add example for OTLP logging via stdout and k8s

Author: zeitlinger

logging-k8s-stdout-otlp-json/README.md

@@ -1,10 +1,37 @@
 # Exporting Application logs using JSON logging in Kubernetes
 
-## Running the example
-
-1. Build the Docker image using using `build.sh`
-2. Deploy the manifest using `kubectl apply -f k8s/` (e.g. using [k3d.sh](k3d.sh))
-3. Generate traffic using [generate-traffic.sh](./generate-traffic.sh)
-4. Log in to [http://localhost:3000](http://localhost:3000) with user _admin_ and password _admin_.
-5. Go to "Explore"
-6. Select "Loki" as data source
+If you want to get logs from your Java application ingested into an
+OpenTelemetry-compatible logs backend, the easiest and recommended way is using
+an OpenTelemetry protocol (OTLP) exporter,
+which is explained in the [logging](../logging) example. 
+
+However, some scenarios require logs
+to be output to files or stdout due to organizational or reliability needs.
+Refer to [Collecting OpenTelemetry-compliant Java logs from files](https://opentelemetry.io/blog/2024/collecting-otel-compliant-java-logs-from-files/) for more details.
+
+This example contains
+
+- a Java application that uses the experimental 
+  [experimental-otlp/stdout](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#in-development-exporter-selection) logs exporter
+- a OTel collector configuration that uses the 
+  [OTLP/JSON connector](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/connector/otlpjsonconnector) to turn Pod logs into `OTLP`
+
+
+![OTLP/JSON Architecture](otlpjson-architecture.png)
+
+## Getting Started
+
+The k8s directory contains the Kubernetes manifests to deploy the application and the collector.
+
+Ignore the `lgtm.yaml` file, which is only used for running locally and automated testing
+using [OATs](https://github.com/grafana/oats).
+
+## Running locally
+
+You can run the application locally using the following steps:
+
+1. Run [k3d.sh](./k3d.sh) to start a local Kubernetes cluster with all the necessary components.
+2. Generate traffic using [generate-traffic.sh](./generate-traffic.sh)
+3. Log in to [http://localhost:3000](http://localhost:3000)
+4. Go to "Explore"
+5. Select "Loki" as data source to view the logs

logging-k8s-stdout-otlp-json/oats.yaml

@@ -1,4 +1,5 @@
-# OATS is an acceptance testing framework for OpenTelemetry - https://github.com/grafana/oats/tree/main/yaml
+# OATS is an acceptance testing framework for OpenTelemetry - https://github.com/grafana/oats
+
 kubernetes:
   dir: k8s
   app-service: dice