I need to connect my db container with my server container. Now I just red about the legacy parameter --link, which works perfect
$> docker run -d -P --name rethinkdb1 rethinkdb
$> docker run -d --link rethinkdb:db my-server
But, if this parameter will be dropped eventually, how would I do something like the above ?
The docs says to use the docker network command instead (which is available since Docker 1.9.0 - 2015-11-03)
Instead of
$> docker run -d -P --name rethinkdb rethinkdb
$> docker run -d --link rethinkdb:rethinkdb my-server
you will now use
$> docker network create --name my-network
$> docker run -d -P --name rethinkdb1 --net=my-network rethinkdb
$> docker run -d --net=my-network my-server
Note that in the new form, container names are used, while before you were able to define an alias.
When two containers are part of the same network, their /etc/hosts file is updated so that you can use the container names instead of their IP addresses.
Related
I want to start three RabbitMQ containers that will be joined together in a cluster. I want to keep it simple and not define complex Dockerfiles with specific volumes.
This is what I am doing right now:
docker network create rabbits
docker run -d --rm --net rabbits --hostname rabbit-1 --name rabbit-1 -p 8081:15672 -e RABBITMQ_ERLANG_COOKIE=ASDF rabbitmq:3.8-management
docker run -d --rm --net rabbits --hostname rabbit-2 --name rabbit-2 -p 8082:15672 -e RABBITMQ_ERLANG_COOKIE=ASDF rabbitmq:3.8-management
docker run -d --rm --net rabbits --hostname rabbit-3 --name rabbit-3 -p 8083:15672 -e RABBITMQ_ERLANG_COOKIE=ASDF rabbitmq:3.8-management
When I then try to tell the nodes to join each other with the following commands, I get an error message:
docker exec -it rabbit-2 rabbitmqctl stop_app
docker exec -it rabbit-2 rabbitmqctl reset
docker exec -it rabbit-2 rabbitmqctl join_cluster rabbit#rabbit-1
docker exec -it rabbit-2 rabbitmqctl start_app
docker exec -it rabbit-2 rabbitmqctl cluster_status
This results in:
RABBITMQ_ERLANG_COOKIE env variable support is deprecated and will be REMOVED in a future version. Use the $HOME/.erlang.cookie file or the --erlang-cookie switch instead.
However I do not know how to pass this switch. When I add this to the docker run command it does not work. So i thought maybe add this after the join_cluster command, but then the cookie is already set.
How do I need to change the docker run command?
In response to your and other questions about RABBITMQ_ERLANG_COOKIE, I opened this issue:
https://github.com/rabbitmq/rabbitmq-server/issues/7262
Currently you should use the environment variable and disregard the warning.
The best practice is to use docker compose and your own image based off of the official RabbitMQ images:
https://github.com/lukebakken/docker-rabbitmq-cluster/blob/main/docker-compose.yml
https://github.com/lukebakken/docker-rabbitmq-cluster/blob/main/rmq/Dockerfile
NOTE: the RabbitMQ team monitors the rabbitmq-users mailing list and only sometimes answers questions on StackOverflow.
The RABBITMQ_ERLANG_COOKIE environment variable is no longer used in RabbitMQ starting from version 3.7.0. Instead, you can set the Erlang cookie value by using the -e option in the docker run command and setting the RABBITMQ_ERLANG_COOKIE environment variable to your desired value. Here's an example:
docker run -d --name rabbitmq -e RABBITMQ_ERLANG_COOKIE='your_cookie_value' rabbitmq:3
Alternatively, you can store the Erlang cookie in a file and mount it as a volume in your container. For example:
Create a file named erlang.cookie with your desired cookie value
echo 'your_cookie_value' > erlang.cookie
Start the RabbitMQ container, mounting the erlang.cookie file
docker run -d --name rabbitmq -v $(pwd)/erlang.cookie:/var/lib/rabbitmq/.erlang.cookie rabbitmq:3
I want to run docker inside another docker container. My main container is running in a virtualbox of OS Ubuntu 18.04 which is there on my Windows 10. On trying to run it, it is showing me as:
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
How can I resolve this issue?
