I'm trying to connect to the Kafka using a KafkaTool. I got an error:
Error connecting to the cluster. failed create new KafkaAdminClient
Kafka and Zookeeper is hosting in the Docker. I run next commands
docker network create kafka
docker run --network=kafka -d --name zookeeper -e ZOOKEEPER_CLIENT_PORT=2181 confluentinc/cp-zookeeper:latest
docker run --network=kafka -d -p 9092:9092 --name kafka -e KAFKA_ZOOKEEPER_CONNECT=zookeeper:2181 -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://kafka:9092 -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 confluentinc/cp-kafka:latest
Settings for KafkaTool
Why does KafkaTool not connect to the Kafka that is hosting in the Docker?
I'm assuming this GUI is not coming from a Docker container. Therefore, your host machine doesn't know what zookeeper or kafka are, only the Docker network does.
In the GUI, you will want to use localhost for both, then in your Kafka run command, leave all the other variables alone but change -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://localhost:9092
Zookeeper run command is fine, but add -p 2181:2181 to expose the port out to the host so that the GUI can connect
Related
Well, the set up is simple, there should be two containers: one of them for the mysql database and the other one for web application.
What I do to run the containers,
the first one for database and the second for the app:
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d mysql
docker run -p 8081:8081 myrepo/myapp
The application tries to connect to database using localhost:3306, but as I found out the issue is that each container has its own localhost.
One of the solution I found was to add the same network for containers using --net and the docker commands happend to be like the following:
docker network create my-network
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d
--net my-network mysql
docker run --net my-network -p 8081:8081 myrepo/myapp
Though, the web application still is not able to connect to the database. What am I doing wrong and what is the proper flow to connect application to database when they are both inside containers?
You could use the name of the container (i.e. mysql-container) to connect to mysql. Example:
Run the mysql container:
docker run --name mysql-container -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=db -p 3306:3306 -d --net my-network mysql
Connect from another container using the mysql client:
docker run --net my-network -it mysql mysql -u root -p db -h mysql-container
In your application you should replace in the database URL, whatever IP you have with mysql-container.
Well, after additional research, I successfully managed to connect to the database.
The approach I used is the following:
On my host I grabbed the IP address of the docker itself but not the specific container:
sudo ip addr show | grep docker0
The IP address of the docker0 I added to the database connection URL inside my application and thus application managed to connect to the database (note: with this flow I don't add the --net keyword when start container)
What definitely strange is that even adding shared network like --net=my-nework for both the container didn't work. Moreover I did try to use --net=host to share the host network with container's one, still it was unsuccessful. If there's any who can explain why it couldn't work, please - share your knowledge.
I want to install elasticsearch and kibana, on dockers, on my host machine:
$sudo docker run -dit --name elasticsearch -h elasticsearch --net host -p 9200:9200 -p 9300:9300 -v $(pwd)/elasticsearch/data/:/usr/share/elasticsearch/data/ -e "discovery.type=single-node" elasticsearch:6.6.1
WARNING: Published ports are discarded when using host network mode
$sudo docker run -dit --name kibana -h kibana --net host -p 5601:5601 kibana:6.6.1
WARNING: Published ports are discarded when using host network mode
and I get the following errors on kibana:
log [14:32:26.655] [warning][admin][elasticsearch] Unable to revive connection: http://elasticsearch:9200/
log [14:32:26.656] [warning][admin][elasticsearch] No living connections
But If I don't use host machine:
sudo docker network create mynetwork
sudo docker run -dit --name elasticsearch -h elasticsearch --net mynetwork -p 9200:9200 -p 9300:9300 -v $(pwd)/elasticsearch/data/:/usr/share/elasticsearch/data/ -e "discovery.type=single-node" elasticsearch:6.6.1
sudo docker run -dit --name kibana -h kibana --net mynetwork -p 5601:5601 kibana:6.6.1
all working fine. What is the problem?
--net host disables most of the Docker networking stack. Basic features like communicating between containers using their container name as a host name don’t work. Except in very unusual circumstances it’s never necessary.
Your second setup that uses standard Docker networking and publishes selected ports through the host is a best practice.
The docker daemon is running on an Ubuntu machine. I'm trying to start up a zookeeper ensemble in a swarm. The zookeeper nodes themselves can talk to each other. However, from the host machine, I don't seem to be able to access the published ports.
If I start the container with -
docker run \
-p 2181:2181 \
--env ZOO_MY_ID=1 \
--env ZOO_SERVERS="server.1=0.0.0.0:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888" \
zookeeper
It works like a charm. On my host machine I can say echo conf | nc localhost 2181 and zookeeper says something back.
However if I do,
docker service create \
-p 2181:2181 \
--env ZOO_MY_ID=1 \
--env ZOO_SERVERS="server.1=0.0.0.0:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888" \
zookeeper
and run the same command echo conf | nc localhost 2181,
it just gets stuck. I don't even get a new prompt on my terminal.
This works just as expected on the Docker Playground on the official Zookeeper Docker Hub page. So I expect it should for me too.
But... If I docker exec -it $container sh and then try the command in there, it works again.
Aren't published ports supposed to be accessible even by the host machine for a service?
Is there some trick I'm missing about working with overlay networks?
Try to use docket service create --publish 2181:2181 instead.
I believe the container backing the service is not directly exposed and has to go through the Swarm networking.
