feat: report call count to redis for server-wide drain coordination

A server may run several sbc-inbound and sbc-outbound processes.  When
one of the sbc-inbound processes handles an AWS autoscale drain it must
complete the terminating lifecycle hook only when the whole server is
idle, not just its own process — otherwise the instance is terminated
while sibling processes still have calls in progress.

Each process now writes its own call count to a per-pid redis key
(120s expiry, refreshed every 15s from activeCallIds.size) and
registers that key in a per-host set, which the draining process
enumerates and sums.  See the companion change in sbc-inbound.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -29,9 +29,19 @@ Configuration is provided via environment variables:
 |JAMBONES_RTPENGINES| commans-separated list of ip:ng-port for rtpengines (e.g. '172.31.32.10:22222')|yes|
 |JAMBONES_TIME_SERIES_HOST| influxdb host |yes|
 |JAMBONES_RECORD_ALL_CALLS| enable auto record calls |no|
+|JAMBONES_CODEC_OFFER_WITH_ORDER| comma-separated codec list to use as the outbound offer toward the carrier; the original codecs from the feature server are stripped first (e.g. `'opus,PCMU,PCMA,telephone-event'`) |no|
+|JAMBONES_CODEC_TRANSCODE| comma-separated codec list that rtpengine should add to the outbound offer and transcode on the fly when the carrier selects them — used to support codecs the feature server does not speak (e.g. `'AMR-WB/16000'`). Requires an rtpengine build that includes the corresponding codec module. |no|
+|JAMBONES_ACCEPT_AND_TRANSCODE| comma-separated codec list to accept on the outbound leg and transcode to PCMU/PCMA toward the feature server |no|
+|JAMBONES_ACCEPT_G729| if set, accept G.729 on the outbound leg and transcode to PCMU/PCMA (shorthand for `JAMBONES_ACCEPT_AND_TRANSCODE=g729`) |no|
 |K8S| service running as kubernetes service |no|
 |K8S_RTPENGINE_SERVICE_NAME| rtpengine service name(required for K8S) |no|
 
+#### Codec transcoding notes
+
+`JAMBONES_CODEC_OFFER_WITH_ORDER` and `JAMBONES_CODEC_TRANSCODE` can be combined. When both are set, rtpengine first strips the original codecs from the SDP, then adds the codecs listed in `JAMBONES_CODEC_OFFER_WITH_ORDER` to the offer, and finally adds the codecs from `JAMBONES_CODEC_TRANSCODE` with transcoding enabled. When only `JAMBONES_CODEC_TRANSCODE` is set, the original codecs from the feature server are kept in the offer and the transcode codecs are appended.
+
+Codecs that require licensed or optional rtpengine modules (AMR, AMR-WB, G.729, etc.) only work if rtpengine was compiled with support for them. Carrier-specific fmtp parameters (for example, `octet-align=1` for AMR-WB) can be appended to the codec name as needed (e.g. `AMR-WB/16000;octet-align=1`).
+
 ### running under pm2
 Typically, this application runs under [pm2](https://pm2.io) using an [ecosystem.config.js](https://pm2.keymetrics.io/docs/usage/application-declaration/) file similar to this:
 ```js

app.js

@@ -70,7 +70,8 @@ const {
   isMemberOfSet,
   addKey,
   deleteKey,
-  retrieveKey
+  retrieveKey,
+  addToSet
 } = require('@jambonz/realtimedb-helpers')({}, logger);
 
 const activeCallIds = new Map();
@@ -124,6 +125,17 @@ const {getRtpEngine, setRtpEngines} = require('@jambonz/rtpengine-utils')([], lo
 });
 srf.locals.getRtpEngine = getRtpEngine;
 
+/* report our call count to redis so a draining sbc-inbound process can count
+   calls across all sbc-inbound and sbc-outbound processes on this server */
+if (!process.env.K8S && 'test' !== process.env.NODE_ENV) {
+  srf.locals.callCountReporter = require('./lib/call-count-reporter')({
+    logger,
+    addKey,
+    addToSet,
+    getCount: () => activeCallIds.size
+  });
+}
+
 if (process.env.DRACHTIO_HOST && !process.env.K8S) {
   const cidrs = process.env.JAMBONES_NETWORK_CIDR
     .split(',')

data/srtp-transcoding.json

@@ -4,7 +4,7 @@
     "ICE": "force",
     "SDES": "off",
     "flags": ["generate mid", "SDES-no", "port latching"],
-    "rtcp-mux": ["require"]  
+    "rtcp-mux": ["offer"]
   },
   "teams": {
     "transport-protocol": "RTP/SAVP",

lib/call-count-reporter.js

@@ -0,0 +1,31 @@
+const os = require('os');
+
+/**
+ * Periodically report this process's count of calls in progress to redis.
