| // Copyright 2014 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // TODO(andybons): add logging |
| // TODO(andybons): restrict memory use |
| |
| package main |
| |
| import ( |
| "bytes" |
| "context" |
| "crypto/sha256" |
| "encoding/json" |
| "errors" |
| "fmt" |
| "go/ast" |
| "go/doc" |
| "go/parser" |
| "go/token" |
| "io" |
| "io/ioutil" |
| "net" |
| "net/http" |
| "os" |
| "os/exec" |
| "path/filepath" |
| "runtime" |
| "strconv" |
| "strings" |
| "sync" |
| "text/template" |
| "time" |
| "unicode" |
| "unicode/utf8" |
| |
| "cloud.google.com/go/compute/metadata" |
| "github.com/bradfitz/gomemcache/memcache" |
| "golang.org/x/playground/internal" |
| "golang.org/x/playground/internal/gcpdial" |
| "golang.org/x/playground/sandbox/sandboxtypes" |
| ) |
| |
| const ( |
| maxCompileTime = 5 * time.Second |
| maxRunTime = 5 * time.Second |
| |
| // progName is the implicit program name written to the temp |
| // dir and used in compiler and vet errors. |
| progName = "prog.go" |
| ) |
| |
| const ( |
| goBuildTimeoutError = "timeout running go build" |
| runTimeoutError = "timeout running program" |
| ) |
| |
| // internalErrors are strings found in responses that will not be cached |
| // due to their non-deterministic nature. |
| var internalErrors = []string{ |
| "out of memory", |
| "cannot allocate memory", |
| } |
| |
| type request struct { |
| Body string |
| WithVet bool // whether client supports vet response in a /compile request (Issue 31970) |
| } |
| |
| type response struct { |
| Errors string |
| Events []Event |
| Status int |
| IsTest bool |
| TestsFailed int |
| |
| // VetErrors, if non-empty, contains any vet errors. It is |
| // only populated if request.WithVet was true. |
| VetErrors string `json:",omitempty"` |
| // VetOK reports whether vet ran & passsed. It is only |
| // populated if request.WithVet was true. Only one of |
| // VetErrors or VetOK can be non-zero. |
| VetOK bool `json:",omitempty"` |
| } |
| |
| // commandHandler returns an http.HandlerFunc. |
| // This handler creates a *request, assigning the "Body" field a value |
| // from the "body" form parameter or from the HTTP request body. |
| // If there is no cached *response for the combination of cachePrefix and request.Body, |
| // handler calls cmdFunc and in case of a nil error, stores the value of *response in the cache. |
| // The handler returned supports Cross-Origin Resource Sharing (CORS) from any domain. |
| func (s *server) commandHandler(cachePrefix string, cmdFunc func(context.Context, *request) (*response, error)) http.HandlerFunc { |
| return func(w http.ResponseWriter, r *http.Request) { |
| cachePrefix := cachePrefix // so we can modify it below |
| w.Header().Set("Access-Control-Allow-Origin", "*") |
| if r.Method == "OPTIONS" { |
| // This is likely a pre-flight CORS request. |
| return |
| } |
| |
| var req request |
| // Until programs that depend on golang.org/x/tools/godoc/static/playground.js |
| // are updated to always send JSON, this check is in place. |
| if b := r.FormValue("body"); b != "" { |
| req.Body = b |
| req.WithVet, _ = strconv.ParseBool(r.FormValue("withVet")) |
| } else if err := json.NewDecoder(r.Body).Decode(&req); err != nil { |
| s.log.Errorf("error decoding request: %v", err) |
| http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest) |
| return |
| } |
| |
| if req.WithVet { |
| cachePrefix += "_vet" // "prog" -> "prog_vet" |
| } |
| |
| resp := &response{} |
| key := cacheKey(cachePrefix, req.Body) |
| if err := s.cache.Get(key, resp); err != nil { |
| if !errors.Is(err, memcache.ErrCacheMiss) { |
| s.log.Errorf("s.cache.Get(%q, &response): %v", key, err) |
| } |
| resp, err = cmdFunc(r.Context(), &req) |
| if err != nil { |
| s.log.Errorf("cmdFunc error: %v", err) |
| http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError) |
| return |
| } |
