feat(provider): implement ProxyProvider reverse proxy
Replace the Phase 3 stub with a working ProxyProvider that reverse-proxies requests to upstream provider binaries via httputil.ReverseProxy. Implements Provider + Renderable interfaces. Includes 9 tests covering proxy routing, health passthrough, element spec, and invalid upstream handling. Co-Authored-By: Virgil <virgil@lethean.io>
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2 changed files with 301 additions and 8 deletions
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@ -2,11 +2,111 @@
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package provider
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// ProxyProvider will wrap polyglot (PHP/TS) providers that publish an OpenAPI
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// spec and run their own HTTP handler. The Go API layer reverse-proxies to
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// their endpoint.
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//
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// This is a Phase 3 feature. The type is declared here as a forward reference
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// so the package structure is established.
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//
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// See the design spec SS Polyglot Providers for the full ProxyProvider contract.
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import (
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"net/http"
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"net/http/httputil"
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"net/url"
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"strings"
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"github.com/gin-gonic/gin"
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)
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// ProxyConfig configures a ProxyProvider that reverse-proxies to an upstream
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// process (typically a runtime provider binary listening on 127.0.0.1).
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type ProxyConfig struct {
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// Name is the provider identity, e.g. "cool-widget".
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Name string
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// BasePath is the API route prefix, e.g. "/api/v1/cool-widget".
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BasePath string
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// Upstream is the full URL of the upstream process,
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// e.g. "http://127.0.0.1:9901".
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Upstream string
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// Element describes the custom element for GUI rendering.
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// Leave zero-value if the provider has no UI.
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Element ElementSpec
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// SpecFile is the filesystem path to the provider's OpenAPI spec.
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// Used by the Swagger aggregator. Leave empty if none.
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SpecFile string
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}
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// ProxyProvider reverse-proxies requests to an upstream HTTP process.
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// It implements Provider and Renderable so it integrates with the
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// service provider framework and GUI discovery.
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type ProxyProvider struct {
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config ProxyConfig
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proxy *httputil.ReverseProxy
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}
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// NewProxy creates a ProxyProvider from the given configuration.
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// The upstream URL must be valid or NewProxy will panic.
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func NewProxy(cfg ProxyConfig) *ProxyProvider {
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target, err := url.Parse(cfg.Upstream)
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if err != nil {
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panic("provider.NewProxy: invalid upstream URL: " + err.Error())
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}
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proxy := httputil.NewSingleHostReverseProxy(target)
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// Preserve the original Director but strip the base path so the
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// upstream receives clean paths (e.g. /items instead of /api/v1/cool-widget/items).
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defaultDirector := proxy.Director
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basePath := strings.TrimSuffix(cfg.BasePath, "/")
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proxy.Director = func(req *http.Request) {
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defaultDirector(req)
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// Strip the base path prefix from the request path.
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req.URL.Path = strings.TrimPrefix(req.URL.Path, basePath)
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if req.URL.Path == "" {
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req.URL.Path = "/"
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}
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req.URL.RawPath = strings.TrimPrefix(req.URL.RawPath, basePath)
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}
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return &ProxyProvider{
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config: cfg,
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proxy: proxy,
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}
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}
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// Name returns the provider identity.
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func (p *ProxyProvider) Name() string {
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return p.config.Name
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}
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// BasePath returns the API route prefix.
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func (p *ProxyProvider) BasePath() string {
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return p.config.BasePath
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}
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// RegisterRoutes mounts a catch-all reverse proxy handler on the router group.
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func (p *ProxyProvider) RegisterRoutes(rg *gin.RouterGroup) {
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rg.Any("/*path", func(c *gin.Context) {
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// Use the underlying http.ResponseWriter directly. Gin's
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// responseWriter wrapper does not implement http.CloseNotifier,
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// which httputil.ReverseProxy requires for cancellation signalling.
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var w http.ResponseWriter = c.Writer
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if uw, ok := w.(interface{ Unwrap() http.ResponseWriter }); ok {
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w = uw.Unwrap()
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}
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p.proxy.ServeHTTP(w, c.Request)
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})
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}
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// Element returns the custom element specification for GUI rendering.
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func (p *ProxyProvider) Element() ElementSpec {
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return p.config.Element
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}
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// SpecFile returns the path to the provider's OpenAPI spec file.
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func (p *ProxyProvider) SpecFile() string {
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return p.config.SpecFile
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}
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// Upstream returns the upstream URL string.