+ * A server may host several sbc-inbound and sbc-outbound processes; when one
+ * of them handles an autoscale drain it needs to know when the entire server
+ * has no calls in progress, not just its own process.  Each process writes
+ * its own count under a per-pid key (with a short expiry, so keys from dead
+ * processes evaporate) and registers that key in a per-host set that the
+ * draining process can enumerate.
+ */
+const REPORT_INTERVAL = 15000;
+const KEY_EXPIRY_SECS = 120;
+
+module.exports = ({logger, addKey, addToSet, getCount}) => {
+  const prefix = process.env.JAMBONES_CLUSTER_ID || 'default';
+  const setName = `${prefix}:call-count-keys:${os.hostname()}`;
+  const key = `${prefix}:call-count:${os.hostname()}:${process.pid}`;
+
+  const report = () => {
+    addKey(key, `${getCount()}`, KEY_EXPIRY_SECS)
+      .catch((err) => logger.error({err}, 'call-count-reporter: error writing call count'));
+  };
+
+  addToSet(setName, key)
+    .catch((err) => logger.error({err}, `call-count-reporter: error adding ${key} to ${setName}`));
+  setInterval(report, REPORT_INTERVAL);
+  report();
+
+  return {key, setName};
+};

lib/call-session.js

@@ -237,7 +237,20 @@ class CallSession extends Emitter {
         this.logger.info(`sending call to registered user ${destUri}`);
       }
       else if (this.req.locals.target === 'forward') {
-        if (process.env.JAMBONES_SIPS_FORWARD_SRTP && this.req.uri.startsWith('sips:')) {
+        /* the feature-server sets X-Jambonz-SRTP (from the dial verb's srtpEncryption
+           option) to request encrypted media on a per-call basis */
+        const srtpMode = this.req.get('X-Jambonz-SRTP');
+        if (srtpMode) {
+          /* SDES (RTP/SAVP): pass teams=true to select the SDES srtp profile, matching
+             the proven carrier tls/srtp path above. This offers a=crypto to the target
+             (what SIP endpoints such as LiveKit expect), not DTLS-SRTP. */
+          this.logger.info({uri: this.req.uri, srtpMode},
+            'using SRTP (SDES) for forwarded call per X-Jambonz-SRTP');
+          this.rtpEngineOpts = makeRtpEngineOpts(this.req, false, true, false, true);
+          encryptedMedia = true;
+        }
+        else if (process.env.JAMBONES_SIPS_FORWARD_SRTP && this.req.uri.startsWith('sips:')) {
+          /* legacy global opt-in for sips: forwards (uses the DTLS srtp profile) */
           this.logger.info({uri: this.req.uri}, 'using SRTP/TLS for forwarded sips: call');
           this.rtpEngineOpts = makeRtpEngineOpts(this.req, false, true, false, false);
           encryptedMedia = true;
@@ -531,6 +544,7 @@ class CallSession extends Emitter {
               '-X-Preferred-From-Host',
               '-X-Jambonz-FS-UUID',
               '-X-Voip-Carrier-Sid',
+              '-X-Jambonz-SRTP',
               '-X-SIP-Proxy'
             ],
             proxyResponseHeaders: [
@@ -665,7 +679,21 @@ class CallSession extends Emitter {
         }
       }
     } catch (err) {
-      if ('abandonded' !== err.message) this.logger.error({err}, `Error setting up outbound call to: ${uris}`);
+      if ('abandoned' !== err.message) this.logger.error({err}, `Error setting up outbound call to: ${uris}`);
+
+      /* the call count was incremented on 'init' but we bailed out before connecting (e.g. caller
+         hung up before the B leg answered), so we must decrement it here - no failure response is
+         sent on this path, so the res.once('end') safety net in middleware would not fire.