| if strings.Contains(resp.Errors, goBuildTimeoutError) || strings.Contains(resp.Errors, runTimeoutError) { |
| // TODO(golang.org/issue/38576) - This should be a http.StatusBadRequest, |
| // but the UI requires a 200 to parse the response. It's difficult to know |
| // if we've timed out because of an error in the code snippet, or instability |
| // on the playground itself. Either way, we should try to show the user the |
| // partial output of their program. |
| s.writeResponse(w, resp, http.StatusOK) |
| return |
| } |
| for _, e := range internalErrors { |
| if strings.Contains(resp.Errors, e) { |
| s.log.Errorf("cmdFunc compilation error: %q", resp.Errors) |
| http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError) |
| return |
| } |
| } |
| for _, el := range resp.Events { |
| if el.Kind != "stderr" { |
| continue |
| } |
| for _, e := range internalErrors { |
| if strings.Contains(el.Message, e) { |
| s.log.Errorf("cmdFunc runtime error: %q", el.Message) |
| http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError) |
| return |
| } |
| } |
| } |
| if err := s.cache.Set(key, resp); err != nil { |
| s.log.Errorf("cache.Set(%q, resp): %v", key, err) |
| } |
| } |
| |
| s.writeResponse(w, resp, http.StatusOK) |
| } |
| } |
| |
| func (s *server) writeResponse(w http.ResponseWriter, resp *response, status int) { |
| var buf bytes.Buffer |
| if err := json.NewEncoder(&buf).Encode(resp); err != nil { |
| s.log.Errorf("error encoding response: %v", err) |
| http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError) |
| return |
| } |
| w.WriteHeader(status) |
| if _, err := io.Copy(w, &buf); err != nil { |
| s.log.Errorf("io.Copy(w, &buf): %v", err) |
| return |
| } |
| } |
| |
| func cacheKey(prefix, body string) string { |
| h := sha256.New() |
| io.WriteString(h, body) |
| return fmt.Sprintf("%s-%s-%x", prefix, runtime.Version(), h.Sum(nil)) |
| } |
| |
| // isTestFunc tells whether fn has the type of a testing function. |
| func isTestFunc(fn *ast.FuncDecl) bool { |
| if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 || |
| fn.Type.Params.List == nil || |
| len(fn.Type.Params.List) != 1 || |
| len(fn.Type.Params.List[0].Names) > 1 { |
| return false |
| } |
| ptr, ok := fn.Type.Params.List[0].Type.(*ast.StarExpr) |
| if !ok { |
| return false |
| } |
| // We can't easily check that the type is *testing.T |
| // because we don't know how testing has been imported, |
| // but at least check that it's *T or *something.T. |
| if name, ok := ptr.X.(*ast.Ident); ok && name.Name == "T" { |
| return true |
| } |
| if sel, ok := ptr.X.(*ast.SelectorExpr); ok && sel.Sel.Name == "T" { |
| return true |
| } |
| return false |
| } |
| |
| // isTest tells whether name looks like a test (or benchmark, according to prefix). |
| // It is a Test (say) if there is a character after Test that is not a lower-case letter. |
| // We don't want mistaken Testimony or erroneous Benchmarking. |
| func isTest(name, prefix string) bool { |
| if !strings.HasPrefix(name, prefix) { |
| return false |
| } |
| if len(name) == len(prefix) { // "Test" is ok |
| return true |
| } |
| r, _ := utf8.DecodeRuneInString(name[len(prefix):]) |
| return !unicode.IsLower(r) |
| } |
| |
| // getTestProg returns source code that executes all valid tests and examples in src. |
| // If the main function is present or there are no tests or examples, it returns nil. |
| // getTestProg emulates the "go test" command as closely as possible. |
| // Benchmarks are not supported because of sandboxing. |
| func getTestProg(src []byte) []byte { |
| fset := token.NewFileSet() |
| // Early bail for most cases. |
| f, err := parser.ParseFile(fset, progName, src, parser.ImportsOnly) |
| if err != nil || f.Name.Name != "main" { |
| return nil |
| } |
| |
| // importPos stores the position to inject the "testing" import declaration, if needed. |
| importPos := fset.Position(f.Name.End()).Offset |
