feat(aws): support lambda (#334)

vendor/github.com/aws/aws-lambda-go/lambdacontext/context.go

@@ -0,0 +1,89 @@
+// Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Helpers for accessing context information from an Invoke request. Context information
+// is stored in a https://golang.org/pkg/context/#Context. The functions FromContext and NewContext
+// are used to retrieving and inserting an isntance of LambdaContext.
+
+package lambdacontext
+
+import (
+	"context"
+	"os"
+	"strconv"
+)
+
+// LogGroupName is the name of the log group that contains the log streams of the current Lambda Function
+var LogGroupName string
+
+// LogStreamName name of the log stream that the current Lambda Function's logs will be sent to
+var LogStreamName string
+
+// FunctionName the name of the current Lambda Function
+var FunctionName string
+
+// MemoryLimitInMB is the configured memory limit for the current instance of the Lambda Function
+var MemoryLimitInMB int
+
+// FunctionVersion is the published version of the current instance of the Lambda Function
+var FunctionVersion string
+
+func init() {
+	LogGroupName = os.Getenv("AWS_LAMBDA_LOG_GROUP_NAME")
+	LogStreamName = os.Getenv("AWS_LAMBDA_LOG_STREAM_NAME")
+	FunctionName = os.Getenv("AWS_LAMBDA_FUNCTION_NAME")
+	if limit, err := strconv.Atoi(os.Getenv("AWS_LAMBDA_FUNCTION_MEMORY_SIZE")); err != nil {
+		MemoryLimitInMB = 0
+	} else {
+		MemoryLimitInMB = limit
+	}
+	FunctionVersion = os.Getenv("AWS_LAMBDA_FUNCTION_VERSION")
+}
+
+// ClientApplication is metadata about the calling application.
+type ClientApplication struct {
+	InstallationID string `json:"installation_id"`
+	AppTitle       string `json:"app_title"`
+	AppVersionCode string `json:"app_version_code"`
+	AppPackageName string `json:"app_package_name"`
+}
+
+// ClientContext is information about the client application passed by the calling application.
+type ClientContext struct {
+	Client ClientApplication
+	Env    map[string]string `json:"env"`
+	Custom map[string]string `json:"custom"`
+}
+
+// CognitoIdentity is the cognito identity used by the calling application.
+type CognitoIdentity struct {
+	CognitoIdentityID     string
+	CognitoIdentityPoolID string
+}
+
+// LambdaContext is the set of metadata that is passed for every Invoke.
+type LambdaContext struct {
+	AwsRequestID       string
+	InvokedFunctionArn string
+	Identity           CognitoIdentity
+	ClientContext      ClientContext
+}
+
+// An unexported type to be used as the key for types in this package.
+// This prevents collisions with keys defined in other packages.
+type key struct{}
+
+// The key for a LambdaContext in Contexts.
+// Users of this package must use lambdacontext.NewContext and lambdacontext.FromContext
+// instead of using this key directly.
+var contextKey = &key{}
+
+// NewContext returns a new Context that carries value lc.
+func NewContext(parent context.Context, lc *LambdaContext) context.Context {
+	return context.WithValue(parent, contextKey, lc)
+}
+
+// FromContext returns the LambdaContext value stored in ctx, if any.
+func FromContext(ctx context.Context) (*LambdaContext, bool) {
+	lc, ok := ctx.Value(contextKey).(*LambdaContext)
+	return lc, ok
+}