It's been several days now trying to create a redis cluster with docker-compose, but it doesn't work because redis doesn't send a good ip address when my client sends a request (it sends to my host internal ip from docker, but i want he send host ip).
I'm looking for "cluster-announce-ip" but no success.
I've tried to create with host mode but it doesn't work ... I don't understand why..
Now redis-cli shows:
Waiting for the cluster to join
You could find my work here: https://github.com/fhebuterne/redis-cluster
If someone has a solution, I'm interested
Thanks
After some tests, it not possible to use internal network in docker with multiple docker container and redis cluster (even with "cluster-announce-ip"), so the only solution i has found, is to define on each service (on docker compose), this option :
network_mode: "host"
And using the brige docker ip between host and containers, on windows i found it with ipconfig and look for "vEthernet (DockerNAT)", base ip is 10.0.75.1, on my redis-cli and redis.conf, i put 10.0.75.2, so each containers can be connected with others and cluster send good response when i send request with my host computer, i'm sorry if is not clear, i has push my solution on my repository (the link is on my previous message).
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
I have a client running in a docker container that subscribes to a MQTT broker and then writes the data into a database.
To connect to the MQTT Broker i will have to set up port forwarding.
While developing the client on my local machine the following worked fine:
SSH -L <mqtt-port:1883>:localhost:<9000> <user>#<ip-of-server-running-broker>
The client is then configured to subscribe to the MQTT broker via localhost:9000.
This all works fine on my local machine.
Within the container it wont, unless I run the container with --net=host but I'd rather not do that due to security concerns.
I tried the following:
Create docker network "testNetwork"
Run a ssh_tunnel container within "testNetwork" and implement port forwarding inside this container.
Run the database_client container within "testNetwork" and subscribe to the mqtt broker via the bridge network like ("ssh_tunnel.testNetwork:")
(I want 2 seperate containers for this because the ip address will have to be altered quite often and I don't want to re-build the client container all the time)
But all of my attempts have failed so far. The forwarding seems to work (I can access the shell on the server in the ssh container) but I haven't found a way to actually subscribe to the mqtt broker from within the client container.
Maybe this is actually quite simple and I just don't see how it works, but I've been stuck on this problem for hours by now...
Any help or hints are appreciated!
The solution was actually quite simple and works without using -net=host.
I needed to bind to 0.0.0.0 and use the Gateway Forwarding Option to allow remote hosts (the database client) to connect to the forwarded ports.
ssh -L -g *:<hostport>:localhost:<mqtt-port/remote port> <user>#<remote-ip>
Other containers within the same Docker bridge network can then simply use the connection string <name-of-ssh-container>:<hostport>.
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 am setting up a simple cluster using docker on several hosts. Before using docker the processes were simply started with a argument giving the address to a config server. The first thing each process does is to connect to the config server, get the addresses (host and port) of all the other services as well as register itself with host (and several different ports, one for each the services it provides).
However, it does not seem to be possible to dockerize this workflow? Since a process in a container seems not to be able to get the address and ports on the host (based on for example How to get the IP address of the docker host from inside a docker container) it does not know what to register itself as. Is this really not possible?
If not, are there any alternative ways this sort of setup is intended to be run using docker?
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/