I am new to Docker. And have few easy questions hope you could help.
I have a windows 10 machine which installed "docker for windows". In its HyperV manager I could see a virtual machine called "MobyLinuxVM".
So my questions are:
1, When people talking about "Docker Host" and "Docker Engine", what are they according to my situation?
-- I assume "Docker Host" should be my windows PC, and "Docker Engine" is that Virtual machine inside Hyper-V.
2, If I use ipconfig to see my PC, I will find I got at lease 2 networks and IP addresses:
(a) Lan Adapter -- show my IP is 192.168.xxx.yyy
(b) DockerNAT -- show my IP is 10.0.75.1
Then when I try to use dock-compose.yml to create container, I found I could ONLY use:
environment:
- MAGENTO_HOST=10.0.75.2
- MARIADB_HOST=10.0.75.2
to create container and can be directly accessed (e.g. via browser to Magento website). So question is:
If my machine is 10.0.75.1 within Docker network, then what is 10.0.75.2? why I cannot use e.g. 10.0.75.3?
3, My yml script actually contains multiple containers creation -- e.g. 2 Magento containers + 2 MariaDB containers + etc. When I specify their docker 'HOST', why it's not my machine? (If we call my machine to be 'docker host' & hyper-v virtual image to be 'docker engine' in my 1st question.)
4, Also according to my 3rd question, I current deploy all containers within 1 host. Is it worth to use Docker Swarm which people can use to cluster multiple Docker hosts? If so, does that mean I need to use Hyper-V to create another "MobyLinuxVM"?
Thanks a lot!
1 Docker Engine + Docker Host
The Docker Engine is the group of processes that manage Docker containers. dockerd is usually the head of that process tree.
The Docker Host is the OS running Docker engine, that is MobyLinuxVM
Your VM host is your Windows box.
2 Docker Host IP
10.0.75.2 is most likely the address assigned to MobyLinuxVM. I don't run Docker for Windows so can't entirely confirm but searching the web seems to back this up.
3 - see 1
4 Swarm
You would need to run multiple VMs to setup swarm. Docker machine is the tool to use when setting up swarm instances. It allows you to manage multiple Docker instances and comes with a HyperV driver.
Related
I have two laptops, Ubuntu-14 and Mac (Big Sur) and both of them have docker (with swarm support) installed in it.
I used Ubuntu as my Swarm manager (and) Mac as my worker node.
Ubuntu private IP is 192.168.0.14 (and) Mac private IP is 192.168.0.11 [Private IP can be shared in public without any issues because every class C network has the same IP's :P]
"docker swarm init --advertise-addr" was the command I used to make my Ubuntu host, the Manager (and) I entered the join command in Mac to make the Mac node to join the Swarm as worker.
So, On a highlevel, I used docker-compose.yml (which has only 1 python webservice). Using the compose file, I started a "docker stack" and then replicated the "python webservice" instance to 5. All these actions were carried out in Manager node.
Ubuntu Manager Node (also had 2 container instance and behaved as worker) (and) Mac Node had 3 container instances of the "python webservice". I have set up "ports" to be "80:1234" which means If I hit the port 80 of the host machine, It will redirect to the "python application webservice port" which is 1234 running inside the container.
When I hit the Manager IP (192.168.0.14:80) some 50 times and when I checked the logs of all the 5 containers in both Mac and Ubuntu,
I found all the 2 containers in Ubuntu, got 25 hits each (in a round robin fashion) BUT,
I couldn't find any logs for any of the containers present in Mac machine.
Is this an expected behavior?
Only when I hit the IP address (192.168.0.11:80) of the Mac machine (worker) directly, I was able to get the logs/request hits for the containers present in the Mac machine.
So, there is two types of load balancing happening here,
When I hit the IP:port (of a worker/manager), then, only the containers present in that worker/manager machine will be load balanced and served in a round-robin fashion (I can see that's the algorithm used). Let's name this load balancing type as "Container level load balancer"
But, When I hit 192.168.0.14 (Manager IP), I expected the load will be balanced across all the 5 containers which is deployed across 2 nodes. Somehow this didn't work. Let's call it "Node level load balancer"
I have tried searching a lot in google for this but found nothing. Most sites are using external technologies like Nginx, HaProxy load balancers for solving "Node level load balancer".
Isn't there an out of the box support for this by docker itself?
