Fix data race issue by synchronizing events channel through waiting group

Previously, there was a data race condition error when `op
.#PushContainer` was called. It was because of the `Export` func
in `solver.go` that create a sub build pipeline and forward his
events to the main events channel (that catch all events that we log).
To fix it, channel are now split between build pipeline and
centralize into the old output channel (`ch`).

Signed-off-by: Tom Chauveau <tom.chauveau@epitech.eu>

client/client.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"go.opentelemetry.io/otel"
 	"golang.org/x/sync/errgroup"
@@ -103,6 +104,9 @@ func (c *Client) Do(ctx context.Context, state *state.State, fn DoFunc) error {
 }
 
 func (c *Client) buildfn(ctx context.Context, st *state.State, env *environment.Environment, fn DoFunc, ch chan *bk.SolveStatus) error {
+	// Close output channel
+	defer close(ch)
+
 	lg := log.Ctx(ctx)
 
 	// Scan local dirs to grant access
@@ -139,20 +143,35 @@ func (c *Client) buildfn(ctx context.Context, st *state.State, env *environment.
 		Interface("attrs", opts.FrontendAttrs).
 		Msg("spawning buildkit job")
 
-	solverCh := make(chan *bk.SolveStatus)
+	wg := sync.WaitGroup{}
-	defer close(solverCh)
+	// Catch output from events
-	go func() {
+	catchOutput := func(inCh chan *bk.SolveStatus) {
-		for e := range solverCh {
+		for e := range inCh {
-			fmt.Println("J'envoie un event depuis pushContainer")
 			ch <- e
 		}
-	}()
+		wg.Done()
+	}
+
+	// Catch solver's events
+	// Closed manually
+	eventsCh := make(chan *bk.SolveStatus)
+	wg.Add(1)
+	go catchOutput(eventsCh)
+
+	// Catch build events
+	// Closed by buildkit
+	buildCh := make(chan *bk.SolveStatus)
+	wg.Add(1)
+	go catchOutput(buildCh)
 
 	resp, err := c.c.Build(ctx, opts, "", func(ctx context.Context, gw bkgw.Client) (*bkgw.Result, error) {
+		// Close events channel
+		defer close(eventsCh)
+
 		s := solver.New(solver.Opts{
 			Control: c.c,
 			Gateway: gw,
-			Events:  solverCh,
+			Events:  eventsCh,
 			Auth:    auth,
 			Secrets: secrets,
 			NoCache: c.cfg.NoCache,
@@ -193,7 +212,7 @@ func (c *Client) buildfn(ctx context.Context, st *state.State, env *environment.
 		res := bkgw.NewResult()
 		res.SetRef(ref)
 		return res, nil
-	}, ch)
+	}, buildCh)
 	if err != nil {
 		return solver.CleanError(err)
 	}
@@ -205,6 +224,9 @@ func (c *Client) buildfn(ctx context.Context, st *state.State, env *environment.
 			Str("value", v).
 			Msg("exporter response")
 	}
+
+	// Wait until all the events are caught
+	wg.Wait()
 	return nil
 }