Image Resizer Service

Description

The service is designed for making a preview (creating an image with new dimensions based on a colored image).

Architecture structure

The service is a web server (proxy) that loads images, scales/crops them to the desired format and returns them to the user.

Endpoint description

The service must receive the URL of the original image, download it, change it to the required size and return it as an HTTP response.

• Works only with HTTP requests.
• Proxy errors from the remote service and respond to the client with 502 Bad Gateway.
• Support only JPEG image encoding.

Http GET request

http://localhost:2891/fill/{height}/{width}/{img-url}

Cache

The service saves (cache) the received preview on the local disk and, when requested again, send the image from the disk, without a request to the remote HTTP server.

Since the cache space is limited, the "Least Recent Used" algorithm must be used to remove rarely used images.

Configuration

There are multiple configurations parameters. It may be grouped by:

• logger
• server
• cache
• resizer
• storage

There is example of config.toml file

[logger]
Level = "INFO"
FilePath = "logs/app.log"
EnableFileLog = false

[server]
Host="0.0.0.0"
HostPort=2891

[cache]
ExpireSeconds=20
CapacityValues=5

[resizer]
TargetQuality=90

[storage]
UseFilesystem=true
UploadDirectory="uploads"

Launch and Deploy

The microservice should be deployed using the make run command (within docker compose up) in the project directory.

Build and run:

make run

Build and run docker container:

make run-img

Build and run by docker compose:

make run-compose

Run linter:

make lint

Run tests:

make test

Testing tasks

It is necessary to check the operation of the server in different scenarios:

• the image was found in the cache;
• the remote server does not exist;
• the remote server exists, but the image was not found (404 Not Found);
• the remote server exists, but the image is not an image, but, say, an exe file;
• the remote server returned an error;
• the remote server returned the image;
• the image is smaller than the required size; etc.

Recension

Maximum - 15 points (subject to fulfillment of mandatory requirements):

• Implemented an HTTP server that proxies requests to a remote server - 2 points.
• Implemented image slicing - 2 points.
• Caching sliced images on disk - 1 point.
• Cache limit by location (LRU cache) - 1 point.
• The proxy server correctly transmits the request headers - 1 point.
• Integration tests written - 3 points.
• The tests are adequate and fully cover the functionality - 1 point.
• The project can be built using make build, run using make run and tested using make test - 1 point.
• Code clarity and purity - up to 3 points.