imgdeflator

Imgdeflator is a small web server which handles POST requests with image attachments. It passes the received image through libvips to resize it to the specified width/height and then it stores it on S3 at the specified path.

It uses urlsign to validate the signature token in the request URL.

Kudos to DarthSim for writing imgproxy, which served as inspiration for this library!

Building imgdeflator locally

go get github.com/Nitro/imgdeflator

Running imgdeflator locally

Just run the executable. By default, it will bind to port 8080 and handle POST requests in the following format:

http://127.0.0.1:8080/base64_encoded_s3_location?width=1024&token=valid_token

or

http://127.0.0.1:8080/base64_encoded_s3_location?height=768&token=valid_token

Configuration is done using environment variables:

• IMGDEFLATOR_LOGGING_LEVEL: The cut off level for log messages. Accepted values: debug, info, warn, error (default info).
• IMGDEFLATOR_MAX_UPLOAD_SIZE: The maximum allowed size for the POSTed image (default 5242880 which is 5MB).
• IMGDEFLATOR_HTTP_PORT: The port to listen on for HTTP connections (default 8080).
• IMGDEFLATOR_UPLOAD_TIMEOUT: The maximum allowed processing duration of the HTTP handler before sending an error to the user (default 10s).
• IMGDEFLATOR_REQUEST_TIMEOUT: The maximum allowed duration of the entire HTTP request before sending an error to the user (default 11s).
• IMGDEFLATOR_DEFAULT_S3_REGION: The default S3 region where to look for the S3 bucket of the received S3 location (default eu-central-1).
• IMGDEFLATOR_MAX_WIDTH: The maximum POSTed image width (default 4096).
• IMGDEFLATOR_MAX_HEIGHT: The maximum POSTed image height (default 4096).
• IMGDEFLATOR_URL_SIGNING_SECRET: A secret to use when validating signed URLs (default: deadbeef). Set it to empty string to disable signature validation.
• IMGDEFLATOR_SIGNING_BUCKET_SIZE: The urlsign time bucket size (default 8h). It provides a 3*bucketSize window of validity for each signature. See the urlsign documentation for more information.

Testing imgdeflator locally

• base64-encode a valid S3 location where you wish the image to be stored and append that to the imgdeflator URL:

> echo -n "s3://nitro-junk/imgdeflator.jpg" | base64 | tr '=' '\0' | xargs -I {} echo "http://127.0.0.1:8080/{}"
http://127.0.0.1:8080/czM6Ly9uaXRyby1qdW5rL2ltZ2RlZmxhdG9yLmpwZw

• Instruct imgdeflator to shrink resources/tweety.jpg to have width=1024 and store it at s3://nitro-junk/imgdeflator.jpg:

> curl -v -H "Content-Type: image/jpeg" --data-binary "@resources/tweety.jpg" "http://127.0.0.1:8080/czM6Ly9uaXRyby1qdW5rL2ltZ2RlZmxhdG9yLmpwZw?width=1024"

Copyright

Copyright (c) 2019 Nitro Software.