Unable to access DynamoDb Locally from Kotlin - kotlin

Question

First I want to say I am pretty new to Kotlin and DynamoDB. I am writing a sample program in Kotlin to play with DynamoDb. I am following the steps in this link: https://docs.aws.amazon.com/sdk-for-kotlin/latest/developer-guide/examples-dynamodb-tables.html
First I instantiate a client object for making requests to DynamoDB
val dynamoDbClient = DynamoDbClient { region = "us-east-1" }
Then I run the code below to create a new table.
suspend fun createNewTable(ddb: DynamoDbClient, newTableName: String, key: String): String {
val attDef = AttributeDefinition {
attributeName = key
attributeType = ScalarAttributeType.S
}
val keySchemaVal = KeySchemaElement {
attributeName = key
keyType = KeyType.Hash
}
val provisionedVal = ProvisionedThroughput {
readCapacityUnits = 10
writeCapacityUnits = 10
}
val request = CreateTableRequest {
attributeDefinitions = listOf(attDef)
keySchema = listOf(keySchemaVal)
provisionedThroughput = provisionedVal
tableName = newTableName
}
try {
val response = ddb.createTable(request)
val tableActive = false
// Wait until the table is in Active state.
while (!tableActive) {
val tableStatus = checkTableStatus(ddb, newTableName)
if (tableStatus.equals("ACTIVE"))
break
delay(500)
}
return response.tableDescription?.tableArn.toString()
} catch (e: DynamoDbException) {
println("ERROR (DynamoDbException): " + e.message)
} catch (e: UnknownServiceErrorException) {
println("ERROR (UnknownServiceErrorException): " + e.message)
} finally {
ddb.close()
}
return ""
}
I can see the table created on my AWS account. However I want to modify my DynamoDbClient to execute the table creation on a local instance of the DynamoDB. I followed the instructions from AWS pages and I installed DynamoDB locally.
Here is how I am running it locally:
c:\code\dynamodb_local_latest>java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb
Initializing DynamoDB Local with the following configuration:
Port: 8000
InMemory: false
DbPath: null
SharedDb: true
shouldDelayTransientStatuses: false
CorsParams: *
I am able to access the local DynamoDB instance from the aws cli tool.
In order to try accessing the local instance of DynamoDB from the Kotlin code, I changed DynamoDbClient from this:
val dynamoDbClient = DynamoDbClient { region = "us-east-1" }
to this:
val endpoint = aws.sdk.kotlin.runtime.endpoint.Endpoint( "localhost",
"http",
port=8000,
false,
null,
"us-west-1")
val myEndpointResolver = StaticEndpointResolver(endpoint)
val dynamoDbClient = DynamoDbClient {endpointResolver = myEndpointResolver; region ="us-west-1" }
However I get the following error:
Exception in thread "DefaultDispatcher-worker-1" software.amazon.awssdk.crt.http.HttpException: socket connection refused.
at software.amazon.awssdk.crt.http.HttpClientConnection.onConnectionAcquired(HttpClientConnection.java:85)
What is the proper way to resolve that?
Thanks!

Answer 1

You can specify the EndPointResolver for the DynamoDbClient with the address of your DynamoDb local instance.
For example:
class LocalHostDynamoDb: AwsEndpointResolver {
override suspend fun resolve(service: String, region: String): AwsEndpoint
= AwsEndpoint("http://localhost:8000")
}
class MyClient {
...
val dynamoDbClient = DynamoDbClient {
region = awsRegion
endpointResolver = LocalHostDynamoDb()
}
...