[Docker](https://www.docker.com/) greatly simplifies the process of configuring and managing your OpenSearch clusters. You can pull official images from [Docker Hub](https://hub.docker.com/u/opensearchproject) or [Amazon Elastic Container Registry (Amazon ECR)](https://gallery.ecr.aws/opensearchproject/) and quickly deploy a cluster using [Docker Compose](https://github.com/docker/compose) and any of the sample Docker Compose files included in this guide. Experienced OpenSearch users can further customize their deployment by creating a custom Docker Compose file.
Docker containers are portable and will run on any compatible host that supports Docker (such as Linux, MacOS, or Windows). The portability of a Docker container offers flexibility over other installations methods, like [RPM]({{site.url}}{{site.baseurl}}/opensearch/install/rpm/) or a manual [Tarball]({{site.url}}{{site.baseurl}}/opensearch/install/tar/) installation, which both require additional configuration after downloading and unpacking.
This guide assumes that you are comfortable working from the Linux command line interface (CLI). You should understand how to input commands, navigate between directories, and edit text files. For help with [Docker](https://www.docker.com/) or [Docker Compose](https://github.com/docker/compose), refer to the official documentation on their websites.
Visit [Get Docker](https://docs.docker.com/get-docker/) for guidance on installing and configuring Docker for your environment. If you are installing Docker Engine using the CLI, then Docker, by default, will not have any constraints on available host resources. Depending on your environment, you may wish to configure resource limits in Docker. See [Runtime options with Memory, CPUs, and GPUs](https://docs.docker.com/config/containers/resource_constraints/) for information.
Docker Compose is a utility that allows users to launch multiple containers with a single command. You pass a file to Docker Compose when you invoke it. Docker Compose reads those settings and starts the requested containers. Docker Compose is installed automatically with Docker Desktop, but users operating in a command line environment must install Docker Compose manually. You can find information about installing Docker Compose on the official [Docker Compose GitHub page](https://github.com/docker/compose).
If you need to install Docker Compose manually and your host supports Python, you can use [pip](https://pypi.org/project/pip/) to install the [Docker Compose package](https://pypi.org/project/docker-compose/) automatically.
Before launching OpenSearch you should review some [important system settings]({{site.url}}{{site.baseurl}}/opensearch/install/important-settings/){:target='\_blank'} that can impact the performance of your services.
1. Disable memory paging and swapping performance on the host to improve performance.
```bash
sudo swapoff -a
```
1. Increase the number of memory maps available to OpenSearch.
Official OpenSearch images are hosted on [Docker Hub](https://hub.docker.com/u/opensearchproject/) and [Amazon ECR](https://gallery.ecr.aws/opensearchproject/). If you want to inspect the images you can pull them individually using `docker pull`, such as in the following examples.
To download a specific version of OpenSearch or OpenSearch Dashboards other than the latest available version, modify the image tag where it is referenced (either in the command line or in a Docker Compose file). For example, `opensearchproject/opensearch:{{site.opensearch_version}}` will pull OpenSearch version {{site.opensearch_version}}. Refer to the official image repositories for available versions.
{: .tip}
Before continuing, you should verify that Docker is working correctly by deploying OpenSearch in a single container.
1. Run the following command:
```bash
# This command maps ports 9200 and 9600, sets the discovery type to "single-node" and requests the newest image of OpenSearch
docker run -d -p 9200:9200 -p 9600:9600 -e "discovery.type=single-node" opensearchproject/opensearch:latest
```
1. Send a request to port 9200. The default username and password are `admin`.
"tagline" : "The OpenSearch Project: https://opensearch.org/"
}
```
1. Before stopping the running container, display a list of all running containers and copy the container ID for the OpenSearch node you are testing. In the following example, the container ID is `a937e018cee5`:
```bash
$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a937e018cee5 opensearchproject/opensearch:latest "./opensearch-docker…" 19 minutes ago Up 19 minutes 0.0.0.0:9200->9200/tcp, 9300/tcp, 0.0.0.0:9600->9600/tcp, 9650/tcp wonderful_boyd
```
1. Stop the running container by passing the container ID to `docker stop`.
```bash
docker stop <containerId>
```
Remember that `docker container ls` does not list stopped containers. If you would like to review stopped containers, use `docker container ls -a`. You can remove unneeded containers manually with `docker container rm <containerId_1> <containerId_2> <containerId_3> [...]` (pass all container IDs you wish to stop, separated by spaces), or if you want to remove all stopped containers, you can use the shorter command `docker prune`.
