Add fleet worker lifecycle tracking service example

serverless-fleet-worker-registration/.dockerignore

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+# Binaries
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+fleet-register
+
+# Test files
+*_test.go
+
+# Output files
+*.csv
+
+# Git
+.git
+.gitignore
+
+# IDE
+.vscode
+.idea
+*.swp
+*.swo
+*~
+
+# Documentation
+README.md
+
+# Docker
+Dockerfile
+.dockerignore
+
+# OS
+.DS_Store
+Thumbs.db

serverless-fleet-worker-registration/Dockerfile

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+# Stage 1: Build stage
+FROM quay.io/projectquay/golang:1.25 AS builder
+
+# Set working directory
+WORKDIR /build
+
+# Copy go mod files
+COPY go.mod go.sum ./
+
+# Download dependencies
+RUN go mod download
+
+# Copy source code
+COPY main.go ./
+
+# Build the application
+# CGO_ENABLED=0 for static binary
+# -ldflags="-w -s" to reduce binary size
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-w -s" -o fleet-register .
+
+# Stage 2: Runtime stage
+FROM registry.access.redhat.com/ubi10/ubi-minimal
+
+# Copy binary from builder
+COPY --from=builder /build/fleet-register /app/fleet-register
+
+# Set working directory
+WORKDIR /app
+
+# Expose port
+EXPOSE 8080
+
+RUN mkdir /fleet-workers
+
+# Set environment variable for the CSV path
+ENV CSV_PATH=/fleet-workers/fleet-register.csv
+
+# Run the application
+CMD ["/app/fleet-register"]

serverless-fleet-worker-registration/README.md

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+# Fleet Register
+
+A lightweight Go HTTP server that monitors IBM Cloud Code Engine fleet workers by tracking their lifecycle events in a CSV file.
+
+## Use Case
+
+This application is deployed as a Code Engine application to monitor fleet workers. Fleet workers call the `/register` endpoint when they start and the `/deregister` endpoint before they shut down. The application maintains a persistent CSV file tracking all worker activity, including registration and completion timestamps.
+
+**Deployment Flow:**
+1. Deploy this app as a Code Engine application with persistent storage
+2. Configure the fleet with register/deregister hooks pointing to this app
+3. Fleet workers automatically report their status throughout their lifecycle
+
+## Endpoints
+
+- `POST /register`
+  Creates a row in `fleet-register.csv` with status `running` and records the registration timestamp.
+
+- `POST /deregister`
+  Updates the matching row by `worker_name` and `worker_ip` to `completed` and records the completion timestamp.
+  If no row exists, it creates a new row with status `completed`.
+
+- `GET /download`
+  Downloads the CSV file.
+
+## Request body
+
+```json
+{
+  "worker_name": "worker-01",
+  "worker_ip": "192.168.1.10"
+}
+```
+
+## Deployment
+
+### Code Engine (Production)
+
+1. **Deploy the application with persistent storage:**
+   ```bash
+   ibmcloud ce app create --name fleet-workers \
+     --build-dockerfile Dockerfile \
+     --build-source . \
+     --mount-data-store /fleet-workers=fleet-data
+   ```
+
+2. **Run fleet with hooks:**
+
+   The `run` script automatically retrieves the app URL and creates a fleet with register/deregister hooks:
+   ```bash
+   ./run
+   ```
+
+   Or manually create a fleet:
+   ```bash
+   APP_URL=$(ibmcloud ce app get --name fleet-workers -o url)
+
+   PREHOOK="curl -X POST \${APP_URL}/register -H 'Content-Type: application/json' -d '{\"worker_name\":\"\${CE_WORKER_NAME}\",\"worker_ip\":\"\${CE_WORKER_IP}\"}'"
+
+   POSTHOOK="curl -X POST \${APP_URL}/deregister -H 'Content-Type: application/json' -d '{\"worker_name\":\"\${CE_WORKER_NAME}\",\"worker_ip\":\"\${CE_WORKER_IP}\"}'"
+
+   ibmcloud code-engine fleet create --name my-fleet \
+     --tasks-state-store fleet-task-store \
+     --subnetpool-name fleet-subnetpool \
+     --image registry.access.redhat.com/ubi10/ubi-minimal \
+     --max-scale 100 \
+     --command="sleep" \
+     --arg "30" \
+     --tasks 100 \
+     --env __CE_INTERNAL_HOOK_AFTER_STARTUP="${PREHOOK}" \
+     --env __CE_INTERNAL_HOOK_AFTER_STARTUP_RETRY_LIMIT=3 \
+     --env __CE_INTERNAL_HOOK_AFTER_STARTUP_MAX_EXECUTION_TIME=30m \
+     --env __CE_INTERNAL_HOOK_BEFORE_SHUTDOWN="${POSTHOOK}" \
+     --env __CE_INTERNAL_HOOK_BEFORE_SHUTDOWN_RETRY_LIMIT=3 \
+     --env __CE_INTERNAL_HOOK_BEFORE_SHUTDOWN_MAX_EXECUTION_TIME=30m \
+     --env APP_URL="${APP_URL}" \
+     --cpu 2 \
+     --memory 4G
+   ```
+
+### Local Development
+
+```bash
+go run .
+```
+
+Server listens on `:8080`.
+
+### Docker
+
+```bash
+docker build -t fleet-register .
+docker run -p 8080:8080 -v fleet-data:/fleet-workers fleet-register
+```
+
+The CSV file is saved to `/fleet-workers/fleet-register.csv` and persisted in the volume.
+
+## Examples
+
+Register a worker:
+
+```bash
+curl -X POST http://localhost:8080/register \
+  -H "Content-Type: application/json" \
+  -d '{
+    "worker_name": "worker-01",
+    "worker_ip": "192.168.1.10"
+  }'
+```
+
+Deregister a worker:
+
+```bash
+curl -X POST http://localhost:8080/deregister \
+  -H "Content-Type: application/json" \
+  -d '{
+    "worker_name": "worker-01",
+    "worker_ip": "192.168.1.10"
+  }'
+```
+
+Download the CSV file:
+
+```bash
+curl -O -J http://localhost:8080/download
+```
+
+## CSV file
+
+The server automatically creates `fleet-register.csv` in the project root (or `/fleet-workers/` in Docker) if it does not exist.
+
+The CSV file contains the following columns:
+
+- `worker_name` - Name of the worker
+- `worker_ip` - IP address of the worker
+- `status` - Current status (running/completed)
+- `registered_at` - Timestamp when the worker was registered (ISO 8601 format)
+- `completed_at` - Timestamp when the worker completed (ISO 8601 format)

serverless-fleet-worker-registration/go.mod

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+module fleet-register
+
+go 1.22