Go Microservices with Ambassador API Gateway - docker

Question

I'm having a few issues getting Ambassador to work correctly. I'm new to Kubernetes and just teaching myself.
I have successfully managed to work through the demo material Ambassador provide - e.g /httpbin/ endpoint is working correctly, but when I try to deploy a Go service it is falling over.
When hitting the 'qotm' endpoint, the page this is the response:
upstream request timeout
Pod status:
CrashLoopBackOff
From my research, it seems to be related to the yaml file not being configured correctly but I'm struggling to find any documentation relating to this use case.
My cluster is running on AWS EKS and the images are being pushed to AWS ECR.
main.go:
package main
import (
"fmt"
"net/http"
"os"
)
func main() {
var PORT string
if PORT = os.Getenv("PORT"); PORT == "" {
PORT = "3001"
}
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello World from path: %s\n", r.URL.Path)
})
http.ListenAndServe(":" + PORT, nil)
}
Dockerfile:
FROM golang:alpine
ADD ./src /go/src/app
WORKDIR /go/src/app
EXPOSE 3001
ENV PORT=3001
CMD ["go", "run", "main.go"]
test.yaml:
apiVersion: v1
kind: Service
metadata:
name: qotm
annotations:
getambassador.io/config: |
---
apiVersion: ambassador/v1
kind: Mapping
name: qotm_mapping
prefix: /qotm/
service: qotm
spec:
selector:
app: qotm
ports:
- port: 80
name: http-qotm
targetPort: http-api
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: qotm
spec:
replicas: 1
strategy:
type: RollingUpdate
template:
metadata:
labels:
app: qotm
spec:
containers:
- name: qotm
image: ||REMOVED||
ports:
- name: http-api
containerPort: 3001
readinessProbe:
httpGet:
path: /health
port: 5000
initialDelaySeconds: 30
periodSeconds: 3
resources:
limits:
cpu: "0.1"
memory: 100Mi
Pod description:
Name: qotm-7b9bf4d499-v9nxq
Namespace: default
Priority: 0
PriorityClassName: <none>
Node: ip-192-168-89-69.eu-west-1.compute.internal/192.168.89.69
Start Time: Sun, 17 Mar 2019 17:19:50 +0000
Labels: app=qotm
pod-template-hash=3656908055
Annotations: <none>
Status: Running
IP: 192.168.113.23
Controlled By: ReplicaSet/qotm-7b9bf4d499
Containers:
qotm:
Container ID: docker://5839996e48b252ac61f604d348a98c47c53225712efd503b7c3d7e4c736920c4
Image: IMGURL
Image ID: docker-pullable://IMGURL
Port: 3001/TCP
Host Port: 0/TCP
State: Waiting
Reason: CrashLoopBackOff
Last State: Terminated
Reason: Error
Exit Code: 1
Started: Sun, 17 Mar 2019 17:30:49 +0000
Finished: Sun, 17 Mar 2019 17:30:49 +0000
Ready: False
Restart Count: 7
Limits:
cpu: 100m
memory: 200Mi
Requests:
cpu: 100m
memory: 200Mi
Readiness: http-get http://:3001/health delay=30s timeout=1s period=3s #success=1 #failure=3
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-5bbxw (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-5bbxw:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-5bbxw
Optional: false
QoS Class: Guaranteed
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 12m default-scheduler Successfully assigned default/qotm-7b9bf4d499-v9nxq to ip-192-168-89-69.eu-west-1.compute.internal
Normal Pulled 10m (x5 over 12m) kubelet, ip-192-168-89-69.eu-west-1.compute.internal Container image "IMGURL" already present on machine
Normal Created 10m (x5 over 12m) kubelet, ip-192-168-89-69.eu-west-1.compute.internal Created container
Normal Started 10m (x5 over 11m) kubelet, ip-192-168-89-69.eu-west-1.compute.internal Started container
Warning BackOff 115s (x47 over 11m) kubelet, ip-192-168-89-69.eu-west-1.compute.internal Back-off restarting failed container

Answer 1

In your kubernetes deployment file you have exposed a readiness probe on port 5000 while your application is exposed on port 3001, also while running the container a few times I got OOMKilled so increased the memory limit. Anyways below deployment file should work fine.
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: qotm
spec:
replicas: 1
strategy:
type: RollingUpdate
template:
metadata:
labels:
app: qotm
spec:
containers:
- name: qotm
image: <YOUR_IMAGE>
imagePullPolicy: Always
ports:
- name: http-api
containerPort: 3001
readinessProbe:
httpGet:
path: /health
port: 3001
initialDelaySeconds: 30
periodSeconds: 3
resources:
limits:
cpu: "0.1"
memory: 200Mi