{: .tip}
## Deploy an OpenSearch cluster using Docker Compose
Although it is technically possible to build an OpenSearch cluster by creating containers one command at a time, it is far easier to define your environment in a YAML file and let Docker Compose manage the cluster. The following section contains example YAML files that you can use to launch a predefined cluster with OpenSearch and OpenSearch Dashboards. These examples are useful for testing and development, but are not suitable for a production environment. If you don't have prior experience using Docker Compose, you may wish to review the Docker [Compose specification](https://docs.docker.com/compose/compose-file/) for guidance on syntax and formatting before making any changes to the dictionary structures in the examples.
The YAML file that defines the environment is referred to as a Docker Compose file. By default, `docker-compose` commands will first check your current directory for a file that matches any of the following names:
-`docker-compose.yml`
-`docker-compose.yaml`
-`compose.yml`
-`compose.yaml`
If none of those files exist in your current directory, the `docker-compose` command fails.
You can specify a custom file location and name when invoking `docker-compose` with the `-f` flag:
If this is your first time launching an OpenSearch cluster using Docker Compose, use the following example `docker-compose.yml` file. Save it in the home directory of your host and name it `docker-compose.yml`. This file will create a cluster that contains three containers: two containers running the OpenSearch service and a single container running OpenSearch Dashboards. These containers will communicate over a bridge network called `opensearch-net` and use two volumes, one for each OpenSearch node. Because this file does not explicitly disable the demo security configuration, self-signed TLS certificates are installed and internal users with default names and passwords are created.
image: opensearchproject/opensearch-dashboards:latest # Make sure the version of opensearch-dashboards matches the version of opensearch installed on other nodes
OPENSEARCH_HOSTS: '["https://opensearch-node1:9200","https://opensearch-node2:9200"]' # Define the OpenSearch nodes that OpenSearch Dashboards will query
If you override `opensearch_dashboards.yml` settings using environment variables in your compose file, use all uppercase letters and replace periods with underscores (for example, for `opensearch.hosts`, use `OPENSEARCH_HOSTS`). This behavior is inconsistent with overriding `opensearch.yml` settings, where the conversion is just a change to the assignment operator (for example, `discovery.type: single-node` in `opensearch.yml` is defined as `discovery.type=single-node` in `docker-compose.yml`).
{: .note}
From the home directory of your host (containing `docker-compose.yml`), create and start the containers in detached mode:
```bash
docker-compose up -d
```
Verify that the service containers started correctly:
```bash
docker-compose ps
```
If a container failed to start, you can review the service logs:
```bash
# If you don't pass a service name, docker-compose will show you logs from all of the nodes
docker-compose logs <serviceName>
```
Verify access to OpenSearch Dashboards by connecting to http://localhost:5601 from a browser. The default username and password are `admin`. We do not recommend using this configuration on hosts that are accessible from the public internet until you have customized the security configuration of your deployment.
Remember that `localhost` cannot be accessed remotely. If you are deploying these containers to a remote host, then you will need to establish a network connection and replace `localhost` with the IP or DNS record corresponding to the host.
`docker-compose down` will stop the running containers, but it will not remove the Docker volumes that exist on the host. If you don't care about the contents of these volumes, use the `-v` option to delete all volumes, for example, `docker-compose down -v`.
Unlike the RPM distribution of OpenSearch, which requires a large amount of post-installation configuration, running OpenSearch clusters with Docker allows you to define the environment before the containers are even created. This is possible whether you use Docker or Docker Compose.
By reviewing each part of the command, you can see that it:
- Maps ports `9200` and `9600` (`HOST_PORT`:`CONTAINER_PORT`).
- Sets `discovery.type` to `single-node` so that bootstrap checks don't fail for this single-node deployment.
- Uses the [-v flag](https://docs.docker.com/engine/reference/commandline/run#mount-volume--v---read-only) to pass a local file called `custom-opensearch.yml` to the container, replacing the `opensearch.yml` file included with the image.
- Requests the `opensearchproject/opensearch:latest` image from Docker Hub.
- Runs the container.
