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runtime/v2: net.Dial gRPC shim sockets before trying grpc

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This is mostly to workaround an issue with gRPC based shims after containerd
restart. If a shim dies while containerd is also down/restarting, on reboot
grpc.DialContext with our current set of DialOptions will make us wait for
100 seconds per shim even if the socket no longer exists or has no listener.

Signed-off-by: Danny Canter <danny@dcantah.dev>
This commit is contained in:
Danny Canter 2023-11-30 19:15:50 -08:00
parent 8459273f80
commit 0bc9633414
1 changed files with 23 additions and 3 deletions
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26
runtime/v2/shim.go
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@ -22,12 +22,14 @@ import (
"errors"
"fmt"
"io"
"net"
"os"
"path/filepath"
"strings"
"time"
"github.com/containerd/containerd/v2/pkg/atomicfile"
"github.com/containerd/containerd/v2/pkg/dialer"
"github.com/containerd/ttrpc"
"google.golang.org/grpc"
"google.golang.org/grpc/connectivity"
@ -39,7 +41,6 @@ import (
"github.com/containerd/containerd/v2/errdefs"
"github.com/containerd/containerd/v2/events/exchange"
"github.com/containerd/containerd/v2/identifiers"
"github.com/containerd/containerd/v2/pkg/dialer"
"github.com/containerd/containerd/v2/pkg/timeout"
"github.com/containerd/containerd/v2/protobuf"
ptypes "github.com/containerd/containerd/v2/protobuf/types"
@ -275,7 +276,7 @@ func makeConnection(ctx context.Context, id string, params client.BootstrapParam
grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithBlock(),
}
return grpcDialContext(ctx, dialer.DialAddress(params.Address), onClose, gopts...)
return grpcDialContext(ctx, params.Address, onClose, gopts...)
default:
return nil, fmt.Errorf("unexpected protocol: %q", params.Protocol)
}
@ -286,10 +287,29 @@ func makeConnection(ctx context.Context, id string, params client.BootstrapParam
// a callback run when the connection is severed or explicitly closed.
func grpcDialContext(
ctx context.Context,
target string,
address string,
onClose func(),
gopts ...grpc.DialOption,
) (*grpcConn, error) {
// If grpc.WithBlock is specified in gopts this causes the connection to block waiting for
// a connection regardless of if the socket exists or has a listener when Dial begins. This
// specific behavior of WithBlock is mostly undesirable for shims, as if the socket isn't
// there when we go to load/connect there's likely an issue. However, getting rid of WithBlock is
// also undesirable as we don't want the background connection behavior, we want to ensure
// a connection before moving on. To bring this in line with the ttrpc connection behavior
// lets do an initial dial to ensure the shims socket is actually available. stat wouldn't suffice
// here as if the shim exited unexpectedly its socket may still be on the filesystem, but it'd return
// ECONNREFUSED which grpc.DialContext will happily trudge along through for the full timeout.
//
// This is especially helpful on restart of containerd as if the shim died while containerd
// was down, we end up waiting the full timeout.
conn, err := net.DialTimeout("unix", address, time.Second*10)
if err != nil {
return nil, err
}
conn.Close()
target := dialer.DialAddress(address)
client, err := grpc.DialContext(ctx, target, gopts...)
if err != nil {
return nil, fmt.Errorf("failed to create GRPC connection: %w", err)