The AWS Serverless Application Model (AWS SAM) helps you to define serverless applications in simple and clean syntax. You can use the SAM CLI to manage Serverless applications written with AWS Serverless Application Model (SAM). SAM CLI can be used to test functions locally, start a local API Gateway from a SAM template, validate a SAM template, fetch logs, generate sample payloads for various event sources, and generate a SAM project in your favorite Lambda Runtime.
In this tutorial you’ll use the AWS SAM CLI to test a Flogo app that has a Lambda trigger, without deploying it to AWS Lambda. This will obviously increase the developer productivity even more!
This demo makes use of the Flogo CLI. If you don’t have that one running yet, please check out Getting Started with the Flogo CLI
The demo makes use of the AWS SAM CLI. If you haven’t installed it yet, please check out the installation instructions for your OS.
The AWS SAM CLI makes use of Docker images to run your app locally. You need to have Docker installed and running on your machine to complete this tutorial.
If you have any questions, feel free to post an issue on GitHub and tag it as a question or chat with the team and community:
For this tutorial, you can make use of any app that uses the Lambda trigger. If you don’t have an app yet, you can use this one:
The Flogo app has a Lambda trigger and a PATH parameter called name.
{
"name": "Tutorial",
"type": "flogo:app",
"version": "0.0.1",
"appModel": "1.0.0",
"triggers": [
{
"id": "start_flow_as_a_function_in_lambda",
"ref": "github.com/TIBCOSoftware/flogo-contrib/trigger/lambda",
"name": "Start Flow as a function in Lambda",
"description": "Simple Lambda Trigger",
"settings": {},
"handlers": [
{
"action": {
"ref": "github.com/TIBCOSoftware/flogo-contrib/action/flow",
"data": {
"flowURI": "res://flow:lambda_flow"
},
"mappings": {
"input": [
{
"mapTo": "name",
"type": "assign",
"value": "$.evt.name"
}
],
"output": [
{
"mapTo": "data",
"type": "assign",
"value": "$.greeting"
}
]
}
}
}
]
}
],
"resources": [
{
"id": "flow:lambda_flow",
"data": {
"name": "LambdaFlow",
"metadata": {
"input": [
{
"name": "name",
"type": "string"
}
],
"output": [
{
"name": "greeting",
"type": "any"
}
]
},
"tasks": [
{
"id": "log_2",
"name": "Log Message",
"description": "Simple Log Activity",
"activity": {
"ref": "github.com/TIBCOSoftware/flogo-contrib/activity/log",
"input": {
"message": "",
"flowInfo": "false",
"addToFlow": "false"
},
"mappings": {
"input": [
{
"type": "expression",
"value": "string.concat(\"Hello \", $flow.name)",
"mapTo": "message"
}
]
}
}
},
{
"id": "actreturn_3",
"name": "Return",
"description": "Simple Return Activity",
"activity": {
"ref": "github.com/TIBCOSoftware/flogo-contrib/activity/actreturn",
"input": {
"mappings": [
{
"mapTo": "greeting",
"type": "object",
"value": {"Hello": "{{$flow.name}}"}
}
]
}
}
}
],
"links": [
{
"from": "log_2",
"to": "actreturn_3"
}
]
}
}
]
}
To create a Lambda file from this, you can run:
// Create the app
flogo create -f flogo.json myapp
// Build the app
cd myapp
flogo build -e -shim start_flow_as_a_function_in_lambda
You can use the
sam local invokecommand to manually test your code by running Lambda function locally. With SAM CLI, you can easily author automated integration tests by first running tests against local Lambda functions before deploying to the cloud.
Now that is awesome! In order to make that work, SAM needs to have a descriptor called template.yml that describes what the function is and what other parameters it has. Assuming you’ve used the app above, a YAML file could look like
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: Serverless Application Model
Resources:
flogoapp: # The name you want to give your Lambda function
Type: 'AWS::Serverless::Function'
Properties:
CodeUri: bin/ # The location where to find the executable file (not the zip file from the Web UI)
Handler: handler # The name of the handler generated by the flogo build command
Runtime: go1.x
Tracing: Active
Timeout: 120
Events:
flogoevent: # This is a sample event
Type: Schedule
Properties:
Schedule: cron(0 2 * * ? *) # Run at 2:00 am (UTC) every day
Description: Run Hello World every night! # A description for your Lambda app
MemorySize: 128 # The amount of memory you want to give your app in Lambda
For clarity sake, you can create a new directory called lambda and put all files in that directory.
To be able to test the apps locally, SAM makes use of events from JSON files. Events describe the input that would normally come from external apps like Amazon S3 or Amazon API Gateway. In this case, the event will be really simple. You’ll have to create a new file called event.json and the content of the file will be:
{
"name": "World"
}
Before you can run the app, the final step is to copy the executable file (generated in step 1) to the right location. Create a bin folder in the lambda folder you created earlier and copy the file /src/myapp/handler to that location.
From a terminal window you can now use the SAM CLI to run your app locally:
sam local invoke <function> -e <event.json file>
So in this case the command will be
sam local invoke flogoapp -e event.json
As you run that, the output will look like (the last line will display the result of your app)
2018-10-03 16:53:03 Invoking handler (go1.x)
2018-10-03 16:53:03 Found credentials in shared credentials file: ~/.aws/credentials
Fetching lambci/lambda:go1.x Docker container image......
2018-10-03 16:53:04 Mounting /Users/lstigter/Downloads/myapp/lambda/bin as /var/task:ro inside runtime container
START RequestId: 8791ddd9-c612-1864-f381-75d1506ad692 Version: $LATEST
2018-10-03 23:53:05.119 INFO [trigger-flogo-lambda] - Starting AWS Lambda Trigger
2018/10/03 23:53:05 Starting AWS Lambda Trigger
2018/10/03 23:53:05 Received evt: 'map[name:World]'
2018/10/03 23:53:05 Received ctx: 'map[awsRequestId:8791ddd9-c612-1864-f381-75d1506ad692 functionName:test functionVersion:$LATEST logGroupName:/aws/lambda/test logStreamName:2018/10/03/[$LATEST]b1ff97369e34dbbe4f8ee4f578cde273 memoryLimitInMB:128]'
2018-10-03 23:53:05.123 INFO [activity-flogo-log] - Hello World
END RequestId: 8791ddd9-c612-1864-f381-75d1506ad692
REPORT RequestId: 8791ddd9-c612-1864-f381-75d1506ad692 Duration: 5.38 ms Billed Duration: 100 ms Memory Size: 128 MB Max Memory Used: 8 MB
{"Hello":"World"}