github.com/lalkh/containerd@v1.4.3/leases/grpc.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package leases
    18  
    19  import (
    20  	"context"
    21  
    22  	"google.golang.org/grpc/metadata"
    23  )
    24  
    25  const (
    26  	// GRPCHeader defines the header name for specifying a containerd lease.
    27  	GRPCHeader = "containerd-lease"
    28  )
    29  
    30  func withGRPCLeaseHeader(ctx context.Context, lid string) context.Context {
    31  	// also store on the grpc headers so it gets picked up by any clients
    32  	// that are using this.
    33  	txheader := metadata.Pairs(GRPCHeader, lid)
    34  	md, ok := metadata.FromOutgoingContext(ctx) // merge with outgoing context.
    35  	if !ok {
    36  		md = txheader
    37  	} else {
    38  		// order ensures the latest is first in this list.
    39  		md = metadata.Join(txheader, md)
    40  	}
    41  
    42  	return metadata.NewOutgoingContext(ctx, md)
    43  }
    44  
    45  func fromGRPCHeader(ctx context.Context) (string, bool) {
    46  	// try to extract for use in grpc servers.
    47  	md, ok := metadata.FromIncomingContext(ctx)
    48  	if !ok {
    49  		return "", false
    50  	}
    51  
    52  	values := md[GRPCHeader]
    53  	if len(values) == 0 {
    54  		return "", false
    55  	}
    56  
    57  	return values[0], true
    58  }