1-setup

Step 1: Setup

In this step, you will set up your "VMs" by running the web and api services on your local machine.

Goals

• Start web and api services.
• Allow web to call api.

Tasks

Web

In one terminal tab, start web:

./vms/start-web-darwin.sh
2020-10-20T14:09:57.046-0700 [INFO]  Starting service: name=web upstreamURIs=http://api upstreamWorkers=1 listenAddress=0.0.0.0:8080 service type=http
2020-10-20T14:09:57.046-0700 [INFO]  Adding handler for UI static files
2020-10-20T14:09:57.046-0700 [INFO]  Settings CORS options: allow_creds=false allow_headers=Accept,Accept-Language,Content-Language,Origin,Content-Type allow_origins=*

Windows command: ./vms/start-web-windows.ps1

The logs say that the service is listening on 0.0.0.0:8080. Let's open our browser to http://localhost:8080:

{
  "name": "web",
  "uri": "/",
  "type": "HTTP",
  "ip_addresses": [
    "192.168.0.127"
  ],
  "start_time": "2020-10-20T14:12:29.470122",
  "end_time": "2020-10-20T14:12:29.472339",
  "duration": "2.216562ms",
  "body": "Hello World",
  "upstream_calls": [
    {
      "uri": "http://api",
      "code": -1,
      "error": "Error communicating with upstream service: Get \"http://api/\": EOF"
    }
  ],
  "code": 500
}

We see that we get a response, but the web service can't talk to its upstream dependency api: Error communicating with upstream service: Get \"http://api/\": EOF.

This makes sense because we haven't started api yet.

Api

Start the api service now in another terminal tab:

sudo ./vms/start-api-darwin.sh
2020-10-20T14:14:53.360-0700 [INFO]  Starting service: name=api-vm upstreamURIs= upstreamWorkers=1 listenAddress=127.0.0.1:80 service type=http
2020-10-20T14:14:53.360-0700 [INFO]  Adding handler for UI static files
2020-10-20T14:14:53.361-0700 [INFO]  Settings CORS options: allow_creds=false allow_headers=Accept,Accept-Language,Content-Language,Origin,Content-Type allow_origins=*

Windows command: ./vms/start-api-windows.ps1

NOTE: You must use sudo because we're binding to port 80. This is necessary to demonstrate our no-downtime migration later in the tutorial.

If we open our browser to http://127.0.0.1/ (http://127.0.0.1:9090/ on Windows) we should see

{
  "name": "api-vm",
  "uri": "/",
  "type": "HTTP",
  "ip_addresses": [
    "192.168.0.127"
  ],
  "start_time": "2020-10-20T14:17:40.530634",
  "end_time": "2020-10-20T14:17:40.530723",
  "duration": "88.931µs",
  "body": "Hello World",
  "code": 200
}

This means our api service is working!

Web calls Api

Windows users: Skip to "Everything Working"

All that's left is for web to call api.

If you look at our start script in vms/start-web-darwin.sh:

#!/usr/bin/env bash
set -euo pipefail

export NAME="web"
export LISTEN_ADDR="0.0.0.0:8080"

export UPSTREAM_URIS="http://api"

./$(dirname "$0")/../bin/web/web-darwin

You'll see export UPSTREAM_URIS="http://api". This tells web to contact the api service at http://api.

This url won't work right now because http://api doesn't resolve to the api service. To get this to work, we need to edit our /etc/hosts file. This file lets us configure what hostnames, e.g. api, route to which IP addresses, e.g. 127.0.0.1.

Edit /etc/hosts with sudo:

sudo vim /etc/hosts

And add this line to the bottom:

127.0.0.1 api

Then save the file.

In your browser, go to http://api. You should see the same response as http://127.0.0.1/:

{
  "name": "api-vm",
  "uri": "/",
  "type": "HTTP",
  "ip_addresses": [
    "192.168.0.127"
  ],
  "start_time": "2020-10-20T14:17:40.530634",
  "end_time": "2020-10-20T14:17:40.530723",
  "duration": "88.931µs",
  "body": "Hello World",
  "code": 200
}

Everything Working

Now that we have:

• web running on http://localhost:8080
• api running on http://127.0.0.1
• /etc/hosts configured to route http://api to http://127.0.0.1

When we navigate to http://localhost:8080, we should see that web calls api successfully:

{
  "name": "web",
  "uri": "/",
  "type": "HTTP",
  "ip_addresses": [
    "192.168.0.127"
  ],
  "start_time": "2020-10-20T14:24:59.192036",
  "end_time": "2020-10-20T14:24:59.194831",
  "duration": "2.794649ms",
  "body": "Hello World",
  "upstream_calls": [
    {
      "name": "api-vm",
      "uri": "http://api",
      "type": "HTTP",
      "ip_addresses": [
        "192.168.0.127"
      ],
      "start_time": "2020-10-20T14:24:59.192933",
      "end_time": "2020-10-20T14:24:59.193110",
      "duration": "176.557µs",
      "headers": {
        "Content-Length": "258",
        "Content-Type": "text/plain; charset=utf-8",
        "Date": "Tue, 20 Oct 2020 21:24:59 GMT"
      },
      "body": "Hello World",
      "code": 200
    }
  ],
  "code": 200
}

We know it's working because upstream_calls has the response from api.

Conclusion

We now have web and api running on our development machine. This mimics running them on VMs.

Next Step

Go to 2-dockerize.