go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/config/cfgclient/context.go (about)

     1  // Copyright 2020 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package cfgclient
    16  
    17  import (
    18  	"context"
    19  	"errors"
    20  
    21  	"go.chromium.org/luci/config"
    22  	"go.chromium.org/luci/config/impl/erroring"
    23  )
    24  
    25  var contextKey = "go.chromium.org/luci/config/cfgclient"
    26  
    27  // Use installs a client implementation into the context.
    28  //
    29  // Primarily used by the framework code to setup an appropriate implementation.
    30  // Can be used in unit tests to install a testing implementation.
    31  //
    32  // Do not call it yourself outside of unit tests.
    33  func Use(ctx context.Context, client config.Interface) context.Context {
    34  	return context.WithValue(ctx, &contextKey, client)
    35  }
    36  
    37  // Client returns a client to access the LUCI Config service.
    38  //
    39  // If there's no client in the context, returns a client that fails all calls
    40  // with an error.
    41  func Client(ctx context.Context) config.Interface {
    42  	if impl, _ := ctx.Value(&contextKey).(config.Interface); impl != nil {
    43  		return impl
    44  	}
    45  	return erroring.New(errors.New("LUCI Config client is not available in the context"))
    46  }