Syncing Prometheus and Kubewatch with Kubernetes Cluster - kubernetes

Question

I want to get all events that occurred in Kubernetes cluster in some python dictionary using maybe some API to extract data from the events that occurred in the past. I found on internet that it is possible by storing all data of Kube-watch on Prometheus and later accessing it. I am unable to figure out how to set it up and see all past pod events in python. Any alternative solutions to access past events are also appreciated. Thanks!

Answer 1

I'll describe a solution that is not complicated and I think meets all your requirements.
There are tools such as Eventrouter that take Kubernetes events and push them to a user specified sink. However, as you mentioned, you only need Pods events, so I suggest a slightly different approach.
In short, you can run the kubectl get events --watch command from within a Pod and collect the output from that command using a log aggregation system like Loki.
Below, I will provide a detailed step-by-step explanation.
1. Running kubectl command from within a Pod
To display only Pod events, you can use:
$ kubectl get events --watch --field-selector involvedObject.kind=Pod
We want to run this command from within a Pod. For security reasons, I've created a separate events-collector ServiceAccount with the view Role assigned and our Pod will run under this ServiceAccount.
NOTE: I've created a Deployment instead of a single Pod.
$ cat all-in-one.yml
apiVersion: v1
kind: ServiceAccount
metadata:
name: events-collector
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: events-collector-binding
subjects:
- kind: ServiceAccount
name: events-collector
namespace: default
roleRef:
kind: ClusterRole
name: view
apiGroup: rbac.authorization.k8s.io
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: events-collector
name: events-collector
spec:
selector:
matchLabels:
app: events-collector
template:
metadata:
labels:
app: events-collector
spec:
serviceAccountName: events-collector
containers:
- image: bitnami/kubectl
name: test
command: ["kubectl"]
args: ["get","events", "--watch", "--field-selector", "involvedObject.kind=Pod"]
After applying the above manifest, the event-collector was created and collects Pod events as expected:
$ kubectl apply -f all-in-one.yml
serviceaccount/events-collector created
clusterrolebinding.rbac.authorization.k8s.io/events-collector-binding created
deployment.apps/events-collector created
$ kubectl get deploy,pod | grep events-collector
deployment.apps/events-collector 1/1 1 1 14s
pod/events-collector-d98d6c5c-xrltj 1/1 Running 0 14s
$ kubectl logs -f events-collector-d98d6c5c-xrltj
LAST SEEN TYPE REASON OBJECT MESSAGE
77s Normal Scheduled pod/app-1-5d9ccdb595-m9d5n Successfully assigned default/app-1-5d9ccdb595-m9d5n to gke-cluster-2-default-pool-8505743b-brmx
76s Normal Pulling pod/app-1-5d9ccdb595-m9d5n Pulling image "nginx"
71s Normal Pulled pod/app-1-5d9ccdb595-m9d5n Successfully pulled image "nginx" in 4.727842954s
70s Normal Created pod/app-1-5d9ccdb595-m9d5n Created container nginx
70s Normal Started pod/app-1-5d9ccdb595-m9d5n Started container nginx
73s Normal Scheduled pod/app-2-7747dcb588-h8j4q Successfully assigned default/app-2-7747dcb588-h8j4q to gke-cluster-2-default-pool-8505743b-p7qt
72s Normal Pulling pod/app-2-7747dcb588-h8j4q Pulling image "nginx"
67s Normal Pulled pod/app-2-7747dcb588-h8j4q Successfully pulled image "nginx" in 4.476795932s
66s Normal Created pod/app-2-7747dcb588-h8j4q Created container nginx
66s Normal Started pod/app-2-7747dcb588-h8j4q Started container nginx
2. Installing Loki
You can install Loki to store logs and process queries. Loki is like Prometheus, but for logs :). The easiest way to install Loki is to use the grafana/loki-stack Helm chart:
$ helm repo add grafana https://grafana.github.io/helm-charts
"grafana" has been added to your repositories
$ helm repo update
...
Update Complete. ⎈Happy Helming!⎈
$ helm upgrade --install loki grafana/loki-stack
$ kubectl get pods | grep loki
loki-0 1/1 Running 0 76s
loki-promtail-hm8kn 1/1 Running 0 76s
loki-promtail-nkv4p 1/1 Running 0 76s
loki-promtail-qfrcr 1/1 Running 0 76s
3. Querying Loki with LogCLI
You can use the LogCLI tool to run LogQL queries against a Loki server. Detailed information on installing and using this tool can be found in the LogCLI documentation. I'll demonstrate how to install it on Linux:
$ wget https://github.com/grafana/loki/releases/download/v2.2.1/logcli-linux-amd64.zip
$ unzip logcli-linux-amd64.zip
Archive: logcli-linux-amd64.zip
inflating: logcli-linux-amd64
$ mv logcli-linux-amd64 logcli
$ sudo cp logcli /bin/
$ whereis logcli
logcli: /bin/logcli
To query the Loki server from outside the Kubernetes cluster, you may need to expose it using the Ingress resource:
$ cat ingress.yml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
annotations:
kubernetes.io/ingress.class: nginx
nginx.ingress.kubernetes.io/rewrite-target: /
name: loki-ingress
spec:
rules:
- http:
paths:
- backend:
serviceName: loki
servicePort: 3100
path: /
$ kubectl apply -f ingress.yml
ingress.networking.k8s.io/loki-ingress created
$ kubectl get ing
NAME CLASS HOSTS ADDRESS PORTS AGE
loki-ingress <none> * <PUBLIC_IP> 80 19s
Finally, I've created a simple python script that we can use to query the Loki server:
NOTE: We need to set the LOKI_ADDR environment variable as described in the documentation. You need to replace the <PUBLIC_IP> with your Ingress IP.
$ cat query_loki.py
#!/usr/bin/env python3
import os
os.environ['LOKI_ADDR'] = "http://<PUBLIC_IP>"
os.system("logcli query '{app=\"events-collector\"}'")
$ ./query_loki.py
...
2021-07-02T10:33:01Z {} 2021-07-02T10:33:01.626763464Z stdout F 0s Normal Pulling pod/backend-app-5d99cf4b-c9km4 Pulling image "nginx"
2021-07-02T10:33:00Z {} 2021-07-02T10:33:00.836755152Z stdout F 0s Normal Scheduled pod/backend-app-5d99cf4b-c9km4 Successfully assigned default/backend-app-5d99cf4b-c9km4 to gke-cluster-1-default-pool-328bd2b1-288w
2021-07-02T10:33:00Z {} 2021-07-02T10:33:00.649954267Z stdout F 0s Normal Started pod/web-app-6fcf9bb7b8-jbrr9 Started container nginx2021-07-02T10:33:00Z {} 2021-07-02T10:33:00.54819851Z stdout F 0s Normal Created pod/web-app-6fcf9bb7b8-jbrr9 Created container nginx
2021-07-02T10:32:59Z {} 2021-07-02T10:32:59.414571562Z stdout F 0s Normal Pulled pod/web-app-6fcf9bb7b8-jbrr9 Successfully pulled image "nginx" in 4.228468876s
...