Machine Examples

Higher level examples using the machine

gRPC Bidirectional Chat Server

• (~ 300 lines)

Design

• clients join a channel with a single request that starts streaming from os.Stdin -> chat server
• messages sent to a channel are broadcasted to all client's that are listening to that channel
• Protobuf API
• Implementation

Start Server

go run chat/server/main.go --port 9000

Start Client

In one terminal:

go run chat/client/main.go --channel accounting --target localhost:9000

In a second terminal:

go run chat/client/main.go --channel accounting --target localhost:9000

now start typing in either terminal, messages should be broadcasted to both terminals since they are bothsubscribed to the accounting channel.

TCP Reverse Proxy

• Implementation

• (~ 150 lines)

• straight up transparent reverse proxy

• zero dependencies besides logger

  go run reverse-proxy/main.go --port 5000 --target $(upstream ip address/port)

Test proxy:

curl $(local proxy)

Concurrent Cron Server

• Implementation

• (~ 150 lines)

• zero dependencies besides logger

• execute any number of shell scripts in separate threads, each with their own timer

• config file to hold cron job configuration

• every cron is cleaned up when the parent goroutine is cancelled/times out

• get crons via http GET request to /cron

• add cron at runtime via http POST request to /cron/job

example config:

name: "example"jobs:  - name: "hello world"    sleep: "1s"    script: |      echo "hello world"  - name: "hello world 2"    sleep: "1s"    script: |      echo "hello world 2"

Start Cron Server

go run cron/main.go --config cron/cron.yaml --port 8000

Get Cron Jobs

curl -X GET http://localhost:8000/cron

Add Cron Job

curl -L -X POST 'http://localhost:8000/cron/job' \-H 'Content-Type: application/json' \--data-raw '{    "name": "whoami",    "script": "whoami",    "sleep": "5s"}'