Question/Request: Directory for data that should persist over updates.

Jamie Strandboge jamie at
Thu Jan 28 18:12:19 UTC 2016

On Thu, 2016-01-28 at 14:33 +0000, John Lenton wrote:
> On 28 January 2016 at 13:44, Lefteris Karapetsas <lefteris at>
> wrote:
> > 
> > Some snaps, including mine need to store some data, a database
> > let's
> > say, or in my case a whole blockchain. So far I was instructed to
> > do
> > that at $SNAP_APP_DATA_PATH. This works fine for now but whenever
> > the user updates the snap from what I understand this whole
> > directory will be copied into the next version's directory, to
> > enable the transaction updating and rollback nature of Snappy
> > Ubuntu.
> > 
> > This is not going to work for my snap and I need to ask if there is
> > any directory where I can store data for the application that will
> > persist over any update. If not then this is something that really
> > should be added at some point since I suppose many snaps will need
> > to utilize behaviour like this.
> Right now there isn't a way to do this, but we do want to do
> something
> like this for 16.04. We still haven't decided whether it'll be a
> separate directory (and associated environment variable), or whether
> it'll be a fixed directory under $SNAP_DATA (and $SNAP_USER_DATA).
Currently SNAP_DATA and SNAP_USER_DATA are versioned, so putting it as
a fixed directory there is possible but likely messy. Unless I'm
missing some important details, it seems a separate directory and
envvar is the cleanest.

> We'll let you know via this mailing list when there's something ready
> for testing.
> Thanks,
Jamie Strandboge             |

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