EDIT 1 - Added docker-compose.yml as Metin asked in comment section
docker-compose.yml
version: '3'
services:
webservice:
image: python_ws_test
ports:
- '80:1234'
command: ["python", "app.py"]
The main issue was, I tried to join a Linux node and a Mac node, because the docker for Mac (only SWARM, I think) is kind of broken as mentioned,
in this comment https://dev.to/aguedeney/comment/172d6 (and)
subsequently the thread (https://dev.to/natterstefan/docker-tip-how-to-get-host-s-ip-address-inside-a-docker-container-5anh).
Mac Private IP is 192.168.0.11, but somehow, 192.168.65.3 is the IP taken for the Mac worker node.
How did I find out?
Point 1
=> I made Mac as my Manager using "swarm init" command without any "advertise-addr" or "lister-addr" or etc.. The "docker swarm join" command I got had the IP address = 192.168.65.3. I don't know why because my Mac host IP is 192.168.0.11. This is not expected behaviour.
=> I did the same in Ubuntu to make my Ubuntu as Manager using "swarm init" raw command and the "docker swarm join" command I got had the IP address = 192.168.0.14 which is the same IP of the ubuntu host machine and that is expected behaviour.
Point 2
Once the stack is deployed, I tried to inspect the overlay network that's used using "docker network inspect $networkName". Linux manager node had the peers as "itself" and 192.168.65.3 which was unreachable because my Mac node's IP is 192.168.0.11.
But somehow, when I auto-scaled by using "scale" command in Manager node (Ubuntu), docker manager was able to scale the containers in both Mac and Ubuntu. This is very odd.
Default Overlay network - behaviour
Also, "docker stack deploy" by default creates an overlay ingress network irrespective of whether you mention in docker-compose.yml or deploy command. Docker manager and nodes communicate between them on top of this network.
Answer to the issue mentioned in question
Docker has out of the box support for "Node level load balancing"? Yes!
I was so frustrated about this odd behaviour in Mac, I installed Ubuntu 20.04 VM in my Mac and tried to use "Ubuntu 14.04" (separate Laptop / Base OS) as Manager and Ubuntu 20.04 (Virtual Machine OS) as worker node. Now, I was able to load balance between two nodes (I was getting hits in worker node), although I kept hitting the IP of manager only.
I'll update why Mac is broken here if I get more insights. Anyone who already has the knowledge about this, please share.
I'm trying to create swarm consisting of 2 nodes, using docker-machine, it is easy to provision a VM and add it as a node, but I want to create a swarm using a ubuntu VM machine and Windows docker as manager without using docker-machine.
Running
docker swarm init
in Windows (Host Machine) gives me a token to add a worker. I have Ubuntu running in VirtualBox, Docker is also installed in the VM and I'm able to ssh into it and run commands but whenever I try to add this Ubuntu Machine as a worker node by using the token generated from Windows Machine, it says
Error response from daemon: Timeout was reached before node joined. The attempt to join the swarm will continue in the background. Use the "docker info" command to see the current swarm status of your node.
I think it is related to port forwarding. I'm forwarding my VM port 22 to 127.0.0.1:22 in VBox for connecting via SSH. But I tried several combinations of forwarding. Still the VM is not able to join as a node in the swarm that I created in Windows.
Any guidance will be of great value.
Check if you have connectivity from your Ubuntu to your Windows machine. First, ssh to your Ubuntu and check:
Windows is addressable, for example using ping windows-ip.
If it is not, make sure both are in the same network, for example setting a bridge network in your VM configuration.
Windows is listening in ports needed by docker swarm:
TCP port 2376 for secure Docker client communication. This port is required for Docker Machine to work. Docker Machine is used to orchestrate Docker hosts.
TCP port 2377. This port is used for communication between the nodes of a Docker Swarm or cluster. It only needs to be opened on manager nodes.
TCP and UDP port 7946 for communication among nodes (container network discovery).
UDP port 4789 for overlay network traffic (container ingress networking).
You can check this using telnet windows-ip port.
If they are not reachable, check your Windows firewall.
I hope it helps!
I tried to create a similar Swarm with a Windows manager node but never really got it to work. You can initialize a single-node Swarm from Windows with docker swarm init. However adding multiple worker nodes does not appear to be supported at the moment:
https://docs.docker.com/engine/swarm/swarm-tutorial/.
"Currently, you cannot use Docker Desktop for Mac or Docker Desktop for Windows alone to test a multi-node swarm".
The following options are possible:
Pure Linux swarm (Linux manager + Linux workers) which runs only Linux containers
Hybrid Swarm (Linux manager + Windows workers + Linux workers) which runs Windows and Linux containers
(Sometimes) Pure Windows Swarm using Win Server 2019 as the manager. The regular Windows updates have been known to break various features of Swarm. For example, https://github.com/moby/moby/issues/40998
Then everyone either tries workarounds or waits for the next Windows update to fix the problem.
