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A standalone service designed to consolidate your graphql APIs into one endpoint.

For a guide to getting started read this post. For full documentation visit the gateway homepage.

Running the Executable

The simplest way to run a gateway is to download the executable from the latest release on GitHub and then run it directly on your machine:

$ ./gateway start --port 4000 --services http://localhost:3000,http://localhost:3001

This will start a server on port 4000 that wraps over the services running at http://localhost:3000 and http://localhost:3001. For more information on possible arguments to pass the executable, run ./gateway --help.


This project is built as a go module and follows the practices outlined in the spec. Please consider all APIs experimental and subject to change until v1 has been released at which point semantic versioning will be strictly followed. Before then, minor version bumps denote an API breaking change.




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const MessageMissingCachedQuery = "PersistedQueryNotFound"

MessageMissingCachedQuery is the string that the server sends when the user assumes that the server knows about a caches query plan


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type AutomaticQueryPlanCache

type AutomaticQueryPlanCache struct {
	// contains filtered or unexported fields

AutomaticQueryPlanCache is a QueryPlanCache that will use the hash if it points to a known query plan, otherwise it will compute the plan and save it for later, to be referenced by the designated hash.

func NewAutomaticQueryPlanCache

func NewAutomaticQueryPlanCache() *AutomaticQueryPlanCache

NewAutomaticQueryPlanCache returns a fresh instance of

func (*AutomaticQueryPlanCache) Retrieve

func (c *AutomaticQueryPlanCache) Retrieve(ctx *PlanningContext, hash *string, planner QueryPlanner) (QueryPlanList, error)

Retrieve follows the "automatic query persistance" technique. If the hash is known, it will use the referenced query plan. If the hash is not know but the query is provided, it will compute the plan, return it, and save it for later use. If the hash is not known and the query is not provided, it will return with an error prompting the client to provide the hash and query

func (*AutomaticQueryPlanCache) WithCacheTTL

func (c *AutomaticQueryPlanCache) WithCacheTTL(duration time.Duration) *AutomaticQueryPlanCache

WithCacheTTL updates and returns the cache with the new cache lifetime. Queries that haven't been used in that long are cleaned up on the next query.

type DefaultLogger

type DefaultLogger struct {
	// contains filtered or unexported fields

DefaultLogger handles the logging in the gateway library

func (*DefaultLogger) Debug

func (l *DefaultLogger) Debug(args ...interface{})

Debug should be used for any logging that would be useful for debugging

func (*DefaultLogger) Info

func (l *DefaultLogger) Info(args ...interface{})

Info should be used for any logging that doesn't necessarily need attention but is nice to see by default

func (*DefaultLogger) QueryPlanStep

func (l *DefaultLogger) QueryPlanStep(step *QueryPlanStep)

QueryPlanStep formats and logs a query plan step for human consumption

func (*DefaultLogger) Warn

func (l *DefaultLogger) Warn(args ...interface{})

Warn should be used for logging that needs attention

func (*DefaultLogger) WithFields

func (l *DefaultLogger) WithFields(fields LoggerFields) Logger

WithFields adds the provided fields to the Log

type ErrExecutor

type ErrExecutor struct {
	Error error

ErrExecutor always returnes the internal error.

func (*ErrExecutor) Execute

func (e *ErrExecutor) Execute(ctx *ExecutionContext) (map[string]interface{}, error)

Execute returns the internet error

type ExecutionContext

type ExecutionContext struct {
	Plan               *QueryPlan
	Variables          map[string]interface{}
	RequestContext     context.Context
	RequestMiddlewares []graphql.NetworkMiddleware

ExecutionContext is a well-type alternative to context.Context and provides the context for a particular execution.

type ExecutionMiddleware

type ExecutionMiddleware interface {

ExecutionMiddleware are things that interject in the execution process

type Executor

type Executor interface {
	Execute(ctx *ExecutionContext) (map[string]interface{}, error)

Executor is responsible for executing a query plan against the remote schemas and returning the result

type ExecutorFunc

type ExecutorFunc func(ctx *ExecutionContext) (map[string]interface{}, error)