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func (p *ProxyProvider) Upstream() string {
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return p.config.Upstream
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}
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193
pkg/provider/proxy_test.go
Normal file
193
pkg/provider/proxy_test.go
Normal file
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@ -0,0 +1,193 @@
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// SPDX-Licence-Identifier: EUPL-1.2
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package provider_test
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import (
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"encoding/json"
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"net/http"
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"net/http/httptest"
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"testing"
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"forge.lthn.ai/core/api"
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"forge.lthn.ai/core/api/pkg/provider"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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// -- ProxyProvider tests ------------------------------------------------------
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func TestProxyProvider_Name_Good(t *testing.T) {
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "cool-widget",
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BasePath: "/api/v1/cool-widget",
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Upstream: "http://127.0.0.1:9999",
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})
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assert.Equal(t, "cool-widget", p.Name())
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}
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func TestProxyProvider_BasePath_Good(t *testing.T) {
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "cool-widget",
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BasePath: "/api/v1/cool-widget",
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Upstream: "http://127.0.0.1:9999",
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})
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assert.Equal(t, "/api/v1/cool-widget", p.BasePath())
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}
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func TestProxyProvider_Element_Good(t *testing.T) {
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elem := provider.ElementSpec{
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Tag: "core-cool-widget",
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Source: "/assets/cool-widget.js",
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}
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "cool-widget",
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BasePath: "/api/v1/cool-widget",
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Upstream: "http://127.0.0.1:9999",
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Element: elem,
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})
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assert.Equal(t, "core-cool-widget", p.Element().Tag)
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assert.Equal(t, "/assets/cool-widget.js", p.Element().Source)
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}
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func TestProxyProvider_SpecFile_Good(t *testing.T) {
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "cool-widget",
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BasePath: "/api/v1/cool-widget",
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Upstream: "http://127.0.0.1:9999",
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SpecFile: "/tmp/openapi.json",
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})
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assert.Equal(t, "/tmp/openapi.json", p.SpecFile())
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}
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func TestProxyProvider_Proxy_Good(t *testing.T) {
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// Start a test upstream server.
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upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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resp := map[string]string{
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"path": r.URL.Path,
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"method": r.Method,
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}
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w.Header().Set("Content-Type", "application/json")
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json.NewEncoder(w).Encode(resp)
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}))
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defer upstream.Close()
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// Create proxy provider pointing to the test server.
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "test-proxy",
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BasePath: "/api/v1/test-proxy",
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Upstream: upstream.URL,
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})
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// Mount on an api.Engine.
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engine, err := api.New()
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require.NoError(t, err)
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engine.Register(p)
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handler := engine.Handler()
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// Send a request through the proxy.
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req := httptest.NewRequest("GET", "/api/v1/test-proxy/items", nil)
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w := httptest.NewRecorder()
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handler.ServeHTTP(w, req)
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assert.Equal(t, http.StatusOK, w.Code)
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var body map[string]string
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err = json.Unmarshal(w.Body.Bytes(), &body)
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require.NoError(t, err)
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// The upstream should see the path with base path stripped.
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assert.Equal(t, "/items", body["path"])
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assert.Equal(t, "GET", body["method"])
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}
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func TestProxyProvider_ProxyRoot_Good(t *testing.T) {
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upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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resp := map[string]string{"path": r.URL.Path}
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w.Header().Set("Content-Type", "application/json")
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json.NewEncoder(w).Encode(resp)
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}))
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defer upstream.Close()
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "test-proxy",
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BasePath: "/api/v1/test-proxy",
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Upstream: upstream.URL,
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})
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engine, err := api.New()
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require.NoError(t, err)
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engine.Register(p)
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handler := engine.Handler()
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// Request to the base path itself (root of the provider).
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req := httptest.NewRequest("GET", "/api/v1/test-proxy/", nil)
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w := httptest.NewRecorder()
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handler.ServeHTTP(w, req)
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assert.Equal(t, http.StatusOK, w.Code)
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var body map[string]string
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err = json.Unmarshal(w.Body.Bytes(), &body)
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require.NoError(t, err)
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assert.Equal(t, "/", body["path"])
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}
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func TestProxyProvider_HealthPassthrough_Good(t *testing.T) {
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upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if r.URL.Path == "/health" {
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w.Header().Set("Content-Type", "application/json")
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w.Write([]byte(`{"status":"ok"}`))
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return
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}
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w.WriteHeader(http.StatusNotFound)
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}))
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defer upstream.Close()
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "health-test",
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BasePath: "/api/v1/health-test",
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Upstream: upstream.URL,
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})
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engine, err := api.New()
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require.NoError(t, err)
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engine.Register(p)
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handler := engine.Handler()
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req := httptest.NewRequest("GET", "/api/v1/health-test/health", nil)
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w := httptest.NewRecorder()
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handler.ServeHTTP(w, req)
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assert.Equal(t, http.StatusOK, w.Code)
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assert.Contains(t, w.Body.String(), `"status":"ok"`)
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}
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func TestProxyProvider_Renderable_Good(t *testing.T) {
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// Verify ProxyProvider satisfies Renderable via the Registry.
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p := provider.NewProxy(provider.ProxyConfig{
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Name: "renderable-proxy",
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BasePath: "/api/v1/renderable",
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Upstream: "http://127.0.0.1:9999",
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Element: provider.ElementSpec{Tag: "core-test-panel", Source: "/assets/test.js"},
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})
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reg := provider.NewRegistry()
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reg.Add(p)
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renderables := reg.Renderable()
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require.Len(t, renderables, 1)
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assert.Equal(t, "core-test-panel", renderables[0].Element().Tag)
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}
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func TestProxyProvider_Ugly_InvalidUpstream(t *testing.T) {
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assert.Panics(t, func() {
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provider.NewProxy(provider.ProxyConfig{
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Name: "bad",
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BasePath: "/api/v1/bad",
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Upstream: "://not-a-url",
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})
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})
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}
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