Docs for "sam local" don't work with Go

[mousedownmike]

Description:

The sam local commands do not work as documented in the AWS Serverless Application Model Developer Guide. They require an additional call to sam build before they will work.

Steps to reproduce:

Assume a simple project structure such as:

simple-go/
├── cmd
│   └── my-func
│       └── main.go
├── go.mod
├── samconfig.toml
└── template.yaml

With a template.yaml of:

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: 'Simple Go SAM'
Resources:
  ExampleRoot:
    Type: 'AWS::Serverless::Function'
    Properties:
      CodeUri: './cmd/my-func/'
      Handler: 'my-func'
      Runtime: 'go1.x'
      Events:
        Get:
          Type: 'Api'
          Properties:
            Path: '/'
            Method: 'get'

The documentation indicates the following commands should work from within the simple-go directory:

• sam local invoke
• sam local start-api

Observed result:

Running sam local invoke gets you:

$ sam local invoke --debug
2020-11-13 20:11:23,487 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
2020-11-13 20:11:23,542 | local invoke command is called
2020-11-13 20:11:23,544 | No Parameters detected in the template
2020-11-13 20:11:23,561 | 2 resources found in the template
2020-11-13 20:11:23,561 | Found Serverless function with name='ExampleRoot' and CodeUri='./cmd/my-func/'
2020-11-13 20:11:23,564 | Found one Lambda function with name 'ExampleRoot'
2020-11-13 20:11:23,564 | Invoking my-func (go1.x)
2020-11-13 20:11:23,564 | No environment variables found for function 'ExampleRoot'
2020-11-13 20:11:23,564 | Environment variables overrides data is standard format
2020-11-13 20:11:23,564 | Loading AWS credentials from session with profile 'None'
2020-11-13 20:11:23,572 | Resolving code path. Cwd=/projects/simple-go, CodeUri=./cmd/my-func/
2020-11-13 20:11:23,572 | Resolved absolute path to code is /projects/simple-go/cmd/my-func
2020-11-13 20:11:23,572 | Code /projects/simple-go/cmd/my-func is not a zip/jar file
2020-11-13 20:11:23,575 | Skip pulling image and use local one: amazon/aws-sam-cli-emulation-image-go1.x:rapid-1.7.0.

2020-11-13 20:11:23,575 | Mounting /projects/simple-go/cmd/my-func as /var/task:ro,delegated inside runtime container
2020-11-13 20:11:23,885 | Starting a timer for 3 seconds for function 'ExampleRoot'
START RequestId: 6961a864-2a06-1dca-b722-c2635e27a299 Version: $LATEST
fork/exec /var/task/my-func: no such file or directory: PathError
fork/exec /var/task/my-func: no such file or directory: PathError
null
END RequestId: 6961a864-2a06-1dca-b722-c2635e27a299
REPORT RequestId: 6961a864-2a06-1dca-b722-c2635e27a299  Init Duration: 57.70 ms Duration: 1.44 ms       Billed Duration: 100 ms Memory Size: 128 MB     Max Memory Used: 16 MB
2020-11-13 20:11:24,184 | Sending Telemetry: {'metrics': [{'commandRun': {'awsProfileProvided': False, 'debugFlagProvided': True, 'region': '', 'commandName': 'sam local invoke', 'duration': 696, 'exitReason': 'success', 'exitCode': 0, 'requestId': '78d50567-a61f-42e3-9fa4-b3d0a2e30179', 'installationId': '72eb7872-74c2-473d-b9e1-6ea1da5e4588', 'sessionId': '7084671a-89d6-4499-b213-bd5cf632c207', 'executionEnvironment': 'CLI', 'pyversion': '3.8.5', 'samcliVersion': '1.7.0'}}]}
2020-11-13 20:11:24,530 | HTTPSConnectionPool(host='aws-serverless-tools-telemetry.us-west-2.amazonaws.com', port=443): Read timed out. (read timeout=0.1)

{"errorType":"PathError","errorMessage":"fork/exec /var/task/my-func: no such file or directory"}

sam local start-api starts the API but fails with almost the same error once a request is made.

