S3 event download file obj python lambda

Looking to setup S3 Object Lambda to transform your S3 data on the fly? This is the article for you. S3 is a storage service that allows developers to store raw data. It is a cost effective data storage solution that is among AWS most popular services.

Raw data sitting in S3 is useful from a storage perspective, but what happens if we need to transform a stored object prior to retrieving it?

Options 1 and 2 are suboptimal in the security and redundancy categories. This is the exact problem that S3 Object Lambda solves. S3 Object lambda allows us to write Lambda functions that directly integrate with S3 and transform data on the fly for our clients. Clients still use a get-object API call, except they point their request to a different key and bucket combination. For example, say I have a raw s3 json file called orders. Behind the scenes, we use Lambda functions to transform the data on the fly back to our caller without needing to create a new custom API.

First, we need an S3 bucket that stores our source data that we would like to transform. In my case, my bucket is called beabetterdev-demo-bucket and it contains a single file called orders. This should launch the Access Points home screen. Afterwards, click on the big orange Create access point button to launch the wizard. This is typically tailored to a particular application or use case.

For Network Origin, click on Internet. This will enable your access point to be globally accessible. If you want to expose your bucket contents to the public internet, disable all options under the Block Public Access settings for this Access Point. After we create our access point, we need to go grab our ARN for the next step. Navigate to the permissions tab of your access point and copy the ARN to a text document and set it aside.

Great, now we have an Access Point that we can link to our Object Lambda. Next, we need to go ahead and create our Lambda function in order to provide it as input in the Object Lambda Wizard.

So lets go ahead and do that now. This should launch a simple wizard allowing you to specify your language of choice and some security settings. Expand the dropdown that says Change default execution role and select the Create a new role from AWS policy templates option.

Give your role a name and select the policy template with the name Amazon S3 object read-only permissions. You can leave everything else as default. This policy will give your Lambda function the permission to read your source object orders. The steps our Lambda function logic should take are:. A couple things to note here. The outputRoute and outputToken are two required parameters that you must send back to S3 as part of our final write operation.

I like to think of these as scoped identifiers that tell S3 which GET request the corresponding transformation operation is matched to. Next, we want to drop in our code.

Go ahead and click on Deploy to activate your newly written code in your lambda function. Head back over to the S3 section of the console and click on Object Lambda Access Point in the left hand side bar as seen below. In the prompt, first give your object lambda a name. Just in case of best practices, I share the objectives of lambda: download S3 raw file resize file and upload new file to another S3 bucket Any suggestion is appreciated.

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TemporaryFile as f: s3. BytesIO s3. Milan Cermak Milan Cermak 5, 2 2 gold badges 37 37 silver badges 53 53 bronze badges. Hope it helps. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Who owns this outage? Building intelligent escalation chains for modern SRE. Podcast Who is building clouds for the independent developer? Featured on Meta. Now live: A fully responsive profile.

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