187 lines
6 KiB
Markdown
187 lines
6 KiB
Markdown
# CSI for S3
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This is a Container Storage Interface ([CSI](https://github.com/container-storage-interface/spec/blob/master/spec.md)) for S3 (or S3 compatible) storage. This can dynamically allocate buckets and mount them via a fuse mount into any container.
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## Kubernetes installation
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### Requirements
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* Kubernetes 1.17+
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* Kubernetes has to allow privileged containers
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* Docker daemon must allow shared mounts (systemd flag `MountFlags=shared`)
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### 1. Create a secret with your S3 credentials
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```yaml
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apiVersion: v1
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kind: Secret
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metadata:
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name: csi-s3-secret
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# Namespace depends on the configuration in the storageclass.yaml
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namespace: kube-system
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stringData:
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accessKeyID: <YOUR_ACCESS_KEY_ID>
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secretAccessKey: <YOUR_SECRET_ACCESS_KEY>
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# For AWS set it to "https://s3.<region>.amazonaws.com", for example https://s3.eu-central-1.amazonaws.com
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endpoint: https://storage.yandexcloud.net
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# For AWS set it to AWS region
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#region: ""
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# For S3-compatible set it to bucket lookup style (choices: Auto [default], DNS, Path)
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#bucketLookup: ""
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```
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The region can be empty if you are using some other S3 compatible storage.
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### 2. Deploy the driver
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```bash
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cd deploy/kubernetes
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kubectl create -f provisioner.yaml
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kubectl create -f attacher.yaml
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kubectl create -f csi-s3.yaml
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```
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### 3. Create the storage class
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```bash
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kubectl create -f examples/storageclass.yaml
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```
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### 4. Test the S3 driver
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1. Create a pvc using the new storage class:
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```bash
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kubectl create -f examples/pvc.yaml
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```
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1. Check if the PVC has been bound:
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```bash
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$ kubectl get pvc csi-s3-pvc
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NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
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csi-s3-pvc Bound pvc-c5d4634f-8507-11e8-9f33-0e243832354b 5Gi RWO csi-s3 9s
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```
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1. Create a test pod which mounts your volume:
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```bash
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kubectl create -f examples/pod.yaml
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```
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If the pod can start, everything should be working.
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1. Test the mount
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```bash
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$ kubectl exec -ti csi-s3-test-nginx bash
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$ mount | grep fuse
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s3fs on /var/lib/www/html type fuse.s3fs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other)
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$ touch /var/lib/www/html/hello_world
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```
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If something does not work as expected, check the troubleshooting section below.
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## Additional configuration
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### Bucket
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By default, csi-s3 will create a new bucket per volume. The bucket name will match that of the volume ID. If you want your volumes to live in a precreated bucket, you can simply specify the bucket in the storage class parameters:
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```yaml
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kind: StorageClass
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apiVersion: storage.k8s.io/v1
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metadata:
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name: csi-s3-existing-bucket
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provisioner: ru.yandex.s3.csi
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parameters:
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mounter: geesefs
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options: "--memory-limit 1000 --dir-mode 0777 --file-mode 0666"
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bucket: some-existing-bucket-name
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```
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If the bucket is specified, it will still be created if it does not exist on the backend. Every volume will get its own prefix within the bucket which matches the volume ID. When deleting a volume, also just the prefix will be deleted.
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### Static Provisioning
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If you want to mount a pre-existing bucket or prefix within a pre-existing bucket and don't want csi-s3 to delete it when PV is deleted, you can use static provisioning.
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To do that you should omit `storageClassName` in the `PersistentVolumeClaim` and manually create a `PersistentVolume` with a matching `claimRef`, like in the following example: [deploy/kubernetes/examples/pvc-manual.yaml](deploy/kubernetes/examples/pvc-manual.yaml).
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### Mounter
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We **strongly recommend** to use the default mounter which is [GeeseFS](https://github.com/yandex-cloud/geesefs).
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However there is also support for two other backends: [s3fs](https://github.com/s3fs-fuse/s3fs-fuse) and [rclone](https://rclone.org/commands/rclone_mount).
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The mounter can be set as a parameter in the storage class. You can also create multiple storage classes for each mounter if you like.
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As S3 is not a real file system there are some limitations to consider here.
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Depending on what mounter you are using, you will have different levels of POSIX compability.
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Also depending on what S3 storage backend you are using there are not always [consistency guarantees](https://github.com/gaul/are-we-consistent-yet#observed-consistency).
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You can check POSIX compatibility matrix here: https://github.com/yandex-cloud/geesefs#posix-compatibility-matrix.
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#### GeeseFS
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* Almost full POSIX compatibility
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* Good performance for both small and big files
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* Does not store file permissions and custom modification times
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* By default runs **outside** of the csi-s3 container using systemd, to not crash
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mountpoints with "Transport endpoint is not connected" when csi-s3 is upgraded
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or restarted. Add `--no-systemd` to `parameters.options` of the `StorageClass`
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to disable this behaviour.
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#### s3fs
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* Almost full POSIX compatibility
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* Good performance for big files, poor performance for small files
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* Very slow for directories with a large number of files
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#### rclone
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* Poor POSIX compatibility
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* Bad performance for big files, okayish performance for small files
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* Doesn't create directory objects like s3fs or GeeseFS
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* May hang :-)
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## Troubleshooting
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### Issues while creating PVC
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Check the logs of the provisioner:
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```bash
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kubectl logs -l app=csi-provisioner-s3 -c csi-s3
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```
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### Issues creating containers
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1. Ensure feature gate `MountPropagation` is not set to `false`
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2. Check the logs of the s3-driver:
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```bash
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kubectl logs -l app=csi-s3 -c csi-s3
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```
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## Development
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This project can be built like any other go application.
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```bash
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go get -u github.com/yandex-cloud/k8s-csi-s3
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```
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### Build executable
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```bash
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make build
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```
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### Tests
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Currently the driver is tested by the [CSI Sanity Tester](https://github.com/kubernetes-csi/csi-test/tree/master/pkg/sanity). As end-to-end tests require S3 storage and a mounter like s3fs, this is best done in a docker container. A Dockerfile and the test script are in the `test` directory. The easiest way to run the tests is to just use the make command:
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```bash
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make test
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```
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