| |
| var testingImported bool |
| for _, s := range f.Imports { |
| if s.Path.Value == `"testing"` && s.Name == nil { |
| testingImported = true |
| break |
| } |
| } |
| |
| // Parse everything and extract test names. |
| f, err = parser.ParseFile(fset, progName, src, parser.ParseComments) |
| if err != nil { |
| return nil |
| } |
| |
| var tests []string |
| for _, d := range f.Decls { |
| n, ok := d.(*ast.FuncDecl) |
| if !ok { |
| continue |
| } |
| name := n.Name.Name |
| switch { |
| case name == "main": |
| // main declared as a method will not obstruct creation of our main function. |
| if n.Recv == nil { |
| return nil |
| } |
| case isTest(name, "Test") && isTestFunc(n): |
| tests = append(tests, name) |
| } |
| } |
| |
| // Tests imply imported "testing" package in the code. |
| // If there is no import, bail to let the compiler produce an error. |
| if !testingImported && len(tests) > 0 { |
| return nil |
| } |
| |
| // We emulate "go test". An example with no "Output" comment is compiled, |
| // but not executed. An example with no text after "Output:" is compiled, |
| // executed, and expected to produce no output. |
| var ex []*doc.Example |
| // exNoOutput indicates whether an example with no output is found. |
| // We need to compile the program containing such an example even if there are no |
| // other tests or examples. |
| exNoOutput := false |
| for _, e := range doc.Examples(f) { |
| if e.Output != "" || e.EmptyOutput { |
| ex = append(ex, e) |
| } |
| if e.Output == "" && !e.EmptyOutput { |
| exNoOutput = true |
| } |
| } |
| |
| if len(tests) == 0 && len(ex) == 0 && !exNoOutput { |
| return nil |
| } |
| |
| if !testingImported && (len(ex) > 0 || exNoOutput) { |
| // In case of the program with examples and no "testing" package imported, |
| // add import after "package main" without modifying line numbers. |
| importDecl := []byte(`;import "testing";`) |
| src = bytes.Join([][]byte{src[:importPos], importDecl, src[importPos:]}, nil) |
| } |
| |
| data := struct { |
| Tests []string |
| Examples []*doc.Example |
| }{ |
| tests, |
| ex, |
| } |
| code := new(bytes.Buffer) |
| if err := testTmpl.Execute(code, data); err != nil { |
| panic(err) |
| } |
| src = append(src, code.Bytes()...) |
| return src |
| } |
| |
| var testTmpl = template.Must(template.New("main").Parse(` |
| func main() { |
| matchAll := func(t string, pat string) (bool, error) { return true, nil } |
| tests := []testing.InternalTest{ |
| {{range .Tests}} |
| {"{{.}}", {{.}}}, |
| {{end}} |
| } |
| examples := []testing.InternalExample{ |
| {{range .Examples}} |
| {"Example{{.Name}}", Example{{.Name}}, {{printf "%q" .Output}}, {{.Unordered}}}, |
| {{end}} |
| } |
| testing.Main(matchAll, tests, nil, examples) |
| } |
| `)) |
| |
| var failedTestPattern = "--- FAIL" |
| |
| // compileAndRun tries to build and run a user program. |
| // The output of successfully ran program is returned in *response.Events. |
| // If a program cannot be built or has timed out, |
| // *response.Errors contains an explanation for a user. |
| func compileAndRun(ctx context.Context, req *request) (*response, error) { |
| // TODO(andybons): Add semaphore to limit number of running programs at once. |
| tmpDir, err := ioutil.TempDir("", "sandbox") |
| if err != nil { |
| return nil, fmt.Errorf("error creating temp directory: %v", err) |
| } |
| defer os.RemoveAll(tmpDir) |
| |
| br, err := sandboxBuild(ctx, tmpDir, []byte(req.Body), req.WithVet) |
| if err != nil { |
| return nil, err |
| } |
| if br.errorMessage != "" { |
| return &response{Errors: br.errorMessage}, nil |
| } |
| |
| execRes, err := sandboxRun(ctx, br.exePath, br.testParam) |
| if err != nil { |
| return nil, err |
| } |
| if execRes.Error != "" { |
| return &response{Errors: execRes.Error}, nil |
| } |
| |
| rec := new(Recorder) |
| rec.Stdout().Write(execRes.Stdout) |
