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Add response type for Lambda Function URL Streaming Responses (#494)
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+166
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lines changed

2 files changed

+166
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lines changed

‎events/lambda_function_urls.go‎

Lines changed: 74 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,14 @@
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33
package events
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5+
import (
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"bytes"
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"encoding/json"
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"errors"
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"io"
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"net/http"
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)
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// LambdaFunctionURLRequest contains data coming from the HTTP request to a Lambda Function URL.
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type LambdaFunctionURLRequest struct {
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Version string `json:"version"` // Version is expected to be `"2.0"`
@@ -59,3 +67,69 @@ type LambdaFunctionURLResponse struct {
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IsBase64Encoded bool `json:"isBase64Encoded"`
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Cookies []string `json:"cookies"`
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}
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// LambdaFunctionURLStreamingResponse models the response to a Lambda Function URL when InvokeMode is RESPONSE_STREAM.
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// If the InvokeMode of the Function URL is BUFFERED (default), use LambdaFunctionURLResponse instead.
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//
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// Example:
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//
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// lambda.Start(func() (*events.LambdaFunctionURLStreamingResponse, error) {
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// return &events.LambdaFunctionURLStreamingResponse{
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// StatusCode: 200,
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// Headers: map[string]string{
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// "Content-Type": "text/html",
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// },
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// Body: strings.NewReader("<html><body>Hello World!</body></html>"),
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// }, nil
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// })
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type LambdaFunctionURLStreamingResponse struct {
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prelude *bytes.Buffer
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StatusCode int
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Headers map[string]string
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Body io.Reader
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Cookies []string
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}
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func (r *LambdaFunctionURLStreamingResponse) Read(p []byte) (n int, err error) {
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if r.prelude == nil {
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if r.StatusCode == 0 {
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r.StatusCode = http.StatusOK
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}
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b, err := json.Marshal(struct {
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StatusCode int `json:"statusCode"`
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Headers map[string]string `json:"headers,omitempty"`
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Cookies []string `json:"cookies,omitempty"`
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}{
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StatusCode: r.StatusCode,
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Headers: r.Headers,
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Cookies: r.Cookies,
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})
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if err != nil {
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return 0, err
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}
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r.prelude = bytes.NewBuffer(append(b, 0, 0, 0, 0, 0, 0, 0, 0))
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}
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if r.prelude.Len() > 0 {
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return r.prelude.Read(p)
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}
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if r.Body == nil {
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return 0, io.EOF
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}
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return r.Body.Read(p)
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}
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func (r *LambdaFunctionURLStreamingResponse) Close() error {
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if closer, ok := r.Body.(io.ReadCloser); ok {
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return closer.Close()
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}
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return nil
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}
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func (r *LambdaFunctionURLStreamingResponse) MarshalJSON() ([]byte, error) {
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return nil, errors.New("not json")
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}
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func (r *LambdaFunctionURLStreamingResponse) ContentType() string {
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return "application/vnd.awslambda.http-integration-response"
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}

‎events/lambda_function_urls_test.go‎

Lines changed: 92 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -4,10 +4,14 @@ package events
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55
import (
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"encoding/json"
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"errors"
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"io/ioutil" //nolint: staticcheck
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"net/http"
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"strings"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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func TestLambdaFunctionURLResponseMarshaling(t *testing.T) {
@@ -55,3 +59,91 @@ func TestLambdaFunctionURLRequestMarshaling(t *testing.T) {
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assert.JSONEq(t, string(inputJSON), string(outputJSON))
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}
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func TestLambdaFunctionURLStreamingResponseMarshaling(t *testing.T) {
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for _, test := range []struct {
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name string
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response *LambdaFunctionURLStreamingResponse
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expectedHead string
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expectedBody string
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}{
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{
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"empty",
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&LambdaFunctionURLStreamingResponse{},
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`{"statusCode":200}`,
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"",
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},
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{
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"just the status code",
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&LambdaFunctionURLStreamingResponse{
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StatusCode: http.StatusTeapot,
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},
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`{"statusCode":418}`,
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"",
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},
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{
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"status and headers and cookies and body",
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&LambdaFunctionURLStreamingResponse{
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StatusCode: http.StatusTeapot,
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Headers: map[string]string{"hello": "world"},
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Cookies: []string{"cookies", "are", "yummy"},
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Body: strings.NewReader(`<html>Hello Hello</html>`),
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},
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`{"statusCode":418, "headers":{"hello":"world"}, "cookies":["cookies","are","yummy"]}`,
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`<html>Hello Hello</html>`,
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},
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} {
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t.Run(test.name, func(t *testing.T) {
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response, err := ioutil.ReadAll(test.response)
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require.NoError(t, err)
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sep := "\x00\x00\x00\x00\x00\x00\x00\x00"
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responseParts := strings.Split(string(response), sep)
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require.Len(t, responseParts, 2)
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head := string(responseParts[0])
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body := string(responseParts[1])
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assert.JSONEq(t, test.expectedHead, head)
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assert.Equal(t, test.expectedBody, body)
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assert.NoError(t, test.response.Close())
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})
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}
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}
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type readCloser struct {
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closed bool
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err error
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reader *strings.Reader
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}
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func (r *readCloser) Read(p []byte) (int, error) {
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return r.reader.Read(p)
119+
}
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func (r *readCloser) Close() error {
122+
r.closed = true
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return r.err
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}
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func TestLambdaFunctionURLStreamingResponsePropogatesInnerClose(t *testing.T) {
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for _, test := range []struct {
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name string
129+
closer *readCloser
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err error
131+
}{
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{
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"closer no err",
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&readCloser{},
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nil,
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},
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{
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"closer with err",
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&readCloser{err: errors.New("yolo")},
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errors.New("yolo"),
141+
},
142+
} {
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t.Run(test.name, func(t *testing.T) {
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response := &LambdaFunctionURLStreamingResponse{Body: test.closer}
145+
assert.Equal(t, test.err, response.Close())
146+
assert.True(t, test.closer.closed)
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})
148+
}
149+
}

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