add lambda info

lambda/.gitignore

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+*.zip

lambda/README.md

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+# Build the tippecanoe layer (binary)
+
+1. On an AWS Linux 2 instance or image:
+
+    sudo yum update
+    sudo yum install git clang sqlite-devel zlib-devel
+
+2. Create a ZIP archive with the `tippecanoe` binary at `bin/tippecanoe` and upload as a Lambda layer
+3. Copy [lambda_function.py](lambda_function.py) (python 3.9 runtime)
+4. set the environment variable `OUTPUT_BUCKET` to your output bucket; give lambda IAM role access to input/output buckets

lambda/lambda_function.py

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+import os
+import json
+import subprocess
+import boto3
+# if the input bucket is publicly readable
+# from botocore import UNSIGNED
+# from botocore.config import Config
+
+def lambda_handler(event, context):
+    bucket = event['Records'][0]['s3']['bucket']['name']
+    key = event['Records'][0]['s3']['object']['key']
+    #s3 = boto3.client('s3',config=Config(signature_version=UNSIGNED))
+    s3 = boto3.client('s3')
+    s3.download_file(bucket,key,'/tmp/input.geojsonseq')
+    p = subprocess.check_call(['tippecanoe','-o','/tmp/output.mbtiles','/tmp/input.geojsonseq','--force'])
+    s3.upload_file('/tmp/output.mbtiles',os.environ['OUTPUT_BUCKET'],key + ".mbtiles")
+    return {
+        'statusCode': 200,
+        'body': json.dumps('Done!')
+    }

lambda/requirements.txt

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+boto3==1.20.32
+botocore==1.23.32