| rec.Stderr().Write(execRes.Stderr) |
| events, err := rec.Events() |
| if err != nil { |
| log.Printf("error decoding events: %v", err) |
| return nil, fmt.Errorf("error decoding events: %v", err) |
| } |
| var fails int |
| if br.testParam != "" { |
| // In case of testing the TestsFailed field contains how many tests have failed. |
| for _, e := range events { |
| fails += strings.Count(e.Message, failedTestPattern) |
| } |
| } |
| return &response{ |
| Events: events, |
| Status: execRes.ExitCode, |
| IsTest: br.testParam != "", |
| TestsFailed: fails, |
| VetErrors: br.vetOut, |
| VetOK: req.WithVet && br.vetOut == "", |
| }, nil |
| } |
| |
| // buildResult is the output of a sandbox build attempt. |
| type buildResult struct { |
| // goPath is a temporary directory if the binary was built with module support. |
| // TODO(golang.org/issue/25224) - Why is the module mode built so differently? |
| goPath string |
| // exePath is the path to the built binary. |
| exePath string |
| // useModules is true if the binary was built with module support. |
| useModules bool |
| // testParam is set if tests should be run when running the binary. |
| testParam string |
| // errorMessage is an error message string to be returned to the user. |
| errorMessage string |
| // vetOut is the output of go vet, if requested. |
| vetOut string |
| } |
| |
| // cleanup cleans up the temporary goPath created when building with module support. |
| func (b *buildResult) cleanup() error { |
| if b.useModules && b.goPath != "" { |
| return os.RemoveAll(b.goPath) |
| } |
| return nil |
| } |
| |
| // sandboxBuild builds a Go program and returns a build result that includes the build context. |
| // |
| // An error is returned if a non-user-correctable error has occurred. |
| func sandboxBuild(ctx context.Context, tmpDir string, in []byte, vet bool) (*buildResult, error) { |
| files, err := splitFiles(in) |
| if err != nil { |
| return &buildResult{errorMessage: err.Error()}, nil |
| } |
| |
| br := new(buildResult) |
| defer br.cleanup() |
| var buildPkgArg = "." |
| if files.Num() == 1 && len(files.Data(progName)) > 0 { |
| buildPkgArg = progName |
| src := files.Data(progName) |
| if code := getTestProg(src); code != nil { |
| br.testParam = "-test.v" |
| files.AddFile(progName, code) |
| } |
| } |
| |
| br.useModules = allowModuleDownloads(files) |
| if !files.Contains("go.mod") && br.useModules { |
| files.AddFile("go.mod", []byte("module play\n")) |
| } |
| |
| for f, src := range files.m { |
| // Before multi-file support we required that the |
| // program be in package main, so continue to do that |
| // for now. But permit anything in subdirectories to have other |
| // packages. |
| if !strings.Contains(f, "/") { |
| fset := token.NewFileSet() |
| f, err := parser.ParseFile(fset, f, src, parser.PackageClauseOnly) |
| if err == nil && f.Name.Name != "main" { |
| return &buildResult{errorMessage: "package name must be main"}, nil |
| } |
| } |
| |
| in := filepath.Join(tmpDir, f) |
| if strings.Contains(f, "/") { |
| if err := os.MkdirAll(filepath.Dir(in), 0755); err != nil { |
| return nil, err |
| } |
| } |
| if err := ioutil.WriteFile(in, src, 0644); err != nil { |
| return nil, fmt.Errorf("error creating temp file %q: %v", in, err) |
| } |
| } |
| |
| br.exePath = filepath.Join(tmpDir, "a.out") |
| goCache := filepath.Join(tmpDir, "gocache") |
| |
| cmd := exec.Command("/usr/local/go-faketime/bin/go", "build", "-o", br.exePath, "-tags=faketime") |
| cmd.Dir = tmpDir |
| cmd.Env = []string{"GOOS=linux", "GOARCH=amd64", "GOROOT=/usr/local/go-faketime"} |
| cmd.Env = append(cmd.Env, "GOCACHE="+goCache) |
| if br.useModules { |
| // Create a GOPATH just for modules to be downloaded |
| // into GOPATH/pkg/mod. |
| cmd.Args = append(cmd.Args, "-modcacherw") |
| br.goPath, err = ioutil.TempDir("", "gopath") |
| if err != nil { |