Yes, you can do this. Check for dind (docker in docker) on docker webpage how to achieve it: https://hub.docker.com/_/docker
Your error indicates that either dockerd in the top level container is not running or you didn't mount docker.sock on the dependent container to communicate with dockerd running on your top-level container.
I am running electric-flow in a docker container in my Ubuntu virtual-box using this docker command: docker run --name efserver --hostname=efserver -d -p 8080:8080 -p 9990:9990 -p 7800:7800 -p 7070:80 -p 443:443 -p 8443:8443 -p 8200:8200 -i -t ecdocker/eflow-ce. Inside this docker container, I want to install and run docker so that my CI/CD pipeline in electric-flow can access and use docker commands.
From your above description, ecdocker/eflow-ce is your CI/CD solution container, and you just want to use docker command in this container, then you did not need dind solution. You can just access to a container's host docker server.
Something like follows:
docker run --privileged --name efserver --hostname=efserver -d -p 8080:8080 -p 9990:9990 -p 7800:7800 -p 7070:80 -p 443:443 -p 8443:8443 -p 8200:8200 -v $(which docker):/usr/bin/docker -v /var/run/docker.sock:/var/run/docker.sock -i -t ecdocker/eflow-ce
Compared to your old command:
Add --privileged
Add -v $(which docker):/usr/bin/docker, then you can use docker client in container.
Add -v /var/run/docker.sock:/var/run/docker.sock, then you can access host's docker daemon using client in container.
I've been doing a bit of reading up about setting up a dockerized RabbitMQ cluster and google turns up all sorts of results for doing so on the same machine.
I am trying to set up a RabbitMQ cluster across multiple machines.
I have three machines with the names dockerswarmmodemaster1, dockerswarmmodemaster2 and dockerswarmmodemaster3
On the first machine (dockerswarmmodemaster1), I issue the following command:
docker run -d -p 4369:4369 -p 5671:5671 -p 5672:5672 -p 15671:15671 -p 15672:15672 \
-p 25672:25672 --hostname dockerswarmmodemaster1 --name roger_rabbit \
-e RABBITMQ_ERLANG_COOKIE='secret cookie here' rabbitmq:3-management
Now this starts up a rabbitMQ just fine, and I can go to the admin page on 15672 and see that it is working as expected.
I then SSH to my second machine (dockerswarmmodemaster2) and this is the bit I am stuck on. I have been trying variations on the following command:
docker run -d -p 4369:4369 -p 5671:5671 -p 5672:5672 -p 15671:15671 \
-p 15672:15672 -p 25672:25672 --name jessica_rabbit -e CLUSTERED=true \
-e CLUSTER_WITH=rabbit#dockerswarmmodemaster1 \
-e RABBITMQ_ERLANG_COOKIE='secret cookie here' \
rabbitmq:3-management
No matter what I try, the web page on both RabbitMQ machines says that there is no cluster under the 'cluster links' section. I haven't tried involving the third machine yet.
So - some more info:
The machine names are resolvable by DNS.
I have tried using the --net=host switch in the docker run command on both machines; no change.
I am not using docker swarm or swarm mode.
I do not have docker compose installed. I'd prefer not to use it if possible.
Is there any way of doing this from the docker run command or will I have to download the rabbit admin cli and manually join to the cluster?
You can use this plugin https://github.com/aweber/rabbitmq-autocluster to create a RabbitMQ docker cluster.
The plugin uses etcd2 or consul as service discovery, in this way you don't need to use the rabbitmqctl command line.
I used it with docker swarm, but it is not necessary.
Here is the result
The official container seems to not support environment variables CLUSTERED and CLUSTER_WITH. It supports only a list variables that are specified in RabbitMQ Configuration.
According to official Clustering Guide, one of possible solutions is via configuration file. Thus, you can just provide your own configuration to the container.
Modified default configuration in your case will look like:
[
{ rabbit, [
{ loopback_users, [ ] },
{ cluster_nodes, {['rabbit#dockerswarmmodemaster1'], disc }}
]}
].
Save this snippet to, for example, /home/user/rmq/rabbitmq.config.
