hello-app

Tiny Go webserver that prints hostname and version as HTML or JSON. The app includes /health and /metrics prometheus endpoints.

There are four versions available which is handy for testing different scenario's:

1.0.0: OK
1.0.1: FAIL, error while starting.
1.0.2: FAIL, will start but health check will report HTTP 503 unhealthy.
1.0.3: OK
2.0.0: OK

Usage

Paths

/: prints hostname and version as HTML.
/api: prints hostname and version as JSON.
/health: health check which will return HTTP 200 Healthy.
/down: mark the server as down, this will result in a HTTP 503 Unhealthy when checking /health.
/metrics: prometheus endpoint for scraping metrics.

Flags

bind: the socket to bind to (default is :8080).

Environment

BACKGROUND_COLOR: you can optionally set a different background color for the HTML page. This can be useful when testing blue/green scenarios.

Examples

Run hello app:

$ docker run -d -P --name hello-app avthart/hello-app:1.0.0

If you would like to have a different background-color in the HTML page, run with -e BACKGROUND_COLOR=blue.

Get host and port:

$ HELLO_PORT=`docker port hello-app 8080`

Get HTML using httpie:

$ http $HELLO_PORT
HTTP/1.1 200 OK
Content-Length: 144
Content-Type: text/html; charset=utf-8
Date: Fri, 27 Sep 2019 12:50:14 GMT

<html><head><title>Hello World</title></head><body style="background-color: white"><h1>Hello from 2a80a0a5eac3 version v1.0.0</h1></body></html>

Get API

$ http $HELLO_PORT/api
HTTP/1.1 200 OK
Content-Length: 47
Content-Type: application/json
Date: Fri, 27 Sep 2019 13:01:27 GMT

{
    "Hostname": "22e72af228ab",
    "Version": "v1.0.0"
}

Get health check report:

$ http $HELLO_PORT/api
HTTP/1.1 200 OK
Content-Length: 7
Content-Type: text/plain; charset=utf-8
Date: Fri, 27 Sep 2019 12:50:05 GMT

Healthy

Mark server as down:

$ http POST $HELLO_PORT/down

HTTP/1.1 200 OK
Content-Length: 0
Date: Fri, 27 Sep 2019 12:51:08 GMT

Get health check report again:

$ http $HELLO_PORT/api
HTTP/1.1 503 Service Unavailable
Content-Length: 9
Content-Type: text/plain; charset=utf-8
Date: Fri, 27 Sep 2019 12:51:35 GMT

Unhealthy

avthart / hello-app