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Backup and Restore Volumes of a DaemonSet
This guide will show you how to use Stash to backup and restore volumes of a DaemonSet.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectl
command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.Install
Stash
in your cluster following the steps here.You should be familiar with the following
Stash
concepts:
To keep everything isolated, we are going to use a separate namespace called demo
throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/guides/workloads/daemonset/examples directory of stashed/docs repository.
Backup Volumes of a DaemonSet
This section will show you how to use Stash to backup volumes of a DaemonSet. Here, we are going to deploy a DaemonSet and generate some sample data in it. Then, we are going to backup this sample data using Stash.
Deploy DaemonSet:
At first, we are going to deploy a DaemonSet. This DaemonSet will automatically generate sample data (data.txt
file) in /source/data
directory.
Below is the YAML of the DaemonSet that we are going to create,
apiVersion: apps/v1
kind: DaemonSet
metadata:
labels:
app: stash-demo
name: stash-demo
namespace: demo
spec:
selector:
matchLabels:
app: stash-demo
template:
metadata:
labels:
app: stash-demo
name: busybox
spec:
containers:
- args: ["echo sample_data > /source/data/data.txt && sleep 3000"]
command: ["/bin/sh", "-c"]
image: busybox
imagePullPolicy: IfNotPresent
name: busybox
volumeMounts:
- mountPath: /source/data
name: source-data
restartPolicy: Always
volumes:
- name: source-data
hostPath:
path: /stash/source/data
Let’s create the DaemonSet we have shown above.
$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.10.9/docs/guides/workloads/daemonset/examples/daemon.yaml
daemonset.apps/stash-demo created
Now, wait for the pod of the DaemonSet to go into the Running
state.
$ kubectl get pod -n demo
NAME READY STATUS RESTARTS AGE
stash-demo-c4nqw 1/1 Running 0 39s
Verify that the sample data has been created in /source/data
directory using the following command,
$ kubectl exec -n demo stash-demo-c4nqw -- cat /source/data/data.txt
sample_data
Prepare Backend
We are going to store our backed up data into a GCS bucket. We have to create a Secret with necessary credentials and a Repository crd to use this backend. If you want to use a different backend, please read the respective backend configuration doc from here.
For GCS backend, if the bucket does not exist, Stash needs
Storage Object Admin
role permissions to create the bucket. For more details, please check the following guide.
Create Secret:
Let’s create a secret called gcs-secret
with access credentials to our desired GCS bucket,
$ echo -n 'changeit' > RESTIC_PASSWORD
$ echo -n '<your-project-id>' > GOOGLE_PROJECT_ID
$ cat /path/to/downloaded-sa-key.json > GOOGLE_SERVICE_ACCOUNT_JSON_KEY
$ kubectl create secret generic -n demo gcs-secret \
--from-file=./RESTIC_PASSWORD \
--from-file=./GOOGLE_PROJECT_ID \
--from-file=./GOOGLE_SERVICE_ACCOUNT_JSON_KEY
secret/gcs-secret created
Create Repository:
Now, create a Repository
using this secret. Below is the YAML of Repository
crd we are going to create,
apiVersion: stash.appscode.com/v1alpha1
kind: Repository
metadata:
name: gcs-repo
namespace: demo
spec:
backend:
gcs:
bucket: appscode-qa
prefix: /source/data/sample-daemonset
storageSecretName: gcs-secret
Let’s create the Repository we have shown above,
$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.10.9/docs/guides/workloads/daemonset/examples/repository.yaml
repository.stash.appscode.com/gcs-repo created
Now, we are ready to backup our sample data into this backend.
Backup
We have to create a BackupConfiguration
crd targeting the stash-demo
DaemonSet that we have deployed earlier. Stash will inject a sidecar container into the target. It will also create a CronJob
to take periodic backup of /source/data
directory of the target.
