Adding custom headers

Hi,

I am looking for the way to add a custom header in all the request sent to AppSync. I was able to do it with the Amplify library but since I need some the advanced functionnalities from aws-appsync-sdk, I am trying to do it with the appsync-sdk as well.

I didn’t find any documentation on this topic. Is there a way to do it?

For example, I tried to add request option when creating the AWSAppSyncClient without any success:

const appSyncClient = new AWSAppSyncClient({
  url: config.amplify_config.aws_appsync_graphqlEndpoint,
  request: async (operation) => {
    const user = await Auth.currentUserInfo();
    logger.debug("AWSAppSyncClient request:", user);
    operation.setContext({
      headers: {
        'amt-custom-username': user.username
      }
    });
  },
  region: config.amplify_config.aws_appsync_region,
  auth: {
    type: AUTH_TYPE.AWS_IAM,
    credentials: () => Auth.currentCredentials(),
  },
});

[elorzafe]

Hi @OlivierPT

Try this sample code here

In order to read the custom header on your request mapping template use this $context.request.headers.your_header_name

I used this on the previous sample

{
    "version": "2017-02-28",
    "payload": {
    	"id": "${context.arguments.id}",
        "title": "$context.request.headers.hi"
    }
}

Let me know how it goes

[ziggy6792]

@elorzafe you are an absolute legend. Copied your sample into my project and used $context.request.headers.your_header_name in my request mapping to get my custom header. Worked first time!

In my case I am accessing a graphql api through a lambda and using IAM credentials. Here is my code to setup the AWSAppSyncClient if anyone is interested.

const AWS = require('aws-sdk');
const AWSAppSyncClient = require('aws-appsync').default;
const { createAppSyncLink } = require('aws-appsync');
require('es6-promise').polyfill();
require('isomorphic-fetch');
const { ApolloLink } = require('apollo-link');
const { createHttpLink } = require('apollo-link-http');
const { setContext } = require('apollo-link-context');

const buildApiClient = (connection, customHeaders) => {
  const { URL, REGION, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN } = connection;

  AWS.config.update({
    region: REGION,
    credentials: new AWS.Credentials(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN),
  });
  const { credentials } = AWS.config;

  const AppSyncConfig = {
    url: URL,
    region: REGION,
    auth: {
      type: 'AWS_IAM',
      credentials,
    },
    disableOffline: true,
  };

  const appsyncClient = new AWSAppSyncClient(AppSyncConfig, {
    defaultOptions: {
      query: {
        fetchPolicy: 'network-only',
        errorPolicy: 'all',
      },
    },
    link: createAppSyncLink({
      ...AppSyncConfig,
      resultsFetcherLink: ApolloLink.from([
        setContext((request, previousContext) => ({
          headers: {
            ...previousContext.headers,
            ...customHeaders,
          },
        })),
        createHttpLink({
          uri: AppSyncConfig.url,
        }),
      ]),
    }),
  });

  return appsyncClient;
};

module.exports = buildApiClient;