Using Go to connect to a Neptune DB instance

If you can, always use the latest version of the Apache TinkerPop Go Gremlin client, gremlingo, that your engine version supports. Newer versions contain numerous bug fixes that improve the stability, performance and usability of the client.

The gremlingo version to use will typically align with the TinkerPop versions described in the table for the Java Gremlin client.

Note

The gremlingo 3.5.x versions are backwards compatible with TinkerPop 3.4.x versions as long as you only use 3.4.x features in the Gremlin queries you write.

The following section walks you through the running of a Go sample that connects to an Amazon Neptune DB instance and performs a Gremlin traversal.

You must follow these instructions from an Amazon EC2 instance in the same virtual private cloud (VPC) as your Neptune DB instance.

Before you begin, do the following:

• Download and install Go 1.17 or later from the go.dev website.

To connect to Neptune using Go

1. Starting from an empty directory, initialize a new Go module:

   go mod init example.com/gremlinExample

2. Add gremlin-go as a dependency of your new module:

   go get github.com/apache/tinkerpop/gremlin-go/v3/driver

3. Create a file named gremlinExample.go and then open it in a text editor.

4. Copy the following into the gremlinExample.go file, replacing (your neptune endpoint) with the address of your Neptune DB instance:

   package main
   
   import (
     "fmt"
     gremlingo "github.com/apache/tinkerpop/gremlin-go/v3/driver"
   )
   
   func main() {
     // Creating the connection to the server.
     driverRemoteConnection, err := gremlingo.NewDriverRemoteConnection("wss://(your neptune endpoint):8182/gremlin",
       func(settings *gremlingo.DriverRemoteConnectionSettings) {
         settings.TraversalSource = "g"
       })
     if err != nil {
       fmt.Println(err)
       return
     }
     // Cleanup
     defer driverRemoteConnection.Close()
   
     // Creating graph traversal
     g := gremlingo.Traversal_().WithRemote(driverRemoteConnection)
   
     // Perform traversal
     results, err := g.V().Limit(2).ToList()
     if err != nil {
       fmt.Println(err)
       return
     }
     // Print results
     for _, r := range results {
       fmt.Println(r.GetString())
     }
   }
   

   Note

   The Neptune TLS certificate format is not currently supported on Go 1.18+ with macOS, and may give a 509 error when trying to initiate a connection. For local testing, this can be skipped by adding "crypto/tls" to the imports and modifying the DriverRemoteConnection settings as follows:

   // Creating the connection to the server.
   driverRemoteConnection, err := gremlingo.NewDriverRemoteConnection("wss://your-neptune-endpoint:8182/gremlin",
     func(settings *gremlingo.DriverRemoteConnectionSettings) {
         settings.TraversalSource = "g"
         settings.TlsConfig = &tls.Config{InsecureSkipVerify: true}
     })

5. Enter the following command to run the sample:

   go run gremlinExample.go

The Gremlin query at the end of this example returns the vertices (g.V().Limit(2)) in a slice. This slice is then iterated through and printed with the standard fmt.Println function.

Note

The final part of the Gremlin query, ToList(), is required to submit the traversal to the server for evaluation. If you don't include that method or another equivalent method, the query is not submitted to the Neptune DB instance.

The following methods submit the query to the Neptune DB instance:

• ToList()

• ToSet()

• Next()

• GetResultSet()

• Iterate()

The preceding example returns the first two vertices in the graph by using the g.V().Limit(2).ToList() traversal. To query for something else, replace it with another Gremlin traversal with one of the appropriate ending methods.