MVFC.Aspire.Helpers.ApigeeEmulator 7.3.2

MVFC.Aspire.Helpers.ApigeeEmulator

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Helpers for integrating the Google Apigee Emulator with .NET Aspire projects, enabling local API proxy development and testing.

Motivation

Working with Apigee API proxies locally usually means:

• Spinning up the emulator container manually with the correct image and ports.
• Remembering to build and deploy the proxy bundle (ZIP) every time you make changes.
• Manually configuring TargetServers to point at your backend services.
• Dealing with host.docker.internal and port mismatches between your host and Docker.

With .NET Aspire you can define containers, but you still need to:

• Configure the emulator image, control port, and traffic port.
• Build and deploy your apiproxy bundle to the emulator on startup.
• Dynamically wire TargetServers to match the Aspire-allocated backend ports.

MVFC.Aspire.Helpers.ApigeeEmulator provides:

• AddApigeeEmulator(...) to start the emulator with sensible defaults.
• WithWorkspace(...) to point at your local proxy bundle and define a proxy health endpoint.
• WithEnvironment(...) to set the Apigee environment name.
• WithBackend(...) to automatically resolve Aspire backend endpoints as TargetServers.

Overview

This project facilitates the configuration and integration of the Apigee Emulator in distributed .NET Aspire applications, providing extension methods to:

• Add the Apigee Emulator container with pre-configured ports.
• Deploy the proxy bundle (apiproxy) automatically on startup.
• Dynamically inject TargetServer configurations pointing at Aspire-managed backends.
• Merge static and dynamic targetservers.json definitions for hybrid scenarios.

Apigee Emulator advantages

• Develop and test API proxies locally without a Google Cloud account.
• Validate traffic policies, security flows, and SharedFlows before pushing to production.
• Support Trace/Debug sessions for request inspection.
• Integrate emulator traffic with Aspire-managed backend services.

Compatible Images

• Emulator
  • gcr.io/apigee-release/hybrid/apigee-emulator (default in this helper)

Project Structure

• MVFC.Aspire.Helpers.ApigeeEmulator: Helpers and extensions library for Apigee Emulator.

Features

• Adds the Apigee Emulator container with default image and ports.
• Deploys the proxy bundle automatically when the emulator is ready.
• Resolves Aspire backend ports and injects TargetServer configurations.
• Merges existing static targetservers.json with dynamically generated entries.
• Provides fluent AppHost configuration methods.

Installation

dotnet add package MVFC.Aspire.Helpers.ApigeeEmulator

Quick Aspire usage (AppHost)

using Aspire.Hosting;
using MVFC.Aspire.Helpers.ApigeeEmulator;

var builder = DistributedApplication.CreateBuilder(args);

var apigeeWorkspace = Path.Combine(
    Directory.GetCurrentDirectory(),
    "apigee-workspace");

var api = builder.AddProject<Projects.MyApi>("my-api");

var apigee = builder.AddApigeeEmulator("apigee-emulator")
    .WithWorkspace(
        workspacePath: apigeeWorkspace,
        healthCheckPath: "/demo/health-check")
    .WithEnvironment("local")
    .WithBackend(api, "origin");

await builder.Build().RunAsync();

Ports

Provisioning diagram

sequenceDiagram
    participant Aspire as .NET Aspire
    participant Container as Apigee Emulator Container
    participant Hook as Deploy Lifecycle Hook
    participant Backend as Aspire Backend

    Aspire->>Container: Start container (apigee-emulator)
    Container-->>Aspire: Ready (control port available)
    Aspire->>Hook: Trigger AfterResourcesCreatedEvent
    Hook->>Backend: Wait for backend Running state
    Backend-->>Hook: Running (port resolved)
    Hook->>Hook: Build ZIP (merge targetservers.json)
    Hook->>Container: POST /v1/emulator/deploy
    Container-->>Hook: Deploy successful
    Hook-->>Aspire: Deployment completed

Public methods

• AddApigeeEmulator – Adds the emulator container with default image and ports.
• WithWorkspace – Sets the local path to the apiproxy bundle and the proxy health check path.
• WithEnvironment – Sets the Apigee environment name (default: "local").
• WithDockerImage – Overrides the Docker image and tag.
• WithBackend – Configures an Aspire backend as a TargetServer for the proxy.