Create BackupConfiguration:
Below is the YAML of the BackupConfiguration
crd that we are going to create,
apiVersion: stash.appscode.com/v1beta1
kind: BackupConfiguration
metadata:
name: dmn-backup
namespace: demo
spec:
repository:
name: gcs-repo
schedule: "*/5 * * * *"
target:
ref:
apiVersion: apps/v1
kind: DaemonSet
name: stash-demo
volumeMounts:
- name: source-data
mountPath: /source/data
paths:
- /source/data
retentionPolicy:
name: 'keep-last-5'
keepLast: 5
prune: true
Here,
spec.repository
refers to theRepository
objectgcs-repo
that holds backend information.spec.schedule
is a cron expression that indicatesBackupSession
will be created at 5 minute interval.spec.target.ref
refers to thestash-demo
DaemonSet.spec.target.volumeMounts
specifies a list of volumes and their mountPath that contain the target paths.spec.target.paths
specifies list of file paths to backup.
Let’s create the BackupConfiguration
crd we have shown above,
$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.10.9/docs/guides/workloads/daemonset/examples/backupconfiguration.yaml
backupconfiguration.stash.appscode.com/dmn-backup created
Verify Backup Setup Successful
If everything goes well, the phase of the BackupConfiguration
should be Ready
. The Ready
phase indicates that the backup setup is successful. Let’s verify the Phase
of the BackupConfiguration,
$ kubectl get backupconfiguration -n demo
NAME TASK SCHEDULE PAUSED PHASE AGE
dmn-backup */5 * * * * Ready 11s
Verify Sidecar:
Stash will inject a sidecar container into the stash-demo
DaemonSet to take backup of /source/data
directory. Let’s check that the sidecar has been injected successfully,
$ kubectl get pod -n demo
NAME READY STATUS RESTARTS AGE
stash-demo-6lnbp 2/2 Running 0 10s
Look at the pod. It now has 2 containers. If you view the resource definition of this pod, you will see that there is a container named stash
which is running run-backup
command.
$ kubectl get pod -n demo stash-demo-6lnbp -o yaml
apiVersion: v1
kind: Pod
metadata:
name: stash-demo-6lnbp
namespace: demo
...
spec:
containers:
- args:
- echo sample_data > /source/data/data.txt && sleep 3000
command:
- /bin/sh
- -c
image: busybox
imagePullPolicy: IfNotPresent
name: busybox
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
volumeMounts:
- mountPath: /source/data
name: source-data
- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
name: default-token-4tzgg
readOnly: true
- args:
- run-backup
- --backup-configuration=dmn-backup
- --secret-dir=/etc/stash/repository/secret
- --enable-cache=true
- --max-connections=0
- --metrics-enabled=true
- --pushgateway-url=http://stash-operator.kube-system.svc:56789
- --enable-status-subresource=true
- --use-kubeapiserver-fqdn-for-aks=true
- --logtostderr=true
- --alsologtostderr=false
- --v=3
- --stderrthreshold=0
env:
- name: NODE_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.nodeName
- name: POD_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.name
name: stash
volumeMounts:
- mountPath: /etc/stash
name: stash-podinfo
- mountPath: /etc/stash/repository/secret
name: stash-secret-volume
- mountPath: /tmp
name: tmp-dir
- mountPath: /source/data
name: source-data
- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
name: default-token-4tzgg
readOnly: true
volumes:
- name: source-data
persistentVolumeClaim:
claimName: stash-sample-data
- emptyDir: {}
name: tmp-dir
- downwardAPI:
defaultMode: 420
items:
- fieldRef:
apiVersion: v1
fieldPath: metadata.labels
path: labels
name: stash-podinfo
- name: stash-secret-volume
secret:
defaultMode: 420
secretName: gcs-secret
- name: default-token-4tzgg
secret:
defaultMode: 420
secretName: default-token-4tzgg
...
...
Verify CronJob:
It will also create a CronJob
with the schedule specified in spec.schedule
field of BackupConfiguration
crd.
Verify that the CronJob
has been created using the following command,
$ kubectl get backupconfiguration -n demo
NAME TASK SCHEDULE PAUSED AGE
dmn-backup */5 * * * * 3m
Wait for BackupSession:
The dmn-backup
CronJob will trigger a backup on each schedule by creating a BackupSession
crd. The sidecar container watches for the BackupSession
crd. When it finds one, it will take backup immediately.