ExecutorFunc wraps a function to be used as an executor.

func (ExecutorFunc) Execute

func (e ExecutorFunc) Execute(ctx *ExecutionContext) (map[string]interface{}, error)

Execute invokes and returns the internal function

type FieldURLMap

type FieldURLMap map[string][]string

FieldURLMap holds the intformation for retrieving the valid locations one can find the value for the field

func (FieldURLMap) Concat

func (m FieldURLMap) Concat(other FieldURLMap) FieldURLMap

Concat returns a new field map url whose entries are the union of both maps

func (FieldURLMap) RegisterURL

func (m FieldURLMap) RegisterURL(parent string, field string, locations ...string)

RegisterURL adds a new location to the list of possible places to find the value for parent.field

func (FieldURLMap) URLFor

func (m FieldURLMap) URLFor(parent string, field string) ([]string, error)

URLFor returns the list of locations one can find parent.field.

type Gateway

type Gateway struct {
	// contains filtered or unexported fields

Gateway is the top level entry for interacting with a gateway. It is responsible for merging a list of remote schemas into one, generating a query plan to execute based on an incoming request, and following that plan

func New

func New(sources []*graphql.RemoteSchema, configs ...Option) (*Gateway, error)

New instantiates a new schema with the required stuffs.

func (*Gateway) Execute

func (g *Gateway) Execute(ctx *RequestContext, plans QueryPlanList) (map[string]interface{}, error)

Execute takes a query string, executes it, and returns the response

func (*Gateway) GetPlans

func (g *Gateway) GetPlans(ctx *RequestContext) (QueryPlanList, error)

func (*Gateway) GraphQLHandler

func (g *Gateway) GraphQLHandler(w http.ResponseWriter, r *http.Request)

GraphQLHandler returns a http.HandlerFunc that should be used as the primary endpoint for the gateway API. The endpoint will respond to queries on both GET and POST requests. POST requests can either be a single object with { query, variables, operationName } or a list of that object.

func (*Gateway) PlaygroundHandler

func (g *Gateway) PlaygroundHandler(w http.ResponseWriter, r *http.Request)

PlaygroundHandler returns a http.HandlerFunc which on GET requests shows the user an interface that they can use to interact with the API. On POSTs the endpoint executes the designated query

func (*Gateway) Query

func (g *Gateway) Query(ctx context.Context, input *graphql.QueryInput, receiver interface{}) error

Query takes a query definition and writes the result to the receiver

type HTTPOperation

type HTTPOperation struct {
	Query         string                 `json:"query"`
	Variables     map[string]interface{} `json:"variables"`
	OperationName string                 `json:"operationName"`
	Extensions    struct {
		QueryPlanCache *PersistedQuerySpecification `json:"persistedQuery"`
	} `json:"extensions"`

HTTPOperation is the incoming payload when sending POST requests to the gateway

type Logger

type Logger interface {
	Debug(args ...interface{})
	Info(args ...interface{})
	Warn(args ...interface{})

	WithFields(fields LoggerFields) Logger
	QueryPlanStep(step *QueryPlanStep)

Logger logs messages

type LoggerFields

type LoggerFields map[string]interface{}

LoggerFields is a wrapper over a map of key,value pairs to associate with the log

type Merger

type Merger interface {
	Merge([]*ast.Schema) (*ast.Schema, error)

Merger is an interface for structs that are capable of taking a list of schemas and returning something that resembles a "merge" of those schemas.

type MergerFunc

type MergerFunc func([]*ast.Schema) (*ast.Schema, error)

MergerFunc is a wrapper of a function of the same signature as Merger.Merge

func (MergerFunc) Merge

func (m MergerFunc) Merge(sources []*ast.Schema) (*ast.Schema, error)

