Deploying ElasticSearch 7 in Kubernetes or Docker

Deploying an ElasticSearch container on Kubernetes or Docker is not as easy as it was on previous version, there are some changes there and if you just deploy it on a development or staging it will fail with below error message:

ERROR: [1] bootstrap checks failed
[1]: the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured
ERROR: Elasticsearch did not exit normally - check the logs at /usr/share/elasticsearch/logs/docker-cluster.log

And there is no /usr/share/elasticsearch/logs/docker-cluster.log to check for logs, at least I could not find it.

What you need to do is to configure it to run in single-node mode, initially I tried to do that by adding it to the ES_JAVA_OPTS environment variable, but for some reason ElasticSearch is not honoring it.

So the solution is to mount a configuration file with the configurations you want, and that is how you can do that on Kubernetes.

Running Elasticsearch in Kubernetes

Step 1: Create a ConfigMap

Create a ConfigMap named elasticsearch-config with your desired configuration settings. Save the following YAML to a file named elasticsearch_config.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: elasticsearch-config
data:
  elasticsearch.yml: |
    cluster.name: "my-cluster"
    network.host: 0.0.0.0
    discovery.type: single-node

Step 2: Create a Deployment

Next, create a Deployment YAML file named elasticsearch.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: elasticsearch
spec:
  replicas: 1
  selector:
    matchLabels:
      app: elasticsearch
  template:
    metadata:
      labels:
        app: elasticsearch
    spec:
      containers:
      - name: elasticsearch
        image: elasticsearch:7.10.1
        volumeMounts:
          - name: elasticsearch-config
            mountPath: /usr/share/elasticsearch/config/elasticsearch.yml
            subPath: elasticsearch.yml
        ports:
          - containerPort: 9200
      volumes:
      - name: elasticsearch-config
        configMap:
          name: elasticsearch-config

With the above you are ready to run an ElasticSearch 7 on Kubernetes, the same solution applies to docker, you will need to mount the configuration file elasticsearch.yaml overwriting it with the settings you want, as the variable ES_JAVA_OPTS is also not honored.

Running Elasticsearch in Docker

Create the elasticsearch.yml file with the following content

cluster.name: "my-cluster"
network.host: 0.0.0.0
discovery.type: single-node

Run Docker with the following command:

docker run -ti \
  -v $(pwd)/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml \
  elasticsearch:7.10.1

Be happy, By Safe!