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Last pushed: a month ago
Short Description
Kubernetes state backup to git
Full Description

kube-backup


Quick 'n dirty kubernetes state backup script, designed to be ran as kubernetes Job. Think of it like RANCID for kubernetes.

Props to @gianrubio for coming up with the idea.

Setup

Use the deployment example (ssh or AWS CodeCommit authentication) and deploy a kubernetes CronJob primitive in your kubernetes (1.5 and up) cluster ensuring backups of kubernetes resource definitions to your private git repo.

Define the following environment parameters:

  • GIT_REPO - GIT repo url. Required
  • GIT_PREFIX_PATH - Path to the subdirectory in your repository. Default: .
  • NAMESPACES - List of namespaces to export. Default: all
  • GLOBALRESOURCES - List of global resource types to export. Default: namespace
  • RESOURCETYPES - List of resource types to export. Default: ingress deployment configmap svc rc ds thirdpartyresource networkpolicy statefulset storageclass cronjob. Notice that Secret objects are intentionally not exported by default (see git-crypt section for details).
  • GIT_USERNAME - Display name of git user. Default: kube-backup
  • GIT_EMAIL - Email address of git user. Default: kube-backup@example.com
  • GIT_BRANCH - Use a specific git branch . Default: master
  • GITCRYPT_ENABLE - Use git-crypt for data encryption. See git-crypt section for details. Default: false
  • GITCRYPT_PRIVATE_KEY - Path to private gpg key for git-crypt. See git-crypt section for details. Default: /secrets/gpg-private.key
  • GITCRYPT_SYMMETRIC_KEY - Path to shared symmetric key for git-crypt. See git-crypt section. Default: /secrets/symmetric.key

Chose one of two authentication mechanisms:

  • If using AWS CodeCommit and policy-based access from AWS, modify your cluster configuration to provide GitPull and GitPush access for that CodeCommit repo to your cluster. If using kops, the configuration will look something like this:

    additionalPolicies:
      node: |
        [
          {
            "Effect": "Allow",
            "Action": [
              "codecommit:GitPull",
              "codecommit:GitPush"
            ],
            "Resource": "arn:aws:codecommit:<region>:<account name>:<repo-name>"
          }
        ]
    

    NOTE: in this deployment, the ssh volume and secret are not present.

  • If using a different repository (GitHub, BitBucket, etc.), mount a configured ssh directory in /backup/.ssh with the following files:

    • known_hosts - Preloaded with SSH host key of $GIT_REPO host.
    • id_rsa - SSH private key of user allowed to push to $GIT_REPO.

    Easiest way of doing this is:

    ssh-keygen -f ./id_rsa
    ssh-keyscan $YOUR_GIT_HOST > known_hosts
    
    kubectl create secret generic kube-backup-ssh -n kube-system --from-file=id_rsa --from-file=known_hosts
    

    NOTE: If id_rsa isn't found in your ssh directory, the backup script will assume you're using AWS CodeCommit.

Optional:

  • Modify the snapshot frequency in spec.schedule using the cron format.
  • Modify the number of successful and failed finished jobs to retain in spec.successfulJobsHistoryLimit and spec.failedJobsHistoryLimit.
  • If using RBAC (1.6+), use the ClusterRole and ClusterRoleBindings in rbac.yaml.

git-crypt

For security reason Secret objects are not exported by default. However there is a possibility to store them safely using git-crypt project.

Prerequisites

Your repository have to be already initialized with git-crypt. Minimal configuration is listed below. For details and full information see using git-crypt.

cd repo
git-crypt init
cat <<EOF > .gitattributes
secret.yaml filter=git-crypt diff=git-crypt
.gitattributes !filter !diff
EOF
git-crypt add-gpg-user <USER_ID>
git add -A
git commit -a -m "initialize git-crypt"

Optional:

  • You may choose any subdirectory for storing .gitattributes file (useful when using GIT_PREFIX_PATH).
  • You may encrypt additional files than secret.yaml. Add additional line before .gitattribute filter. You may also use wildcard * to encrypt all files within chosen directory.