Hint: If you want to see node in management console, you need to add another file /home/user/rmq/enabled_plugins with only string
[rabbitmq_management].
after that, your command will look like
docker run -d -p 4369:4369 -p 5671:5671 -p 5672:5672 -p 15671:15671 \
-p 15672:15672 -p 25672:25672 --name jessica_rabbit \
-v /home/user/rmq:/etc/rabbmitmq \
-e RABBITMQ_ERLANG_COOKIE='secret cookie here' \
rabbitmq:3-management
PS You may also need to consider setting environment variable RABBITMQ_USE_LONGNAME.
In order to create a cluster, all rabbitmq nodes that are to form up a cluster must be accessible (each one by others) by node name (hostname).
You need to specify a hostname for each docker container with --hostname option and to add /etc/host entries for all the other containers, this you can do with --add-host option or by manually editing /etc/hosts file.
So, here is the example for a 3 rabbitmq nodes cluster with docker containers (rabbitmq:3-management image).
First, create a network so that you can assign IPs: docker network create --subnet=172.18.0.0/16 mynet1. We are going to have the following:
3 docker containers named rab1con, rab2con and rab3con
IPs respectively will be 172.18.0.11 , -12 and -13
each of them will have the host name respectively rab1, rab2 and rab3
all of them must share the same erlang cookie
Spin up the first one
docker run -d --net mynet1 --ip 172.18.0.11 --hostname rab1 --add-host rab2:172.18.0.12 --add-host rab3:172.18.0.13 --name rab1con -e RABBITMQ_ERLANG_COOKIE='secret cookie here' rabbitmq:3-management
second one
docker run -d --net mynet1 --ip 172.18.0.12 --hostname rab2 --add-host rab1:172.18.0.11 --add-host rab3:172.18.0.13 --name rab2con -e RABBITMQ_ERLANG_COOKIE='secret cookie here' rabbitmq:3-management
last one
docker run -d --net mynet1 --ip 172.18.0.13 --hostname rab3 --add-host rab2:172.18.0.12 --add-host rab1:172.18.0.11 --name rab3con -e RABBITMQ_ERLANG_COOKIE='secret cookie here' rabbitmq:3-management
Then, in container rab2con, do
rabbitmqctl stop_app
rabbitmqctl join_cluster rabbit#rab1
rabbitmqctl start_app
and the same in rab3con and that's it.
I've been following these two tutorials to understand a bit about Docker networking:
https://docs.docker.com/engine/examples/running_redis_service/
https://docs.docker.com/engine/userguide/networking/default_network/dockerlinks
The first tutorial says that the container is not exposing ports by not using -p or -P flags.
$ docker run --name redis-server -d <your username>/redis
And when running another container it uses the --link flag to "redis" container:
$ docker run --name redis-client --link redis:db -i -t ubuntu:14.04 /bin/bash
And that way I can connect from redis-client container to redis-server container because they are linked. But while experimenting with other configurations, I run another container, let's call it redis-client-2 -- just after I stoped and removed redis-client container -- that doesn't use the --link flag:
$ docker run --name redis-client-2 -i -t ubuntu:14.04 /bin/bash
And I noticed that even without the --link flag set I can connect to redis-server container's redis server from redis-client-2
My question is, am I misunderstanding the concept of --link and exposed ports on Docker? Why can I still connect to redis-server container with or without the --link flag?
Thanks in advance
Docker containers on the same Docker network (if none is setup, default) as each other can communicate with each other freely. --link is a vestigial feature from before the days of first-class Docker networking.
The -p & -P options only relate to exposing ports outside of the Docker network (i.e. to the host) and has no bearing on container-to-container communication.
I used docker for wordpress like this:
Create volume containers:
$ docker create -v /home/juanda/project/bbdd:/var/lib/mysql --name bbdd ubuntu /bin/true
$ docker create -v /home/juanda/project/web:/var/www/html --name web ubuntu /bin/true
Mysql container:
$ docker run --volumes-from bbdd --name mysql -e MYSQL_ROOT_PASSWORD="xxxx" -d mysql
Apache, php and wordpress container:
$ docker run --volumes-from web --name apache --link mysql:mysql -d -p 5555:80 wordpress
I installed and ran everything ok. If I remove apache container (stop and rm) and I launch it awain in another port (8080 instead of 5555), it rewrites url in navigator to 5555 and I get a connection error. Any idea?