Deploying the image scaling function

[specious]

While most of the lambda functions are currently implemented in pure nodejs, which can be deployed simply by providing the source code¹, functions which include a native binary component must be built from source and packaged as a zip file.

The built packages are not included in the git source tree itself as they are a direct derivative of the source code.

This project currently includes an experimental partial implementation of an on-request image scaling function which is a native binary compiled from C++ source code. It runs directly on the CPU and does not require an interpreter.

The function is currently experimental and in development (and by default commented out in the serverless stack template).

Track this feature: #2

Technical considerations when building from source:

• Building the deployable package involves launching a Docker container which is set up to compile the source code and package the deployable zip package
• Building the Docker container image which can do that involves building the latest git versions of the AWS C++ SDK, the AWS C++ lambda runtime library and the vips image processing library
• In addition, if building inside the Docker container, the process may require a slight modification to the script that automates the production of the zip package, pending Packager improvements awslabs/aws-lambda-cpp#136

The process is described in the README and is made accessible by functions provided in the manage toolkit.

However, all it takes to deploy this function is to include an already built zip package in:

functions/
  scale-image-experimental/
    build/
      scale-image-experimental.zip

Built packages can be posted in this discussion as attachments.

Footnotes

1. Setting the CodeUri parameter to refer to a local directory in the stack template will result in the deployment process creating a zip package of the source code for deployment. See: sam package ↩

[specious]

As of 2013194, the scaling function is only partially implemented.

If deployed, given an uploaded image with id 0364169bac17494730dfa103, one could call:

api/scale-image?key=/media/0364169bac17494730dfa103/600

The function parses the query and returns:

{
  "bucket": "littermap-backend-mediabucket-16qk04mwmtrb9",
  "key": "/media/0364169bac17494730dfa103/600",
  "query_parts": 3,
  "object_id": "0364169bac17494730dfa103",
  "requested_size": 600
}

Further code doesn't run in this build, but it would correctly contact the media bucket and retrieve the image information.

After that step, the code is currently faulty.

Download the package: scale-image-experimental.zip

[specious]

As of 07200f8, place this zip file into functions/scale-image/build before deploying the stack.

Package: scale-image.zip
Build: 988068b888e8

Might need to mkdir -p functions/scale-image/build to create the directory.

[specious]

Quick way is to run (from the project root directory):

wget -P functions/scale-image/build/ <link-to-latest-zip>