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backup-ns

Introduction

This project is currently in an alpha state and only used internally at allaboutapps.
Thus is not ready for production use! Expect breaking changes.

This project extends Kubernetes CSI-based snapshots with application-aware (also called application-consistent) creation mechanisms. It is designed to be used in a multi-tenant cluster environments where namespaces are used to separate different customer applications.

Current focus:

  • Simple cli util for backup and restore without the need for operators or custom resource definitions (CRDs).
  • Using the proper compatible mysqldump and pg_dump is crucial when doing dumps! By executing these dumps in the same pod as the database container, compatibility is guaranteed.
  • Stick to the primitives. Just use k8s CronJobs for daily backup and handle retention with labels.
  • Control backup job concurrency on the node-level via flock.
  • Mark and sweep like handling, giving you time between marking and deleting.
  • Low-dependency, only kubectl must be in the PATH.

Processes

This section describes the various processes of the backup-ns tool.

Application-aware backup creation

This diagram shows the process of a backup job for a PostgreSQL database. The same is possible with MySQL or by entirely skipping the database.

sequenceDiagram
    participant BACKUP_NS as k8s Job Backup create
    participant K8S_NODE as k8s Node
    participant K8S_API as k8s API
    participant K8S_POD as k8s Pod

    Note over BACKUP_NS: Load ENV
    Note over BACKUP_NS: Shuffle {1,2}.lock based on Node CPU count
    
    BACKUP_NS->>K8S_NODE: Acquire flock /mnt/host-backup-locks/2.lock

    Note over BACKUP_NS,K8S_NODE: Block until another backup-ns job is done

    K8S_NODE-->>BACKUP_NS: Flock lock acquired
    
    BACKUP_NS->>K8S_API: Check pvc/data exists
    K8S_API-->>BACKUP_NS: PVC OK

    BACKUP_NS->>K8S_API: Check deployment/database is up
    K8S_API-->>BACKUP_NS: Pod OK

    Note over BACKUP_NS,K8S_POD: backup-ns now execs into the pod. All commands are run in the same container as your database.

    BACKUP_NS->>K8S_POD: Check postgres prerequisites
    K8S_POD-->>BACKUP_NS: gzip, pg_dump available. DB accessible.
    
    BACKUP_NS->>K8S_POD: Check free disk space of mounted dir inside pod
    K8S_POD-->>BACKUP_NS: <90% disk space used, OK
    
    BACKUP_NS->>K8S_POD: Execute pg_dump, check dump file size
    K8S_POD-->>BACKUP_NS: Dump OK
    
    Note over BACKUP_NS,K8S_API: With the dump ready, we can now create a VolumeSnapshot via the CSI driver.

    BACKUP_NS->>K8S_API: Create VolumeSnapshot. Label for adhoc, daily, weekly, monthly retention.
    K8S_API-->>BACKUP_NS: VS created
    Note over BACKUP_NS: Wait for VS ready
    
    BACKUP_NS->>K8S_NODE: Release flock lock
  
    Note over BACKUP_NS: Backup complete
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Label retention process

This diagram shows how the retention process works for managing snapshots based on daily, weekly and monthly policies. This process is typically run globally, but can also be run on a per-namespace basis (as to how the RBAC service account allows access).

sequenceDiagram
    participant RETAIN as k8s Job Retain
    participant K8S_API as k8s API
    
    Note over RETAIN: Load ENV
    
    RETAIN->>K8S_API: Get namespaces with backup-ns.sh/retain labeled snapshots
    K8S_API-->>RETAIN: List of namespaces
    
    loop Each namespace
        RETAIN->>K8S_API: Get unique PVCs with snapshots
        K8S_API-->>RETAIN: List of PVCs
        
        loop Each PVC
            Note over RETAIN,K8S_API: Process daily retention
            RETAIN->>K8S_API: Get daily labeled snapshots sorted by date
            K8S_API-->>RETAIN: VS list
            Note over RETAIN,K8S_API: Keep newest 7 daily snapshots by label.<br/>Remove daily labels from the other snapshots.
            
            Note over RETAIN,K8S_API: Process weekly retention
            RETAIN->>K8S_API: Get weekly labeled snapshots sorted by date
            K8S_API-->>RETAIN: VS list
            Note over RETAIN,K8S_API: Keep newest 4 weekly snapshots by label.<br/>Remove weekly labels from the other snapshots.
            