Expected result:

my-func should be built and executed or the documentation should be updated to indicate an additional step is necessary.

Working result:

Running sam build followed by sam local invoke does work:

$ sam build                                          
Building codeuri: ./cmd/my-func/ runtime: go1.x metadata: {} functions: ['ExampleRoot']  
Running GoModulesBuilder:Build                                                           
                                            
Build Succeeded                                                                          
                                                                                         
Built Artifacts  : .aws-sam/build                                                        
Built Template   : .aws-sam/build/template.yaml                                          
                                                                                         
Commands you can use next                                                                                                                                                         
=========================                                                                                                                                                         
[*] Invoke Function: sam local invoke                                                    
[*] Deploy: sam deploy --guided                                                                                                                                                   
                                                                                                                                                                                  
$ sam local invoke --debug                                                                                                                    
2020-11-13 20:23:37,364 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics                                              
2020-11-13 20:23:37,415 | local invoke command is called                                                                                                                          
2020-11-13 20:23:37,416 | No Parameters detected in the template                                                                                                                  
2020-11-13 20:23:37,432 | 2 resources found in the template                                                                                                                       
2020-11-13 20:23:37,432 | Found Serverless function with name='ExampleRoot' and CodeUri='ExampleRoot'                                                                             
2020-11-13 20:23:37,434 | Found one Lambda function with name 'ExampleRoot'                                                                                                       
2020-11-13 20:23:37,434 | Invoking my-func (go1.x)                                                                                                                                
2020-11-13 20:23:37,434 | No environment variables found for function 'ExampleRoot'                                                                                               
2020-11-13 20:23:37,434 | Environment variables overrides data is standard format                                                                                                 
2020-11-13 20:23:37,434 | Loading AWS credentials from session with profile 'None'                                                                                                
2020-11-13 20:23:37,443 | Resolving code path. Cwd=/projects/simple-go/.aws-sam/build, CodeUri=ExampleRoot                                                                        
2020-11-13 20:23:37,443 | Resolved absolute path to code is /projects/simple-go/.aws-sam/build/ExampleRoot           
2020-11-13 20:23:37,443 | Code /projects/simple-go/.aws-sam/build/ExampleRoot is not a zip/jar file                                                                               
2020-11-13 20:23:37,447 | Skip pulling image and use local one: amazon/aws-sam-cli-emulation-image-go1.x:rapid-1.7.0.                                                             
                                                                                                                                                                                  2020-11-13 20:23:37,447 | Mounting /projects/simple-go/.aws-sam/build/ExampleRoot as /var/task:ro,delegated inside runtime container                                              2020-11-13 20:23:37,755 | Starting a timer for 3 seconds for function 'ExampleRoot'                                                                                               
2020/11/14 04:23:37 Simple Function                                                                                                                                               
2020/11/14 04:23:37 <nil>                                                                                                                                                         
2020-11-13 20:23:40,756 | Function 'ExampleRoot' timed out after 3 seconds                                                                                                        
2020-11-13 20:23:41,122 | Sending Telemetry: {'metrics': [{'commandRun': {'awsProfileProvided': False, 'debugFlagProvided': True, 'region': '', 'commandName': 'sam local invoke',
 'duration': 3755, 'exitReason': 'success', 'exitCode': 0, 'requestId': 'cef4037b-9689-4610-876c-93413bc413bb', 'installationId': '72eb7872-74c2-473d-b9e1-6ea1da5e4588', 'session
Id': '547dafa5-7733-42bc-96d1-1ebe099d469b', 'executionEnvironment': 'CLI', 'pyversion': '3.8.5', 'samcliVersion': '1.7.0'}}]}                                                    
2020-11-13 20:23:41,437 | Telemetry response: 200  

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

$ go version
go version go1.15.4 linux/amd64
$ sam --version
SAM CLI, version 1.7.0
$ cat /etc/issue
Ubuntu 20.04.1 LTS \n \l

Maybe there should be additional instructions for non-interpreted languages?

[mousedownmike]

Moved to docs repository.