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[bsr-383] Fix flaky studio agent test #1306

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merged 9 commits into from
Aug 5, 2022
Merged

[bsr-383] Fix flaky studio agent test #1306

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bfa9bc4
Sometimes conn.Close is mapped as unavailable?
unmultimedio Jul 29, 2022
7eaddba
Comment for CodeUnavailable, and sync test
unmultimedio Jul 29, 2022
4bb2aa7
test
unmultimedio Jul 29, 2022
103de2b
Setting custom timeout to the agent client
unmultimedio Jul 29, 2022
7446a8a
Rewrite how StatusBadGateway is triggered
unmultimedio Aug 2, 2022
a40dafc
Merge branch 'main' into jfigueroa/bsr-383-fix-flaky-test
unmultimedio Aug 2, 2022
e25ca0d
Remove agent server timeout
unmultimedio Aug 2, 2022
902ddba
Changelog and test path fix
unmultimedio Aug 5, 2022
bc7617e
Revert changes, improve code comments
unmultimedio Aug 5, 2022
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16 changes: 14 additions & 2 deletions private/bufpkg/bufstudioagent/bufstudioagent_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,12 +20,14 @@ import (
"crypto/x509"
"encoding/base64"
"errors"
"fmt"
"io"
"net"
"net/http"
"net/http/httptest"
"strconv"
"testing"
"time"

studiov1alpha1 "github.com/bufbuild/buf/private/gen/proto/go/buf/alpha/studio/v1alpha1"
"github.com/bufbuild/connect-go"
Expand Down Expand Up @@ -141,6 +143,7 @@ func testPlainPostHandlerErrors(t *testing.T, upstreamServer *httptest.Server) {
nil,
),
)
agentServer.Client().Timeout = time.Second
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defer agentServer.Close()

t.Run("forbidden_header", func(t *testing.T) {
Expand Down Expand Up @@ -188,11 +191,16 @@ func testPlainPostHandlerErrors(t *testing.T, upstreamServer *httptest.Server) {
t.Run("invalid_upstream", func(t *testing.T) {
listener, err := net.Listen("tcp", "127.0.0.1:")
require.NoError(t, err)
go func() {
listening := make(chan struct{}, 1)
go func(listening chan<- struct{}) {
listening <- struct{}{}
fmt.Println("signal sent")
conn, err := listener.Accept()
fmt.Println("connection arrived")
require.NoError(t, err)
require.NoError(t, conn.Close())
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@unmultimedio unmultimedio Aug 2, 2022 •
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This line is inherently flaky because of the behavior of http clients handling closed connections. So we can write a similiar test instead, to return the Unknown code, and test the same behavior.

}()
fmt.Println("connection closed")
}(listening)
defer listener.Close()

requestProto := &studiov1alpha1.InvokeRequest{
Expand All @@ -205,7 +213,11 @@ func testPlainPostHandlerErrors(t *testing.T, upstreamServer *httptest.Server) {
request, err := http.NewRequest(http.MethodPost, agentServer.URL, bytes.NewReader(requestBytes))
require.NoError(t, err)
request.Header.Set("Content-Type", "text/plain")
fmt.Println("waiting before doing the request")
<-listening
fmt.Println("unblocked, starting request")
response, err := agentServer.Client().Do(request)
fmt.Println("request completed")
require.NoError(t, err)
assert.Equal(t, http.StatusBadGateway, response.StatusCode)
})
Expand Down
7 changes: 5 additions & 2 deletions private/bufpkg/bufstudioagent/plain_post_handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,7 @@ func (i *plainPostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// TODO: should this context be cloned to remove attached values (but keep timeout)?``
response, err := client.CallUnary(r.Context(), request)
if err != nil {
// Connect marks any issues connecting with the Unavailable
// Any issue connecting is mapped by Connect to the Unavailable
// status code. We need to differentiate between server sent
// errors with the Unavailable code and client connection
// errors.
Expand All @@ -182,7 +182,10 @@ func (i *plainPostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
return
}
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I wonder if we need https://github.com/bufbuild/connect-go/issues/222 to accurately determine what to return here? I don't like that to get a test passing we're treating any CodeUnavailable errors (whether from client connection or returned from server) as StatusBadGateway.

I'd feel better if this fix was restricted to the unit tests and didn't change this logic.

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If you check carefully the code that was written, the only logic I changed was adding connect.CodeUnavailable as another connect error code to trigger an http.StatusBadGateway. All the other cases: net.OpError, url.Error, or the catch-all in L196, all of them were doing the same thing, triggering an http.StatusBadGateway. All I did was simplify that code into a single catch-all in new L186.

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The main difference from before is that if you had a handler that returned CodeUnavailable (perhaps with error details) and it didn't wrap net.OpError or url.Error, we'd call i.writeProtoMessage with the error metadata.

Now we're treating CodeUnavailable (whether from a network error or from the handler) as StatusBadGateway. This means that people who use CodeUnavailable for whatever reason in their handler won't be able to dig into more details in the error.

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As I understand it, this PR is purely attempting to improve test flakiness. Is that correct? If so, it's important but not super urgent.

@pkwarren is correct about the error handling gotchas we're introducing here. If this change can wait a few days, or if we're comfortable reverting it in a few days, let's address bufbuild/connect-go#222 and use that logic here.

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Just had a zoom with @pkwarren, explained me the error logic here, thank you! I'll update this PR to just be skipping the flaky test, and improving comments.

if connectErr := new(connect.Error); errors.As(err, &connectErr) {
if connectErr.Code() == connect.CodeUnknown {
switch connectErr.Code() {
// The server is in some kind of bad and/or unreachable state, forward
// CodeUnavailable information as well.
case connect.CodeUnknown, connect.CodeUnavailable:
http.Error(w, err.Error(), http.StatusBadGateway)
return
}
Expand Down