fix: Fixed issue parsing docker container id

lib/utilization/docker-info.js

@@ -116,11 +116,27 @@ function fetchDockerVendorInfo(agent, callback, logger = log) {
       logger.debug(
         `${CGROUPS_V2_PATH} not found, trying to parse container id from ${CGROUPS_V1_PATH}`
       )
-      findCGroupsV1(callback)
+      findCGroupsV1(callback, logger)
       return
     }
 
-    parseCGroupsV2(data, callback)
+    parseCGroupsV2(
+      data,
+      (_, v2Data) => {
+        if (v2Data !== null) {
+          // We found a valid Docker identifier in the v2 file, so we are going
+          // to prioritize it.
+          return callback(null, v2Data)
+        }
+
+        // For some reason, we have a /proc/self/mountinfo but it does not have
+        // any Docker information in it (that we have detected). So we will
+        // fall back to trying the cgroups v1 file.
+        logger.debug(`Attempting to fall back to cgroups v1 parsing.`)
+        findCGroupsV1(callback, logger)
+      },
+      logger
+    )
   })
 }
 
@@ -136,6 +152,7 @@ function parseCGroupsV2(data, callback, logger = log) {
   const containerLine = new RegExp('/docker/containers/([0-9a-f]{64})/')
   const line = containerLine.exec(data)
   if (line) {
+    logger.debug(`Found docker id from cgroups v2: ${line[1]}`)
     callback(null, { id: line[1] })
   } else {
     logger.debug(`Found ${CGROUPS_V2_PATH} but failed to parse Docker container id.`)
@@ -169,7 +186,8 @@ function findCGroupsV1(callback, logger = log) {
     })
 
     if (id) {
-      vendorInfo = { id: id }
+      vendorInfo = { id }
+      logger.debug(`Found docker id from cgroups v1: ${id}`)
       callback(null, vendorInfo)
     } else {
       logger.debug('No matching cpu group found.')

test/unit/utilization/docker-info.test.js

@@ -31,9 +31,11 @@ test.beforeEach(async (ctx) => {
   utilCommon.readProc = (path, cb) => {
     cb(null, 'docker-1')
   }
+  ctx.nr.utilCommon = utilCommon
 
-  const { getBootId } = require('../../../lib/utilization/docker-info')
+  const { getBootId, getVendorInfo } = require('../../../lib/utilization/docker-info')
   ctx.nr.getBootId = getBootId
+  ctx.nr.getVendorInfo = getVendorInfo
 
   ctx.nr.agent = helper.loadMockedAgent()
   ctx.nr.agent.config.utilization = {
@@ -100,3 +102,31 @@ test('data on success', (t, end) => {
     end()
   }
 })
+
+test('falls back to v1 correctly', (t, end) => {
+  const { agent, logger, getVendorInfo, utilCommon } = t.nr
+  let invocation = 0
+
+  utilCommon.readProc = (path, callback) => {
+    if (invocation === 0) {
+      invocation += 1
+      return callback(null, 'invalid cgroups v2 file')
+    }
+    callback(null, '4:cpu:/docker/f37a7e4d17017e7bf774656b19ca4360c6cdc4951c86700a464101d0d9ce97ee')
+  }
+
+  getVendorInfo(agent, gotInfo, logger)
+
+  function gotInfo(error, info) {
+    assert.ifError(error)
+    assert.deepStrictEqual(info, {
+      id: 'f37a7e4d17017e7bf774656b19ca4360c6cdc4951c86700a464101d0d9ce97ee'
+    })
+    assert.deepStrictEqual(t.nr.logs, [
+      'Found /proc/self/mountinfo but failed to parse Docker container id.',
+      'Attempting to fall back to cgroups v1 parsing.',
+      'Found docker id from cgroups v1: f37a7e4d17017e7bf774656b19ca4360c6cdc4951c86700a464101d0d9ce97ee'
+    ])
+    end()
+  }
+})