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Overview

KrakenD can consume GraphQL APIs and expose them as traditional REST endpoints. This allows clients to access GraphQL data using simple HTTP GET requests without learning GraphQL query syntax.

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Example: Star Wars Films

The /starwars_films/{movie_id} endpoint queries the Star Wars GraphQL API and returns film data as a REST response.

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Try It

curl http://localhost:8080/starwars_films/1
This returns detailed information about “A New Hope” including species and homeworld data.

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Configuration

From config/krakend/krakend.json: 
{
  "endpoint": "/starwars_films/{movie_id}",
  "backend": [
    {
      "host": ["https://swapi-graphql.netlify.app/"],
      "url_pattern": "/.netlify/functions/index",
      "target": "data.film",
      "extra_config": {
        "backend/graphql": {
          "type": "query",
          "query": "query Query ($movie_id: ID!) {\nfilm (filmID: $movie_id) {\nid\nepisodeID\ntitle\ndirector\nreleaseDate\nspeciesConnection {\nspecies {\nname\nclassification\nhomeworld {\nname\n}\n}\n}\n}\n}",
          "variables": {
            "movie_id": "{movie_id}"
          }
        }
      }
    }
  ]
}

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How It Works

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1. GraphQL Query Definition

The actual GraphQL query (formatted for readability): 
query Query ($movie_id: ID!) {
  film (filmID: $movie_id) {
    id
    episodeID
    title
    director
    releaseDate
    speciesConnection {
      species {
        name
        classification
        homeworld {
          name
        }
      }
    }
  }
}
This query:
  • Accepts a $movie_id parameter
  • Fetches film details including nested species and homeworld data
  • Demonstrates GraphQL’s ability to request specific nested fields

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2. Variable Mapping

"variables": {
  "movie_id": "{movie_id}"
}
The {movie_id} placeholder in the endpoint path is passed as the $movie_id variable to the GraphQL query.

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3. Response Targeting

"target": "data.film"
GraphQL responses typically wrap results in a data object. The target parameter extracts just the film object, removing the GraphQL envelope. GraphQL Response: 
{
  "data": {
    "film": {
      "id": "ZmlsbXM6MQ==",
      "title": "A New Hope"
    }
  }
}
KrakenD Response (after targeting): 
{
  "id": "ZmlsbXM6MQ==",
  "title": "A New Hope"
}

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Query Types

The type parameter specifies the GraphQL operation: 
"type": "query"
Supported values:
  • query - Read operations (used in this example)
  • mutation - Write operations (create, update, delete)

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Example Response

{
  "id": "ZmlsbXM6MQ==",
  "episodeID": 4,
  "title": "A New Hope",
  "director": "George Lucas",
  "releaseDate": "1977-05-25",
  "speciesConnection": {
    "species": [
      {
        "name": "Human",
        "classification": "mammal",
        "homeworld": {
          "name": "Tatooine"
        }
      },
      {
        "name": "Droid",
        "classification": "artificial",
        "homeworld": null
      }
    ]
  }
}

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Benefits

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For Clients

  • Simple REST Interface - No need to construct GraphQL queries
  • Standard HTTP GET - Works with any HTTP client
  • URL Parameters - Familiar RESTful patterns

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For APIs

  • GraphQL Power - Leverage GraphQL’s efficient data fetching
  • Nested Data - Request related data in a single query
  • Type Safety - GraphQL schema validation

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For Teams

  • Gradual Migration - Expose GraphQL gradually as REST
  • Legacy Support - Support clients that only speak REST
  • API Gateway Pattern - Centralize GraphQL complexity

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Advanced Usage

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Multiple GraphQL Queries

You can aggregate multiple GraphQL queries: 
{
  "endpoint": "/movie-and-character/{movie_id}/{character_id}",
  "backend": [
    {
      "host": ["https://swapi-graphql.netlify.app/"],
      "url_pattern": "/.netlify/functions/index",
      "extra_config": {
        "backend/graphql": {
          "type": "query",
          "query": "query ($movie_id: ID!) { film(filmID: $movie_id) { title } }",
          "variables": { "movie_id": "{movie_id}" }
        }
      },
      "group": "film"
    },
    {
      "host": ["https://swapi-graphql.netlify.app/"],
      "url_pattern": "/.netlify/functions/index",
      "extra_config": {
        "backend/graphql": {
          "type": "query",
          "query": "query ($character_id: ID!) { person(personID: $character_id) { name } }",
          "variables": { "character_id": "{character_id}" }
        }
      },
      "group": "character"
    }
  ]
}

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Combining with Data Aggregation

GraphQL responses can be combined with REST API calls using Data Aggregation.

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Learn More

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