I am deploying a eureka server on a VM(say host external IP is a.b.c.d) as a docker image. Trying this in 2 ways.
1.I am running the docker image without explicit port mapping : docker run -p 8671 test/eureka-server
Then running docker ps command shows the port mapping as : 0.0.0.0:32769->8761/tcp
Try accessing the eureka server from outside of the VM with http://a.b.c.d:32769 , its not available.
2.I am running the docker image with explicit port mapping : docker run -p 8761:8761 test/eureka-server
Then running docker ps command shows the port mapping as : 0.0.0.0:8761->8761/tcp
Try accessing the eureka server from outside of the VM with http://a.b.c.d:8761 , its available.
Why in the first case the eureka server is not available from out side the host machine even if there is a random port(32769) assigned by docker.
Is it necessary to have explicit port mapping to have docker app available from external network ?
Since you're looking for access from the outside world to the host via the mapped port you'll need to ensure that the source traffic is allowed to reach that port on the host and given protocol. I'm not a network security specialist, but I'd suggest that opening up an entire range of ports simply because you don't know which port docker will pick would be a bad idea. If you can, I'd say pick a port and explicitly map it and ensure the firewall allows access to that port from the appropriate source address(es) e.g. ALLOW TCP/8671 in from 10.0.1.2/32 as an example - obviously your specific address range will vary on your network configuration. Docker compose may help you keep this consistent (as will other orchestration technologies like Kubernetes). In addition if you use cloud hosting services like AWS you may be able to leverage VPC security groups to help you whitelist source traffic to the port without knowing all possible source IP addresses ahead of time.
You either have the firewall blocking this port, or from wherever you are making the requests, for certain ports your outgoing traffic is disabled, so your requests never leave your machine.
Some companies do this. They leave port 80, 443, and couple of more for their intranet, and disable all other destination ports.
Related
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
How do you access remote Docker container by its hostname?
I need to access remote Docker containers by its hostnames (or some constant IP's) for development and testing purposes. I have tried:
looking for any DNS approach (have not found any clues),
importing /ets/hosts (probably impossible),
creating tunnes (only this works but it is very time consuming).
It's the same as running any other process on a host, Docker or not Docker: you access it via the host name or IP address of the host and the port the service is listening on (the first port of the docker run -p argument). Docker containers don't have externally visible individual IP addresses any more than non-Docker HTTP or ssh daemons do.
If you do have DNS infrastructure available to you, you could set up CNAME records to resolve particular service names to the specific hosts that are running them.
One solution that may help you is some sort of service registry; in the past I've used Consul with some success. You can configure Consul with some health checks or other probes ("look for an HTTP service on port 12345 that answers GET / calls"), and it will provide its own DNS service ("okay, http://whatevername.service.consul:12345/ will reach your service on whichever hosts it happens to be running on").
Nothing in the Docker infrastructure specifically helps this. Using /etc/hosts is distinctly not a best practice: the name-to-IP mapping needs to be kept in sync across all machines and you'll start wishing you had a network service to publish it for you, which is exactly what DNS is for.
I have some docker containers talking together through docker bridge networks. They cannot be accessed from outside (I was said) as they are launched from a script with a default command which does not include 'expose' nor '-p' option. I cannot change that script.
I would like to connect to one of this containers which runs a server and listens for requests on port 8080. I tried connecting that bridge to a newly created docker bridge network, but i did not succede.
Now I am thinking of creating a new container and letting it talk to the server one (through bridge networks). As it is a new contaienr I can use the 'expose' or '-p' options, so it would be able to talk to the host machine.
Is it a good idea? How can I forward every request made to that container to the server one and get responses back to the host machine then?
Thanks
Within the default docker network, all ports are exposed. So you only need a container that exposes a port to the host machine and is in the same network as the other containers you have already created.
This is a relatively normal pattern. You can use a reverse proxy like nginx to achieve something like this.
There are some containers that automate this process:
https://github.com/jwilder/nginx-proxy
If you have no control over the other containers though, you will need to write the proxy config by hand.
If the container to which you are trying to connect is an http server, you may be able to use a ready-made container image that can work as an http forwarder (e.g., nginx - it is relatively easy to configure it as an http forwarder).
If you need plain tcp forwarding, you could make a container running 'socat' (socat can work as a tcp forwarder).
NOTE: in either case, you will be exposing a listener that wasn't meant to be on a public address. Do take measures not to allow unauthorized connections.
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.
An application server is running as one Docker container and database running in another container. IP address of the database server is obtained as:
sudo docker inspect -f '{{ .NetworkSettings.IPAddress }}' db
Setting up JDBC resource in the application server to point to the database gives "java.net.ConnectException".
Linking containers is not an option since that only works on the same host.
How do I ensure that IP address of the database container is visible to the application server container?
If you want private networking between docker containers on remote hosts you can use weave to setup an overlay network between docker containers. If you don't need a private network just expose the ports using the -p switch and configure the addresses of the host machine as the destination IP in the required docker container.
One simple way to solve this would be using Weave. It allows you to create many application-specific networks that can span multiple hosts as well as datacenters. It also has a very neat DNS-based service discovery mechanism.
I should disclaim, I am one of Weave engineering team.
Linking containers is not an option since that only works on the same host.
So are you saying your application is a container running on docker server 1 and your db is a container on docker server 2? If so, you treat it like ordinary remote hosts. Your DB port needs to be exposed on docker server 2 and that IP:port needs to be configured into your application server, typically via environment variables.
The per host docker subnetwork is a Private Network. It's perhaps possible to have this address be routable, but it would be much pain. And it's further complicated because container IP's are not static.
What you need to do is publish the ports/services up to the host (via PORT in dockerfile and -p in your docker run) Then you just do host->host. You can resolve hosts by IP, Environment Variables, or good old DNS.
Few things were missing that were not allowing the cross-container communication:
WildFly was not bound to 0.0.0.0 and thus was only accepting requests on eht0. This was fixed using "-b 0.0.0.0".
Firewall was not allowing the containers to communication. This was removed using "systemctl stop firewall; systemctl disable firewall"
Virtual Box image required a Host-only adapter
After this, the containers are able to communicate. Complete details are available at:
http://blog.arungupta.me/2014/12/wildfly-javaee7-mysql-link-two-docker-container-techtip65/