Otherwise, inspect your service to check which port are published: docker service inspect <service_name>
Source: documentation
I have an error whith docker swarm new services when I'm added somes services with a port like :
docker service create --name=elasticSearch --network=swarm-net -e xpack.security.enabled=false -e xpack.monitoring.enabled=false -e xpack.graph.enabled=false -e xpack.watcher.enabled=false -p 9200:9200 -p 9300:9300 -d docker.elastic.co/elasticsearch/elasticsearch:5.3.2
When I don't publish any ports the service works well but when I'm added it, the process stay at state "new" not running.
Did you have an idea ?
Regards
I found this docker image for Kafka
https://hub.docker.com/r/spotify/kafka/
and I can easily create a docker container using command documented in the link
docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=`boot2docker ip` --env ADVERTISED_PORT=9092 spotify/kafka
This is good. But I want to configure a "multiple" node Kafka cluster running on a docker swarm.
How can I do that?
Edit 28/11/2017:
Kafka added listener.security.protocol.map to their config. This allows you to set different listener addresses and protocols depending on whether you are inside or outside the cluster, and stops Kafka getting confused by any load balancing or ip translation which occurs in docker. Wurstmeister has a working docker image and example compose file here. I tried this a while back with a few docker machine nodes set up as a swarm and it seems to work.
tbh though I just attach a Kafka image to the overlay network and run the Kafka console commands when ever I want to interact with it now.
Hope that helps
Old Stuff Below
I have been trying this with docker 1.12 using docker swarm mode
create nodes
docker-machine create -d virtualbox master
docker-machine create -d virtualbox worker
master_config=$(docker-machine config master | tr -d '\"')
worker_config=$(docker-machine config worker | tr -d '\"')
master_ip=$(docker-machine ip master)
docker $master_config swarm init --advertise-addr $master_ip --listen-addr $master_ip:2377
worker_token=$(docker $master_config swarm join-token worker -q)
docker $worker_config swarm join --token $worker_token $master_ip:2377
eval $(docker-machine env master)
create the zookeeper service
docker service create --name zookeeper \
--constraint 'node.role == manager' \
-p 2181:2181 \
wurstmeister/zookeeper
create the kafka service
docker service create --name kafka \
--mode global \
-e 'KAFKA_PORT=9092' \
-e 'KAFKA_ADVERTISED_PORT=9092' \
-e 'KAFKA_LISTENERS=PLAINTEXT://0.0.0.0:9092' \
-e 'KAFKA_ZOOKEEPER_CONNECT=tasks.zookeeper:2181' \
-e "HOSTNAME_COMMAND=ip r | awk '{ ip[\$3] = \$NF } END { print ( ip[\"eth0\"] ) }'" \
--publish '9092:9092' \
wurstmeister/kafka
Though for some reason this will only work from within the ingress or user defined overlay network and the connection will break to Kafka if you try and connect to it through one of the guest machines.
Changing the advertised IP doesn't make things any better...
docker service create --name kafka \
--mode global \
-e 'KAFKA_PORT=9092' \
-e 'KAFKA_ADVERTISED_PORT=9092' \
-e 'KAFKA_LISTENERS=PLAINTEXT://0.0.0.0:9092' \
-e 'KAFKA_ZOOKEEPER_CONNECT=tasks.zookeeper:2181' \
-e 'KAFKA_LOG_DIRS=/kafka/kafka-logs' \
-e "HOSTNAME_COMMAND=curl 192.168.99.1:5000" \
--publish '9092:9092' \
wurstmeister/kafka
I think the new mesh networking and load balancing in docker might be interfering with the Kafka connection some how....
to get the host container I have a flask app running locally which I curl
from flask import Flask
from flask import request
app = Flask(__name__)
#app.route('/')
def hello_world():
return request.remote_addr
The previous approach raise some questions:
How to specify the IDs for the zookeeper nodes?
How to specify the id of the kafka nodes, and the zookeeper nodes?
#kafka configs
echo "broker.id=${ID}
advertised.host.name=${NAME}
zookeeper.connect=${ZOOKEEPERS}" >> /opt/kafka/config/server.properties
Everything should be resolvable in the overlay network.
Moreover, in the issue Cannot create a Kafka service and publish ports due to rout mesh network there is a comment to don't use the ingress network.
I think the best option is to specify your service by using a docker compose with swarm. I'll edit the answer with an example.
There are 2 concerns to consider: networking and storage.
Since Kafka is stateful service, until cloud native storage is figured out, it is advisable to use global deployment mode. That is each swarm node satisfying constraints will have one kafka container.
Another recommendation is to use host mode for published port.
It's also important to properly set advertised listeners option so that each kafka broker knows which host it's running on. Use swarm service templates to provide real hostname automatically.
Also make sure that published port is different from target port.
kafka:
image: debezium/kafka:0.8
volumes:
- ./kafka:/kafka/data
environment:
- ZOOKEEPER_CONNECT=zookeeper:2181
- KAFKA_AUTO_CREATE_TOPICS_ENABLE=true
- KAFKA_MAX_MESSAGE_BYTES=20000000
- KAFKA_MESSAGE_MAX_BYTES=20000000
- KAFKA_CLEANUP_POLICY=compact
- LISTENERS=PLAINTEXT://:9092
- BROKER_ID=-1
- ADVERTISED_LISTENERS=PLAINTEXT://{{.Node.Hostname}}:11092
depends_on:
- zookeeper
deploy:
mode: global
ports:
- target: 9092
published: 11092
protocol: tcp
mode: host
networks:
- kafka
I can't explain all the options right now, but it's the configuration that works.
set broker.id=-1 in server.properties to allow kafka to auto generate the broker ID. Helpful in Swarm mode.