Author your AWS Lambda function code in Go.
AWS Lambda lets you run code without provisioning or managing servers. For now, you can author your Lambda function code in Node.js, Java, C# and Python, but not in Go. This project fills the gap.
go get -u -d github.com/eawsy/aws-lambda-go-core/...
docker pull eawsy/aws-lambda-go-shim
wget -O Makefile https://github.com/eawsy/aws-lambda-go-shim/raw/master/src/Makefile.example
package main
// /* Required, but no C code needed. */
import "C"
import (
"encoding/json"
"github.com/eawsy/aws-lambda-go-core/service/lambda/runtime"
)
func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) {
return "Hello, World!", nil
}
make
aws lambda create-function \
--role arn:aws:iam::AWS_ACCOUNT_NUMBER:role/lambda_basic_execution \
--function-name preview-go \
--zip-file fileb://package.zip \
--runtime python2.7 \
--handler handler.Handle
Although not required, we recommand you review AWS Lambda Developer Guide first.
This section explains how common programming patterns and core concepts apply when authoring AWS Lambda function code in Go.
The handler is an exported function in your code, that AWS Lambda invokes when executing your code.
func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) {
...
}-
AWS Lambda uses
evtparameter to pass in event data to the handler. An automatic JSON unmarshalling is performed before passing in the data, so that you can use any valid Go type. Refer to eawsy/aws-lambda-go-event for AWS services event definitions.func Handle(evt *MyCustomType, ctx *runtime.Context) (interface{}, error) { ... }
-
AWS Lambda uses
ctxparameter to provide runtime information to the handler. Refer to eawsy/aws-lambda-go-core for more details. -
The handler can either return any valid Go value or an error. What happens to the result depends on the invocation type. In a synchronous execution, AWS Lambda returns the result, serialized in JSON, to the client.
func Handle(evt json.RawMessage, ctx *runtime.Context) (*MyCustomType, error) { ... }
The context is an object containing runtime information, that AWS Lambda passes as the second parameter of the handler when executing your code. Refer to eawsy/aws-lambda-go-core for more details.
-
RemainingTimeInMillis()returns the remaining execution time, in milliseconds, until Lambda terminates the function. -
FunctionNameis the name of the Lambda function that is executing. -
FunctionVersionis the version of the Lambda function that is executing. If an alias is used to invoke the function, then it will be the version the alias points to. -
InvokedFunctionARNis the ARN used to invoke this function. It can be function ARN or alias ARN. An unqualified ARN executes the $LATEST version and aliases execute the function version it is pointing to. -
MemoryLimitInMBis the memory limit, in MB, you configured for the Lambda function. -
AWSRequestIDis the AWS request ID associated with the request. This is the ID returned to the client. If Lambda retries the invocation (in case of execution failure), the AWS request ID remains the same. -
LogGroupNameis the name of the CloudWatch log group where you can find logs written by your Lambda function. -
LogStreamNameis the name of the CloudWatch log stream where you can find logs written by your Lambda function. The log stream may or may not change for each invocation of the Lambda function. -
Identityis the information about the Amazon Cognito identity provider when invoked through the AWS Mobile SDK. -
ClientContextis the information about the client application and device when invoked through the AWS Mobile SDK.
The handler can contain logging statements by using the standard Go fmt or log
packages. Both fmt and log functions write logs to AWS CloudWatch Logs but the log functions write additional
information to each log entry, such as timestamp and request id.
-
fmt.Print[f|ln]func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) { fmt.Println("Hello, World!") return nil, nil } // Hello, World!
-
log.Print[f|ln],log.Fatal[f|ln],log.Panic[f|ln]func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) { log.Println("Hello, World!") return nil, nil } // 2017-01-01T00:00:00.000Z 12ad5f64-d111-11e6-b4b4-b757a100146b Hello, World!
The handler can return any standard Go error. AWS Lambda recognizes the error and serializes its information into JSON and returns it to the client.
func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) {
return nil, errors.New("Oh, Snap!")
}
// {
// "errorMessage": "Oh, Snap!"
// }It is worth noting that if the handler panics, the returned error will be generic but the stack trace will be logged.
func Handle(evt json.RawMessage, ctx *runtime.Context) (interface{}, error) {
panic("Oh, Snap!")
return nil, nil
}
// {
// "errorMessage": "RequestId: 7322cf9e-d10d-11e6-ad86-d3cd48e293cf Process exited before completing request"
// }
Although not required, we recommand you review AWS Lambda Developer Guide first.
This section explains how to build AWS Lambda function code in Go, create a Zip package and configure deployment.
To streamline common use cases, we provide an example Makefile with two environment variables
(HANDLER and PACKAGE) to control the name of the generated binary and package. Feel free to customize build flags,
append static assets to the package, etc.
By default, HANDLER is set to handler and PACKAGE to package.
-
Create
func Handle...
-
Build
make # handler.so # package.zip
-
Deployment
- Runtime: Python 2.7
- Handler: handler.Handle
By setting HANDLER to foo, the generated binary becomes foo.so.
-
Create
func Bar...
-
Build
HANDLER=foo make # foo.so # package.zip
-
Deployment
- Runtime: Python 2.7
- Handler: foo.Bar
By setting PACKAGE to baz, the generated package becomes baz.zip.
-
Create
func Handle...
-
Build
PACKAGE=baz make # handler.so # baz.zip
-
Deployment
- Runtime: Python 2.7
- Handler: handler.Handle
This project is maintained and funded by Alsanium, SAS.
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