Merge invokes and returns the wrapped function

type Middleware

type Middleware interface {

Middleware are things that can modify a gateway normal execution

type MiddlewareList

type MiddlewareList []Middleware

MiddlewareList is a list of Middlewares

type MinQueriesPlanner

type MinQueriesPlanner struct {
	LocationPriorities []string

MinQueriesPlanner does the most basic level of query planning

func (*MinQueriesPlanner) Plan

Plan computes the nested selections that will need to be performed

func (*MinQueriesPlanner) WithLocationPriorities

func (p *MinQueriesPlanner) WithLocationPriorities(priorities []string) QueryPlanner

func (*MinQueriesPlanner) WithQueryerFactory

func (p *MinQueriesPlanner) WithQueryerFactory(factory *QueryerFactory) QueryPlanner

WithQueryerFactory returns a version of the planner with the factory set

type MockErrPlanner

type MockErrPlanner struct {
	Err error

MockErrPlanner always returns the provided error. Useful in testing.

func (*MockErrPlanner) Plan

type MockExecutor

type MockExecutor struct {
	Value map[string]interface{}

MockExecutor always returns a success with the provided value

func (*MockExecutor) Execute

func (e *MockExecutor) Execute(ctx *ExecutionContext) (map[string]interface{}, error)

Execute returns the provided value

type MockPlanner

type MockPlanner struct {
	Plans QueryPlanList

MockPlanner always returns the provided list of plans. Useful in testing.

func (*MockPlanner) Plan

type NoQueryPlanCache

type NoQueryPlanCache struct{}

NoQueryPlanCache will always compute the plan for a query, regardless of the value passed as `hash`

func (*NoQueryPlanCache) Retrieve

func (p *NoQueryPlanCache) Retrieve(ctx *PlanningContext, hash *string, planner QueryPlanner) (QueryPlanList, error)

Retrieve just computes the query plan

type Option

type Option func(*Gateway)

Option is a function to be passed to New that configures the resulting schema

func WithAutomaticQueryPlanCache

func WithAutomaticQueryPlanCache() Option

WithAutomaticQueryPlanCache enables the "automatic persisted query" technique

func WithExecutor

func WithExecutor(e Executor) Option

WithExecutor returns an Option that sets the executor of the gateway

func WithLocationPriorities

func WithLocationPriorities(priorities []string) Option

func WithLogger

func WithLogger(l Logger) Option

WithLogger returns an Option that sets the logger of the gateway

func WithMerger

func WithMerger(m Merger) Option

WithMerger returns an Option that sets the merger of the gateway

func WithMiddlewares

func WithMiddlewares(middlewares ...Middleware) Option

WithMiddlewares returns an Option that adds middlewares to the gateway

func WithNoQueryPlanCache

func WithNoQueryPlanCache() Option

WithNoQueryPlanCache is the default option and disables any persisted query behavior

func WithPlanner

func WithPlanner(p QueryPlanner) Option

WithPlanner returns an Option that sets the planner of the gateway

func WithQueryFields

func WithQueryFields(fields ...*QueryField) Option

WithQueryFields returns an Option that adds the given query fields to the gateway

func WithQueryPlanCache

func WithQueryPlanCache(p QueryPlanCache) Option

WithQueryPlanCache sets the query plan cache that the gateway will use

func WithQueryerFactory

func WithQueryerFactory(factory *QueryerFactory) Option

WithQueryerFactory returns an Option that changes the queryer used by the planner when generating plans that interact with remote services.

type ParallelExecutor

type ParallelExecutor struct{}

ParallelExecutor executes the given query plan by starting at the root of the plan and walking down the path stitching the results together

func (*ParallelExecutor) Execute

func (executor *ParallelExecutor) Execute(ctx *ExecutionContext) (map[string]interface{}, error)

Execute returns the result of the query plan

type PersistedQuerySpecification

type PersistedQuerySpecification struct {
	Version int    `json:"version"`
	Hash    string `json:"sha256Hash"`

type Planner

type Planner struct {
	QueryerFactory *QueryerFactory
	// contains filtered or unexported fields

Planner is meant to be embedded in other QueryPlanners to share configuration

func (*Planner) GetQueryer

func (p *Planner) GetQueryer(ctx *PlanningContext, url string) graphql.Queryer

GetQueryer returns the queryer that should be used to resolve the plan

type PlannerWithLocationPriorities

type PlannerWithLocationPriorities interface {
	WithLocationPriorities(priorities []string) QueryPlanner

