Prober Server

Prober Server probe your services deploy in kubernetes as a sidecar.

Run in your host

$ export PROBER_SERVER_PORT="9078"
$ export PROBER_DURATION="5s"
$ export PROBER_RETRY="5"
$ export PROBER_TYPE="HTTP"
$ export PROBER_HTTP_URL="http://example.com/healthcheck"
$ go run main.go
2020/10/23 14:34:56 Env `PROBER_HTTP_TIMEOUT` is not set, using default value 30
2020/10/23 14:34:56 Prober server running in `HTTP` type; Probe Duration: 5s
2020/10/23 14:34:56 HTTP URL: http://example.com:5000/healthcheck; HTTP Timeout: 30
2020/10/23 14:35:26 STATUS: RETRYING - 2020-10-23 06:35:26.304173 +0000 UTC
2020/10/23 14:36:01 STATUS: RETRYING - 2020-10-23 06:36:01.312028 +0000 UTC
2020/10/23 14:36:36 STATUS: RETRYING - 2020-10-23 06:36:36.31496 +0000 UTC
2020/10/23 14:37:11 STATUS: FAILED - 2020-10-23 06:37:11.320504 +0000 UTC

Then you can get the status by HTTP API:

$ curl http://localhost:9078
{"code":0,"status":"SUCCESS","last_status":"PENDING","message":"","retry_time":0,"last_updated":"2020-10-23T06:32:49.779909Z"}

$ curl http://localhost:9078
{"code":1,"status":"RETRYING","last_status":"SUCCESS","message":"Get \"http://example.com:5000/healthcheck\": dial tcp 93.184.216.34:5000: i/o timeout","retry_time":1,"last_updated":"2020-10-23T06:35:26.304172Z"}

$ curl http://localhost:9078
{"code":2,"status":"FAILED","last_status":"RETRYING","message":"Get \"http://example.com:5000/healthcheck\": dial tcp 93.184.216.34:5000: i/o timeout","retry_time":4,"last_updated":"2020-10-23T06:39:17.679375Z"}

Using docker

$ docker build --tag prober-server:latest .
$ docker run -tid --name prober-server -p 9078:9078 \
  -e PROBER_TYPE=http \
  -e PROBER_DURATION=5s \
  -e PROBER_RETRY=5 \
  -e PROBER_HTTP_URL="http://example.com/healthcheck" \
  prober-server:latest

TCP and UDP

You can also probe TCP service by set PROBER_TYPE environment variables:

$ export PROBER_SERVER_PORT="9078"
$ export PROBER_DURATION="5s"
$ export PROBER_RETRY="5"
$ export PROBER_TYPE="TCP"    # this changed
$ export PROBER_TCP_HOST="example.com"
$ export PROBER_TCP_PORT="8080"
$ go run main.go

And UDP service by:

$ export PROBER_SERVER_PORT="9078"
$ export PROBER_DURATION="5s"
$ export PROBER_RETRY="5"
$ export PROBER_TYPE="UDP"    # this changed
$ export PROBER_UDP_HOST="example.com"
$ export PROBER_UDP_PORT="4093"
$ go run main.go

Adding Webhook

You can setup webhook URL for recieving result of prober. To achieve webhook just setup PROBER_NAME and PROBER_WEBHOOK environment variables.

NOTE: PROBER_NAME is set for identity your service.

$ export PROBER_NAME="YOUR_SERVER"
$ export PROBER_WEBHOOK="http://your-webhook.com"

Then you will recieve a POST Request with following payload:

{
  "code": 1,
  "last_updated": "2020-10-23T10:21:05.312644Z",
  "message": "Get \"http://localhost:80\": dial tcp [::1]:80: connect: connection refused",
  "name": "NGINX",
  "retry_times": 1,
  "status": "RETRYING",
  "last_status": "PENDING"
}

Custom HTTP headers and body

By setting PROBER_CONFIG, you can setup custom headers and body

$ cat << EOF > /tmp/config.yaml
version: "1"
headers:
  Content-Type: application/json;charset=utf-8
  User-Agent: My-Prober
body:
  template: |
    {
      "text": "{{ .Name }} change to {{ .Status }} from {{ .LastStatus }}at {{ .LastUpdated }}"
    }
EOF

$ export PROBER_CONFIG=/tmp/config.yaml
$ go run main.go

Then you will recieve a HTTP POST Request like:

POST / HTTP/1.1
Host: example.com:8080
User-Agent: My-Prober
Content-Length: 73
Content-Type: application/json;charset=utf-7
Accept-Encoding: gzip

{
  "text": "SomeService change to RETRYING from PENDING at 2021-02-20 09:39:12.002609 +0000 UTC"
}

Only trigger webhook on status changes

Set PROBER_TRIGGER_ON_STATUS_CHANGE to be "true" may make prober-server POST to webhook only when status changed.