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try! Serverless App with Swift
'19/03/19 try! Swift Pre Talks 2019
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YU TAWATA
• Job: iOS Engineer at DMM.com
• Twitter: yuta24
• GitHub: yuta24
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Why Serverless App with Swift?
• Custom Runtime for AWS Lambda
• Can execute programs written in any programming
languages.
• Swift 5
• Easier to bridge to python, compared with Swift4
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What's AWS Lambda Custom Runtime?
• bootstrap
• execute programs using request params and return the
results as responses
#!/bin/sh
set -euo pipefail
# Initialization - load function handler
source $LAMBDA_TASK_ROOT/"$(echo $_HANDLER | cut -d. -f1).sh"
# Processing
while true
do
HEADERS="$(mktemp)"
# Get an event
EVENT_DATA=$(curl -sS -LD "$HEADERS" -X GET "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next")
REQUEST_ID=$(grep -Fi Lambda-Runtime-Aws-Request-Id "$HEADERS" | tr -d '[:space:]' | cut -d: -f2)
# Execute the handler function from the script
RESPONSE=$($(echo "$_HANDLER" | cut -d. -f2) "$EVENT_DATA")
# Send the response
curl -X POST "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/$REQUEST_ID/response" -d "$RESPONSE"
done
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Let's, try!
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How?
1. Create table on AWS Dynamo DB.
2. Create AWS Lambda function.
3. Create sample project using SPM.
4. Make executable file (Using Docker: Swift 5 on Ubuntu 16.04).
5. Deploy executable file and bootstrap to AWS Lambda.
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let boto3 = Python.import("boto3")
let dynamodb = boto3.resource("dynamodb")
let table = dynamodb.Table("swift-sample")
print("\(table.scan())")
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But, a program stopped
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Problems
1. Can't load shared libraries.
2. The environment variable PYTHON_LIBRARY isn’t set.
3. Can't find boto3 module.
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Use aws-lambda-swift
Use aws-lambda-swift (Changed to use Swift 5).
Deploy to shared libraries as a layer.
And link dynamically when handling request in bootstrap.
EXECUTABLE=$LAMBDA_TASK_ROOT/"$(echo $_HANDLER | cut -d. -f1)"
/opt/swift-shared-libs/ld-linux-x86-64.so.2 --library-path /opt/swift-shared-libs/lib $EXECUTABLE
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Set env var and deploy boto3
1. Search python lib path and Set an environment variable.
PYTHON_LIBRARY=/usr/lib64/libpython2.7.so.1.0
2. Deploy boto3 module as a layer. And set /opt/python as
PYTHONPATH.
$ docker run --privileged -it -v `pwd`:`pwd` -w `pwd` --rm amazonlinux
$ yum install python2-pip
$ pip install -t ./python boto3
$ zip -r boto3.zip python
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import AWSLambdaSwift
struct Event: Codable {
}
struct Result: Codable {
let result: String
}
func sample(event: Event, context: Context) -> Result {
let boto3 = Python.import("boto3")
let dynamodb = boto3.resource("dynamodb")
let table = dynamodb.Table("swift-sample")
return Result(result: "\(table.scan())")
}
let runtime = try Runtime()
runtime.registerLambda("sample", handlerFunction: sample)
try runtime.start()
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No content
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We can develop
Serverless app with Swift!!
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Reference
• Custom AWS Lambda Runtimes
• AWS Lambda Layers
• Boto 3 - The AWS SDK for Python
• aws-lambda-swift
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Thanks!