42 lines
1.3 KiB
Markdown
42 lines
1.3 KiB
Markdown
---
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tags:
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- AWS
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- aws-lambda
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---
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# AWS Lambda examples
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## Reconstruct CloudFront URLs
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```js
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exports.handler = (event, context, callback) => {
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// Extract the request from the CloudFront event that is sent to Lambda@Edge
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var request = event.Records[0].cf.request;
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// Extract the URI from the request
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var olduri = request.uri;
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// Match any '/' that occurs at the end of a URI. Replace it with a default index
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var newuri = olduri.replace(/\/$/, "/index.html");
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// Replace the received URI with the URI that includes the index page
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request.uri = newuri;
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// Return to CloudFront
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return callback(null, request);
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};
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```
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Let's walk through the above example making reference to the general structure
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of the
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[AWS Lambda handler function](Lambda_handler_function.md):
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1. The `event` parameter is invoked to gain access to the event that triggered
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the function. This is a CloudFront request event which is targetted with
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`event.Records[0].cf.request`
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2. We classify this request as the `olduri` since it doesn't have the form we
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want.
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3. We mutate the original request by replacing `/` with `/index.html`
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4. We then re-assign the `request.uri` value to the value of the new URI.
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5. Finally we invoke the `callback` parameter to signal the completion of the
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transformation and return the new request as the return value.
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