Demo Deploying and Viewing Application Logs

This guide shows how to deploy a tiny example application to a Kubernetes cluster where logs are already collected and forwarded to Grafana Loki. You will:

Retrieve Grafana credentials and (optionally) install Alloy.
Deploy a simple app that writes structured JSON logs to stdout.
Verify logs locally with kubectl logs.
Confirm the logs are visible in Grafana Assistant (Grafana Loki) using a LogQL query.

Prerequisites:

A running Kubernetes cluster with the logging stack (Loki + Grafana) already installed.
kubectl, helm, and base64 (or equivalent) available on your workstation.

1) Retrieve Grafana admin credentials and install Alloy

Inspect the Grafana secret in the logging namespace and decode the admin user and password:

# Inspect secret data keys
kubectl get secret -n logging grafana -o jsonpath='{.data}'

# Retrieve and decode admin user and password
kubectl get secret -n logging grafana -o jsonpath='{.data.admin-user}' | base64 -d
kubectl get secret -n logging grafana -o jsonpath='{.data.admin-password}' | base64 -d

If Alloy is not already installed, install it via Helm (using your values file):

helm install alloy grafana/alloy --values alloy-values.yaml -n logging

Example output from the Helm install and the pods in the logging namespace (condensed):

# Helm install
NAME: alloy
LAST DEPLOYED: Wed Jul 29 15:02:50 2026
NAMESPACE: logging
STATUS: deployed

# Pods in the logging namespace (example)
kubectl get pods -n logging
NAME                            READY   STATUS    RESTARTS   AGE
alloy-15qrd                     1/2     Running   0          27s
grafana-667db46f55-5phkq        1/1     Running   0          17m
loki-0                          2/2     Running   0          11m
loki-canary-74kxn               1/1     Running   0          11m
loki-chunks-cache-0             2/2     Running   0          11m
loki-gateway-d896ddd77-lws4f    2/2     Running   0          11m
loki-results-cache-0            2/2     Running   0          11m
seaweedfs-filer-0               1/1     Running   0          39m
seaweedfs-master-0              1/1     Running   0          39m
seaweedfs-s3-6fd7b5c6f9-qrvxp   1/1     Running   0          39m
seaweedfs-volume-0              1/1     Running   0          39m

2) Deploy the example application

Create a Deployment named api that uses the kodekloud/loki-demo image and emits structured JSON logs to stdout. app-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api
spec:
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
      - name: api
        image: kodekloud/loki-demo
        resources:
          limits:
            memory: "128Mi"
            cpu: "500m"

Apply the manifest and watch the pod start:

kubectl apply -f app-deployment.yaml
kubectl get pods --watch

Example progress (condensed):

deployment.apps/api created

# Watching pods
NAME                        READY   STATUS              RESTARTS   AGE
api-68b9dbd6b5-hxp22        0/1     ContainerCreating   0          6s
api-68b9dbd6b5-hxp22        1/1     Running             0          39s

3) Verify logs are emitted to stdout

Once the pod is Running, tail its logs to confirm the app emits structured JSON lines:

kubectl logs api-68b9dbd6b5-hxp22 -f

Sample JSON log lines emitted by the app (streamed):

{"level":30,"time":1785337590529,"pid":1,"hostname":"api-68b9dbd6b5-hxp22","method":"GET","route":"/users","code":"500"}
{"level":30,"time":1785337591529,"pid":1,"hostname":"api-68b9dbd6b5-hxp22","method":"GET","route":"/cart","code":"200"}
{"level":40,"time":1785337592530,"pid":1,"hostname":"api-68b9dbd6b5-hxp22","method":"DELETE","route":"/users","code":"401"}
{"level":30,"time":1785337593531,"pid":1,"hostname":"api-68b9dbd6b5-hxp22","method":"PATCH","route":"/cart","code":"401"}
{"level":40,"time":1785337594532,"pid":1,"hostname":"api-68b9dbd6b5-hxp22","method":"POST","route":"/users","code":"201"}
...

The log collector performs automatic discovery of pod logs (stdout/stderr) and forwards them to Grafana Loki, so applications that write to standard output are collected without extra configuration.

4) Query the logs in Grafana (Explore view)

Open Grafana Assistant (Explore view) and run a Loki query that filters by the Deployment label we applied. For example:

{app="api"} |= ""

This LogQL expression selects log streams with the app="api" label and returns all log lines. Running it should stream the same JSON lines you saw with kubectl logs, confirming the logs reached Grafana Loki. Example formatted output in Grafana Assistant (condensed):

2026-07-29 18:07:35.593 UNK {
  "level": 30,
  "time": 1785337655592,
  "pid": 1,
  "hostname": "api-68b9dbd6b5-hxp22",
  "method": "DELETE",
  "route": "/cart",
  "code": "401"
}
2026-07-29 18:07:34.592 UNK {
  "level": 30,
  "time": 1785337654591,
  "pid": 1,
  "hostname": "api-68b9dbd6b5-hxp22",
  "method": "GET",
  "route": "/cart",
  "code": "200"
}
...

Quick reference

Task	Command / Query	Purpose
Inspect Grafana secret keys	`kubectl get secret -n logging grafana -o jsonpath='{.data}'`	Show encoded keys in the secret
Decode admin credentials	`kubectl get secret -n logging grafana -o jsonpath='{.data.admin-password}' \| base64 -d`	Print admin user/password
Install Alloy (Helm)	`helm install alloy grafana/alloy --values alloy-values.yaml -n logging`	Optional Alloy install for Grafana
Deploy example app	`kubectl apply -f app-deployment.yaml`	Create the `api` Deployment
Tail pod logs	`kubectl logs <pod-name> -f`	Verify logs are emitted to stdout
Loki query	`{app="api"} \|= ""`	Filter logs in Grafana by `app=api`

Summary

Deploy the example app and verify it writes structured JSON logs to stdout using kubectl logs.
The cluster log collector auto-discovers pod stdout/stderr and forwards those logs to Grafana Loki—no per-app config required for stdout logs.
Use a Grafana (Explore) LogQL query such as {app="api"} |= "" to view application logs in Grafana Assistant.

Course Introduction

Grafana Loki Essentials

Grafana Loki on Kubernetes

Demo Deploying and Viewing Application Logs

1) Retrieve Grafana admin credentials and install Alloy

2) Deploy the example application

3) Verify logs are emitted to stdout

4) Query the logs in Grafana (Explore view)

Quick reference

Summary

Links and references

Watch Video

​1) Retrieve Grafana admin credentials and install Alloy

​2) Deploy the example application

​3) Verify logs are emitted to stdout

​4) Query the logs in Grafana (Explore view)

​Quick reference

​Summary

​Links and references

Watch Video

1) Retrieve Grafana admin credentials and install Alloy

2) Deploy the example application

3) Verify logs are emitted to stdout

4) Query the logs in Grafana (Explore view)

Quick reference

Summary

Links and references