| log.Printf("error creating temp directory: %v", err) |
| return nil, fmt.Errorf("error creating temp directory: %v", err) |
| } |
| cmd.Env = append(cmd.Env, "GO111MODULE=on", "GOPROXY="+playgroundGoproxy()) |
| } else { |
| br.goPath = os.Getenv("GOPATH") // contains old code.google.com/p/go-tour, etc |
| cmd.Env = append(cmd.Env, "GO111MODULE=off") // in case it becomes on by default later |
| } |
| cmd.Args = append(cmd.Args, buildPkgArg) |
| cmd.Env = append(cmd.Env, "GOPATH="+br.goPath) |
| out := &bytes.Buffer{} |
| cmd.Stderr, cmd.Stdout = out, out |
| |
| if err := cmd.Start(); err != nil { |
| return nil, fmt.Errorf("error starting go build: %v", err) |
| } |
| ctx, cancel := context.WithTimeout(ctx, maxCompileTime) |
| defer cancel() |
| if err := internal.WaitOrStop(ctx, cmd, os.Interrupt, 250*time.Millisecond); err != nil { |
| if errors.Is(err, context.DeadlineExceeded) { |
| br.errorMessage = fmt.Sprintln(goBuildTimeoutError) |
| } else if ee := (*exec.ExitError)(nil); !errors.As(err, &ee) { |
| log.Printf("error building program: %v", err) |
| return nil, fmt.Errorf("error building go source: %v", err) |
| } |
| // Return compile errors to the user. |
| // Rewrite compiler errors to strip the tmpDir name. |
| br.errorMessage = br.errorMessage + strings.Replace(string(out.Bytes()), tmpDir+"/", "", -1) |
| |
| // "go build", invoked with a file name, puts this odd |
| // message before any compile errors; strip it. |
| br.errorMessage = strings.Replace(br.errorMessage, "# command-line-arguments\n", "", 1) |
| |
| return br, nil |
| } |
| const maxBinarySize = 100 << 20 // copied from sandbox backend; TODO: unify? |
| if fi, err := os.Stat(br.exePath); err != nil || fi.Size() == 0 || fi.Size() > maxBinarySize { |
| if err != nil { |
| return nil, fmt.Errorf("failed to stat binary: %v", err) |
| } |
| return nil, fmt.Errorf("invalid binary size %d", fi.Size()) |
| } |
| if vet { |
| // TODO: do this concurrently with the execution to reduce latency. |
| br.vetOut, err = vetCheckInDir(tmpDir, br.goPath, br.useModules) |
| if err != nil { |
| return nil, fmt.Errorf("running vet: %v", err) |
| } |
| } |
| return br, nil |
| } |
| |
| // sandboxRun runs a Go binary in a sandbox environment. |
| func sandboxRun(ctx context.Context, exePath string, testParam string) (sandboxtypes.Response, error) { |
| var execRes sandboxtypes.Response |
| exeBytes, err := ioutil.ReadFile(exePath) |
| if err != nil { |
| return execRes, err |
| } |
| ctx, cancel := context.WithTimeout(ctx, maxRunTime) |
| defer cancel() |
| sreq, err := http.NewRequestWithContext(ctx, "POST", sandboxBackendURL(), bytes.NewReader(exeBytes)) |
| if err != nil { |
| return execRes, fmt.Errorf("NewRequestWithContext %q: %w", sandboxBackendURL(), err) |
| } |
| sreq.Header.Add("Idempotency-Key", "1") // lets Transport do retries with a POST |
| if testParam != "" { |
| sreq.Header.Add("X-Argument", testParam) |
| } |
| sreq.GetBody = func() (io.ReadCloser, error) { return ioutil.NopCloser(bytes.NewReader(exeBytes)), nil } |
| res, err := sandboxBackendClient().Do(sreq) |
| if err != nil { |
| if errors.Is(ctx.Err(), context.DeadlineExceeded) { |
| execRes.Error = runTimeoutError |
| return execRes, nil |
| } |
| return execRes, fmt.Errorf("POST %q: %w", sandboxBackendURL(), err) |
| } |
| defer res.Body.Close() |
| if res.StatusCode != http.StatusOK { |
| log.Printf("unexpected response from backend: %v", res.Status) |
| return execRes, fmt.Errorf("unexpected response from backend: %v", res.Status) |
| } |
| if err := json.NewDecoder(res.Body).Decode(&execRes); err != nil { |
| log.Printf("JSON decode error from backend: %v", err) |
| return execRes, errors.New("error parsing JSON from backend") |
| } |
| return execRes, nil |
| } |
| |
| // allowModuleDownloads reports whether the code snippet in src should be allowed |
| // to download modules. |