Wait for the next schedule for backup. Run the following command to watch BackupSession
crd,
$ watch -n 3 kubectl get backupsession -n demo
Every 3.0s: kubectl get backupsession -n demo suaas-appscode: Wed Jun 26 16:05:26 2019
NAME INVOKER-TYPE INVOKER-NAME PHASE AGE
dmn-backup-1561543509 BackupConfiguration dmn-backup Succeeded 2m20s
We can see from the above output that the backup session has succeeded. Now, we are going to verify whether the backed up data has been stored in the backend.
Verify Backup:
Once a backup is complete, Stash will update the respective Repository
crd to reflect the backup. Check that the repository gcs-repo
has been updated by the following command,
$ kubectl get repository -n demo
NAME INTEGRITY SIZE SNAPSHOT-COUNT LAST-SUCCESSFUL-BACKUP AGE
gcs-repo true 0 B 3 47s 4m
Now, if we navigate to the GCS bucket, we are going to see backed up data has been stored in source/data/sample-daemonset
directory as specified by spec.backend.gcs.prefix
field of Repository crd.
Note: Stash keeps all the backed up data encrypted. So, data in the backend will not make any sense until they are decrypted.
Restore the Backed up Data
This section will show you how to restore the backed up data from the backend we have taken in the earlier section.
Stop Taking Backup of the Old DaemonSet:
At first, let’s stop taking any further backup of the old DaemonSet so that no backup is taken during the restore process. We are going to pause the BackupConfiguration
that we created to backup the stash-demo
DaemonSet. Then, Stash will stop taking any further backup for this DaemonSet. You can learn more how to pause a scheduled backup here
Let’s pause the dmn-backup
BackupConfiguration,
$ kubectl patch backupconfiguration -n demo dmn-backup --type="merge" --patch='{"spec": {"paused": true}}'
backupconfiguration.stash.appscode.com/dmn-backup patched
Now, wait for a moment. Stash will pause the BackupConfiguration. Verify that the BackupConfiguration has been paused,
$ kubectl get backupconfiguration -n demo
NAME TASK SCHEDULE PAUSED PHASE AGE
dmn-backup */5 * * * * true Ready 26m
Notice the PAUSED
column. Value true
for this field means that the BackupConfiguration has been paused.
Deploy DaemonSet:
We are going to create a new DaemonSet named stash-recovered
and restore the backed up data inside it.
Below is the YAML of the DaemonSet that we are going to create,
apiVersion: apps/v1
kind: DaemonSet
metadata:
labels:
app: stash-recovered
name: stash-recovered
namespace: demo
spec:
selector:
matchLabels:
app: stash-recovered
template:
metadata:
labels:
app: stash-recovered
name: busybox
spec:
containers:
- args:
- sleep
- "3600"
image: busybox
imagePullPolicy: IfNotPresent
name: busybox
volumeMounts:
- mountPath: /source/data
name: source-data
restartPolicy: Always
volumes:
- name: source-data
hostPath:
path: /stash/recovered/data
Let’s create the DaemonSet we have shown above.
$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.10.9/docs/guides/workloads/daemonset/examples/recovered_daemon.yaml
daemonset.apps/stash-recovered configured
Create RestoreSession:
Now, we need to create a RestoreSession
crd targeting the stash-recovered
DaemonSet to restore the backed up data inside it.
Below is the YAML of the RestoreSesion
crd that we are going to create,
apiVersion: stash.appscode.com/v1beta1
kind: RestoreSession
metadata:
name: dmn-restore
namespace: demo
spec:
repository:
name: gcs-repo
target: # target indicates where the recovered data will be stored
ref:
apiVersion: apps/v1
kind: DaemonSet
name: stash-recovered
volumeMounts:
- name: source-data
mountPath: /source/data
rules:
- paths:
- /source/data
Here,
spec.repository.name
specifies theRepository
crd that holds the backend information where our backed up data has been stored.spec.target.ref
refers to the target workload where the recovered data will be stored.spec.target.volumeMounts
specifies a list of volumes and their mountPath where the data will be restored.mountPath
must be samemountPath
as the original volume because Stash stores absolute path of the backed up files. If you use differentmountPath
for the restored volume the backed up files will not be restored into your desired volume.
