Add automatic self-update capability to agent

The agent now checks for updates every hour and automatically updates
itself when a new version is available on Docker Hub.

Features:
- Periodic update checks (hourly via scheduler)
- Automatic Docker image pull when update available
- Graceful exit and restart with new version
- Non-blocking, runs in background task
- Requires Docker socket mount for self-update

Changes:
- Add UpdateInfo struct and get_update_info() function
- Add perform_self_update() to pull new image and restart
- Add update check ticker to scheduler (hourly)
- Include docker-cli in Dockerfile runtime stage
- Update docker-compose.example.yml with socket mount
- Update README and CLAUDE.md with auto-update docs

The agent will log update status:
- "Already running latest version" - no action
- "Performing self-update: X -> Y" - pulling new image
- "Exiting to allow restart with new version" - restarting

Requires:
- Docker socket mounted: /var/run/docker.sock:/var/run/docker.sock
- restart: unless-stopped in docker-compose (to restart after exit)

CLAUDE.md

@@ -37,6 +37,7 @@ Lightweight Rust agent for remote SNMP polling. Deployed on customer networks to
   - Heartbeat every 60 seconds
   - Cleanup every hour
   - Poll check every 5 seconds
+  - Update check and auto-update every hour
 
 - [x] **Executor** (`poller/executor.rs`)
   - poll_sensors() - Poll configured sensors
@@ -51,11 +52,14 @@ Lightweight Rust agent for remote SNMP polling. Deployed on customer networks to
   - Graceful startup/shutdown
   - Docker image version checking on startup
 
-- [x] **Version Checking** (`version.rs`)
+- [x] **Version Checking & Auto-Update** (`version.rs`)
   - Checks Docker Hub for newer image versions on startup
+  - Performs periodic checks every hour (configurable in scheduler)
+  - Automatically pulls new image and restarts when update available
   - Compares current version with latest available
   - Logs warnings if updates are available
   - Non-blocking, fails gracefully if Docker Hub unavailable
+  - Requires Docker socket mount (`/var/run/docker.sock`) for self-update
 
 ### Protocol Buffers Integration
 - [x] **Protobuf Definitions** (`proto/agent.proto`)

Dockerfile

@@ -45,7 +45,8 @@ RUN RUST_TARGET=$(cat /tmp/rust-target) && \
 FROM alpine:3.19
 
 # Install runtime dependencies
-RUN apk add --no-cache ca-certificates su-exec
+# docker-cli is needed for self-update functionality
+RUN apk add --no-cache ca-certificates su-exec docker-cli
 
 # Create data directory
 RUN mkdir -p /data

README.md

@@ -12,6 +12,7 @@ The Towerops agent enables customers to deploy SNMP polling infrastructure on th
 - **Secure Communication**: All communication with Towerops API uses HTTPS with token authentication
 - **Metric Buffering**: Stores up to 24 hours of metrics in SQLite when API is unavailable
 - **Automatic Configuration**: Fetches polling configuration from the Towerops API
+- **Automatic Updates**: Checks for new versions hourly and self-updates when available (requires Docker socket access)
 - **Low Resource Usage**: Built in Rust for minimal memory and CPU footprint (< 256 MB RAM typical)
 - **Docker Ready**: Pre-built Docker images for easy deployment
 
@@ -40,6 +41,8 @@ services:
       - TOWEROPS_AGENT_TOKEN=your-agent-token-here
     volumes:
       - ./data:/data
+      # Required for automatic self-updates
+      - /var/run/docker.sock:/var/run/docker.sock
 ```
 
 2. Start the agent:
@@ -48,6 +51,8 @@ services:
 docker-compose up -d
 ```
 
+**Note**: The Docker socket mount (`/var/run/docker.sock`) is required for automatic updates. The agent checks for new versions hourly and will automatically pull and restart with the latest version when available.
+
 ### Configuration
 
 The agent is configured via environment variables:

docker-compose.example.yml

@@ -30,6 +30,10 @@ services:
       # Persistent storage for metrics buffering
       - ./data:/data
 
+      # Docker socket (required for automatic self-updates)
+      # The agent will check for updates hourly and automatically update itself
+      - /var/run/docker.sock:/var/run/docker.sock
+
     # Optional: Resource limits
     deploy:
       resources:

src/poller/scheduler.rs

@@ -101,6 +101,7 @@ impl Scheduler {
         let mut heartbeat_ticker = interval(Duration::from_secs(60));
         let mut cleanup_ticker = interval(Duration::from_secs(3600)); // Cleanup every hour
         let mut poll_ticker = interval(Duration::from_secs(5)); // Check if polling needed every 5s
+        let mut update_ticker = interval(Duration::from_secs(3600)); // Check for updates every hour
 
         loop {
             tokio::select! {
@@ -133,6 +134,10 @@ impl Scheduler {
                         error!("Polling error: {}", e);
                     }
                 }
+
+                _ = update_ticker.tick() => {
+                    self.check_and_update().await;
+                }
             }
         }
     }
@@ -250,4 +255,27 @@ impl Scheduler {
 
