taskhandler

A simple OTP application that basically does a topological sort on a list of tasks, written using Cowboy

Run with docker

$ docker compose up run

Run with OTP (OTP 25 was used for development)

$ rebar3 shell

Ordering a list of tasks

$ curl --location --request POST 'localhost:8080' \
    --header 'Content-Type: application/json' \
    --data-raw '{
        "tasks": [
            {
                "name": "task-1",
                "command": "touch /tmp/file1"
            },
            {
                "name": "task-2",
                "command": "cat /tmp/file1",
                "requires": [
                    "task-3"
                ]
            },
            {
                "name": "task-3",
                "command": "echo '\''Hello World!'\'' > /tmp/file1",
                "requires": [
                    "task-1"
                ]
            },
            {
                "name": "task-4",
                "command": "rm /tmp/file1",
                "requires": [
                    "task-2",
                    "task-3"
                ]
            }
        ]
    }'

Requesting the ordered list of tasks as a bash script

To retrieve the list of tasks as a bash script, simply add a format=bash query parameter

$ curl --location --request POST 'localhost:8080?format=bash' \
    --header 'Content-Type: application/json' \
    --data-raw '{
        "tasks": [
            {
                "name": "task-1",
                "command": "touch /tmp/file1"
            },
            {
                "name": "task-2",
                "command": "cat /tmp/file1",
                "requires": [
                    "task-3"
                ]
            },
            {
                "name": "task-3",
                "command": "echo '\''Hello World!'\'' > /tmp/file1",
                "requires": [
                    "task-1"
                ]
            },
            {
                "name": "task-4",
                "command": "rm /tmp/file1",
                "requires": [
                    "task-2",
                    "task-3"
                ]
            }
        ]
    }'

Future improvements

• decide response format based on Accept header
• move JSON schema validation into the task_list module
• add tests for schema validation
• add automated tests for the http endpoint

Development

For more portability, development can be done using docker. Just spin up the dev box using docker compose, the taskhandler folder will be mounted under /taskhandler. Rebar can then be used to compile the project, start it up or run tests

$ docker compose up dev