Configure Introspection

When running wunderctl up, WunderGraph automatically sets up a number of file watchers to automatically re-generate the configuration and re-start the WunderGraph Server when changes are made to the configuration.

This approach has two downsides. First, we can only detect changes to the file system. So, if you're changing the schema of your database, you'd have to manually re-start the process, which would be inconvenient.

Second, whenever you change one of the configuration files, e.g. you modify a GraphQL Operation, wunderctl would have to re-introspect all data sources. This works fine for a small number of data sources, but doesn't really scale.

That's why we've introduced introspection caching.

When caching is enabled, if a cache entry is found for a data source, it's always used instead of introspecting the data source again. Cache is optional and might be turned off globally using the --no-cache flag.

Cache can be emptied when wunderctl starts by using the --clear-cache flag. Additionally, wunderctl up will automatically clear the cache when it starts up. To clear the cache again, just restart it.

For CI environments that cannot perform network requests, it might be useful to generate the cache contents and make the tests run offline.

To populate the cache contents run wunderctl generate --clear-cache. This will delete any previous cache, introspect the data sources, and finally write the cache entries. .wunderctl/cache can then be stored and deployed to CI runners.

To verify that your tests can run without fetching data from the network in a connected machine, the --offline flag can be used to disable loading remote resources.

By default, wunderctl up will poll remote data sources periodically every 5 seconds, which should be fine for most data sources. The default interval can be changed using the --default-polling-interval flag.

For remote data sources with large schemas, we recommend setting the interval to a higher value to not overload the remote server. To set a different polling interval, use pollingIntervalSeconds:

// wundergraph.config.ts
const spaceX = introspect.graphql({
  apiNamespace: 'spacex',
  url: 'https://spacex-api.fly.dev/graphql/',
  introspection: {
    pollingIntervalSeconds: 30,
  },
});

To disable polling for a given data source, set its pollingIntervalSeconds to 0. Additionally, the default polling interval can also be disabled using --default-polling-interval=5.

It's also possible to disable introspection caching for a given data source. Set disableCache to true, and wunderctl up will ignore the cache for this data source.

// wundergraph.config.ts
const spaceX = introspect.graphql({
  apiNamespace: 'spacex',
  url: 'https://spacex-api.fly.dev/graphql/',
  introspection: {
    disableCache: true,
  },
});

Disabling the cache can result in reduced performance, because the data source is introspected every time a configuration file is changed.

In order to authorize introspection request you have to add header either via headers configuration or by a similar headers builder in the introspection configuration.

Using this approach you could use the same static headers for introspection and for requests at runtime.

Specifying dynamic (client request headers) will have no effect on introspection. That's because at introspection time, there's no client request. So, only static headers (string or environment variables) will work.

// simple graphql api
const countries = introspect.graphql({
  apiNamespace: 'countries',
  url: ' http://localhost:4000/',
  headers: (builder) =>
    builder
      // this header has no effect on introspection
      .addClientRequestHeader('X-Authorization', 'Authorization')
      // this header is shared between introspection and actual requests
      .addStaticHeader('Authorization', 'Secret'),
});

// or federated api
const federatedApi = introspect.federation({
  apiNamespace: 'federated',
  upstreams: [
    {
      url: 'http://localhost:4001/graphql',
      headers: (builder) => builder.addStaticHeader('Authorization', 'Secret'),
    },
  ],
});

By providing headers in the introspection configuration you could avoid using static header for all requests. Headers configured in a such way will be used only for the graphql introspection and getting the service sdl query in case of federated api.

// simple graphql api
const countries = introspect.graphql({
  apiNamespace: 'countries',
  url: ' http://localhost:4000/',
  headers: (builder) => builder.addClientRequestHeader('X-Authorization', 'Authorization'),
  introspection: {
    headers: (builder) => builder.addStaticHeader('Authorization', 'Secret'),
  },
});

// or federated api
const federatedApi = introspect.federation({
  apiNamespace: 'federated',
  upstreams: [
    {
      url: 'http://localhost:4001/graphql',
      introspection: {
        headers: (builder) => builder.addStaticHeader('Authorization', 'Secret'),
      },
    },
  ],
});

You could even mix up both approaches. In this case introspection headers will be merged with the headers provided in the headers configuration and the headers provided in the introspection configuration will have higher priority for the introspection request.

const countries = introspect.graphql({
  apiNamespace: 'countries',
  url: ' http://localhost:4000/',
  headers: (builder) => builder.addStaticHeader('Authorization', 'Secret One'),
  introspection: {
    headers: (builder) => builder.addStaticHeader('Authorization', 'Secret Two'),
  },
});