Rob Allen's DevNotes – Developing software in the Real World

PHP Architect: Serverless PHP With Bref, Part 2

Part two of my article on using Serverless PHP using Bref has been published! In part one, I introduced Bref as we wrote a simple "Hello World" application. Part follows this up exploring a more complete serverless application, my Project365 website. This S3 hosted static website is build using a serverless PHP function that connects to the Flickr API to retrieve my my one-photo-per-day images and present them on a single page per year. In… continue reading.

Posted on 19 June 2019 in AWS Lambda, More Rob, PHP Leave a comment

Keyboard shortcut to Save as PDF on Mac

I regularly print to PDF on my Mac, This is done from the print dialog by selecting Save as PDF from the drop down in the bottom left of the dialog which is a bit of a pain to get using the mouse. I recently discovered that I could create a keyboard shortcut to make this much easier. In System Preferences -> Keyboard -> Shortcuts -> App Shortcuts you can create a keyboard shortcut to… continue reading.

Posted on 12 June 2019 in Computing, Software View all 2 comments

Extracting the base name of a file in Bash

I have a handy bash script that transcodes videos using Don Meton's video_transcoding tools. This script was written in a hurry and one limitation it had was that it re-transcoded any source file even if the output file already existed. The script looked like this:

#!/usr/bin/env bash

readonly source_dir="${1:-MKV}"
readonly output_dir="${2:-MP4}"

for file in "$source_dir"/*.mkv; do
    ./transcode.sh "$file" "$output_dir"
done

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#!/usr/bin/env bash

readonly source_dir="${1:-MKV}"

readonly output_dir="${2:-MP4}"

for file in "$source_dir"/*.mkv; do

./transcode.sh "$file" "$output_dir"

done

What it should do is only run transcode.sh if the output file doesn't exist, so I updated it. Parameter expansion to the rescue! I needed to extract the base… continue reading.

Posted on 5 June 2019 in Development Leave a comment

Circular dependencies in AWS SAM Policies

I'm trying to tighten up the policies of my AWS Lambda function so that it only has access to the one S3 bucket that it needed, so I added an S3CrudPolicy with the BucketName referencing the bucket that's defined in the template. The relevant part of template.yaml looks like this:

Resources:
    ImagesBucket:
        Type: AWS::S3::Bucket
        Properties:
            BucketName: !Sub "${ProjectName}-${UniqueKey}-images"

    ResizeFunction:
        Type: AWS::Serverless::Function
        Properties:
            FunctionName: resize
			# ...
            Events:
                CreateThumbnailEvent:
                    Type: S3
                    Properties:
                        Bucket: !Ref ImagesBucket
                        Events: s3:ObjectCreated:*
            Policies:
                - S3CrudPolicy:
                    BucketName: !Ref ImagesBucket

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Resources:

ImagesBucket:

Type: AWS::S3::Bucket

Properties:

BucketName: !Sub "${ProjectName}-${UniqueKey}-images"

ResizeFunction:

Type: AWS::Serverless::Function

Properties:

FunctionName: resize

# ...

Events:

CreateThumbnailEvent:

Type: S3

Properties:

Bucket: !Ref ImagesBucket

Events: s3:ObjectCreated:*

Policies:

- S3CrudPolicy:

BucketName: !Ref ImagesBucket

However, this creates an error:

Failed to create the changeset: Waiter ChangeSetCreateComplete failed: Waiter encountered
a terminal failure state Status: FAILED. Reason: Circular dependency between resources:
[ImagesBucket, ResizeFunctionRole, ResizeFunction, ResizeFunctionCreateThumbnailEventPermission]

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Failed to create the changeset: Waiter ChangeSetCreateComplete failed: Waiter encountered

a terminal failure state Status: FAILED. Reason: Circular dependency between resources:

[ImagesBucket, ResizeFunctionRole, ResizeFunction, ResizeFunctionCreateThumbnailEventPermission]

(Who is this waiter anyway? This isn't a restaurant!) Solution To solve this, instead of referencing ImageBucket in… continue reading.

Posted on 29 May 2019 in AWS Lambda Leave a comment

Changing the AWS API Gateway response status code in SAM

When creating an API with AWS Lambda and Api Gateway, I discovered that a client request to a given resource with a verb that wasn't supported resulted in an unexpected response. You can see this from this curl command to the /test resource which is only defined for GET:

$ curl -i -X PUT https://mh5rwr9q25.execute-api.eu-west-2.amazonaws.com/prod/test
HTTP/2 403
content-type: application/json
content-length: 42

{"message":"Missing Authentication Token"}

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$ curl -i -X PUT https://mh5rwr9q25.execute-api.eu-west-2.amazonaws.com/prod/test

HTTP/2 403

content-type: application/json

content-length: 42

{"message":"Missing Authentication Token"}

Given that I can GET the /Prod/hello resource, I would not expect to see 405 Method Not Allowed for PUT, and 403 Forbidden is a… continue reading.

Posted on 21 May 2019 in AWS Lambda Leave a comment

My Bref Makefile

In order to use Bref efficiently, I've developed a Makefile so that I don't have to remember all the various commands required. In particular, looking up the correct parameters to sam package & sam deploy is a pain and it's much easier to type make deploy and it all works as I expect. It looks like this:

Posted on 15 May 2019 in AWS Lambda, PHP View all 2 comments

PHP Architect: Serverless PHP With Bref, Part 1

I've written a two-part series on Serverless PHP on AWS Lambda using Matthieu Napoli's Bref for php[architect]. Part one has been published in the May 2019 issue and if you're not already a subscriber, you should be! If you just want to learn about Bref though, then my introduction to Bref is available for free, just for you!

Posted on 9 May 2019 in AWS Lambda, More Rob, PHP One comment so far

Slim 4 Cyclomatic Complexity

There's not much wrong with Slim 3; lots of people are using it very successfully producing APIs and websites of all kinds. For Slim 4 the main goals have been to support PSR-15, make it easier to use your own PSR-7 implementation, improve error handling and remove assumptions that look magical if you don't know they are there. The latter one is the most important to me, personally! Secondarily, Pierre has concentrated on making Slim's… continue reading.

Posted on 3 April 2019 in PHP, Slim Framework Leave a comment

Using img2lambda to publish your Serverless PHP layer

This interesting tweet by Clare Liguori came to my attention last week: This new img2lambda tool will take the layers of a Docker container and convert them to AWS layers for use in Lambda. I poked around with Clare's example and updated my lambda-php project in order to understand how it works. I also rewrote my runtime's bootstrap to make it clearer. The clever thing from my point of view is that you can build… continue reading.

Posted on 31 January 2019 in AWS Lambda, PHP View all 2 comments

rst2pdf: back from the dead!

Today marks a momentous day! I've released 0.94 of rst2pdf to PyPI! If you have a need to convert plain text files to PDF, check it out. As the last release, 0.93, was December 2012, I think you could have reasonably assumed that the project was abandoned. So why did I bring it back from the dead?

Posted on 24 January 2019 in rst2pdf Leave a comment

PHP Architect: Serverless PHP With Bref, Part 2

Keyboard shortcut to Save as PDF on Mac

Extracting the base name of a file in Bash

Circular dependencies in AWS SAM Policies

Changing the AWS API Gateway response status code in SAM

My Bref Makefile

PHP Architect: Serverless PHP With Bref, Part 1

Slim 4 Cyclomatic Complexity

Using img2lambda to publish your Serverless PHP layer

rst2pdf: back from the dead!

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