VerneMQ is a high-performance, distributed MQTT message broker. It scales
horizontally and vertically on commodity hardware to support a high number of
concurrent publishers and consumers while maintaining low latency and fault
tolerance. VerneMQ is the reliable message hub for your IoT platform or smart
products.
VerneMQ is an Apache2 licensed distributed MQTT broker, developed in Erlang.
## How to use this image
### Start a VerneMQ cluster node
docker run --name vernemq1 -d erlio/docker-vernemq
Somtimes you need to configure a forwarding for ports (on a Mac for example):
docker run -p 1883:1883 --name vernemq1 -d erlio/docker-vernemq
This starts a new node that listens on 1883 for MQTT connections and on 8080 for MQTT over websocket connections. However, at this moment the broker won't be able to authenticate the connecting clients. To allow anonymous clients use the ```DOCKER_VERNEMQ_ALLOW_ANONYMOUS=on``` environment variable.
docker run -e "DOCKER_VERNEMQ_ALLOW_ANONYMOUS=on" --name vernemq1 -d erlio/docker-vernemq
### Autojoining a VerneMQ cluster
This allows a newly started container to automatically join a VerneMQ cluster. Assuming you started your first node like the example above you could autojoin the cluster (which currently consists of a single container 'vernemq1') like the following:
docker run -e "DOCKER_VERNEMQ_DISCOVERY_NODE=<IP-OF-VERNEMQ1>" --name vernemq2 -d erlio/docker-vernemq
(Note, you can find the IP of a docker container using `docker inspect <containername/cid> | grep \"IPAddress\"`).
### Automated clustering on Kubernetes
When running VerneMQ inside Kubernetes, it is possible to cause pods matching a specific label to cluster altogether automatically.
This feature uses Kubernetes' API to discover other peers, and relies on the [default pod service account](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/) which has to be enabled.
Simply set ```DOCKER_VERNEMQ_DISCOVERY_KUBERNETES=1``` in your pod's environment, and expose your own pod name through ```MY_POD_NAME``` . By default, this setting will cause all pods in the ```default``` namespace with the ```app=vernemq``` label to join the same cluster. Namespace and label settings can be overridden with ```DOCKER_VERNEMQ_KUBERNETES_NAMESPACE``` and ```DOCKER_VERNEMQ_KUBERNETES_APP_LABEL```.
An example configuration of your pod's environment looks like this:
env:
- name: DOCKER_VERNEMQ_DISCOVERY_KUBERNETES
value: "1"
- name: MY_POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: DOCKER_VERNEMQ_KUBERNETES_NAMESPACE
value: "mynamespace"
- name: DOCKER_VERNEMQ_KUBERNETES_APP_LABEL
value: "myverneinstance"
When enabling Kubernetes autoclustering, don't set ```DOCKER_VERNEMQ_DISCOVERY_NODE```.
> If you encounter "SSL certification error (subject name does not match the host name)" like below, you may try to set ```DOCKER_VERNEMQ_KUBERNETES_INSECURE``` to "1".
>
> ```text
> kubectl logs vernemq-0
> % Total % Received % Xferd Average Speed Time Time Time Current
> Dload Upload Total Spent Left Speed
> 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (51) SSL: certificate subject name 'client' does not match target host name 'kubernetes.default.svc.cluster.local'
> % Total % Received % Xferd Average Speed Time Time Time Current
> Dload Upload Total Spent Left Speed
> 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (51) SSL: certificate subject name 'client' does not match target host name 'kubernetes.default.svc.cluster.local'
> vernemq failed to start within 15 seconds,
> see the output of 'vernemq console' for more information.
> If you want to wait longer, set the environment variable
> WAIT_FOR_ERLANG to the number of seconds to wait.
> ...
> ```
### Checking cluster status
To check if the bove containers have successfully clustered you can issue the ```vmq-admin``` command:
docker exec vernemq1 vmq-admin cluster show
+--------------------+-------+
| Node |Running|
+--------------------+-------+
|VerneMQ@172.17.0.151| true |
|VerneMQ@172.17.0.152| true |
+--------------------+-------+
If you started VerneMQ cluster inside Kubernetes using ```DOCKER_VERNEMQ_DISCOVERY_KUBERNETES=1```, you can execute ```vmq-admin``` through ```kubectl```:
# If you encounter "SSL certification error (subject name does not match the host name)", you may try to set DOCKER_VERNEMQ_KUBERNETES_INSECURE to "1".
insecure=""
if env | grep"DOCKER_VERNEMQ_KUBERNETES_INSECURE"-q;then
insecure="--insecure"
fi
if env | grep"DOCKER_VERNEMQ_DISCOVERY_KUBERNETES"-q;then
sed -i.bak -r"s/VerneMQ@.+/VerneMQ@${VERNEMQ_KUBERNETES_HOSTNAME}/" /vernemq/etc/vm.args
# Hack into K8S DNS resolution (temporarily)
kube_pod_names=$(curl -X GET $insecure--cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt https://kubernetes.default.svc.$DOCKER_VERNEMQ_KUBERNETES_CLUSTER_NAME/api/v1/namespaces/$DOCKER_VERNEMQ_KUBERNETES_NAMESPACE/pods?labelSelector=$DOCKER_VERNEMQ_KUBERNETES_LABEL_SELECTOR-H"Authorization: Bearer $(cat /var/run/secrets/kubernetes.io/serviceaccount/token)" | jq '.items[].spec.hostname' | sed 's/"//g' | tr '\n'' ')
for kube_pod_name in$kube_pod_names;do
if[$kube_pod_name=="null"];then
echo"Kubernetes discovery selected, but no pods found. Maybe we're the first?"
echo"Anyway, we won't attempt to join any cluster."
break
fi
if[$kube_pod_name!=$MY_POD_NAME];then
echo"Will join an existing Kubernetes cluster with discovery node at ${kube_pod_name}.${VERNEMQ_KUBERNETES_SUBDOMAIN}.${DOCKER_VERNEMQ_KUBERNETES_NAMESPACE}.svc.${DOCKER_VERNEMQ_KUBERNETES_CLUSTER_NAME}"