+         nudgeCallCounts is a no-op if the count was already decremented elsewhere. */
+      const {writeCallCount, writeCallCountSP, writeCallCountApp} = this.req.srf.locals;
+      nudgeCallCounts(this.req, 'failure', {
+        service_provider_sid: this.service_provider_sid,
+        account_sid: this.account_sid,
+        application_sid: this.application_sid,
+        callId: this.req.locals.callId
+      }, this.decrKey, {writeCallCountSP, writeCallCount, writeCallCountApp})
+        .catch((err) => this.logger.error(err, 'Error decrementing call counts'));
+
       this.emit('failed');
       this.srf.endSession(this.req);
       this.rtpEngineResource.destroy();
@@ -892,8 +920,14 @@ Duration=${payload.duration} `
         process.env.JAMBONES_ACCEPT_G729 ? 'g729' : '';
       offerMedia = { ...offerMedia, ...(acceptCodecs && dlg.type === 'uac' &&
         { codec: { mask: acceptCodecs, transcode: 'pcmu,pcma' } })};
-      answerMedia = { ...answerMedia, ...(process.env.JAMBONES_CODEC_OFFER_WITH_ORDER && dlg.type === 'uac' &&
-        { codec: {offer: process.env.JAMBONES_CODEC_OFFER_WITH_ORDER.split(','), strip: 'all' }})};
+      answerMedia = { ...answerMedia, ...((process.env.JAMBONES_CODEC_OFFER_WITH_ORDER ||
+        process.env.JAMBONES_CODEC_TRANSCODE) && dlg.type === 'uac' &&
+        { codec: {
+          ...(process.env.JAMBONES_CODEC_OFFER_WITH_ORDER &&
+            { offer: process.env.JAMBONES_CODEC_OFFER_WITH_ORDER.split(','), strip: 'all' }),
+          ...(process.env.JAMBONES_CODEC_TRANSCODE &&
+            { transcode: process.env.JAMBONES_CODEC_TRANSCODE.split(',') })
+        }})};
       let opts = {
         ...this.rtpEngineOpts.common,
         ...offerMedia,

lib/utils.js

@@ -58,6 +58,10 @@ function makeRtpEngineOpts(req, srcIsUsingSrtp, dstIsUsingSrtp, padCrypto, teams
         offer: process.env.JAMBONES_CODEC_OFFER_WITH_ORDER.split(','),
         strip: 'all'
       }),
+    ...(process.env.JAMBONES_CODEC_TRANSCODE &&
+      {
+        transcode: process.env.JAMBONES_CODEC_TRANSCODE.split(',')
+      }),
   };
 
   return {

package-lock.json

@@ -1,19 +1,19 @@
 {
   "name": "sbc-outbound",
-  "version": "0.9.6",
+  "version": "0.9.9",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "sbc-outbound",
-      "version": "0.9.6",
+      "version": "0.9.9",
       "license": "MIT",
       "dependencies": {
         "@babel/helpers": "^7.26.10",
         "@jambonz/db-helpers": "^0.9.18",
         "@jambonz/http-health-check": "^0.0.1",
         "@jambonz/mw-registrar": "0.2.7",
-        "@jambonz/realtimedb-helpers": "^0.8.13",
+        "@jambonz/realtimedb-helpers": "^0.8.21",
         "@jambonz/rtpengine-utils": "^0.4.4",
         "@jambonz/siprec-client-utils": "^0.2.10",
         "@jambonz/stats-collector": "^0.1.10",
@@ -594,9 +594,10 @@
       }
     },
     "node_modules/@jambonz/realtimedb-helpers": {
-      "version": "0.8.13",
-      "resolved": "https://registry.npmjs.org/@jambonz/realtimedb-helpers/-/realtimedb-helpers-0.8.13.tgz",
-      "integrity": "sha512-/7c8kCu/dMSk8CWTYdEv4xU/7+vmVL30VCjtHPRAXVBRIVejAPDf1xK5n0rXwG8Fda1Oa+0TFsymkiRpew8P6w==",
+      "version": "0.8.21",
+      "resolved": "https://registry.npmjs.org/@jambonz/realtimedb-helpers/-/realtimedb-helpers-0.8.21.tgz",
+      "integrity": "sha512-Zn/Zw14U0L1pB2RlN5i160FwWqphonhQ7p880OzsKOuvg+wmj6qIkxdLjDXo6TSxFPXDHD25s33zfGOT6ZIfsw==",
+      "license": "MIT",
       "dependencies": {
         "debug": "^4.3.4",
         "ioredis": "^5.3.2"

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sbc-outbound",
-  "version": "0.9.6",
+  "version": "0.9.9",
   "main": "app.js",
   "engines": {
     "node": ">= 20.0.0"
@@ -31,7 +31,7 @@
     "@jambonz/db-helpers": "^0.9.18",
     "@jambonz/http-health-check": "^0.0.1",
     "@jambonz/mw-registrar": "0.2.7",
-    "@jambonz/realtimedb-helpers": "^0.8.13",
+    "@jambonz/realtimedb-helpers": "^0.8.21",
     "@jambonz/rtpengine-utils": "^0.4.4",
     "@jambonz/siprec-client-utils": "^0.2.10",
     "@jambonz/stats-collector": "^0.1.10",