container in the Docker Machine vbox. This lets me refer to VM services at <docker-machine-vm-name>.local. No editing /etc/hosts, no crazy networking settings.
I use different Virtualbox VMs for different projects for my work, which keeps a nice separation of concerns (prevents port collisions, lets me blow away all the containers and images without affecting my other projects, etc.)
Using docker-compose, I just put an Avahi instance at the top of each project:
version: '2'
services:
avahi:
image: 'enernoclabs/avahi:latest'
network_mode: 'host'
Then if I run a webserver in the VM with a docker container forwarding to port 80, it's just http://machine-name.local in the browser.
You can add a domain name entry in your hosts file :
X.X.X.X mymachine # Replace X.X.X.X by the IP of your docker machine
You could also set up a DNS server on your local network if your app is meant to be reachable from your coworkers at your workplace and if your windows machine is meant to remain up as a server.
that would require to make your VM accessible from local network though, but port forwarding could then be a simple solution if your app is the only webservice running on your windows host. (Note that you could as well set up a linux server to avoid using docker-machine on windows, but you would still have to set up a static IP for this server to ensure that your domain name resolution works).
You could also buy your own domain name (or get a free one) and assign it your docker-machine's IP if you don't have rights to write in your hosts file.
But these solution may not work anymore after some time if app host doesn't have a static IP and if your docker-machine IP changes). Not setting up a static IP doesn't imply it will automatically change though, there should be some persistence if you don't erase the machine to create a new one, but that wouldn't be guaranteed either.
Also note that if you set up a DNS server, you'd have to host it on a device with a static IP as well. Your coworkers would then have to configure their machine to use this one.
I suggest nginx-proxy. This is what I use all the time. It comes in especially handy when you are running different containers that are all supposed to answer to the same port (e.g. multiple web-services).
nginx-proxy runs seperately from your service and listens to docker-events to update it's own configuration. After you spun up your service and query the port nginx-proxy is listening to, you will be redirected to your service. Therefore you either need to start nginx-proxy with the DEFAULT_HOST flag or send the desired host as header param with the request.
As I am running this only with plain docker, I don't know if it works with docker-machine, though.
If you go for this option, you can decide for a certain domain (e.g. .docker) to be completely resolved to localhost. This can be either done company-wide by DNS, locally with hosts file or an intermediate resolver (the specific solution depends on your OS, of course). If you then try to reach http://service1.docker nginx-proxy will route to the container that has then ENV VIRTUAL_HOST=service1.docker. This is really convenient, because it only needs one-time setup and is from then on dynamic.
We are using docker-compose to bring up multiple containers and link them together.
We need to be able to persist the url of a service running in containerA in our data store so that we can look it up at a later date and use it to access the service from containerB. containerB should not have to know whether the service is running as a local container or not, it should just be able to grab the url and use it.
We can get the address of a linked container using envoronment variables in the standard way eg
http://$CONTAINER_A_SERVICE_PORT_9000_TCP_ADDR:$CONTAINER_A_SERVICE_PORT_9000_TCP_PORT/someresource
but my understanding is that if we store this url and try to access the service after restarting the containers, docker may have assigned a new port and/or ip to the container and the address could be invlaid.
At the moment all I can think of is exposing the port of the container on the host machine and using the public address of the host as the stable endpoint to the container but I would really like a solution that avoided going out to the public network.
Any ideas would be greatly appreciated.
I would use the hostname of serviceB that gets put into /etc/hosts