Runtime behavior

• The helper waits until the emulator resource reaches the Running state before deployment.
• It also waits for configured backend resources to become available before generating TargetServers.
• The apiproxy bundle is copied to a temporary directory, optionally merged with dynamic targetservers.json, zipped, deployed, and then cleaned up.
• Backend resolution supports both Aspire projects and container resources.

Troubleshooting

Container does not become ready

• The first startup may take longer because the emulator image needs to be downloaded locally.
• Pull the image manually before running Aspire if startup time becomes an issue:

  docker pull gcr.io/apigee-release/hybrid/apigee-emulator
  

• Check whether Docker is running and able to create containers normally.

Bundle deploy is skipped

• Automatic deploy only happens when WithWorkspace(...) is configured with both a workspace path and a proxy health endpoint.
• If those values are not set, the container still starts, but the helper intentionally skips deployment.

Backend is unreachable from the emulator

• When using .WithBackend(...), the helper configures the backend endpoint to bypass the Aspire proxy.
• For ASP.NET Core projects, it also forces the backend to bind to 0.0.0.0, which is required for Docker-to-host access.
• If you configure the backend manually, make sure the service listens on an address reachable from Docker.

host.docker.internal issues on Linux

• On Linux, the helper adds --add-host host.docker.internal:host-gateway automatically.
• If Docker still cannot resolve it, verify that your Docker Engine supports host-gateway.

Port already in use

• Override the default ports if 7071 or 8998 are already occupied:

  builder.AddApigeeEmulator(
      name: "apigee-emulator",
      controlPort: 7072,
      trafficPort: 8999);
  

Proxy health check never succeeds

• Confirm that the healthCheckPath passed to WithWorkspace(...) is a valid route exposed by your deployed proxy.
• If the proxy deploys successfully but that route returns non-success status codes, Aspire startup may continue retrying until timeout.

Playground proxy (example only)

The sections below document the example proxy included in the playground/ folder. They describe the sample Apigee proxy used to demonstrate the helper in a realistic setup. They are not required to use the NuGet package itself.

Architecture and policies of the example proxy

After validating the example project and the final configuration present in proxies/default.xml, this document reflects the actual routing structure, request flow, and configured policies.

General flow diagram

flowchart TD
    A["Request → /demo/*"] --> B{"Method / Route?"}
    
    B -->|OPTIONS| C["CORS Preflight (AM-Cors) → 200 No Backend"]
    B -->|DELETE/PUT/PATCH| D["Method Not Allowed (RF) → 405"]
    
    B -->|/sharedflow-check| Q["SharedFlow Check (FC-CallLogging)"]
    B -->|/spike-arrest| E["Spike Arrest Test (SA-SpikeArrest)"]
    B -->|/notfound| F["Not Found Demo (RF-NotFound) → 404"]
    B -->|/transform| G["Transform Envelope (JS-TransformResponse)"]
    B -->|/quota-test| H["Quota Rate Limit (QU-RateLimit)"]
    B -->|/health-check| I["Health Check (ServiceCallout + AM)"]
    B -->|/cached| J{"Cache Hit? (LookupCache)"}
    B -->|/admin| K["Admin Panel (AccessControl IP)"]
    B -->|/secure| L["Secure Resource (BasicAuth + JS Valid.)"]
    B -->|/xml| M["XML to JSON Format Convert"]
    B -->|/status/**| N["TargetRule: public (httpbin)"]
    B -->|Others| O["TargetRule: default (origin)"]

    J -->|Yes| J1["AM-CacheHit → Responds 200"]
    J -->|No| J2["Target Backend → Populates PC-Cache + AM-Miss"]

    E & G & H & I & J2 & K & L & M & N & O & Q --> P["PostFlow: Adds CORS + Custom Headers + FC-CallLogging"]

Policies implemented directly in flows

PostFlow policies

Whether the response comes from backend success, an intercepted response, or a planned error, the PostFlow enriches the outgoing message:

• AM-AddCorsHeaders.xml: Adds headers required to avoid browser CORS issues.
• AM-AddCustomHeaders.xml: Appends extra request and tracking metadata.
• FC-CallLogging.xml: Delegates shared logging behavior to the common-logging SharedFlow.

Global faults

• AM-DefaultFaultResponse.xml: Standardizes the JSON fault payload when Apigee raises an unhandled system error.

Requirements

• .NET 9+
• Aspire.Hosting >= 9.5.0
• Docker running locally

License

Apache-2.0