Add health check support #967

Dockerfile

@@ -51,3 +51,7 @@ VOLUME ["/scan"]
 ENTRYPOINT ["/init"]
 CMD ["/app.sh"]
 
+# Health check
+HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
+  CMD curl -f http://localhost:3000/health || exit 1
+

root/app.sh

@@ -1,6 +1,6 @@
 #!/command/with-contenv sh
 
-ARGS="-d /scan "
+ARGS="--health-check -d /scan "
 
 if [ ! -z "$IP" ]; then
     ARGS="${ARGS} -ip ${IP}"

src/healthcheck.ts

@@ -0,0 +1,17 @@
+import http from "http";
+
+export function startHealthCheckServer(PORT: number) {
+  const server = http.createServer((req, res) => {
+    if (req.method === "GET" && req.url === "/health") {
+      res.writeHead(200, { "Content-Type": "application/json" });
+      res.end(JSON.stringify({ status: "healthy" }));
+    } else {
+      res.writeHead(404, { "Content-Type": "text/plain" });
+      res.end("Not Found");
+    }
+  });
+
+  server.listen(PORT, () => {
+    console.log(`Health endpoint exposed on port ${PORT} on path: /health`);
+  });
+}

src/index.ts

@@ -26,6 +26,8 @@ import {
 } from "./scanProcessing";
 import * as commitInfo from "./commitInfo.json";
 import { PaperlessConfig } from "./paperless/PaperlessConfig";
+import { startHealthCheckServer } from "./healthcheck";
+
 
 let iteration = 0;
 
@@ -299,6 +301,10 @@ function getPaperlessConfig(
     getConfig("paperless_post_document_url");
   const configPaperlessToken: string =
     parentOption.paperlessToken || getConfig("paperless_token");
+  const configPaperlessKeepFiles =
+    parentOption.paperlessKeepFiles ||
+    getConfig("paperless_keep_files") ||
+    false;
 
   if (paperlessPostDocumentUrl && configPaperlessToken) {
     const configPaperlessKeepFiles: boolean =
@@ -329,6 +335,21 @@ function getPaperlessConfig(
   }
 }
 
+function getHealthCheckSetting(option: OptionValues) {
+  const healthCheckEnabled: boolean =
+    option.healthCheck || getConfig("enableHealthCheck") === true;
+  let healthCheckPort: number;
+  if (option.healthCheckPort) {
+    healthCheckPort = parseInt(option.healthCheckPort, 10);
+  } else {
+    healthCheckPort = getConfig<number>("healthCheckPort") || 3000;
+  }
+  return {
+    isHealthCheckEnabled: healthCheckEnabled,
+    healthCheckPort: healthCheckPort,
+  };
+}
+
 function getScanConfiguration(option: OptionValues) {
   const directoryConfig: DirectoryConfig = {
     directory: option.directory || getConfig("directory"),
@@ -380,6 +401,15 @@ async function main() {
       "-l, --label <label>",
       "The label to display on the device (the default is the hostname)",
     )
+    .addOption(
+      new Option("--health-check", "Start an http health check endpoint"),
+    )
+    .addOption(
+      new Option(
+        "--health-check-port <health-check-port>",
+        "Start an http health check endpoint",
+      ),
+    )
     .action(async (options, cmd) => {
       const parentOption = cmd.parent.opts();
 
@@ -395,6 +425,11 @@ async function main() {
 
       const deviceUpPollingInterval = getDeviceUpPollingInterval(parentOption);
 
+      const healthCheckSetting = getHealthCheckSetting(options);
+      if (healthCheckSetting.isHealthCheckEnabled) {
+        startHealthCheckServer(healthCheckSetting.healthCheckPort);
+      }
+
       const scanConfig = getScanConfiguration(options);
 
       await listenCmd(registrationConfig, scanConfig, deviceUpPollingInterval);
@@ -427,6 +462,15 @@ async function main() {
         "Once document are detected to be in the adf, this specify the wait delay in millisecond before triggering the scan",
       ),
     )
+    .addOption(
+      new Option("--health-check", "Start an http health check endpoint"),
+    )
+    .addOption(
+      new Option(
+        "--health-check-port <port>",
+        "Start an http health check endpoint",
+      ),
+    )
     .description(
       "Automatically trigger a new scan job to this target once paper is detected in the automatic document feeder (adf)",
     )
@@ -441,6 +485,11 @@ async function main() {
 
       const deviceUpPollingInterval = getDeviceUpPollingInterval(parentOption);
 
+      const healthCheckSetting = getHealthCheckSetting(options);
+      if (healthCheckSetting.isHealthCheckEnabled) {
+        startHealthCheckServer(healthCheckSetting.healthCheckPort);
+      }
+
       const scanConfig = getScanConfiguration(options);
 
       const adfScanConfig: AdfAutoScanConfig = {