I'm looking for a way to access containers that are running on server in our company lan by domain names. By far I only managed to access them by IPs
So the setup is. Docker (for windows) is running on server srv1.ourdomain.com (Windows Server 2019), network for container is configured with l2bridge driver, container's dns name, as specifiedn in run command, is cont1. It is accessible by dns name on the docker host (srv1) and by IP from my machine.
What can I do to access the container by dns name cont1.ourdomain.com from my local machine located in the same lan?
I tried to use proxy (traefik) but it cant rewrite urls in the content, so web applications running inside the container are failing. Bacause of this I can't host multiple web application behind that proxy.
I know that it is possible to map container's port to host port and then it will be accessible from lan through the host name and host port, but applications I'm running are requiring many ports to be mapped (like 8 ports for each container) and with those containers being short-lived developer's environments it will be a hell to find a port pool when running new container.
So again if I can access container and its' ports by IP, is there a way to do the same by DNS name?
UPD1. Container host is a virtual server running on vmware. I tried to follow those recommendations and configure promiscuous mode. Thise doesn't help with dns though.
UPD2. I tried transparent network as well. For some reason DHCP can never assign propper IP and container ends up with autoconfigured ip from 168.x.x.x subnet.
You could create a transparent network and make the container discoverable on the network just like host. However, using host ports is what's recommended.
Did you try PathStrip or PathPrefixStrip with Traefik? That should let you rewrite the URLs for the backend.
Related
I am using Docker Windows with WSL2.
From some answers I understand that connecting to an IP address exposed to the host network can be done from within a Docker container without any particular setup, but I cannot do it. Note that I do not want to access localhost, but a specific IP address (and port) of another device exposed to the host network.
I read a couple reasons on what could be the issue:
Missing firewall exception to allow communication between the external IP and the IP of the container.
I may have to use network_mode: "host", which however only seems to work in Linux
Many thanks.
I have docker compose running with several containers. One of those containers is a dns server running bind. In my docker daemon configuration I specify the dns like this:
"dns" : [
"10.1.1.8", /* static ip address of my dockerized bind container defined in compose */
"x.x.x.x", /* my companies internal vpn dns */
"8.8.8.8" /* google dns */
]
This all works fine. My containers in the compose file will use the bind server running on 10.1.1.8 for dns lookup and then fall back on my companies internal dns and lastly googles dns for external websites.
Docker provides a special dns host.docker.internal which should point at the host IP (lets say you want docker containers to connect to services running locally but not on docker). I want to use this in a few containers which should allow the container to reference the host IP address without hardcoding an IP which can change. In fact docker inserts this value into the hosts file (windows/system32/driver/etc/host) on the host operating system and updates it when you host IP gets assigned a new dns.
The issue is docker uses dns to resolve "host.docker.internal". When using my custom dns configuration in the daemon it breaks things and I get issues reaching the host os service. I spent 2 hours debugging this issue till I realized host.docker.internal starts working only when I delete the dns configuration from the daemon config. Is there any way to make docker resolve the dns correctly and still use custom dns bind server on the same machine? Can I somehow update the daemon dns to also point at some docker dns ip address?
Have you considered to rely on Docker Compose and how it helps defining custom DNS addressing policies.
I provide you the link to the Compose DNS configuration official guide.
my client and server hosted in a Linux host using docker as container. From other machine of same network able to connect using host IP address but I am not able to connect using container name or container IP address. I want to call a API of my server side application using container name or IP not using host machine IP
You cannot.
The (Docker) container runtime(s) are entirely distinct; there's no shared state that would permit the container on one host to be able to enumerate the container names on another host.
The easiest way for you to connect a client container on one host with a server container on another host is publish the server containers' ports to the host and to leverage the (shared) networking between the client and server and use either the server host's name or IP address to access it from the client.
Say I have a Swarm of 3 nodes on my local system. And I create a service say Drupal with a replication of 3 in this swarm. Now, say each of the node has one container each running Drupal. Now when I have to access this in my browser I will have to use the IP address of one of the nodes <IP Address>:8080 to access Drupal.
Is there a way I can set a DNS name for this service and access it using DNS name instead of having to use IP Address and port number?
You need to configure the DNS server that you use on the host making the query. So if your laptop queries the public DNS, you need to create a public DNS entry that would resolve from the internet (on a domain you own). This should resolve to the docker host IPs running the containers, or an LB in front of those hosts. And then you publish the port on the host to the container you want to access.
You should not be trying to talk directly to the container IP, these are not routeable from outside of the docker host. And the docker DNS used for service discovery is for container to container communication. This is separate from communication outside of docker that goes through a published port.
I am using Docker desktop, I have a couple of docker containers running using docker-compose and port forwarding. I can access the containers from my mac using localhost. On the second container, I am exposing on different ports. I can see ip addresses are associated to both containers by using docker inspect, but I cannot access using the ip address.
I would like access the container from my local mac by
dns domain
ip address
Any help appreciated.
Thanks
You cannot directly connect to the container-private IP addresses on MacOS. You also can't connect to them using a VM-based Docker implementation like Docker Toolbox or Kubernetes' minikube, or from a different host. Looking up and using these IP addresses, or trying to manually set them, usually isn't a best practice.
Instead you can use the docker run -p option to publish a port from your container to the host. Programs running directly on the host can access the container using localhost as a host name and the published port number. This works on all platforms; on VM-based solutions use the VM's IP address instead of localhost; from a different host, use the Docker host's DNS name or IP address.