            Note over RETAIN,K8S_API: Process monthly retention
            RETAIN->>K8S_API: Get monthly labeled snapshots sorted by date
            K8S_API-->>RETAIN: VS list
            Note over RETAIN,K8S_API: Keep newest 12 monthly snapshots by label.<br/>Remove monthly labels from the other snapshots.
        end
    end
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Mark and delete process

Volume snapshots that have lost all retention-related labels will be marked for deletion and subsequently deleted. This diagram shows that. Like the retain process, this process is typically run globally, but can also be run on a per-namespace basis (as to how the RBAC service account allows access).

sequenceDiagram
    participant MAD as k8s Job Mark and Delete
    participant K8S_API as k8s API
    
    Note over MAD: Phase 1: Mark snapshots
    
    MAD->>K8S_API: Get VS with backup-ns.sh/retain=daily_weekly_monthly<br/>but no daily/weekly/monthly labels
    K8S_API-->>MAD: List of snapshots to mark
    
    loop Each snapshot to mark
        MAD->>K8S_API: Label with backup-ns.sh/delete-after=today
        K8S_API-->>MAD: Label updated
    end
    
    Note over MAD: Phase 2: Delete marked snapshots
    
    MAD->>K8S_API: Get VS with delete-after label
    K8S_API-->>MAD: List of marked snapshots
    
    Note over MAD: Filter snapshots where<br/>delete-after date < today
    
    loop Each snapshot to delete
        MAD->>K8S_API: Delete VolumeSnapshot
        K8S_API-->>MAD: VS deleted
        Note over MAD: Wait 5s between deletions
    end
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Usage

TODO Helm chart repo within deploy/backup-ns -> gh-pages and static deployment

Labels

Here are some typical labels backup-ns currently uses and how to manipulate them manually:

# Remove a deleteAfter labeled vs (this prevents the backup-ns pruner from deleting the vs):
kubectl label vs/<vs> "backup-ns.sh/delete-after"-

# Remove a specific label for daily/weekly/monthly retention
kubectl label vs/<vs> "backup-ns.sh/daily"-
kubectl label vs/<vs> "backup-ns.sh/weekly"-
kubectl label vs/<vs> "backup-ns.sh/monthly"-

# Add a specific label daily/weekly/monthly
kubectl label vs/<vs> "backup-ns.sh/daily"="YYYY-MM-DD"
kubectl label vs/<vs> "backup-ns.sh/weekly"="YYYY-w04"
kubectl label vs/<vs> "backup-ns.sh/monthly"="YYYY-MM"

# Add a specific deleteAfter label (the pruner will delete the vs after the specified date)!
kubectl label vs/<vs> "backup-ns.sh/delete-after"="YYYY-MM-DD"

Development

Development Setup

Requires the following local setup for development:

This project makes use of the Remote - Containers extension provided by Visual Studio Code. A local installation of the Go tool-chain is no longer required when using this setup.

Please refer to the official installation guide how this works for your host OS and head to our FAQ: How does our VSCode setup work? if you encounter issues.

We test the functionality of the backup-ns tool against a kind (Kubernetes in Docker) cluster.

# Ensure you have docker (for mac) and kind installed on your **local** host.
# This project requires kind (Kubernetes in Docker) to do the testing.

# Launch a new kind cluster on your *LOCAL* host:
brew install kind
make kind-cluster-init

# the dev container is autoconfigured to use the above kind cluster
./docker-helper --up

development@f4a7ad3b5e3d:/app$ k get nodes
# NAME                      STATUS   ROLES           AGE   VERSION
# backup-ns-control-plane   Ready    control-plane   69s   v1.28.13
development@f4a7ad3b5e3d:/app$ k version
# Client Version: v1.28.14
# Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
# Server Version: v1.28.13
development@f4a7ad3b5e3d:/app$ make all

# Print all available make targets
development@f4a7ad3b5e3d:/app$ make help

# Shortcut for make init, make build, make info and make test
development@f4a7ad3b5e3d:/app$ make all

# Init install/cache dependencies and install tools to bin
development@f4a7ad3b5e3d:/app$ make init

# Rebuild only after changes to files
development@f4a7ad3b5e3d:/app$ make

# Execute all tests
development@f4a7ad3b5e3d:/app$ make test

# Watch pipeline (rebuilds all after any change)
development@f4a7ad3b5e3d:/app$ make watch

Releasing new versions

This project uses GitHub Actions to build and push the Docker image to the GitHub Container Registry.
Auto-Publish is active for the dev and main branch.

The helm/chart-releaser-action ensures that the Helm chart is published to the GitHub Pages branch.

To deploy a new app and chart version:

  • Bump the version (for the chart) and appVersion (for the docker image) in the charts/backup-ns/Chart.yaml file and push to main.
  • Create a new git tag with the above appVersion (e.g. git tag -a v0.1.1 -m "v0.1.1" ) and push it to the GitHub repository.

Maintainers

License

MIT © 2024 aaa – all about apps GmbH | Mario Ranftl and the backup-ns project contributors

Alternative projects

  • backube/snapscheduler: Based on CSI snapshots, but using CRDs and without the option to do application consistent snapshots (no pre/post hooks).
  • k8up-io/k8up: Based on Restic, requires launching pods with direct access to the PVC to backup and custom CRDs.
  • vmware-tanzu/velero: Global cluster disaster recovery (difficult to target singular namespaces) and custom CRDs.