Logging Handler

logapi.go

package programs

import (
	"encoding/base64"
	"html/template"
	"net/http"
	"time"

	"appengine"
	"appengine/log"
)

const recordsPerPage = 5

func logHandler(c appengine.Context, w http.ResponseWriter, r *http.Request, kwds map[string]string) {
	if !MustBeAdmin(c, w, r) {
		Unauthorized(c, w, r)
		return
	}
	// Get the incoming offset param from the Next link to advance through
	// the logs. (The first time the page is loaded there won't be any offset.)
	offset_str := r.FormValue("offset")
	var offset []byte
	var err error

	if offset_str != "" {
		offset, err = base64.URLEncoding.DecodeString(offset_str)
		if err != nil {
			c.Errorf(err.Error())
		}
	}

	// Set up a data structure to pass to the HTML template.
	var data struct {
		Records []*log.Record
		Offset  string // base-64 encoded string
	}

	// Set up a log.Query.
	query := &log.Query{
		Offset:    offset,
		AppLogs:   true,
		StartTime: time.Now().Add(-time.Hour * 24),
		EndTime:   time.Now(),
	}

	// Run the query, obtaining a Result iterator.
	res := query.Run(c)

	// Iterate through the results populating the data struct.
	for i := 0; i < recordsPerPage; i++ {
		rec, err := res.Next()

		if err == log.Done {
			break
		}

		if err != nil {
			c.Errorf("Failed to retrieve next log: %v", err)
			break
		}

		c.Infof("Saw record %v", rec)

		data.Records = append(data.Records, rec)
		if i == recordsPerPage-1 {
			data.Offset = base64.URLEncoding.EncodeToString(rec.Offset)
		}
	}

	// Render the template to the HTTP response.
	if err := tmpl.Execute(w, data); err != nil {
		c.Errorf("Rendering template: %v", err)
	}
}

var tmpl = template.Must(template.New("").Parse(`
        Records: 
        {{range .Records}}
                <h2>Request Log</h2>
                <p>{{.EndTime}}: {{.IP}} {{.Method}} {{.Resource}}</p>
                {{with .AppLogs}}
                        <h3>App Logs:</h3>
                        <ul>
                        {{range .}}
                                <li>{{.Time}}: {{.Message}}</li>
                        <{{end}}
                        </ul>
                {{end}}
        {{end}}
        {{with .Offset}}
                <a href="?offset={{.}}">Next</a>
        {{end}}
`))