Using libguestfs over HTTP (and FTP)

New in libguestfs upstream and 1.21.39 is the ability to access disks over FTP, FTPS, HTTP, HTTPS and TFTP (read-only).

You can use it like this:

$ export LIBGUESTFS_BACKEND=direct
$ guestfish --ro -a http://x.x.x.x/scratch/winxp.img -i

Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.

Type: 'help' for help on commands
      'man' to read the manual
      'quit' to quit the shell

Operating system: Microsoft Windows XP
/dev/sda1 mounted on /

><fs> ll /
total 1573209
drwxrwxrwx  1 root root       4096 Apr 16  2012 .
drwxr-xr-x 23 1000 1000       4096 May 11 18:45 ..
-rwxrwxrwx  1 root root          0 Oct 11  2011 AUTOEXEC.BAT
-rwxrwxrwx  1 root root          0 Oct 11  2011 CONFIG.SYS
drwxrwxrwx  1 root root       4096 Oct 11  2011 Documents and Settings
-rwxrwxrwx  1 root root          0 Oct 11  2011 IO.SYS
-rwxrwxrwx  1 root root          0 Oct 11  2011 MSDOS.SYS
-rwxrwxrwx  1 root root      47564 Apr 14  2008 NTDETECT.COM
drwxrwxrwx  1 root root       4096 Oct 11  2011 Program Files
drwxrwxrwx  1 root root       4096 Oct 11  2011 System Volume Information
drwxrwxrwx  1 root root      28672 Oct 11  2011 WINDOWS
-rwxrwxrwx  1 root root        211 Oct 11  2011 boot.ini
-rwxrwxrwx  1 root root     250048 Apr 14  2008 ntldr
-rwxrwxrwx  1 root root 1610612736 Oct 11  2011 pagefile.sys

Apart from being a tiny bit slower, it just works as if the disk was local.

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3 Comments

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3 responses to “Using libguestfs over HTTP (and FTP)

  1. Conrad

    Presumably, this only works well on HTTP servers that support byte range queries?

    • rich

      Probably. It’s implemented using curl, so it does whatever curl does. Is there a web server which doesn’t implement byte ranges?

      • Conrad

        Sadly, there are “security” middleboxes acting as semi-transparent proxies that stomp on byte-ranges. My employer uses one of these. I found out by trying to use aria2c to grab Fedora install disks =).

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