env-echgo

A small echo server in docker!

This is a go port of a project I use quite freqently for testing services and/or demoing kube scheduling and load balancing. This project was previously done in Python. It's been pulled about 3k times in the last year, and the python version is 214MB. Yikes. As of writing echgo is 10.4MB woot!

An improvement over the python version is that any envar in the container specified with ECHGO_* adds to the payload.

Usage

There are no command line args. Maybe someday.

• Server runs at 8080
• Add key/values to output by adding an envar with ECHGO_ prefix
  • e.g. ECHGO_DEPLOY_COLOR=Orange shows as {"deploy_color": "Orange"}

For Docker:

docker run --rm -i -t -e ECHGO_FOO=bar -p 8080:8080 timmyolson/env-echgo

For Kube (see kubectl explain pod.spec.containers.env.valueFrom):

env:
- name: ECHGO_POD_NAME
  valueFrom:
    fieldRef:
      fieldPath: metadata.name

Handy things

$ kubectl apply -f deploy.yaml -f k8s/clusterip-service.yaml -f k8s/ingress.yaml
deployment.apps/env-echgo unchanged
service/env-echgo configured
ingress.extensions/env-echgo-ing configured
$ kubectl get -f deploy.yaml -f k8s/clusterip-service.yaml -f k8s/ingress.yaml
NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/env-echgo   2/2     2            2           4h13m

NAME                TYPE           CLUSTER-IP    EXTERNAL-IP     PORT(S)          AGE
service/env-echgo   LoadBalancer   10.0.39.209   20.83.131.161   8080:31642/TCP   53m

NAME                               CLASS    HOSTS                  ADDRESS   PORTS   AGE
ingress.extensions/env-echgo-ing   <none>   envechgo.example.com             80      4h11m

# Replace 203.0.113.10 with your nginx controller loadbalancer
curl -D- http://203.0.113.10 -H 'Host: envechgo.example.com'

Demo

$ kubectl apply -f k8s/
$ curl -s 10.5.1.151:8080 | jq
{
  "message": "Hello from Ecgho Server",
  "node_name": "alyx-01",
  "pod_ip": "192.168.139.135",
  "pod_name": "env-echgo-bbb58fb4-zqwm7"
}
$ curl -s 10.5.1.151:8080 | jq
{
  "message": "Hello from Ecgho Server",
  "node_name": "alyx-02",
  "pod_ip": "192.168.152.91",
  "pod_name": "env-echgo-bbb58fb4-4hdwz"
}
$ curl -s 10.5.1.151:8080 | jq
{
  "message": "Hello from Ecgho Server",
  "node_name": "alyx-01",
  "pod_ip": "192.168.139.134",
  "pod_name": "env-echgo-bbb58fb4-qhc28"
}
$ curl -s 10.5.1.151:8080 | jq
{
  "message": "Hello from Ecgho Server",
  "node_name": "alyx-01",
  "pod_ip": "192.168.139.135",
  "pod_name": "env-echgo-bbb58fb4-zqwm7"
}