Component bean is not injected (autowired) by spring when running AWS lambda function using Spring Cloud function AWS Adapter - spring

Question

I am implementing AWS lambda function creating handler using Spring Cloud function AWS Adapter SpringBootRequestHandler. The functional bean registered in GenericApplicationContext is invoked, but autowiring of component class is giving NullPointer Exception.
I have tried #ComponentScan for base package at Spring Application.
Application class:
#Slf4j
#SpringBootApplication
#ComponentScan({ "com.poc.evthub" })
#EnableConfigurationProperties(EventHubProperties.class)
public class EventHubServerlessApplication implements ApplicationContextInitializer<GenericApplicationContext> {
public EventHubServerlessApplication() {
}
public static void main(String[] args) throws Exception {
FunctionalSpringApplication.run(EventHubServerlessApplication.class, args);
}
#Bean
public KinesisEventFunction ingestEvents() {
return new KinesisEventFunction();
}
#Override
public void initialize(GenericApplicationContext context) {
log.debug("======== initialize ========");
context.registerBean("ingestEvents", FunctionRegistration.class,
() -> new FunctionRegistration<Function<KinesisEvent, ApiResponse>>(ingestEvents())
.type(FunctionType.from(KinesisEvent.class).to(ApiResponse.class).getType()));
}
}
Handler:
public class KinesisEventHandler extends SpringBootRequestHandler<KinesisEvent, ApiResponse> {
}
Functional Bean:
package com.poc.evthub.function;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent;
import com.poc.evthub.beans.ApiResponse;
import com.poc.evthub.constant.Constants;
import com.poc.evthub.service.IngestionServiceFactory;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import java.util.function.Function;
#Slf4j
#Component
public class KinesisEventFunction implements Function<KinesisEvent, ApiResponse> {
private Context context = null;
#Autowired
private IngestionServiceFactory ingestionServiceFactory;
#Autowired
#Qualifier("targetExecutionContext")
public void setContext(Context context) {
log.info("Context: {}", context);
this.context = context;
}
#Override
public ApiResponse apply(final KinesisEvent kinesisEvent) {
log.info("KinesisEventFunction apply called...");
String sourceDomain = System.getenv(Constants.SYSENV.SOURCE_DOMAIN);
log.info("Source Domain = {}", sourceDomain);
if(null == kinesisEvent || null == kinesisEvent.getRecords()) {
log.error("Event contains no data. {}", System.lineSeparator());
//TODO build response NOT FOUND
return null;
}
else
log.info("Received {} records from {}. {}",
kinesisEvent.getRecords().size(),
kinesisEvent.getRecords().get(0).getEventSourceARN(),
System.lineSeparator());
log.info("ingestionServiceFactory = {}",ingestionServiceFactory);
ingestionServiceFactory.ingest();
return null;
}
}
Complete code and pom is uploaded at:
https://github.com/rjavaria/eventhub-serverless
KinesisEventFunction apply called...
Also able to read the environment value(source_domain) from lambda, and receiving Kinesis event record.
But #Autowired ingestionServiceFactory is null. I am injecting this component bean to delegate the business logic.
What is missed here, so spring is not able to inject this component bean?
Thanks in advance!

Answer 1

You could try manual injection of your IngestionServiceFactory bean into your function class via constructor or setter injection.
In your function class, add a constructor and remove #Autowired from your IngestionServiceFactory field, like:
...
public class KinesisEventFunction implements Function<KinesisEvent, ApiResponse> {
...
// No #Autowired here...
private final IngestionServiceFactory ingestionServiceFactory;
...
// The new constructor here...
public KinesisEventFunction(final IngestionServiceFactory pIngestionServiceFactory) {
this.ingestionServiceFactory = pIngestionServiceFactory;
}
...
}
Then in your main class (the one implementing ApplicationContextInitializer<GenericApplicationContext>), pass the reference to the factory when registering the function bean, like:
...
public class EventHubServerlessApplication implements ApplicationContextInitializer<GenericApplicationContext> {
...
#Autowired
private IngestionServiceFactory ingestionServiceFactory;
...
#Bean
public KinesisEventFunction ingestEvents() {
return new KinesisEventFunction(this.ingestionServiceFactory);
}
#Override
public void initialize(GenericApplicationContext context) {
log.debug("======== initialize ========");
context.registerBean("ingestEvents", FunctionRegistration.class,
() -> new FunctionRegistration<>(ingestEvents())
.type(FunctionType.from(KinesisEvent.class).to(ApiResponse.class).getType()));
}
}
Or, as you are already manually registering the function bean with context.registerBean(), you could just:
...
public class EventHubServerlessApplication implements ApplicationContextInitializer<GenericApplicationContext> {
...
#Autowired
private IngestionServiceFactory ingestionServiceFactory;
...
#Override
public void initialize(GenericApplicationContext context) {
log.debug("======== initialize ========");
context.registerBean("ingestEvents", FunctionRegistration.class,
() -> new FunctionRegistration<>(new KinesisEventFunction(this.ingestionServiceFactory))
.type(FunctionType.from(KinesisEvent.class).to(ApiResponse.class).getType()));
}
}
Please, let me know if it works!