Can someone point me in the direction as to how I can attach multiple ext4 filesystems to the same EBS volume in a Cloudformation template?
Should I use AWS::Cloudformation::Init to run commands?
For a running instance, you can use AWS::EC2::VolumeAttachment to:
Attaches an Amazon EBS volume to a running instance and exposes it to the instance with the specified device name.
Obviously, attaching the volume is the first step. If its brand new volume, you have to format it and mount from inside the instance.
For a new instance created using CFN, you can AWS::Cloudformation::Init or User Data to run commands to mount and/or format the volumes.
Related
I am migrating my previous deployment made with docker-compose to Kubernetes.
In my previous deployment, some containers do have some data made at build time in some paths and these paths are mounted in persistent volumes.
Therefore, as the Docker volume documentation states,the persistent volume (not a bind mount) will be pre-populated with the container directory content.
I'd like to achieve this behavior with Kubernetes and its persistent volumes, How can I do ? Do I need to add some kind of logic using scripts in order to copy my container's files to the mounted path when data is not present the first time the container starts ?
Possibly related question: Kubernetes mount volume on existing directory with files inside the container
I think your options are
ConfigMap (are "some data" configuration files?)
Init containers (as mentioned)
CSI Volume Cloning (clone combining an init or your first app container)
there used to be a gitRepo; deprecated in favour of init containers where you can clone your config and data from
HostPath volume mount is an option too
An NFS volume is probably a very reasonable option and similar from an approach point of view to your Docker Volumes
Storage type: NFS, iscsi, awsElasticBlockStore, gcePersistentDisk and others can be pre-populated. There are constraints. NFS probably the most flexible for sharing bits & bytes.
FYI
The subPath might be of interest too depending on your use case and
PodPreset might help in streamlining the op across the fleet of your pods
HTH
I'm having trouble understanding where to store files in a GKE container? I've seen the following documentation of the filesystem layout:
https://cloud.google.com/kubernetes-engine/docs/concepts/node-images#file_system_layout
But then there are also Dockerfile examples on the web that copy executable files to other paths not listed in the layout, such as /usr or /go. One of these examples is here:
https://github.com/GoogleCloudPlatform/kubernetes-engine-samples/blob/master/hello-app/Dockerfile
Another question is: If I have runtime code that needs to download certain configuration information after the container starts, can I write the configuration file to the same directory as my executable? Or do I have to choose /etc or /tmp.
And finally, the layout documentation states that /home and /var store data for the the lifetime of the boot disk? What does that mean? How does that compare to the lifetime of the pod or the node?
When you want to store something in a container you can either store something ephemeral or permanent
To store ephemeral way just choose a path /tmp, /var, /opt etc (this depends on the container set up as well), once the container is restarted the information you would have is the same at the moment the container was created, for instance your binary files and initial config files.
To store permanent you must have to mount a volume, this is a support for your container where a volume (container path) is linked with a external storage. with this if your container is restarted the volume will be mounted once the container is ready again and you are no gonna lose anything.
In kubernetes this is called Persistent Volumes and you can leverage this even if you are in another cloud provider,
steps to used
Define a path where you would mount the volume in your source code example /myfiles/private
Create a storage class in your GKE https://cloud.google.com/kubernetes-engine/docs/how-to/persistent-volumes/ssd-pd
Create a Persistent Volume Claim in your GKE https://cloud.google.com/kubernetes-engine/docs/how-to/persistent-volumes/ssd-pd
Relate this storage class with your Kubernetes deployment
Example
link the volume with your container
volumeMounts:
- mountPath: /myfiles/private
name: any-name-you-want
relate the persistent volume with your deployment
volumes:
- name: any-name-you-want
persistentVolumeClaim:
claimName: my-claim-name
This is really up to you. By default most base images will leave /tmp writeable as per normal. But anything written inside the container will be gone if/when the container restarts for any reason. For something like config data, that might be fine, for a database probably less so. To get more stable storage you need to use a Volume. The exact type to use depends on your environment and how long the data should live. An emptyDir volume lives only as long as the pod but can be shared between containers in the same pod. Beyond that you would probably use a PersistentVolumeClaim to dynamically provision a new Google Cloud disk which will last unless the claim is deleted (or forever depending on your Reclaim setting).
I have node on google kubernetes engine using persistent volume. Is possible edit files on this volume from gcloud, or google cloud shell? For example edit config and recreate node? Or it is only posiible from running pod using kubectl exec?
i think you can have a look to gsutil command it allows you to interact with your buckets .
Guide to Gsutil
The volume would be a block device, so I’d expect it’d not be possible to edit it outside of the pod it’s attached to. So yes, expecting into the pod would do it, but you could also just use kubectl cp to copy files (and directories!) directly from your local machine onto the volume, mounted to the pod.
Here’s the relevant doc:
https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#cp
There are 5 containers in my pod in kubernetes deployment. I want to transfer files from 1 container to another container.
How to go about this?
The most common approach to this would be to use EmptyDir volume, run an initContainer that will spin up the image you want to copy from, mount target volume in it and perform the copy, before the actual containers forming your pod runtime will take the same volume and mount it for their use.
If you need to run the copy (transfer) operation during actual operation then you should mount a shared volume (most likely EmptyDir as well) on both containers and just use it as a shared storage space.
You can do that by using shared volume.
Follow this
In a cloud , we have a cluster of glusterfs nodes (participating in gluster volume) and clients (that mount to gluster volumes). These nodes are created using terraform hashicorp tool.
Once the cluster is up and running, if we want to change the gluster machine configuration like increasing the compute size from 4 cpus to 8 cpus , terraform has the provision to recreate the nodes with new configuration.So the existing gluster nodes are destroyed and new instances are created but with the same ip. In the newly created instance , volume creation command fails saying brick is already part of volume.
sudo gluster volume create VolName replica 2 transport tcp ip1:/mnt/ppshare/brick0 ip2:/mnt/ppshare/brick0
volume create: VolName: failed: /mnt/ppshare/brick0 is already part
of a volume
But no volumes are present in this instance.
I understand if I have to expand or shrink volume, I can add or remove bricks from existing volume. Here, I'm changing the compute of the node and hence it has to be recreated. I don't understand why it should say brick is already part of volume as it is a new machine altogether.
It would be very helpful if someone can explain why it says Brick is already part of volume and where it is storing the volume/brick information. So that I can recreate the volume successfully.
I also tried the below steps from this link to clear the glusterfs volume related attributes from the mount but no luck.
https://linuxsysadm.wordpress.com/2013/05/16/glusterfs-remove-extended-attributes-to-completely-remove-bricks/.
apt-get install attr
cd /glusterfs
for i in attr -lq .; do setfattr -x trusted.$i .; done
attr -lq /glusterfs (for testing, the output should pe empty)
Simply put "force" in the end of "gluster volume create ..." command.
Please check if you have directories /mnt/ppshare/brick0 created.
You should have /mnt/ppshare without the brick0 folder. The create command creates those folders. The error indicates that the brick0 folders are present.