I am trying to run Ubuntu inside of Docker, but my network has several restrictions:
must use network's DNS, when I set it, I do not get a response, I suspect it is because the return address is the docker IP 172 ...
must use network's Proxy, I can set an env, but it is useless without DNS working
I am trying this:
docker run --dns=10.69.114.61 -it ubuntu
docker run --dns=172.17.0.1 -it ubuntu (docker0 interface IP)
Docker containers will use docker host's dns settings by default.
In order to specify DNS server:
docker run --dns=10.69.114.61 -it debian:jessie /bin/bash
root#299849f13f21:/# cat /etc/resolv.conf
nameserver 10.69.114.61
Needless to say you must supply your network's DNS server IP address to the --dns flag.
docker run --dns=<your DNS server IP> -it debian:jessie /bin/bash
As you pointed out you should specify HTTP_PROXY variable to use your proxy server.
Related
I want to create a docker container from one machine (suppose having centos) machine and then access that container from another machine(may be centos or mac). How can we do that? Is it possible with macvlan networking? If yes , what are steps? If not, what is the way?
Depends from what is your final goal. Following are some approaches (depending on what you want to achieve as final goal):
Manage container and execute bash in the container on a remote host:
Easiest way is to use the environment variable DOCKER_HOST
export DOCKER_HOST=ssh://vagrant#192.168.5.178
docker exec -ti centos_remote /bin/bash
You can find more information in this answer https://stackoverflow.com/a/51897942/2816703
Use the container as a form of virtual machine on which user can ssh:
First you will need a container that is running the sshd. You will expose the port 22 on another port on the host network. Finally you will use the ssh with -p to connect that port. Here is a working example:
$ sudo docker run -d -P --name test_sshd rastasheep/ubuntu-sshd:14.04
$ sudo docker port test_sshd 22
0.0.0.0:49154
$ ssh root#localhost -p 49154
# The password is `root`
root#test_sshd $
or if you are on a remote machine, use the host IP address xxx.xxx.xxx.xxx, to connect to the container use:
$ ssh root#xxx.xxx.xxx.xxx -p 49154
# The password is `root`
Also you can pre-select a port (in this case port 22000) and test from the host.
~# docker run -d -p 22000:22 --name test_sshd rastasheep/ubuntu-sshd:14.04
~# ssh root#<ipaddress> -p 22000
Setup a network layer (L2/L3) between the hosts:
Using macvlan is one approach. Another approach is the ipvlan. In both cases, you are converting the host network adapter to a virtual router, after which you need to setup the routes. You can find detailed explanation on this link http://networkstatic.net/configuring-macvlan-ipvlan-linux-networking/
WIthin a Docker container, I would like to connect to a MySQL database that resides on the local network. However, I get errors because it can not find the host name, so my current hot fix is to hardcode the IP (which is bound to change at some time).
Hence; is it possible to forward a hostname from the host machine to the Docker container at docker run?
Yes, it is possible. Just inject hostname variable when run docker run command:
$ hostname
np-laptop
$ docker run -ti -e HOSTNAME=$(hostname) alpine:3.7
/ # env
HOSTNAME=np-laptop
SHLVL=1
HOME=/root
TERM=xterm
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/
Update:
I think you can do two things with docker run for your particular case:
1. Bind /etc/hosts file from the host to a container.
2. Define any dns server you want inside a container with --dns flag.
So, finally the command is:
docker run -ti -v /etc/hosts:/etc/hosts --dns=<IP_of_DNS> alpine:3.7
Docker containers by default has access to the host network, and they're able to resolve DNS names using DNS servers configured on the host, so it should work out of the box.
I remember having similar problem in my corporate network, I solved it by referencing in the app the remote server with FQDN - our-database.mycompany.com instad just using our-database.
Hope this helps.
People has asked similar questions and got good answers:
How do I pass environment variables to Docker containers?
Alternatively you can configure the DHCP/DNS server that serves the docker machines to resolve the hostnames properly. DDNS is another option that can simplify configuration as well.
I am creating an Nginx container that I would like to access locally at http://api. Using Docker Machine, I assumed running docker-machine create default and docker-machine ip default to receive the IP and editing my hosts file to something like this:
# docker-machine ip default --> 192.168.99.100
192.168.99.100 api
should map requests to api\ to the Docker Machine IP and serve my content.
Two things are confusing me:
I launch Docker through the Mac App and can create Nginx containers and access content at http://localhost. However, running docker-machine ls returns no machines. This is confusing because I thought Docker had to run on a VM.
Starting from scratch and starting Docker Machine, then spinning up containers seems to have no effect. In other words, I still can access content at http://localhost but not http://api
Instead of accessing my container at http://localhost I want to access it at http://api. How do I do this?
