Little Bastard

Simple Docker image with a script in golang to execute GET request on an endpoint (Request Repeater).

This is usefull if you cannot do cron jobs in your application settup.

Just expose a certain route in your web application to execute the job (or to schedule backround job) and trigger little_bastard image to execute request on it.

...or you can use this Docker image to test your application against DDOS attack.

There is a known issue with oom - Out of memory restarting Docker container after several hors, please check https://github.com/equivalent/little_bastard/issues/2 for mor details

Usage

Single edpoint

docker pull equivalent/little_bastard

Specify URL env variable

docker run -e "URL=http://www.my-app.dot/execute-something.html" equivalent/little_bastard

Default timeout is 1000ms (1 second), if you need different timeout:

# 2 second timeout
docker run -e "SLEEPFOR=2000" -e "URL=http://www.my-app.dot/execute-something.html" equivalent/little_bastard

To execute on localhost of host image:

docker run -e "SLEEPFOR=2000" -e "URL=http://localhost:3000/execute-something.html" --net="host" equivalent/little_bastard

You want authentication ? How about passing token param.

docker run -e "URL=https://www.my-app.dot/execute-something.html?token=1234556" --net="host" equivalent/little_bastard

docker-compose.yml example

---
version: '2'
services:
  nginx:
    image: quay.io/myorg/my-nginx-image
    ports:
      - "80:80"
  request_repeater:
    image: 'equivalent/little_bastard'
    links:
      - nginx:nginx
    environment:
      URL: 'http://nginx/some-endpoint'
      SLEEPFOR: 7200

AWS Elastic Beanstalk Dockerrun.aws.json example usage

{
  "containerDefinitions": [
    {
      "name": "nginx",
      "image": "........",
      "portMappings": [
        {
          "hostPort": 80,
          "containerPort": 80
        }
      ],
    },
    {
      "name": "request_repeater",
      "image": "equivalent/little_bastard",
      "essential": true,
      "memory": 150,
      "links": [ "nginx" ],
      "environment": [
        {
          "name": "URL",
          "value": "http://nginx/some-endpoint"
        }
      ]
    }
  ]
}

Multiple endpoints

you need to pass URLS env variable with json in format:

{
  "urls": [
    {"url":"http://myserver/some-endpoint", "sleep":4000},
    {"url":"http://myserver/another-endpoint", "sleep":1200},
    {"url":"http://myserver/third-endpoint", "sleep":72000}
  ]
}

docker run -e 'URLS={"urls": [{"url":"http://localhost/some-endpoint", "sleep":1200}, {"url":"http://localhost/another-endpoint","sleep":3000}]}' --net="host" equivalent/little_bastard

URL and SLEEPFOR env variables are ignored when you provide URLS env variable

docker-compose.yml example

---
version: '2'
services:
  nginx:
    image: quay.io/myorg/my-nginx-image
    ports:
      - "80:80"
  request_repeater:
    image: 'equivalent/little_bastard'
    links:
      - nginx:nginx
    environment:
      URLS: '{"urls": [{"url":"http://nginx/some-endpoint", "sleep":1200},
{"url":"http://nginx/another-endpoint","sleep":7200}]}'

AWS Elastic Beanstalk Dockerrun.aws.json example usage

{
  "containerDefinitions": [
    {
      "name": "nginx",
      "image": "........",
      "portMappings": [
        {
          "hostPort": 80,
          "containerPort": 80
        }
      ],
    },
    {
      "name": "request_repeater",
      "image": "equivalent/little_bastard",
      "essential": true,
      "memory": 150,
      "links": [ "nginx" ],
      "environment": [
        {
          "name": "URLS",
          "value":"{\"urls\":[{\"url\":\"http://nginx/some-endpoint\",\"sleep\":1300},{\"url\":\"http://nginx/other-endpoint\",\"sleep\":1200000}]}"

        }
      ]
    }
  ]
}

more sophisticated stuff

If you need something more sophisticated, sorry this image is really basic. But we welcome any suggestions or pull requests.

Minimum Sleeptime

In order to avoid docker container to use all CPU resources there is a minimum sleep time implementend set to 500 miliseconds. If you need to use this image without this limit provide one more extra enviroment variable MINIMUMSLEEP to the docker run:

docker run -e "SLEEPFOR=300" -e 'MINIMUMSLEEP=300' -e "URL=http://www.my-app.dot/execute-something.html" equivalent/little_bastard # 300 ms

docker run -e "SLEEPFOR=0" -e 'MINIMUMSLEEP=0' -e "URL=http://www.my-app.dot/execute-something.html" equivalent/little_bastard # no limit

Memory consumption

I'm recommending to reserve container memory of 150MB (e.g.: in AWS EB). That should be enough.

Allocating lower than 95 MB memory will cause container to crush with oom (out of memory) in /var/log/docker-events (more info)

The lowest number I manage to allocate without causing docker container to crush was 100 MB. (Reater was doing multiple requests to multiple endpoints and it worked).

Kill the container

docker kill $(docker ps | grep -e little_bastard | awk "{print \$1}")

# sudo version
sudo docker kill $(sudo docker ps | grep -e little_bastard | awk "{print \$1}")