Elasticsearch-JavaAPI-connection

This repository shows basic connection between JavaAPI and Elasticsearch server.

Implementation

1. Java client ElasticsearchConnectionCheckHTTP that establishes a connection to an Elasticsearch cluster and checks if the connection is successful using HTTP.

• Variables:
  • The code declares and initializes several variables:
  • host: Represents the IP address or hostname of the Elasticsearch cluster.
  • port: Represents the port number on which the Elasticsearch cluster is running.
  • username: Represents the username for authentication with the Elasticsearch cluster.
  • password: Represents the password for authentication with the Elasticsearch cluster.
• Building the Elasticsearch Client:
  • The code creates a RestClientBuilder object to configure the Elasticsearch client.
  • It uses the RestClient.builder() method and specifies the host, port, and "http" scheme to build an HTTP host.
  • The setHttpClientConfigCallback method is used to configure the HTTP client with authentication credentials.
  • It creates a CredentialsProvider object, sets the AuthScope to ANY, and provides the UsernamePasswordCredentials.
  • The httpClientBuilder is then configured with the setDefaultCredentialsProvider method.
  • Finally, the RestHighLevelClient is created using the configured RestClientBuilder.
• Checking the Connection:
  • The code attempts to ping the Elasticsearch cluster using the client.ping method and passing RequestOptions.DEFAULT
  • If the ping is successful, it prints "Connection is SUCCESSFUL."
  • If an IOException occurs during the ping, it prints "Connection is FAILED" along with the exception message.
• Closing the Client:
  • The client.close() method is called in a finally block to ensure the client resources are released.

2. FileReadabilityCheck checks the readability of a file.

• Import Statement:

  • The code imports the java.io.File class, which represents a file on the file system.

• File Path:

  • The code declares a variable named filePath and assigns it a file path string.

• Creating a File Object:

  • The code creates a File object using the filePath string.
  • The File object represents the file specified by the file path.

• Checking File Readability:

  • The code uses an if statement to check the existence and readability of the file.
  • The exists() method checks if the file exists.
  • The canRead() method checks if the file is readable.
  • If both conditions are true, it prints "File is readable".
  • If either condition is false then it prints "File is not readable".

• Demo run screenshot:

Troubleshooting

• Elasticsearch Java API Client: The Java API client provides strongly typed requests and responses for all Elasticsearch APIs.
• Elasticsearch warning - ignore_throttled parameter is deprecated - Stackoverflow - Elasticsearch warning - ignore_throttled parameter is deprecated issued which has answer
• Do not send default ignore_throttled parameter since it is deprecated - github discussion board about the particular issue
• How to connect to elasticsearch server using rest client with IP address - Stackoverflow: The cluster coordination algorithm has changed in 7.0 234 and in order to be safe it requires some specific configurations. We relax that requirement (that is, we run in a less-safe mode) when you bind to localhost only, but if/when you change network.host we enforce that your configure the cluster safely.
• Discovery configuration is required in production - production deployments of Elasticsearch now require at least one of the following settings to be specified in the elasticsearch.yml configuration file:
  • discovery.seed_hosts
  • discovery.seed_providers
  • cluster.initial_master_nodes
  • discovery.zen.ping.unicast.hosts
  • discovery.zen.hosts_provider