AppSync
A zero-dependency, in-process fake of AWS AppSync (GraphQL APIs).
| Property | Value |
|---|---|
| Port | 4728 |
| Protocol | REST/JSON (paths under /v1) |
| Healthcheck | GET /_parlel/health |
| Reset | POST /_parlel/reset |
Quick start
AWS_REGION=us-east-1
AWS_ENDPOINT_URL=http://127.0.0.1:4728
AWS_ACCESS_KEY_ID=parlel
AWS_SECRET_ACCESS_KEY=parlel
Implemented operations
| Operation | Path |
|---|---|
| CreateGraphqlApi | POST /v1/apis |
| ListGraphqlApis | GET /v1/apis |
| GetGraphqlApi | GET /v1/apis/{apiId} |
| DeleteGraphqlApi | DELETE /v1/apis/{apiId} |
| CreateDataSource | POST /v1/apis/{apiId}/datasources |
| ListDataSources | GET /v1/apis/{apiId}/datasources |
| CreateResolver | POST /v1/apis/{apiId}/types/{typeName}/resolvers |
| ListResolvers | GET /v1/apis/{apiId}/types/{typeName}/resolvers |
| (resolve) | POST /v1/apis/{apiId}/resolve |
The trivial resolver dispatch at /v1/apis/{apiId}/resolve echoes the request
arguments back under the resolved fieldName.
SDK example
import { AppSyncClient, CreateGraphqlApiCommand } from "@aws-sdk/client-appsync";
const appsync = new AppSyncClient({
region: "us-east-1",
endpoint: "http://127.0.0.1:4728",
credentials: { accessKeyId: "parlel", secretAccessKey: "parlel" },
});
const { graphqlApi } = await appsync.send(
new CreateGraphqlApiCommand({ name: "myapi", authenticationType: "API_KEY" }),
);
console.log(graphqlApi?.uris?.GRAPHQL);
Access via MCP / preview URL
Reachable through the parlel pool MCP bridge and preview URL. No auth setup required.
Surface coverage
This emulator faithfully replicates the API surface most application code and agents exercise. Anything below the supported lines is either an intentional design choice for a fast, zero-cost local emulator (✓ By design) or a candidate for a future release (⟳ Roadmap) — never a silent inaccuracy.
Legend: ✅ fully supported · ◐ accepted (stored, not strictly enforced) · ✓ by design · ⟳ on the roadmap.
| Area | Status | Notes |
|---|---|---|
| GraphQL execution | ✓ by design | No real engine; resolver dispatch echoes |
| Schema management | ⟳ roadmap | Schema upload/introspection not modeled |
| VTL templates | ◐ accepted | Stored but not evaluated |
| Auth enforcement | ✓ by design | Types recorded but not enforced |
| Pagination | ⟳ roadmap | List operations return all items |
| CloudWatch logging | ⟳ roadmap | logConfig not modeled |
| X-Ray tracing | ✓ by design | xrayEnabled stored but not enforced |
| Caching | ⟳ roadmap | CachingConfig not modeled |
| Pipeline resolvers | ⟳ roadmap | pipelineConfig not modeled |
Error codes & shapes
Errors follow the real AWS AppSync format: { "__type": "...", "message": "..." } with x-amzn-errortype header.
| Error | Status | When |
|---|---|---|
| BadRequestException | 400 | Missing required field, invalid JSON |
| NotFoundException | 404 | API or resource not found |
| UnknownOperationException | 404 | Unknown route/method |
| InternalFailureException | 500 | Server error |
Manifest
{
"name": "appsync",
"version": "0.1",
"port": 4728,
"protocol": "http",
"healthcheck": "/_parlel/health"
}
Configuration — test.env
Copy these into your test.env (used by the bridge sidecar flow). Tokens are Parlel's seeded test credentials — any non-empty value is accepted by the emulator, so you rarely need to change them. Swap in real credentials only when pointing at the live service in prod.env.
AWS_ACCESS_KEY_ID=parlel
AWS_SECRET_ACCESS_KEY=parlel
AWS_REGION=us-east-1
AWS_ENDPOINT_URL=http://parlel-bridge:4728