Monorail client in Go

go/src/infra/monorail/endpoints.go

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package monorail
+
+import (
+        "bytes"
+        "encoding/json"
+        "fmt"
+        "io"
+        "io/ioutil"
+        "net/http"
+
+        "golang.org/x/net/context"
+        "google.golang.org/grpc"
+
+        "github.com/luci/luci-go/common/errors"
+        "github.com/luci/luci-go/common/logging"
+
+        "infra/httputil"
+)
+
+// epClient implements MonorailClient by sending requests to Monorail's
+// Cloud Endpoints API.
+// See https://monorail-staging.appspot.com/_ah/api/explorer#p/monorail/v1/
+type epClient struct {
+        HTTP *http.Client
+        Host string
+}
+
+// NewEndpointsClient creates a MonorailClient that send requests to Monorail's
+// Cloud Endpoints.
+func NewEndpointsClient(client *http.Client, host string) MonorailClient {
+        return &epClient{HTTP: client, Host: host}
+}
+
+func (c *epClient) call(ctx context.Context, urlSuffix string, request, response interface{}) error {
+        var buf bytes.Buffer
+        if err := json.NewEncoder(&buf).Encode(request); err != nil {
+                return err
+        }
+        reqBytes := buf.Bytes()
+
+        u := fmt.Sprintf("https://%s/_ah/api/monorail/v1/%s", c.Host, urlSuffix)
+        req, err := http.NewRequest("POST", u, nil)
+        if err != nil {
+                return err
+        }
+        req.Header.Set("Content-Type", "application/json")
+        req.Header.Set("Accept", "application/json")
+
+        logging.Debugf(ctx, "POST %s %s", u, reqBytes)
+
+        return httputil.RetryRequest(ctx, c.HTTP, req, reqBytes, func(res *http.Response) error {
+                if res.StatusCode != http.StatusOK {
+                        text, _ := ioutil.ReadAll(io.LimitReader(res.Body, 1024))
+                        err := fmt.Errorf("unexpected status %q. Response: %s", res.Status, text)
+                        if res.StatusCode == http.StatusNotFound {
+                                // Occasionally Cloud Endpoints returns 404.

[seanmccullough1, 2016/06/03 18:45:33]

Even when it really should be a 500 :)

[nodir, 2016/06/03 18:56:12]

yes!

+                                err = errors.WrapTransient(err)
+                        }
+                        return err
+                }
+                if response == nil {
+                        return nil
+                }
+                return json.NewDecoder(res.Body).Decode(response)
+        })
+}
+
+func (c *epClient) InsertIssue(ctx context.Context, req *InsertIssueRequest, options ...grpc.CallOption) (*InsertIssueResponse, error) {

[seanmccullough1, 2016/06/03 18:45:33]

Godoc here and below. Mention that even though the signature accepts
...grpc.CallOption that actually passing any will cause an error. Either that or
don't accept CallOptions at all.

[nodir, 2016/06/03 18:56:12]

these functions are internal, so nobody will see their docstrings.

Mentioned CallOption in NewEndpointsClient docstring

+        if err := checkOptions(options); err != nil {
+                return nil, err
+        }
+        if err := req.Validate(); err != nil {
+                return nil, err
+        }
+        url := fmt.Sprintf("projects/%s/issues?sendEmail=%v", req.ProjectId, req.SendEmail)
+        res := &InsertIssueResponse{&Issue{}}
+        return res, c.call(ctx, url, &req.Issue, res.Issue)
+}
+
+func (c *epClient) InsertComment(ctx context.Context, req *InsertCommentRequest, options ...grpc.CallOption) (*InsertCommentResponse, error) {
+        if err := checkOptions(options); err != nil {
+                return nil, err
+        }
+        url := fmt.Sprintf("projects/%s/issues/%d/comments", req.Issue.ProjectId, req.Issue.IssueId)
+        return &InsertCommentResponse{}, c.call(ctx, url, req.Comment, nil)
+}
+
+func checkOptions(options []grpc.CallOption) error {
+        if len(options) > 0 {
+                return errGrpcOptions
+        }
+        return nil
+}