surrealpatch/web/trace.go
2017-03-03 21:39:37 +00:00

101 lines
2.2 KiB
Go

// Copyright © 2016 Abcum Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package web
import (
"context"
"github.com/abcum/fibre"
"github.com/abcum/surreal/cnf"
"cloud.google.com/go/compute/metadata"
"cloud.google.com/go/trace"
"google.golang.org/api/option"
)
var client *trace.Client
// tracer returns a middleware function for stackdriver trace monitoring.
func tracer() fibre.MiddlewareFunc {
var e error
var s trace.SamplingPolicy
var p string = cnf.Settings.Logging.Google.Project
var c string = cnf.Settings.Logging.Google.Credentials
// If no project id has been set
// then attempt to pull this from
// machine metadata if on GCE.
if p == "" {
if p, e = metadata.ProjectID(); e != nil {
return fibre.MiddlewareSkip
}
}
// Connect to Stackdriver using a
// credentials file if one has been
// specified, or metadata if not.
switch c {
case "":
client, e = trace.NewClient(
context.Background(),
p,
)
default:
client, e = trace.NewClient(
context.Background(),
p,
option.WithServiceAccountFile(c),
)
}
if e != nil {
return fibre.MiddlewareSkip
}
// Attempt to setup the Stackdriver
// client policy so that a fraction
// of requests are sent to google.
if s, e = trace.NewLimitedSampler(1, 5); e != nil {
return fibre.MiddlewareSkip
}
client.SetSamplingPolicy(s)
return func(h fibre.HandlerFunc) fibre.HandlerFunc {
return func(c *fibre.Context) error {
if c.Request().Header().Get("Upgrade") == "websocket" {
return h(c)
}
span := client.SpanFromRequest(c.Request().Request)
span.SetLabel("http/id", c.Get("id").(string))
ctx := trace.NewContext(c.Context(), span)
c = c.WithContext(ctx)
defer span.Finish()
return h(c)
}
}
}