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Karakoram

MongoDB

Manage Percona Server for MongoDB (PSMDB) and Percona Backup for MongoDB (PBM) on Zerops.

Opt-in cluster data MCP uses a private mongodb-mcp-server companion and separate scoped read/write users. Configure scope.databases; system databases cannot be scoped. It is disabled by default and independent of ordinary credential reveal.

At a glance

Section titled “At a glance”
Setting Supported value / default
Engine driver psmdb
PSMDB catalog 6.0.29-23 (deprecated); 7.0.40-22, 7.0.43-23, 8.0.29-13; 8.0.32-14 (default)
PBM 2.16.0-1; Debian package pins append .noble
Topologies replicaSet: 1/3/5/7 data-bearing members; sharded: config set, shard sets and mongos
Resource floors Whole CPU cores ≥1; RAM ≥0.5 GiB; disk ≥5 GiB; maxima ≥minima; start CPU within bounds
Engine driver resource defaults SHARED CPU, min/max 1 core, 1 GiB RAM, 5 GiB disk; omitted maxima follow effective minima
Database TLS requireTLS, generated per-cluster CA
Recovery PBM logical / physical snapshots and PITR
Public TCP Opt-in, CIDR allowlist; project IPv6 or dedicated IPv4

Query your installation with karactl providers get psmdb -o yaml. Catalog defaults are resolved at creation, not automatic upgrades. Package availability is not an upstream lifecycle guarantee; PSMDB 8.3 Technical Preview is excluded. Operations describes supported upgrade paths.

How it runs

Section titled “How it runs”

Each mongod has a singleton Zerops runtime and persistent Local Storage volume. Karakoram deploys its agent and pinned Percona packages, bootstraps the first member through MongoDB’s localhost exception, and establishes reserved management accounts. Sharded creation initializes config servers, shard sets and routers, then registers shards.

Runtime names are {cluster}m{index}, {cluster}s{shard}m{index}, {cluster}c{index} and {cluster}r; volumes append v. Replacement indexes are monotonic. Routers are stateless. Agents supervise engine processes and cache protected configuration; see runtime operations.

Create

Section titled “Create”

Select the target namespace, then Clusters → Create cluster → MongoDB. The wizard exposes:

Step MongoDB choices
Basics Name, exact version, replica set or sharded topology, optional preset
Topology / Resources Member/shard/config-server/router counts; component CPU/RAM/disk bounds; validated YAML overrides; routers have no durable data-disk editor
Backups Registered storage or None, logical/physical schedules, PITR interval, optional backup/time seed and source namespace
Access & TLS TLS mode/CA and optional certificate pairs, exposure/IP family/CIDRs, monitoring
Review All settings, aggregate runtime CPU/RAM, data volumes/capacity, separate runtime disks and placement warning

Custom uses no preset; dev selects one member without redundancy; prod selects three voters; sharded selects two three-member shards, three config servers and one router. Presets use the resource defaults above and remain editable; none certifies capacity or host separation. Check aggregate footprint against project capacity; object storage is additional, and totals are not a price quote or initial allocation.

CLI example (after CLI authentication):

Terminal window
karactl -n default clusters create demo --provider psmdb --topology replicaSet --members 3 --wait

This uses CLI convenience resource bounds; use the explicit bounds in the replica-set guide when sizing a fixed footprint.

Use the replica-set checklist and CLI alternative or sharded creation example. Connect using scoped application users and TLS, not revealed administrative credentials.

Limits

Section titled “Limits”
  • Names and topology type are immutable; names are 2–12 lowercase alphanumeric characters starting with a letter.
  • No arbiters/custom voting layout or per-shard independent component specs; topology bounds and shard administration apply.
  • No shard removal or replica-set-to-sharded conversion; migrate into a compatible new deployment.
  • Singletons incur maintenance downtime; multiple voters do not establish independent failure domains.
  • The RAM floor is for disposable tiny workloads, not a load/recovery guarantee; reserve WiredTiger/PBM headroom.
  • No arbitrary package versions, downgrades or skipped-major upgrades; binary upgrades and explicit FCV are separate.
  • Overrides cannot replace managed networking/authentication/TLS/replication/sharding/process/logging/dbpath/cache settings.
  • Public seeds are not external replica-set HA; read public exposure and discovery.
  • Shared SeaweedFS dbpaths and live volume archives are not supported MongoDB recovery substitutes; use PBM.
  • Restore is disruptive, compatibility-bound and not necessarily a complete logical rollback; restore and clone define coverage and retained-snapshot requirements.
  • Count retention does not guarantee PITR duration; inspect observed continuous windows after backup/storage changes.
  • Monitoring and process tails have bounded coverage; see log retention.
  • Existing agents update on member deployment, not control-plane restart; lost control-plane state cannot safely adopt members. Preserve state and original encryption key.