[Gluster-devel] [Heketi] Block store related API design discussion
Pranith Kumar Karampuri
pkarampu at redhat.com
Tue Sep 20 09:50:09 UTC 2016
On Mon, Sep 19, 2016 at 10:13 AM, Niels de Vos <ndevos at redhat.com> wrote:
> 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.
>
Prasanna, Poornima and I just discussed about this. Prasanna is doing this
experiment to see if we can use qcow from tcmu-runner to get this piece
working. If yes, we definitely will get snapshots for free :-). Prasanna
will confirm it based on his experiments.
>
> 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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> > Gluster-devel at gluster.org
> > http://www.gluster.org/mailman/listinfo/gluster-devel
>
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--
Pranith
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