feature: allow final shutdown notification (#17)

* feature: allow final shutdown notification

* ensure shutdown URL is in debconf

* make shutdown URL not required

* add handling for errors in shutdown

* throw error object

* fix lint

debian/jitsi-autoscaler-sidecar.postinst

@@ -65,6 +65,7 @@ case "$1" in
         INSTANCE_TYPE="JVB"
         POLLING_URL="http://localhost:3000/sidecar/poll"
         STATUS_URL="http://localhost:3000/sidecar/status"
+        SHUTDOWN_URL="http://localhost:3000/sidecar/shutdown"
 
         # and we're done with debconf
         db_stop
@@ -99,6 +100,7 @@ case "$1" in
             sed -i s#INSTANCE_TYPE=#INSTANCE_TYPE=${INSTANCE_TYPE}#g $SIDECAR_CONFIG
             sed -i s#POLLING_URL=#POLLING_URL=${POLLING_URL}#g $SIDECAR_CONFIG
             sed -i s#STATUS_URL=#STATUS_URL=${STATUS_URL}#g $SIDECAR_CONFIG
+            sed -i s#SHUTDOWN_URL=#SHUTDOWN_URL=${SHUTDOWN_URL}#g $SIDECAR_CONFIG
         fi
     ;;
 

env.example

@@ -54,6 +54,10 @@ POLLING_URL=
 # e.g. 'http://localhost:3000/sidecar/status'
 STATUS_URL=
 
+# The autoscaler URL used by the sidecar to report final shutdown status (required)
+# e.g. 'http://localhost:3000/sidecar/shutdown'
+SHUTDOWN_URL=
+
 # The command the sidecar can run on the local instance to gracefully shut it down
 #GRACEFUL_SHUTDOWN_SCRIPT=/usr/local/bin/graceful_shutdown.sh
 

src/app.ts

@@ -35,6 +35,7 @@ const autoscalePoller = new Poller({
     pollUrl: config.PollingURL,
     statusUrl: config.StatusURL,
     statsUrl: config.StatsReportURL,
+    shutdownUrl: config.ShutdownURL,
     instanceDetails,
     asapRequest
 });
@@ -52,6 +53,7 @@ let statsReport: StatsReport;
 
 let reconfigureLock = false;
 let shutdownLock = false;
+let shutdownReported = false;
 
 interface JibriMetadata {
     [key: string]: string;
@@ -90,6 +92,32 @@ async function jibriStateWebhook(req: Request, res: Response) {
     res.send('{"status":"OK"}');
 }
 
+/**
+ * The hook to report final shutdown to server
+ *
+ * @param req the request.
+ * @param res the response.
+ */
+async function instanceShutdownWebhook(req: Request, res: Response) {
+    // update global stats report with
+    if (shutdownReported) {
+        res.status(200);
+        shutdownReported = true;
+        res.send('{"status":"OK", "message":"Already reported shutdown"}');
+    } else {
+        const ret = await autoscalePoller.reportShutdown();
+
+        if (ret) {
+            res.status(200);
+            shutdownReported = true;
+            res.send('{"status":"OK"}');
+        } else {
+            res.status(500);
+            res.send('{"status":"FAILED"}');
+        }
+    }
+}
+
 /**
  * Polls stats every 1 second.
  */
@@ -180,6 +208,14 @@ app.get('/health', (req: express.Request, res: express.Response) => {
     res.send('healthy!');
 });
 
+app.post('/hook/v1/shutdown', async (req, res, next) => {
+    try {
+        await instanceShutdownWebhook(req, res);
+    } catch (err) {
+        next(err);
+    }
+});
+
 app.post('/hook/v1/status', async (req, res, next) => {
     try {
         await jibriStateWebhook(req, res);

src/autoscale_poller.ts

@@ -16,6 +16,7 @@ export interface AutoscalePollerOptions {
     pollUrl: string;
     statusUrl: string;
     statsUrl: string;
+    shutdownUrl: string;
     instanceDetails: InstanceDetails;
     asapRequest: AsapRequest;
 }
@@ -33,6 +34,7 @@ export default class AutoscalePoller {
     private pollUrl: string;
     private statusUrl: string;
     private statsUrl: string;
+    private shutdownUrl: string;
     private asapRequest: AsapRequest;
 
     /**
@@ -43,12 +45,32 @@ export default class AutoscalePoller {
         this.pollUrl = options.pollUrl;
         this.statusUrl = options.statusUrl;
         this.statsUrl = options.statsUrl;
+        this.shutdownUrl = options.shutdownUrl;
         this.instanceDetails = options.instanceDetails;
         this.asapRequest = options.asapRequest;
 
         this.pollWithStats = this.pollWithStats.bind(this);
     }
 
+    /**
+     * Reports shutdown status by sending a json.
+     */
+    async reportShutdown(): Promise<boolean> {
+        try {
+            if (!this.shutdownUrl) {
+                throw new Error('No shutdown URL configured');
+            }
+            await this.asapRequest.postJson(this.shutdownUrl, this.instanceDetails);
+
+            return true;
+        } catch (err) {
+            logger.error('Error sending shutdown report', { err,
+                traceback: err.traceback });
+        }
+
+        return false;
+    }
+
     /**
      * Reports stats by sending a json.
      * @param statsReport

src/config.ts

@@ -15,6 +15,7 @@ const env = envalid.cleanEnv(process.env, {
     ASAP_JWT_AUD: envalid.str({ default: 'jitsi-autoscaler' }),
     ENABLE_REPORT_STATS: envalid.bool({ default: false }),
     POLLING_URL: envalid.str(),
+    SHUTDOWN_URL: envalid.str({ default: '' }),
     STATUS_URL: envalid.str(),
     STATS_RETRIEVE_URL: envalid.str({ default: '' }),
     STATS_REPORT_URL: envalid.str({ default: '' }),
@@ -37,7 +38,14 @@ export default {
 
     // number of seconds to wait between polling for shutdown
     ShutdownPollingInterval: env.SHUTDOWN_POLLING_INTERVAL,
+
+    // url for reporting final shutdown
+    ShutdownURL: env.SHUTDOWN_URL,
+
+    // url to poll for server commands
     PollingURL: env.POLLING_URL,
+
+    // url to report status and stats
     StatusURL: env.STATUS_URL,
 
     // number of seconds to wait before polling for stats