Simple fictitious scripting language (FSL) interpreter

Project description

This is a sample of test code for FSL interpreter. It should have possibility to read and process json input data in format represented in the following sample:

{
  "var1":1,
  "var2":2,

  "init": [
    {"cmd" : "#setup" }
  ],

  "setup": [
    {"cmd":"update", "id": "var1", "value":3.5},
    {"cmd":"print", "value": "#var1"},
    {"cmd":"#sum", "id": "var1", "value1":"#var1", "value2":"#var2"},
    {"cmd":"print", "value": "#var1"},
    {"cmd":"create", "id": "var3", "value":5},
    {"cmd":"delete", "id": "var1"},
    {"cmd":"#printAll"}
  ],

  "sum": [
      {"cmd":"add", "id": "$id", "operand1":"$value1", "operand2":"$value2"}
  ],

  "printAll":
  [
    {"cmd":"print", "value": "#var1"},
    {"cmd":"print", "value": "#var2"},
    {"cmd":"print", "value": "#var3"}
  ]
}

Expected response is the following:

3.5
5.5
undefined
2
5

Other requirements:

• The finished project must support receiving multiple FSL scripts.
• Functions and variables must persist between FSL scripts.
• Resolve conflicts by overwriting existing variables or functions.
• The system will create a representation of the script processed.
• The init function is immediately called after each script is processed.
• The input is a JSON object of named variables and named functions
• Variables are defined as a key value pair.
• References to variables are preceded by a hash mark (#).
• A function is an array of command objects.
• An attribute called “cmd” is required and will define which operation to perform.
• All parameters passed to a function are referenced by a $.
• Function calls are defined in the “cmd” attribute by preceding the function name with a hash mark (#).

Build & run

Installed Golang of any version is required. The project was written with Go v1.18. Before first run vendor packages should be populated. It can be done by running the following command: go mod tidy in the project root directory.

Use make test to run unit tests.

Use make to build & run http server on the local host. By default, the server available on the 8081 port. Use another terminal to reach the service or Ctrl+C to stop it.

Running in a docker container

Build docker image: make image.

Run previously created image: make image-run.

Using docker-compose

Use make up and make down to start/stop service using docker-compose.

Deployment

Service can be deployed on the cluster using helm templates. Configured cluster with established connection is required as well as helm command. Use command like the helm install fsl --namespace=fsl helm/fsl to deploy service. The namespace is optional here.

Notice: When deployment starts the service image should be available on the cluster through the docker pull command. It can be organized with configuring any docker registry and putting the image into it.

Server endpoints

• GET /fsl/v1 - Liveness/Readiness probe.
• POST /fsl/v1/scripts - accepts input data in Json format, parses it and then runs init function (if present). Returns result of processing input data in the http response.

Usage example

Run the server by make. Open another terminal and put the following command:

$ echo '{
  "var1": 111,
  "init": [
    {"cmd" : "print", "value": "#var1"}
  ]
}' | curl -X POST http://localhost:8081/fsl/v1/scripts -d@- ; echo

Expected output: 111