I'm using Docker for Mac 17.12 and Docker Machine 0.14.
On the base of your this question:
Instead of accessing my container at http://localhost I want to access
it at http://api. How do I do this?
Your docker run command:
docker run -it --rm --name test --add-host api:192.168.43.8 -p 80:80 apachehttpd
1st Thing: The --add-host flag add value to /etc/hosts in your container /etc/hosts so http://api will also response inside the container if ping inside that container.
This is how will ping response inside container
2nd Thing: Edit your host etc/hosts file and add
api 192.168.43.8 [your ip]
This is how you can see in Browser.
I'm following the following tutorial on how to start a basic nginx server in a docker container. However, the example's nginx docker container runs on localhost (0.0.0.0) as shown here:
Meanwhile, when I run it it for some reason it runs on the IP 10.0.75.2:
Is there any particular reason why this is happening? And is there any way to get it to run on localhost like in the example?
Edit: I tried using --net=host but had no results:
The default network is bridged. The 0.0.0.0:49166->443 shows a port mapping of exposed ports in the container to high level ports on your host because of the -P option. You can manually map specific ports by changing that flag to something like -p 8080:80 -p 443:443 to have port 8080 and 443 on your host map into the container.
You can also change the default network to be your host network as you've requested. This removes some of the isolation and protections provided by the container, and limits your ability to configure integrations between containers, which is why it is not the default option. That syntax would be:
docker run --name nginx1 --net=host -d nginx
Edit: from your comments and a reread I see you're also asking about where the 10.0.75.2 ip address comes from. This is based on how you launch the docker daemon. That IP binding is assigned when you pass the --ip flag to the daemon documentation here. If you're running docker in a vm with docker-machine, I'd expect this to be the IP of your vm.
A good turnaround is to set using -p flag (--publish short)
docker run -d -p 3000:80 --name <your_image_name> nginx:<version_tag>
I have started to use docker and liking it mostly because Docker containers are kind of light-weight VMs. But I am unable to figure out, how docker containers may be able resolve each-other's hostnames. They can connect to each other using there IPs, but not using their hostnames, I cannot even edit /etc/hosts in the containers to make up for that somehow. When I restart the containers, they get different IPs and hence I want to use the hostnames in place of IPs to communicate with each other. Let us say, I want to run Zookeeper instances of a Zookeeper cluster in the containers and I want to put the hostnames of the Zookeeper servers in the config (zoo.cfg) files.
As of Docker 1.10, if you create a distinct docker network, Docker will resolve hostnames intra-container-wise using an internal DNS server [1][2][3].
You can change the network hostname by specifying one with --name within the docker run. Otherwise the hostname will refer to the container id (12 char long hash, shown by docker container ls ).
See also:
Docker doesn't resolve hostname
When to use --hostname in docker?
Sources:
[1] = docker docs - Embedded DNS server in user-defined networks
[2] = Docker Engine release notes
- 1.10.0 (2016-02-04) - Networking
[3] = Docker pull requests - Vendoring libnetwork
It may be worth checking out Docker links (https://docs.docker.com/userguide/dockerlinks/). When you link to a running container, a host entry is added for the container you wish to connect to.
In their example they show
$ sudo docker run -t -i --rm --link db:db training/webapp /bin/bash
root#aed84ee21bde:/opt/webapp# cat /etc/hosts
172.17.0.7 aed84ee21bde
. . .
172.17.0.5 db
As you see here, they link the application they're in bash with to the container named db, and subsequently a host entry is added for db with the IP address of that container.
So in the instance of having zookeeper running, you could simply make the containers you start just link to zookeeper. I hope this helps!
Can depend on OS of container, but supposing that container runs Linux
you can check your DNS configuration this way:
cat /etc/resolv.conf
It can return something like:
nameserver 127.0.0.11
options ndots:0
/etc/resolv.conf is standard configuration file for DNS in UNIX-like OS-es.
In this particular case container is configured to use 127.0.0.11 as DNS server.
So container can query it to determine IP address of another container using it's host name.
You can check whether that host actually works by using nslookup command, e.g.:
nslookup redis 127.0.0.11
, which will contact DNS server 127.0.0.11 and ask to resolve host name "redis".
It can return something like:
Server: 127.0.0.11
Address 1: 127.0.0.11
Name: redis
Address 1: 172.21.0.3 counter-app_redis_1.counter-app_counter-net
, which would mean that host name resolved to ip 172.21.0.3.
In this specific case nameserver entry was added by using the following entry in the docker-compose.yml configuration file:
...
networks:
counter-net:
This root entry configured common bridge network shared by several docker containers.