# Installing OpenSearch
## Prerequisites and Setup 
  * uses Docker; which is why i installed Docker and wrote the [[Docker]] wiki yesterday
  * [source](https://opensearch.org/docs/latest/getting-started/quickstart/) 
  * `sudo swapoff -a`
    * disables memory-paging and swapping
  * `sudo vi /etc/sysctl.conf`
    * actually it's `/etc/sysctl.d/10-map-count.conf`
    * `vm.max_map_count=262144`
      * Set max map count to 262144
  * `sudo sysctl -p`
    * reload kernel parameters 

## Install Steps
  * `curl -O https://raw.githubusercontent.com/opensearch-project/documentation-website/2.19/assets/examples/docker-compose.yml`
    * download the example docker-compose (which is a functional OpenSearch cluster)
  * `export OPENSEARCH_INITIAL_ADMIN_PASSWORD=<admin-password>`
    * **NOTE** without this value the opensearch nodes will refuse to start!
    * **ALSO NOTE** OpenSearch has requirements for this password!
      * 8+ chars of at least 1 UPPER-CASE, 1 lower-case, 1 digit, and 1 symbol
      * and there are more undocumented rules (probably no sequences); just use a password generator 
  * `docker compose up -d`
    * start the docker-compose cluster as background process (`-d` = detached)
    * will download about 12 containers (two of which are 968MB and 350MB); takes a while first time

## Testing Steps
  * `curl https://localhost:9200 -ku admin:<admin-password>`
    * response should confirm that the install worked
  * http://localhost:5601/ should respond with dashboards and such
    * change admin-password if you like at this point 

## Shooting Trouble
  * `[ConnectionError]: getaddrinfo ENOTFOUND opensearch-node1`
    * check the logs of the opensearch-node1 container; likely it refused to start because the admin password didn't pass checks
    * `docker compose down` to get rid of the containers
    * `export OPENSEARCH_INITIAL_ADMIN_PASSWORD="<something serious>"`
    * `docker compose up -d`
    * hopefully the password was sufficient to pass checks