Let’s create the RestoreSession
crd we have shown above,
$ kubectl apply -f https://github.com/stashed/docs/raw/v2023.10.9/docs/guides/workloads/daemonset/examples/restoresession.yaml
restoresession.stash.appscode.com/dmn-restore created
Once, you have created the RestoreSession
crd, Stash will inject init-container
into stash-recovered
DaemonSet. The pods of this DaemonSet will restart and the init-container
will restore the desired data on start-up.
Verify Init-Container:
Wait until the init-container
has been injected into the stash-recovered
DaemonSet. Let’s describe the DaemonSet to verify that the init-container
has been injected successfully.
$ kubectl describe daemonset -n demo stash-recovered
Name: stash-recovered
Selector: app=stash-recovered
Node-Selector: <none>
Labels: app=stash-recovered
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
...
Pod Template:
Labels: app=stash-recovered
Annotations: stash.appscode.com/last-applied-restoresession-hash: 4703201294184533055
Init Containers:
stash-init:
Image: suaas21/stash:vs_linux_amd64
Port: <none>
Host Port: <none>
Args:
restore
--restore-session=dmn-restore
--secret-dir=/etc/stash/repository/secret
--enable-cache=true
--max-connections=0
--metrics-enabled=true
--pushgateway-url=http://stash-operator.kube-system.svc:56789
--enable-status-subresource=true
--use-kubeapiserver-fqdn-for-aks=true
--logtostderr=true
--alsologtostderr=false
--v=3
--stderrthreshold=0
Environment:
NODE_NAME: (v1:spec.nodeName)
POD_NAME: (v1:metadata.name)
Mounts:
/etc/stash/repository/secret from stash-secret-volume (rw)
/source/data from source-data (rw)
/tmp from tmp-dir (rw)
Containers:
busybox:
Image: busybox
Port: <none>
Host Port: <none>
Args:
sleep
3600
Environment: <none>
Mounts:
/source/data from source-data (rw)
Volumes:
source-data:
Type: HostPath (bare host directory volume)
Path: /stash/recovered/data
HostPathType:
tmp-dir:
Type: EmptyDir (a temporary directory that shares a pod's lifetime)
Medium:
SizeLimit: <unset>
stash-podinfo:
Type: DownwardAPI (a volume populated by information about the pod)
Items:
metadata.labels -> labels
stash-secret-volume:
Type: Secret (a volume populated by a Secret)
SecretName: gcs-secret
Optional: false
...
Notice the Init-Containers
section. We can see that the init-container stash-init
has been injected which is running restore
command.
Wait for RestoreSession to Succeeded:
Run the following command to watch RestoreSession phase,
$ watch -n 3 kubectl get restoresession -n demo
Every 3.0s: kubectl get restoresession -n demo suaas-appscode: Wed Jun 26 14:28:29 2019
NAME REPOSITORY-NAME PHASE AGE
dmn-restore gcs-repo Succeeded 3m29s
So, we can see from the output of the above command that the restore process succeeded.
Note: If you want to restore the backed up data inside the same DaemonSet whose volumes were backed up, you have to remove the corrupted data from the DaemonSet. Then, you have to create a RestoreSession targeting the DaemonSet.
Verify Restored Data:
In this section, we are going to verify that the desired data has been restored successfully.
At first, check if the stash-recovered
pods of a DaemonSet has gone into running
state by the following command,
$ kubectl get pod -n demo
NAME READY STATUS RESTARTS AGE
stash-recovered-dqlrb 1/1 Running 0 4m4s
Verify that the backed up data has been restored in /source/data
directory of the stash-recovered
pods of a DaemonSet using the following command,
$ kubectl exec -n demo stash-recovered-dqlrb -- cat /source/data/data.txt
sample_data
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete -n demo daemonset stash-demo
kubectl delete -n demo daemonset stash-recovered
kubectl delete -n demo backupconfiguration dmn-backup
kubectl delete -n demo restoresession dmn-restore
kubectl delete -n demo repository gcs-repo
kubectl delete -n demo pvc --all