K8SPSMDB-1084 MongoDB connections leak in backup feature

[steve-nzr]

CHANGE DESCRIPTION

Problem:

We noticed an infinite increase, periodically, of opened connections count to our Mongod instances, on different clusters. It was really noticable on large sharded clusters (10 shards).

Cause:

Every backup, the operator left 1 connection open per ReplicaSet (per shard), in our case. So here for example : 11 connections per backup (10 shards + 1 ConfigServer).

Solution:

Disconnecting the client inside the psmb package after its use. I can't use defer since I'm in a loop, don't hesitate if you wan't to make it a new function instead.

Side note : This fix have been tested successfully in production since a few weeks now.

CHECKLIST

Jira

• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?
• Are OpenShift compare files changed for E2E tests (compare/*-oc.yml)?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported MongoDB version?
• Does the change support oldest and newest supported Kubernetes version?

[CLAassistant]

All committers have signed the CLA.

[JNKPercona]

Test name	Status
arbiter	passed
balancer	passed
custom-replset-name	passed
cross-site-sharded	passed
data-at-rest-encryption	passed
data-sharded	passed
demand-backup	passed
demand-backup-eks-credentials	passed
demand-backup-physical	passed
demand-backup-physical-sharded	passed
demand-backup-sharded	passed
expose-sharded	passed
ignore-labels-annotations	passed
init-deploy	passed
finalizer	passed
ldap	passed
ldap-tls	passed
limits	passed
liveness	passed
mongod-major-upgrade	passed
mongod-major-upgrade-sharded	passed
monitoring-2-0	passed
multi-cluster-service	passed
non-voting	passed
one-pod	passed
operator-self-healing-chaos	passed
pitr	passed
pitr-sharded	passed
pitr-physical	passed
pvc-resize	passed
recover-no-primary	passed
rs-shard-migration	passed
scaling	passed
scheduled-backup	passed
security-context	passed
self-healing-chaos	passed
service-per-pod	passed
serviceless-external-nodes	passed
smart-update	passed
split-horizon	passed
storage	passed
tls-issue-cert-manager	passed
upgrade	passed
upgrade-consistency	passed
upgrade-consistency-sharded-tls	passed
upgrade-sharded	passed
users	passed
version-service	passed
We run 48 out of 48

commit: e268e03
image: perconalab/percona-server-mongodb-operator:PR-1542-e268e038

[hors]

@steve-nzr Thank you for your contribution. We will include it in the next release.