PlannerWithLocationFactory is an interface for planners with configurable location priorities

type PlannerWithQueryerFactory

type PlannerWithQueryerFactory interface {
	WithQueryerFactory(*QueryerFactory) QueryPlanner

PlannerWithQueryerFactory is an interface for planners with configurable queryer factories

type PlanningContext

type PlanningContext struct {
	Query     string
	Schema    *ast.Schema
	Locations FieldURLMap
	Gateway   *Gateway

PlanningContext is the input struct to the Plan method

type QueryField

type QueryField struct {
	Name      string
	Type      *ast.Type
	Arguments ast.ArgumentDefinitionList
	Resolver  func(context.Context, map[string]interface{}) (string, error)

QueryField is a hook to add gateway-level fields to a gateway. Limited to only being able to resolve an id of an already existing type in order to keep business logic out of the gateway.

type QueryPlan

type QueryPlan struct {
	Operation           *ast.OperationDefinition
	RootStep            *QueryPlanStep
	FragmentDefinitions ast.FragmentDefinitionList
	FieldsToScrub       map[string][][]string

QueryPlan is the full plan to resolve a particular query

type QueryPlanCache

type QueryPlanCache interface {
	Retrieve(ctx *PlanningContext, hash *string, planner QueryPlanner) (QueryPlanList, error)

QueryPlanCache decides when to compute a plan

type QueryPlanList

type QueryPlanList []*QueryPlan

QueryPlanList is a list of plans which can be indexed by operation name

func (QueryPlanList) ForOperation

func (l QueryPlanList) ForOperation(name string) (*QueryPlan, error)

ForOperation returns the query plan meant to satisfy the given operation name

type QueryPlanStep

type QueryPlanStep struct {
	// execution meta data
	InsertionPoint []string
	Then           []*QueryPlanStep

	// required info to generate the query
	Queryer      graphql.Queryer
	ParentType   string
	ParentID     string
	SelectionSet ast.SelectionSet

	// pre-generated query stuff
	QueryDocument       *ast.QueryDocument
	QueryString         string
	FragmentDefinitions ast.FragmentDefinitionList
	Variables           Set

QueryPlanStep represents a step in the plan required to fulfill a query.

type QueryPlanner

type QueryPlanner interface {
	Plan(*PlanningContext) (QueryPlanList, error)

QueryPlanner is responsible for taking a string with a graphql query and returns the steps to fulfill it

type QueryerFactory

type QueryerFactory func(ctx *PlanningContext, url string) graphql.Queryer

QueryerFactory is a function that returns the queryer to use depending on the context

type RequestContext

type RequestContext struct {
	Context       context.Context
	Query         string
	OperationName string
	Variables     map[string]interface{}
	CacheKey      string

RequestContext holds all of the information required to satisfy the user's query

type RequestMiddleware

type RequestMiddleware graphql.NetworkMiddleware

RequestMiddleware is a middleware that can modify outbound requests to services

func (RequestMiddleware) Middleware

func (p RequestMiddleware) Middleware()

Middleware marks RequestMiddleware as a valid middleware

type ResponseMiddleware

type ResponseMiddleware func(ctx *ExecutionContext, response map[string]interface{}) error

ResponseMiddleware is a middleware that can modify the response before it is serialized and sent to the user

func (ResponseMiddleware) ExecutionMiddleware

func (p ResponseMiddleware) ExecutionMiddleware()

ExecutionMiddleware marks ResponseMiddleware as a valid execution middleware

func (ResponseMiddleware) Middleware

func (p ResponseMiddleware) Middleware()

Middleware marks ResponseMiddleware as a valid middleware

type Set

type Set map[string]bool

Set is a set

func (Set) Add

func (set Set) Add(k string)

Add adds the item to the set

func (Set) Has

func (set Set) Has(k string) bool

Has returns wether or not the string is in the set

func (Set) Remove

func (set Set) Remove(k string)

Remove removes the item from the set


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