Enable git-crypt

To enable encryption feature:

  • Set pod environment variable GITCRYPT_ENABLE to true
    spec:
      containers:
      - env:
        - name: GITCRYPT_ENABLE
          value: "true"
    
  • Create additional Secret object containing either gpg-private or symmetric key
    apiVersion: v1
    kind: Secret
    metadata:
      name: kube-backup-gpg
      namespace: kube-system
    data:
      gpg-private.key: <base64_encoded_key>
      symmetric.key: <base64_encoded_key>
    
  • Mount keys from Secret as additional volume
    spec:
      containers:
      - volumeMounts:
        - mountPath: /secrets
          name: gpgkey
      volumes:
      - name: gpgkey
        secret:
          defaultMode: 420
          secretName: kube-backup-gpg
    
  • Add secret object name to RESOURCETYPES variable
    spec:
      containers:
      - env:
        - name: RESOURCETYPES
          value: "ingress deployment configmap secret svc rc ds thirdpartyresource networkpolicy statefulset storageclass cronjob"
    
  • If using RBAC (1.6+), add secrets to resources

    rules:
    - apiGroups: ["*"]
      resources: [
        "configmaps",
        "secrets",
    
  • (Optional): $GITCRYPT_PRIVATE_KEY and $GITCRYPT_SYMMETRIC_KEY variables are the combination of path where Secret volume is mounted and the name of item key from that object. If you change any value of them from the above example you may need to set this variables accordingly.

Result

All configured resources will be exported into a directory tree structure in kind: List YAML format following a $namespace/$resourcetype.yaml file structure.

.
├── default
│   ├── configmap.yaml
│   ├── cronjob.yaml
│   ├── deployment.yaml
│   ├── ds.yaml
│   ├── ingress.yaml
│   ├── networkpolicy.yaml
│   ├── petset.yaml
│   ├── rc.yaml
│   ├── statefulset.yaml
│   ├── storageclass.yaml
│   ├── svc.yaml
│   └── thirdpartyresource.yaml
├── kube-system
│   ├── configmap.yaml
│   ├── cronjob.yaml
│   ├── deployment.yaml
│   ├── ds.yaml
│   ├── ingress.yaml
│   ├── networkpolicy.yaml
│   ├── petset.yaml
│   ├── rc.yaml
│   ├── statefulset.yaml
│   ├── storageclass.yaml
│   ├── svc.yaml
│   └── thirdpartyresource.yaml
├── prd
│   ├── configmap.yaml
│   ├── cronjob.yaml
│   ├── deployment.yaml
│   ├── ds.yaml
│   ├── ingress.yaml
│   ├── networkpolicy.yaml
│   ├── petset.yaml
│   ├── rc.yaml
│   ├── statefulset.yaml
│   ├── storageclass.yaml
│   ├── svc.yaml
│   └── thirdpartyresource.yaml
└── staging
    ├── configmap.yaml
    ├── cronjob.yaml
    ├── deployment.yaml
    ├── ds.yaml
    ├── ingress.yaml
    ├── networkpolicy.yaml
    ├── petset.yaml
    ├── rc.yaml
    ├── statefulset.yaml
    ├── storageclass.yaml
    ├── svc.yaml
    └── thirdpartyresource.yaml

4 directories, 48 files

Caveat

This is using a kubernetes alpha feature (cronjobs) and hasn't been tested for idempotency/concurrent behaviour. See the cronjob documentation for details.

If your kubernetes cluster runs under version 1.5 or less, spec.successfulJobsHistoryLimit and spec.failedJobsHistoryLimit will be ignored as they've been introduced in version 1.6. In this case, running an export every 10 minutes will quickly run up your Job (and therefor Pod) count, causing a linear increase in master server load. A fix for this is to deploy a blunt instrument to clean the old kube-backup jobs.

License

This project is MIT licensed.

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Owner
ptlange
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