| func allowModuleDownloads(files *fileSet) bool { |
| if files.Num() == 1 && bytes.Contains(files.Data(progName), []byte(`"code.google.com/p/go-tour/`)) { |
| // This domain doesn't exist anymore but we want old snippets using |
| // these packages to still run, so the Dockerfile adds these packages |
| // at this name in $GOPATH. Any snippets using this old name wouldn't |
| // have expected (or been able to use) third-party packages anyway, |
| // so disabling modules and proxy fetches is acceptable. |
| return false |
| } |
| v, _ := strconv.ParseBool(os.Getenv("ALLOW_PLAY_MODULE_DOWNLOADS")) |
| return v |
| } |
| |
| // playgroundGoproxy returns the GOPROXY environment config the playground should use. |
| // It is fetched from the environment variable PLAY_GOPROXY. A missing or empty |
| // value for PLAY_GOPROXY returns the default value of https://proxy.golang.org. |
| func playgroundGoproxy() string { |
| proxypath := os.Getenv("PLAY_GOPROXY") |
| if proxypath != "" { |
| return proxypath |
| } |
| return "https://proxy.golang.org" |
| } |
| |
| // healthCheck attempts to build a binary from the source in healthProg. |
| // It returns any error returned from sandboxBuild, or nil if none is returned. |
| func (s *server) healthCheck(ctx context.Context) error { |
| tmpDir, err := ioutil.TempDir("", "sandbox") |
| if err != nil { |
| return fmt.Errorf("error creating temp directory: %v", err) |
| } |
| defer os.RemoveAll(tmpDir) |
| br, err := sandboxBuild(ctx, tmpDir, []byte(healthProg), false) |
| if err != nil { |
| return err |
| } |
| if br.errorMessage != "" { |
| return errors.New(br.errorMessage) |
| } |
| return nil |
| } |
| |
| // sandboxBackendURL returns the URL of the sandbox backend that |
| // executes binaries. This backend is required for Go 1.14+ (where it |
| // executes using gvisor, since Native Client support is removed). |
| // |
| // This function either returns a non-empty string or it panics. |
| func sandboxBackendURL() string { |
| if v := os.Getenv("SANDBOX_BACKEND_URL"); v != "" { |
| return v |
| } |
| id, _ := metadata.ProjectID() |
| switch id { |
| case "golang-org": |
| return "http://sandbox.play-sandbox-fwd.il4.us-central1.lb.golang-org.internal/run" |
| } |
| panic(fmt.Sprintf("no SANDBOX_BACKEND_URL environment and no default defined for project %q", id)) |
| } |
| |
| var sandboxBackendOnce struct { |
| sync.Once |
| c *http.Client |
| } |
| |
| func sandboxBackendClient() *http.Client { |
| sandboxBackendOnce.Do(initSandboxBackendClient) |
| return sandboxBackendOnce.c |
| } |
| |
| // initSandboxBackendClient runs from a sync.Once and initializes |
| // sandboxBackendOnce.c with the *http.Client we'll use to contact the |
| // sandbox execution backend. |
| func initSandboxBackendClient() { |
| id, _ := metadata.ProjectID() |
| switch id { |
| case "golang-org": |
| // For production, use a funky Transport dialer that |
| // contacts backend directly, without going through an |
| // internal load balancer, due to internal GCP |
| // reasons, which we might resolve later. This might |
| // be a temporary hack. |
| tr := http.DefaultTransport.(*http.Transport).Clone() |
| rigd := gcpdial.NewRegionInstanceGroupDialer("golang-org", "us-central1", "play-sandbox-rigm") |
| tr.DialContext = func(ctx context.Context, netw, addr string) (net.Conn, error) { |
| if addr == "sandbox.play-sandbox-fwd.il4.us-central1.lb.golang-org.internal:80" { |
| ip, err := rigd.PickIP(ctx) |
| if err != nil { |
| return nil, err |
| } |
| addr = net.JoinHostPort(ip, "80") // and fallthrough |
| } |
| var d net.Dialer |
| return d.DialContext(ctx, netw, addr) |
| } |
| sandboxBackendOnce.c = &http.Client{Transport: tr} |
| default: |
| sandboxBackendOnce.c = http.DefaultClient |
| } |
| } |
| |
| const healthProg = ` |
| package main |
| |
| import "fmt" |
| |
| func main() { fmt.Print("ok") } |
| ` |