Re: [pbs-devel] [PATCH proxmox-backup v12 12/26] add auto-mounting for removable datastores

["Hannes Laimer" <h.laimer@proxmox.com>]

On Mon Oct 14, 2024 at 3:42 PM CEST, Fabian Grünbichler wrote:
> On September 4, 2024 4:11 pm, Hannes Laimer wrote:
> > Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
> > ---
> >  debian/proxmox-backup-server.install        |  1 +
> >  debian/proxmox-backup-server.udev           |  3 ++
> >  etc/Makefile                                |  3 +-
> >  etc/removable-device-attach@.service.in     |  8 +++
> >  src/bin/proxmox_backup_manager/datastore.rs | 55 ++++++++++++++++++++-
> >  5 files changed, 68 insertions(+), 2 deletions(-)
> >  create mode 100644 etc/removable-device-attach@.service.in
> > 
> > diff --git a/debian/proxmox-backup-server.install b/debian/proxmox-backup-server.install
> > index ef1e9ba1..34bfc454 100644
> > --- a/debian/proxmox-backup-server.install
> > +++ b/debian/proxmox-backup-server.install
> > @@ -4,6 +4,7 @@ etc/proxmox-backup-daily-update.service /lib/systemd/system/
> >  etc/proxmox-backup-daily-update.timer /lib/systemd/system/
> >  etc/proxmox-backup-proxy.service /lib/systemd/system/
> >  etc/proxmox-backup.service /lib/systemd/system/
> > +etc/removable-device-attach@.service /lib/systemd/system/
> >  usr/bin/pmt
> >  usr/bin/pmtx
> >  usr/bin/proxmox-tape
> > diff --git a/debian/proxmox-backup-server.udev b/debian/proxmox-backup-server.udev
> > index afdfb2bc..e21b8bc7 100644
> > --- a/debian/proxmox-backup-server.udev
> > +++ b/debian/proxmox-backup-server.udev
> > @@ -16,3 +16,6 @@ SUBSYSTEM=="scsi_generic", SUBSYSTEMS=="scsi", ATTRS{type}=="1", ENV{ID_SCSI_SER
> >    SYMLINK+="tape/by-id/scsi-$env{ID_SCSI_SERIAL}-sg"
> >  
> >  LABEL="persistent_storage_tape_end"
> > +
> > +# triggers the mounting of a removable device
> > +ACTION=="add", SUBSYSTEM=="block", ENV{ID_FS_UUID}!="", TAG+="systemd", ENV{SYSTEMD_WANTS}="removable-device-attach@$env{ID_FS_UUID}"
>
> so this adds a Wants on our new unit for all block devices with an FS
> UUID set?
>

yes, there is not really another way to do this. At least I couldn't
come up with one, I'm open to suggestions tough

> > \ No newline at end of file
> > diff --git a/etc/Makefile b/etc/Makefile
> > index 42f639f6..730de4f8 100644
> > --- a/etc/Makefile
> > +++ b/etc/Makefile
> > @@ -7,7 +7,8 @@ DYNAMIC_UNITS := \
> >  	proxmox-backup-banner.service \
> >  	proxmox-backup-daily-update.service \
> >  	proxmox-backup.service \
> > -	proxmox-backup-proxy.service
> > +	proxmox-backup-proxy.service \
> > +	removable-device-attach@.service
> >  
> >  all: $(UNITS) $(DYNAMIC_UNITS) pbs-enterprise.list
> >  
> > diff --git a/etc/removable-device-attach@.service.in b/etc/removable-device-attach@.service.in
> > new file mode 100644
> > index 00000000..e10d1ea3
> > --- /dev/null
> > +++ b/etc/removable-device-attach@.service.in
>
> why is this `.in` / a dynamic unit?
>

This is mostly because I wasn't sure where else to put it, where should
it be/would you put it?

> > @@ -0,0 +1,8 @@
> > +[Unit]
> > +Description=Try to mount the removable device of a datastore with uuid '%i'.
> > +After=proxmox-backup-proxy.service
> > +Requires=proxmox-backup-proxy.service
> > +
> > +[Service]
> > +Type=simple
> > +ExecStart=/usr/sbin/proxmox-backup-manager datastore uuid-mount %i
>
> does this really need to be a custom command?
>

Is there a good alternative? It does use the normal mount endpoint after
finding tge datastore(s), the UUID belongs to.