If you compare this command to the [Sample docker-compose.yml](#sample-docker-composeyml) file, you might notice some common settings, such as the port mappings and the image reference. The command, however, is only deploying a single container running OpenSearch and will not create a container for OpenSearch Dashboards. Furthermore, if you want to use custom TLS certificates, users, or roles, or define additional volumes and networks, then this "one-line" command rapidly grows to an impractical size. That is where the utility of Docker Compose becomes useful.
When you build your OpenSearch cluster with Docker Compose you might find it easier to pass custom configuration files from your host to the container, as opposed to enumerating every individual setting in `docker-compose.yml`. Similar to how the example `docker run` command mounted a volume from the host to the container using the `-v` flag, compose files can specify volumes to mount as a sub-option to the corresponding service. The following truncated YAML file demonstrates how to mount a file or directory to the container. Refer to the official Docker documentation on [volumes](https://docs.docker.com/storage/volumes/) for comprehensive information about volume usage and syntax.
If you want to build your own compose file from an example, review the following sample `docker-compose.yml` file. This sample file creates two OpenSearch nodes and one OpenSearch Dashboards node with the security plugin disabled. You can use this sample file as a starting point while reviewing [Configuring basic security settings](#configuring-basic-security-settings).
```yml
version: '3'
services:
opensearch-node1:
image: opensearchproject/opensearch:latest
container_name: opensearch-node1
environment:
- cluster.name=opensearch-cluster # Name the cluster
- node.name=opensearch-node1 # Name the node that will run in this container
- discovery.seed_hosts=opensearch-node1,opensearch-node2 # Nodes to look for when discovering the cluster
- cluster.initial_cluster_manager_nodes=opensearch-node1,opensearch-node2 # Nodes eligibile to serve as cluster manager
- "OPENSEARCH_JAVA_OPTS=-Xms512m -Xmx512m" # Set min and max JVM heap sizes to at least 50% of system RAM
- "DISABLE_INSTALL_DEMO_CONFIG=true" # Prevents execution of bundled demo script which installs demo certificates and security configurations to OpenSearch
- "OPENSEARCH_JAVA_OPTS=-Xms512m -Xmx512m" # Set min and max JVM heap sizes to at least 50% of system RAM
- "DISABLE_INSTALL_DEMO_CONFIG=true" # Prevents execution of bundled demo script which installs demo certificates and security configurations to OpenSearch
Before making your OpenSearch cluster available to external hosts, it's a good idea to review the deployment's security configuration. You may recall from the first [Sample docker-compose.yml](#sample-docker-composeyml) file that, unless disabled by setting `DISABLE_SECURITY_PLUGIN=true`, a bundled script will apply a default demo security configuration to the nodes in the cluster. Because this configuration is used for demo purposes, the default usernames and passwords are known. For that reason, we recommend that you create your own security configuration files and use `volumes` to pass these files to the containers. For specific guidance on OpenSearch security settings, see [Security configuration]({{site.url}}{{site.baseurl}}/security-plugin/configuration/index/).
When you add TLS certificates to your OpenSearch nodes with Docker Compose volumes, you should also include a custom `opensearch.yml` file that defines those certificates. For example:
Remember that the certificates you specify in your compose file must be the same as the certificates defined in your custom `opensearch.yml` file. You should replace the root, admin, and node certificates with your own. For more information see [Configure TLS certificates]({{site.url}}{{site.baseurl}}/security-plugin/configuration/tls).
After configuring security settings, your custom `opensearch.yml` file might look something like the following example, which adds TLS certificates and the distinguished name (DN) of the admin certificate, defines a few permissions, and enables verbose audit logging:
Use the same process to specify a [Backend configuration]({{site.url}}{{site.baseurl}}/security-plugin/configuration/configuration/) in `/usr/share/opensearch/config/opensearch-security/config.yml` as well as new internal users, roles, mappings, action groups, and tenants in their respective [YAML files]({{site.url}}{{site.baseurl}}/security-plugin/configuration/yaml/).
After replacing the certificates and creating your own internal users, roles, mappings, action groups, and tenants, use Docker Compose to start the cluster:
To use the OpenSearch image with a custom plugin, you must first create a [`Dockerfile`](https://docs.docker.com/engine/reference/builder/). Review the official Docker documentation for information about creating a Dockerfile.
