form_uploader.go

package agent

import (
	"bytes"
	_ "crypto/sha512" // import sha512 to make sha512 ssl certs work
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	// "net/http/httputil"
	"errors"
	"net/url"
	"os"
	"path/filepath"

	"github.com/buildkite/agent/api"
	"github.com/buildkite/agent/logger"
)

type FormUploader struct {
}

func (u *FormUploader) Setup(destination string) error {
	return nil
}

// The FormUploader doens't specify a URL, as one is provided by Buildkite
// after uploading
func (u *FormUploader) URL(artifact *api.Artifact) string {
	return ""
}

func (u *FormUploader) Upload(artifact *api.Artifact) error {
	// Create a HTTP request for uploading the file
	request, err := createUploadRequest(artifact)
	if err != nil {
		return err
	}

	// Create the client
	client := &http.Client{}

	// Perform the request
	logger.Debug("%s %s", request.Method, request.URL)
	response, err := client.Do(request)

	// Check for errors
	if err != nil {
		return err
	} else {
		// Be sure to close the response body at the end of
		// this function
		defer response.Body.Close()

		if response.StatusCode/100 != 2 {
			body := &bytes.Buffer{}
			_, err := body.ReadFrom(response.Body)
			if err != nil {
				return err
			}

			// Return a custom error with the response body from the page
			message := fmt.Sprintf("%s (%d)", body, response.StatusCode)
			return errors.New(message)
		}
	}

	return nil
}

// Creates a new file upload http request with optional extra params
func createUploadRequest(artifact *api.Artifact) (*http.Request, error) {
	file, err := os.Open(artifact.AbsolutePath)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)

	// Set the post data for the request
	for key, val := range artifact.Uploader.Data {
		err = writer.WriteField(key, val)
		if err != nil {
			return nil, err
		}
	}

	// It's important that we add the form field last because when uploading to an S3
	// form, they are really nit-picky about the field order, and the file needs to be
	// the last one other it doesn't work.
	part, err := writer.CreateFormFile(artifact.Uploader.Action.FileInput, filepath.Base(artifact.AbsolutePath))
	if err != nil {
		return nil, err
	}

	_, err = io.Copy(part, file)
	if err != nil {
		return nil, err
	}

	err = writer.Close()
	if err != nil {
		return nil, err
	}

	// Create the URL that we'll send data to
	uri, err := url.Parse(artifact.Uploader.Action.URL)
	if err != nil {
		return nil, err
	}

	uri.Path = artifact.Uploader.Action.Path

	// Create the request
	req, err := http.NewRequest(artifact.Uploader.Action.Method, uri.String(), body)
	if err != nil {
		return nil, err
	}

	// Finally add the multipart content type to the request
	req.Header.Add("Content-Type", writer.FormDataContentType())

	return req, nil
}