After upgrading to DGS10.0.0 the response headers doesn't have custom headers set

[dokkaraman]

Discussed in #2100

^{Originally posted by dokkaraman January 3, 2025}
After upgrading to DGS10.0.0 the headers (Cache-Control) set via SimplePerformantInstrumentation no longer get set in the final response of a subgraph
This works till version 9.2.1

[paulbakker]

Can you provide some details about what you're doing in the SimplePerformantInstrumentation implementation?

[dokkaraman]

We are adding Cache Control header as part of custom instrumentation which extends SimplePerformantInstrumentation
The value of cache control is variable which gets determined in this class.
This used to work till version 9.1.2 of DGS and after upgrade it started failing

[paulbakker]

SimplePerformantInstrumentation doesn't have access to request/response without using some other context mechanism, so can you share exactly how you're doing this? That might explain why this changed hopefully.

[dokkaraman]

We use spring framework and here is boiler plate code

import com.netflix.graphql.dgs.DgsExecutionResult;
import graphql.ExecutionResult;
import graphql.GraphQLContext;
import graphql.execution.instrumentation.InstrumentationState;
import graphql.execution.instrumentation.SimplePerformantInstrumentation;
import graphql.execution.instrumentation.parameters.InstrumentationExecutionParameters;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpHeaders;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class ResponseHeaderInstrument extends SimplePerformantInstrumentation {

    @Value("${entity.cacheMaxAge:max-age=60}")
    private String cacheMaxAge;


    @Override
    public CompletableFuture<ExecutionResult> instrumentExecutionResult(ExecutionResult executionResult,
                                                                        InstrumentationExecutionParameters parameters,
                                                                        InstrumentationState state) {
        HttpHeaders responseHeaders = new HttpHeaders();
        List<String> subgraphCacheControls = new ArrayList<>();

        try {
            if (parameters != null) {
                var gqlContext = parameters.getGraphQLContext();
                ....
                //Logic to add subgraphCacheControls list
                .....
            }
        } catch (Exception e) {
            log.warn("Exception while processing gqlContext", e);
        }

        if (!subgraphCacheControls.isEmpty()) {
            subgraphCacheControls.forEach(cacheControl -> responseHeaders.add("cache-control", cacheControl));
        } else {
            responseHeaders.add("cache-control", cacheMaxAge);
        }

        return super.instrumentExecutionResult(
                DgsExecutionResult.builder().executionResult(executionResult).headers(responseHeaders).build(),
                parameters,
                state
        );
    }
    

[dokkaraman]

If I change the above code to below it works

import graphql.GraphQLContext;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.graphql.server.WebGraphQlInterceptor;
import org.springframework.graphql.server.WebGraphQlRequest;
import org.springframework.graphql.server.WebGraphQlResponse;
import org.springframework.http.HttpHeaders;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;


@Component
@Slf4j
class ResponseHeaderInstrument implements WebGraphQlInterceptor {
    @Value("${entity.cacheMaxAge:max-age=60}")
    private String cacheMaxAge;


    @Override
    public Mono<WebGraphQlResponse> intercept(WebGraphQlRequest request, Chain chain) {
        return chain.next(request).doOnNext(response -> {
            response.getExecutionInput().getGraphQLContext();
            GraphQLContext
                gqlContext = (response != null && response.getExecutionInput() != null) ? response.getExecutionInput().getGraphQLContext() : null;
            HttpHeaders responseHeaders = getResponseHeadersFromContext(gqlContext, cacheMaxAge);
            log.debug("Response headers: {}", responseHeaders);
                response.getResponseHeaders().addAll(responseHeaders);
        });
    }

    private HttpHeaders getResponseHeadersFromContext(GraphQLContext gqlContext, String cacheMaxAge) {
        HttpHeaders responseHeaders = new HttpHeaders();
        List<String> subgraphCacheControls = new ArrayList<>();

        try {
            if (gqlContext != null) {
                ....
                //Logic to add subgraphCacheControls list
                .....
            }
        } catch (Exception e) {
            log.warn("Exception while processing gqlContext", e);
        }

        if (!subgraphCacheControls.isEmpty()) {
            subgraphCacheControls.forEach(cacheControl -> responseHeaders.add("cache-control", cacheControl));
        } else {
            responseHeaders.add("cache-control", cacheMaxAge);
        }

        return responseHeaders;
    }
   

[paulbakker]

Thanks for the extra information. It looks like what changed is setting headers on DgsExecutionResult.
Using WebGraphQlInterceptor is probably a better mechanism, because it better separates GraphQL execution from transport related concerns, but since this is changed behavior we should look into it further.

[paulbakker]

I have looked into this further and created a fix here: #2104

[paulbakker]

Fixed by #2104