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Thodoris Velmachos
Thodoris Velmachos

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Deploy Promtail as a Sidecar to you Main App.

#devops #kubernetes #observabillity #grafana

Hello, in this tutorial the goal is to describe the steps needed to deploy Promtail as a Sidecar container to your app in order to ship only the logs you will need to the Log Management System in our case we will use Grafana Loki.

Before we start, I would like to explain to you the reasoning behind the use of the two Kubernetes Objects a Configmap and emptyDir Volume. So we will use a emptyDir Volume create a shared temporary space between Containers in which the app logs will reside, also we will use a Configmap to store the necessary configuration used by Promtail in order to know which files need to monitor and where we want to ship the Logs in our case the Loki Url.

So, lets Dive in…

Step1. Create the ConfigMap to store the configuration (promtail.yaml) for Promtail.

apiVersion: v1 kind: ConfigMap metadata: name: promtail-sidecar-config-map data: promtail.yaml: | server: http_listen_port: 9080 grpc_listen_port: 0 log_level: "debug" positions: filename: /tmp/positions.yaml clients: # Specify target - url: http://loki.monitoring.svc.cluster.local:3100/loki/api/v1/push scrape_configs: - job_name: "<app-name>" static_configs: - targets: - localhost labels: app: "storage-service" environment: "<environment-name>" __path__: /app/logs/*.log # Any file .log in the EmptyDir Volume.
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Step2. Make the necessary changes in the Deployment Manifest.

apiVersion: apps/v1 kind: Deployment metadata: name: <app-service> labels: app: <app-service> spec: replicas: 1 selector: matchLabels: app: <app-service> template: metadata: labels: app: <app-service> spec: containers: - name: <app-service> image: <your-name>/<app-service> imagePullPolicy: Always ports: - containerPort: <app-port> readinessProbe: exec: command: ["<your health-check>"] initialDelaySeconds: 5 livenessProbe: exec: command: ["<your health-check>"] initialDelaySeconds: 10 env: - name: <ENV-VAR-1> valueFrom: configMapKeyRef: name: <app-service>-config-map key: appName - name: <ENV-VAR-2> valueFrom: secretKeyRef: name: <app-service>-secret key: <secret-key> volumeMounts: - name: shared-logs # shared space monitored with Promtail mountPath: /app/logs # Sidecar Container Promtail - name: promtail image: grafana/promtail:master args: - "-config.file=/etc/promtail/promtail.yaml" # Found in the ConfigMap volumeMounts: - name: config mountPath: /etc/promtail - name: shared-logs # shared space mountPath: /app/logs imagePullSecrets: - name: <registry-secret> # if needed volumes: - name: config configMap: name: promtail-sidecar-config-map - name: shared-logs # shared space monitored with Promtail emptyDir: sizeLimit: 500Mi
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I hope you like the tutorial, if you do give a thumps up! and follow me in Twitter, also you can subscribe to my Newsletter in order to avoid missing any of the upcoming tutorials.

Media Attribution

I would like to thank Clark Tibbs for designing the awesome photo I am using in my posts.

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