         Ok(())
     }
+
+    async fn check_and_update(&self) {
+        info!("Checking for agent updates");
+
+        // Run version check in blocking thread to avoid blocking event loop
+        let result = tokio::task::spawn_blocking(crate::version::perform_self_update).await;
+
+        match result {
+            Ok(Ok(true)) => {
+                info!("Update initiated, container will restart with new version");
+                // perform_self_update calls std::process::exit(0), so we won't reach here
+            }
+            Ok(Ok(false)) => {
+                info!("Already running latest version");
+            }
+            Ok(Err(e)) => {
+                warn!("Failed to perform self-update: {}", e);
+            }
+            Err(e) => {
+                error!("Update check task failed: {}", e);
+            }
+        }
+    }
 }

src/version.rs

@@ -1,5 +1,6 @@
 use log::{info, warn};
 use serde::Deserialize;
+use std::process::Command;
 
 const DOCKER_IMAGE: &str = "gmcintire/towerops-agent";
 const CURRENT_VERSION: &str = env!("CARGO_PKG_VERSION");
@@ -16,32 +17,92 @@ struct DockerHubTag {
     last_updated: String,
 }
 
+#[derive(Debug, Clone, PartialEq)]
+pub struct UpdateInfo {
+    pub current_version: String,
+    pub latest_version: Option<String>,
+    pub update_available: bool,
+}
+
 /// Check if a newer version of the Docker image is available
 pub fn check_for_updates() {
     info!("Current version: {}", CURRENT_VERSION);
     info!("Checking for newer Docker image versions...");
 
-    match check_docker_hub() {
-        Ok(Some(latest_version)) => {
-            if latest_version != CURRENT_VERSION {
-                warn!(
-                    "⚠️  Newer version available: {} (current: {})",
-                    latest_version, CURRENT_VERSION
-                );
-                warn!("   Update with: docker pull {}:latest", DOCKER_IMAGE);
+    match get_update_info() {
+        Ok(info) => {
+            if info.update_available {
+                if let Some(ref latest) = info.latest_version {
+                    warn!(
+                        "⚠️  Newer version available: {} (current: {})",
+                        latest, info.current_version
+                    );
+                    warn!("   Update with: docker pull {}:latest", DOCKER_IMAGE);
+                }
             } else {
-                info!("✓ Running latest version ({})", CURRENT_VERSION);
+                info!("✓ Running latest version ({})", info.current_version);
             }
         }
-        Ok(None) => {
-            info!("Unable to determine latest version from Docker Hub");
-        }
         Err(e) => {
             warn!("Failed to check for updates: {}", e);
         }
     }
 }
 
+/// Get update information without logging
+pub fn get_update_info() -> Result<UpdateInfo, String> {
+    let latest_version = check_docker_hub().map_err(|e| e.to_string())?;
+    let update_available = if let Some(ref latest) = latest_version {
+        latest != CURRENT_VERSION
+    } else {
+        false
+    };
+
+    Ok(UpdateInfo {
+        current_version: CURRENT_VERSION.to_string(),
+        latest_version,
+        update_available,
+    })
+}
+
+/// Perform self-update by pulling new image and exiting
+/// Returns Ok(true) if update was initiated, Ok(false) if already up-to-date
+pub fn perform_self_update() -> Result<bool, String> {
+    let info = get_update_info()?;
+
+    if !info.update_available {
+        info!("Already running latest version, no update needed");
+        return Ok(false);
+    }
+
+    if let Some(ref latest) = info.latest_version {
+        warn!(
+            "Performing self-update: {} -> {}",
+            info.current_version, latest
+        );
+
+        // Pull the new image
+        info!("Pulling new Docker image: {}:latest", DOCKER_IMAGE);
+        let output = Command::new("docker")
+            .args(["pull", &format!("{}:latest", DOCKER_IMAGE)])
+            .output()
+            .map_err(|e| format!("Failed to execute docker command: {}", e))?;
+
+        if !output.status.success() {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            return Err(format!("Failed to pull image: {}", stderr));
+        }
+
+        info!("Successfully pulled new image");
+        info!("Exiting to allow restart with new version...");
+
+        // Exit with success code - orchestrator (docker-compose/k8s) will restart with new image
+        std::process::exit(0);
+    }
+
+    Ok(true)
+}
+
 fn check_docker_hub() -> Result<Option<String>, Box<dyn std::error::Error>> {
     let url = format!(
         "https://hub.docker.com/v2/repositories/{}/tags?page_size=10",