Personally I've had good luck with hybrid Swarm. It works fine with simple Ubuntu manager + standard Windows 10 workers. No need for Win Server.
I have Windows Server 2016 Core(Hyper-V VM). Docker is installed, working and I want to create swarm.
IP config at the beginning:
1. Ethernet - 192.168.0.1
2. vEthernet (HSN Internal NIC) - 172.30.208.1
Then I run
docker swarm init --advertise-addr 192.168.0.1
Swarm is created, but I have lost my main IP address. IP config:
1. vEthernet (HNS internal NIC) - 172.30.208.1
2. vEthernet (HNS Transparent) - 169.254.225.229
Created swarm manager node is not reachable on main address 192.168.0.1. I can't connect to it and swarm workers are not able to join with this IP. Where is the problem?
A little late answering this but ... Docker is going to take over your network card when you bring up the Swarm. What I did was use two network cards: one I left alone for Docker to use and the second I used for everything else including virtual machines.
Currently, you cannot use Docker for Mac or Docker for Windows alone to test a multi-node swarm. For single node swarm cluster,
If you are using Docker for Mac or Docker for Windows to test single-node swarm, simply run docker swarm init with no arguments
However, you can use the included version of Docker Machine to create the swarm nodes (see Get started with Docker Machine and a local VM), then follow the tutorial for all multi-node features
For furthere info read this
Edit:
Also refer to this
we have two machine…one is windows machine and another in Linux machine. My application is running under Docker Container at Linux machine. our data base is running at Windows machine.our application need to get data from windows machine DB.
As we have given proper data source detail like IP, username ,password in our application. it works when we do not use docker container but when we use docker container it do not work.
Can anyone help me out to get this solution that how we can connect outside DB from Docker enabled application as we are totally new guys in term of Docker.
Any help would be much appreciated.
Container's default network is "bridge",you should choose macvlan or host network.
method 1
docker run -d --net host image
this container will share your host IP address and will be able to access your database.
method 2
Use docker network create command to create a macvlan network,refrence here
then create your container by
docker run -d --net YOURNETWORK image
The container will have an IP address which is the same gateway with its host.
There are a lot of issues that could be affecting your container's ability to communicate with your database. In the future you should compose your question with as much detail as possible. To correctly answer this you will, at a minimum, need to include the following details:
Linux distribution name & version
Docker version
Output of docker inspect from the container
Linux firewall configuration
Network configuration
Is your Windows machine running on the same local network / subnet as your Linux machine? If so, please provide information about the subnet, as the default bridge set up by Docker may restrict access to local resources, whereas those over a wide area network would still be accessible.
You can try passing the --network=host option to your docker run command like so: docker run --network=host <image name>. Doing so eliminates the need to specify port mappings in your run command, as they are ignored when using the host's network.
Please edit your question and include the above requested details to get a complete answer.
I currently have three hosts (docker1, docker2 and docker3) which I have not set up using Docker Machine, each one running the v1.12-rc4 Docker daemon.
I run docker swarm init on docker1, which in turn prints a docker swarm join command which I run on both docker2 and docker3. At that point, running docker info on each host contains the Swarm: active line.
It is at this point that the behavior seems to differ from what I used to get with the standalone Swarm container. Especially, running docker network ls will only show me the networks on the local host, and when trying to create an overlay network, it does not seem like worker nodes are aware of it (i.e. it does not show up on their docker network ls.)
I feel like I have missed out on some important information relating to the workings of the Swarm Mode as opposed to the Swarm container.
What is the correct way of setting up such a cluster without Docker Machine on Docker 1.12 while getting the overlay network feature?
I too thought this was an issue when I first started using it.
This works a little differently in 1.12rc4 - when you deploy a container to your swarm with that network attached to it, it should then create the network on the other nodes as well.
Hope this helps!
Issue
You are using the docker command (used to communicate with your localhost Docker daemon) and not the "swarm" command (used to communicate with the Swarm master).
Solution
It depends on the command you used to start Swarm.
A full step-by-step tutorial (including details on how to deploy an overlay network) is detailled on this answer. I'm sure that reading this will help you ;)
With a network scope of swarm, the network is only propagated to worker nodes on an as-needed basis. If you create a service using that network, and it gets scheduled on that worker node, the network will show up in the docker network ls.
With the now-upcoming 1.13 release, you can get a network that has similar behavior to the non-swarm networks by doing docker network create --attachable .... That network will be valid for both services and normal containers, and will be available to all members of the cluster. As of 1.13.0-rc2, those don't seem to show up in the output of docker network ls.