Actually, it only mounts the first, I feel like this is not what we
want. Either none or all? I'm actually not sure what we want here.

> > diff --git a/src/bin/proxmox_backup_manager/datastore.rs b/src/bin/proxmox_backup_manager/datastore.rs
> > index f2795b39..e74c8537 100644
> > --- a/src/bin/proxmox_backup_manager/datastore.rs
> > +++ b/src/bin/proxmox_backup_manager/datastore.rs
> > @@ -1,4 +1,4 @@
> > -use anyhow::{format_err, Error};
> > +use anyhow::{bail, format_err, Error};
> >  use serde_json::Value;
> >  
> >  use proxmox_router::{cli::*, ApiHandler, RpcEnvironment};
> > @@ -195,6 +195,55 @@ async fn delete_datastore(mut param: Value, rpcenv: &mut dyn RpcEnvironment) ->
> >      Ok(())
> >  }
> >  
> > +#[api(
> > +    protected: true,
> > +    input: {
> > +        properties: {
> > +            uuid: {
> > +                type: String,
> > +                description: "The UUID of the device that should be mounted",
> > +            },
> > +            "output-format": {
> > +                schema: OUTPUT_FORMAT,
> > +                optional: true,
> > +            },
> > +        },
> > +    },
> > +)]
> > +/// Try mounting a removable datastore given the UUID.
> > +async fn uuid_mount(param: Value, rpcenv: &mut dyn RpcEnvironment) -> Result<Value, Error> {
> > +    let uuid = param["uuid"]
> > +        .as_str()
> > +        .ok_or_else(|| format_err!("uuid has to be specified"))?;
> > +
> > +    let info = &api2::config::datastore::API_METHOD_LIST_DATASTORES;
> > +    let data: Value = match info.handler {
> > +        ApiHandler::Sync(handler) => (handler)(serde_json::json!({}), info, rpcenv)?,
> > +        _ => unreachable!(),
> > +    };
> > +
> > +    let store_name = data.as_array().and_then(|list| {
> > +        list.iter()
> > +            .filter_map(Value::as_object)
> > +            .find(|store| store.get("backing-device").map_or(false, |d| d.eq(&uuid)))
> > +            .and_then(|s| s.get("name").and_then(Value::as_str))
> > +    });
>
> wouldn't it be easier to just call
>
> let config = pbs_config::datastore::config()?;
> if let Some(store) = config.convert_to_typed_array("datastore")?.into_iter().find(...) {
>     ... store.name

well, yes :)

> }
>
> if we stay with this approach?
>
> > +
> > +    if let Some(store_name) = store_name {
> > +        let info = &api2::admin::datastore::API_METHOD_MOUNT;
> > +        let mount_param = serde_json::json!({
> > +            "store": store_name,
> > +        });
> > +        let result = match info.handler {
> > +            ApiHandler::Sync(handler) => (handler)(mount_param, info, rpcenv)?,
> > +            _ => unreachable!(),
> > +        };
> > +        crate::wait_for_local_worker(result.as_str().unwrap()).await?;
> > +        return Ok(Value::Null);
> > +    }
> > +    bail!("'{uuid}' is not associated with any datastore")
>
> if this triggers for all block devices, isn't it kinda noisy? or am I
> missing some point where additional filtering takes place..
>

it is, relatively, depending on how often things are plugged in. It might
make sense to drop this logging (before having found a matching ds) all together?

> > +}
> > +
> >  pub fn datastore_commands() -> CommandLineInterface {
> >      let cmd_def = CliCommandMap::new()
> >          .insert("list", CliCommand::new(&API_METHOD_LIST_DATASTORES))
> > @@ -240,6 +289,10 @@ pub fn datastore_commands() -> CommandLineInterface {
> >                      pbs_config::datastore::complete_calendar_event,
> >                  ),
> >          )
> > +        .insert(
> > +            "uuid-mount",
> > +            CliCommand::new(&API_METHOD_UUID_MOUNT).arg_param(&["uuid"]),
> > +        )
> >          .insert(
> >              "remove",
> >              CliCommand::new(&API_METHOD_DELETE_DATASTORE)
> > -- 
> > 2.39.2
> > 
> > 
> > 
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> > 
> > 
> > 
>
>
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