[Gluster-devel] [Heketi] Block store related API design discussion
Niels de Vos
ndevos at redhat.com
Mon Sep 19 04:43:04 UTC 2016
On Tue, Sep 13, 2016 at 12:06:00PM -0400, Luis Pabón wrote:
> Very good points. Thanks Prasanna for putting this together. I agree with
> your comments in that Heketi is the high level abstraction API and it should have
> an API similar of what is described by Prasanna.
>
> I definitely do not think any File Api should be available in Heketi,
> because that is an implementation of the Block API. The Heketi API should
> be similar to something like OpenStack Cinder.
>
> I think that the actual management of the Volumes used for Block storage
> and the files in them should be all managed by Heketi. How they are
> actually created is still to be determined, but we could have Heketi
> create them, or have helper programs do that.
Maybe a tool like qemu-img? If whatever iscsi service understand the
format (at the very least 'raw'), you could get functionality like
snapshots pretty simple.
Niels
> We also need to document the exact workflow to enable a file in
> a Gluster volume to be exposed as a block device. This will help
> determine where the creation of the file could take place.
>
> We can capture our decisions from these discussions in the
> following page:
>
> https://github.com/heketi/heketi/wiki/Proposed-Changes
>
> - Luis
>
>
> ----- Original Message -----
> From: "Humble Chirammal" <hchiramm at redhat.com>
> To: "Raghavendra Talur" <rtalur at redhat.com>
> Cc: "Prasanna Kalever" <pkalever at redhat.com>, "gluster-devel" <gluster-devel at gluster.org>, "Stephen Watt" <swatt at redhat.com>, "Luis Pabon" <lpabon at redhat.com>, "Michael Adam" <madam at redhat.com>, "Ramakrishna Yekulla" <rreddy at redhat.com>, "Mohamed Ashiq Liyazudeen" <mliyazud at redhat.com>
> Sent: Tuesday, September 13, 2016 2:23:39 AM
> Subject: Re: [Gluster-devel] [Heketi] Block store related API design discussion
>
>
>
>
>
> ----- Original Message -----
> | From: "Raghavendra Talur" <rtalur at redhat.com>
> | To: "Prasanna Kalever" <pkalever at redhat.com>
> | Cc: "gluster-devel" <gluster-devel at gluster.org>, "Stephen Watt" <swatt at redhat.com>, "Luis Pabon" <lpabon at redhat.com>,
> | "Michael Adam" <madam at redhat.com>, "Humble Chirammal" <hchiramm at redhat.com>, "Ramakrishna Yekulla"
> | <rreddy at redhat.com>, "Mohamed Ashiq Liyazudeen" <mliyazud at redhat.com>
> | Sent: Tuesday, September 13, 2016 11:08:44 AM
> | Subject: Re: [Gluster-devel] [Heketi] Block store related API design discussion
> |
> | On Mon, Sep 12, 2016 at 11:30 PM, Prasanna Kalever <pkalever at redhat.com>
> | wrote:
> |
> | > Hi all,
> | >
> | > This mail is open for discussion on gluster block store integration with
> | > heketi and its REST API interface design constraints.
> | >
> | >
> | > ___ Volume Request ...
> | > |
> | > |
> | > PVC claim -> Heketi --->|
> | > |
> | > |
> | > |
> | > |
> | > | __ BlockCreate
> | > | |
> | > | |__ BlockInfo
> | > | |
> | > |___ Block Request (APIS)-> |__ BlockResize
> | > |
> | > |__ BlockList
> | > |
> | > |__ BlockDelete
> | >
> | > Heketi will have block API and volume API, when user submit a Persistent
> | > volume claim, Kubernetes provisioner based on the storage class(from PVC)
> | > talks to heketi for storage, heketi intern calls block or volume API's
> | > based on request.
> | >
> |
> | This is probably wrong. It won't be Heketi calling block or volume APIs. It
> | would be Kubernetes calling block or volume API *of* Heketi.
> |
> |
> | > With my limited understanding, heketi currently creates clusters from
> | > provided nodes, creates volumes and handover them to the user.
> | > For block related API's, it has to deal with files right ?
> | >
> | > Here is how block API's look like in short-
> | > Create: heketi has to create file in the volume and export it as a iscsi
> | > target device and hand it over to user.
> | > Info: show block stores information across all the clusters, connection
> | > info, size etc.
> | > resize: resize the file in the volume, refresh connections from initiator
> | > side
> | > List: List the connections
> | > Delete: logout the connections and delete the file in the gluster volume
> | >
> | > Couple of questions:
> | > 1. Should Block API have sub API's such as FileCreate, FileList,
> | > FileResize, File delete and etc then get it used in Block API as they
> | > mostly deal with files.
> | >
> |
> | IMO, Heketi should not expose any File related API. It should only have
> | APIs to service request for block devices; how the block devices are
> | created and modified is an implementation detail.
> |
> |
> | > 2. How do we create the actual file in the volume, meaning using FUSE
> | > mount (which may involve an extra process running) or gfapi, again if gfapi
> | > should we go with c API's, python bindings or go bindings ?
> | >
> | 3. Should we get targetcli related (LUN exporting) setup done from heketi
> | > or do we seek help from gdeploy for this ?
> | >
> |
> | I would prefer to either have it in Heketi or in Kubernetes. If the API in
> | Heketi promises just the creation of block device, then the rest of the
> | implementation should be in Kubernetes(the export part). If the API in
> | Heketi promises create and export both, I would say Heketi should have the
> | implementation within itself.
> |
> |
>
> IMO, we should not think about how the clients ( ex: k8s) use it, because there may be different clients.
> We should concentrate mainly on 'in/out' of block API in Heketi. Regardless of which client, the API should act the same way.
>
> --Humble
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