metrics: fix crash if could not translate

src/metrics.js

@@ -28,6 +28,9 @@ const apps = require('./apps.js'),
 function translateContainerStatsSync(stats) {
     assert.strictEqual(typeof stats, 'object');
 
+     // the container is missing or stopped. better not to inspect and check State since a race is possible
+    if (Object.keys(stats.pids_stats) === 0 || Object.keys(stats.memory_stats).length === 0 || stats.blkio_stats.io_service_bytes_recursive === null) return null;
+
     const networkRead = stats.networks ? stats.networks.eth0.rx_bytes : 0; // in host mode (turn), networks is missing
     const networkWrite = stats.networks ? stats.networks.eth0.tx_bytes : 0; // in host mode (turn), networks is missing
 
@@ -41,7 +44,9 @@ function translateContainerStatsSync(stats) {
     const cpuUsageMsecs = stats.cpu_stats.cpu_usage.total_usage / 1e6; // convert from nano to msecs (to match system metrics)
     const systemUsageMsecs = stats.cpu_stats.system_cpu_usage / 1e6;
 
-    return { ts: new Date(stats.read), networkRead, networkWrite, blockRead, blockWrite, memoryUsed, memoryMax, cpuUsageMsecs, systemUsageMsecs };
+    const pidCount = stats.pids_stats.current;
+
+    return { ts: new Date(stats.read), pidCount, networkRead, networkWrite, blockRead, blockWrite, memoryUsed, memoryMax, cpuUsageMsecs, systemUsageMsecs };
 }
 
 async function readContainerMetrics() {
@@ -56,9 +61,10 @@ async function readContainerMetrics() {
     const metrics = {};
     for (const containerName of containerNames) {
         const [error, stats] = await safe(docker.getStats(containerName, { stream: false }));
-        if (error || Object.keys(stats.memory_stats).length === 0) continue; // the container is missing or stopped. better not to inspect and check State since a race is possible
+        if (error) continue;
 
-        metrics[containerName] = translateContainerStatsSync(stats);
+        const translated = translateContainerStatsSync(stats);
+        if (translated) metrics[containerName] = translated;
     }
 
     return metrics;
@@ -349,6 +355,7 @@ async function readSystemFromGraphite(options) {
 }
 
 // CPU: stress --cpu 2 --timeout 60
+// Memory: stress --cpu 2 --timeout 60
 async function getSystem(options) {
     assert.strictEqual(typeof options, 'object');
 
@@ -439,6 +446,7 @@ async function getContainerStream(name, options) {
     statsStream.on('data', (data) => {
         const stats = JSON.parse(data.toString('utf8'));
         const metrics = translateContainerStatsSync(stats);
+        if (!metrics) return; // maybe the container stopped
 
         const { ts, networkRead, networkWrite, blockRead, blockWrite, memoryUsed, cpuUsageMsecs } = metrics;
 
@@ -452,7 +460,7 @@ async function getContainerStream(name, options) {
 
         oldMetrics = metrics;
 
-        const nowSecs = ts.getTime() / 1000; // to match graphite return value
+        const nowSecs = ts.getTime() / 1000; // conver to secs to match graphite return value
         metricsStream.push(JSON.stringify({
             cpu: [ cpuPercent, nowSecs ],
             memory: [ memoryUsed, nowSecs ],