[[!meta title="arbitrary/configurable backends"]] (Retitling as this has drifted..) --- I thought this might be useful, since curl is being used for the URL backend, it might be worth checking for it's existence.
diff --git a/configure.hs b/configure.hs
index 772ba54..1a563e0 100644
--- a/configure.hs
+++ b/configure.hs
@@ -13,6 +13,7 @@ tests = [
        , TestCase "uuid generator" $ selectCmd "uuid" ["uuid", "uuidgen"]
        , TestCase "xargs -0" $ requireCmd "xargs_0" "xargs -0 /dev/null"
+       , TestCase "curl" $ requireCmd "curl" "curl --version >/dev/null"
        , TestCase "unicode FilePath support" $ unicodeFilePath
        ] ++ shaTestCases [1, 256, 512, 224, 384]
> Well, curl is an optional extra, so requireCmd is too strong. Changed > to testCmd and applied, thank you! > > I thought about actually *using* the resulting SysConfig.curl > to disable the URL backend if False.. but probably it's better > to just let it fail if curl is not available. Although, if we wanted > to add a check for wget or something and use it when curl was not > available, that might be worth doing. --[[Joey]] >> I was thinking that is it worth doing a generic "stat", "delete", "get" >> and "put" options, I do like the idea of having the possibility of >> being about to use completely arbitrary storage systems or arbitrary >> transfer systems. If there was the capability of doing so it would be >> interesting to see possibilities of using aria2 for using something >> like bittorrent as backend, or using something like irods or some >> grid storage system as the storage archive. It's just an idea as >> I have seen it implemented quite well in irods. >>> I'm unsure about the idea of having a backend where that is >>> parameterized. It would mean that one annex's GENERIC-foo key >>> might be entirely different from another's key with the same backend >>> and details. And a misconfiguration could get data the wrong >>> way and get the wrong data, etc. >>> >>> I mostly look at the URL backend as an example that can be modified to >>> make this kind of custom backend. You already probably know enough to >>> make a TORRENT backend where keys are the urls to torrents to download >>> with `aria2c --follow-torrent=mem`. >>> >>> I am also interested in doing backends that use eg, cloud storage. >>> A S3 backend that could upload files to S3 in addition to downloading >>> them, for example, would be handy. --[[Joey]] also in Backend/URL.hs is it worth making a minor change to the way curl is called (I'm not sure if the following is correct or not) > It's correct, typewise, but I don't see any real reason to bother > with the change. But I do appreciate patches, which have been rare > so far, probaby because of Haskell.. :) --[[Joey]] >> heh agreed
diff --git a/Backend/URL.hs b/Backend/URL.hs
index 29dc8fe..4afcf86 100644
--- a/Backend/URL.hs
+++ b/Backend/URL.hs
@@ -50,10 +50,13 @@ dummyFsck _ _ _ = return True
 dummyOk :: Key -> Annex Bool
 dummyOk _ = return True
 
+curl :: [CommandParam] -> IO Bool
+curl = boolSystem "curl"
+
 downloadUrl :: Key -> FilePath -> Annex Bool
 downloadUrl key file = do
        showNote "downloading"
        showProgress -- make way for curl progress bar
-       liftIO $ boolSystem "curl" [Params "-# -o", File file, File url]
+       liftIO $ curl [Params "-# -o", File file, File url]
        where
                url = join ":" $ drop 1 $ split ":" $ show key