worker_front

Worker Front

Task runner of worker node. Receives application request with RESTful API and executes the function with Docker.

Base features

• Build image automatically if image not exists
  • Download the target function source code (from S3)
  • Attach environment by function's demands (python3.7, NodeJS 12, Java 8)
  • Build docker image with the function source code
• Creates containers for function execution
  • After execution, remove container and send responses

Optional features

1. Limit the cache size of downloaded user codes

   • In default mode, there is no limitation of built images and cached codes
   • With this option, worker node manages Docker image and user code with LRU policy
   • To use this option, set environment variable USER_CODE_SIZE_LIMIT with proper size.
     • For example, to set limit as 100MB, you can set this variable as 100000000

2. Provides pre-warmed container pool

   • Based on the idea to reduce the preparation time by pre-building the environment before the function is executed
   • To use this option, you need to configure environment variables CONTAINER_POOL_LIMIT and CONTAINER_POOL_NUM.
     • Worker node will generate pre-warmed containers by LRU policy
     • CONTAINER_POOL_LIMIT means the number of caching applications
     • CONTAINER_POOL_NUM means the number of pre-warmed containers per application (default: 6)

3. Supports two-levels of isolation

   • Based on the idea to let share the sandbox among same applications
   • To use this option, set USING_REST_MODE environment variable as true
   • The default lifetime of each idle container is 10 seconds. You can change is value with REST_CONTAINER_LIFE_TIME.

Recommended step before running

As our framework includes automated image build & pull step on running a function. But pulling the base image(e.g. python, java, nodejs) takes quite a lot time, we recommend you to pull base images before running the worker front.

$ docker pull openjdk:8
$ docker pull python:3.7
$ docker pull node:12

How to run

We support two arguments on starting worker front. First argument is the port, and second argument is the option for daemon. Default port number is 8222.

$ go run *.go start
$ go run *.go start 8222
$ go run *.go start 8222 -d

If you use daemonize option, then you can see two files (daemon.log, daemon.pid) on the same directory. To kill the daemon, run command like below.

$ go run *.go stop

After running the worker front, you can access the worker front with visiting http://localhost:8222. To run the function W1, request http://localhost:8222/execute?name=W1. Response would be like below:

{
	"Result": {
		"statusCode": 200,
		"body": "Hello World2998950"
	},
	"ExecutionTime": 3373,
	"InternalExecutionTime": 98,
	"Meta": {
		"ImageBuilt": true,
		"UsingPooledContainer": false,
		"UsingExistingRestContainer": false,
		"ContainerName": "hf_w1__9437_98081",
		"ImageName": "hf_w1"
	}
}

Configure with RESTful API

You can also change configuration after starting the worker front. Visit http://localhost:8222/configure and change options by passing queries like ?using_rest_mode=true&rest_container_life_time=20.