jorgenmodin.net - Blog
I guess these are something like that (untested):
- Google protocol buffers Protocol Buffers | Google Developers
- Cap'n proto Cap'n Proto: Introduction
- Hessian Hessian Binary Web Service Protocol
- BERT and BERT-RPC 1.0 Specification
- Universal Binary Format ⨪ UBF 2.2 User’s Guide
- Apache Thrift
Put just a pipe character on the first line:
Then add the string, indented on the following lines:
foo: | bar baz bletch flum
As explained on StackOverflow:
This code will set the variable A to a new empty array. This is perfect if you don't have references to the original array A anywhere else because this actually creates a brand new (empty) array. You should be careful with this method because if you have referenced this array from another variable or property, the original array will remain unchanged. Only use this if you only reference the array by its original variable A.
A.length = 0
Att liberaler tillåtit negativa räntor, nollräntor och penningtryckning kan vara ett misstag av historiska proportioner och hotar nu liberalismen över hela världen.
Alla dessa åtgärder förstör kapitalismen och desorienterar väljare. Den förstör också kapitalismens och marknadernas goda namn, eftersom åtgärderna utges vara i samklang med dem.
Men: Utan korrekt prisinformation, desorientering. Just någon slags desorientering kan ligga bakom mycket av de förskjutningar mot extremer som vi ser i väljarkårerna både i USA och i Europa, vilket Peter Santesson tagit upp: Den nya pessimismen — Kvartal. Folk reagerar negativt på desorientering, även om mätarna pekar uppåt.
Vi borde aldrig låtit dessa åtgärder passera. Även i de länder där vi inte är i regeringsställning borde vi protesterat högt och ljutt. Det finns inget liberalt i dessa reformer; de förstör informationsflödet mellan långivare och presumtiva låntagare och de flyttar stora värden från de som arbetat ihop dem till de som råkar befinna sig på en speciell plats i systemet. Åtgärderna förstör för fattiga länder genom att skicka penningflöden in och ur dem med stor godtycklighet . Åtgärderna förstör i väst och framför allt i USA genom att invagga oss i en falsk säkerhet att bara för att vi sitter på de finansiella institutionerna just nu och har en slags hävarm, så kommer det alltid att vara så.
Summa summarum kommer vi nog att se en kraftig vänstervridning, ackompanjerat av populistiska högerrörelser bland länder och samhällsskikt som upplever sig vara på tillbakagång.
It seems to have some extra tricks up its sleeve compared to e.g. mpd.
Vanilla Mopidy only plays music from your local disk and radio streams. Through extensions, Mopidy can play music from cloud services like Spotify, SoundCloud, and Google Play Music.
Read more: Link - Mopidy
With these thoughts in mind, I look back at all my failures at reusable code and notice something else: It looks nothing at all like: source → algorithm → sink. In fact, it looks like a bunch of nested loops. The source data enters at the top, and gets swirled around and around in ever smaller and tighter loops, and leaves via the sink in the center of that maelstrom.
Eff.org har en ranking av vilka meddelande-applikationer som har bäst säkerhet. För att få full pott så måste det vara open source. WhatsApp har nu 6 av 7 poäng, med väldigt genomtänkt end-to-end kryptering enligt EFF, men inte open source så det går ju inte att kolla https://www.eff.org/deeplinks/2016/04/whatsapp-rolls-out-end-end-encryption-its-1bn-users
En annan fråga är ju om det är bra eller dåligt med kryptering. Hur som helst, full pott går till:
- ChatSecure + Orbot, https://chatsecure.org/
- Jitsi + Ostel, jitsi.org | Jitsi
- Off-The-Record Messaging for Windows (Pidgin) , Pidgin, the universal chat client
- Signal / RedPhone, Open Whisper Systems, Free, Worldwide, Encrypted Phone Calls for iPhone
- Silent Phone Silent Circle
- Silent Text, Silent Circle
- Telegram (secret chats) Telegram Messenger
- TextSecure.Open Whisper Systems >> Home
Folding back a snapshot in kvm works in Ubuntu 16.10! The whole chain as described below now works. I have not checked if my 16.10 is running on the hand installed debs or if they've been superceded by 16.10 versions.
It seems that the last step, folding back a snapshot in kvm, does not work in Ubuntu 15.10 and indeed has a lot of problems on other systems too. Folding back:
virsh blockcommit guestName vda --active --pivot --wait
error: internal error: unable to execute QEMU command 'block-commit': Device 'drive-virtio-disk0' is busy: block device is in use by block job: commit
It works if you stop the guest, but that kind of defeats the purpose since it is not backing up a running machine anymore. One may try to use RedHat instead and see if patches there have been quicker, since the Qemu/Kvm people seem to be aware of the problems.
Summary 2016-04-08: KVM can be used and can do this (but last step does still not work, see above), but the configuration and packages in Ubuntu 15.10 are buggy, so you have to replace stuff, and disable stuff:
Backing up a running virtual machine on Ubuntu 15.10 turned out to be not so simple. A lot of the information that Google return is outdated, giving recommendations pertaining to 8 year old Ubuntu systems or claiming that KVM cannot run GUI systems.
I started out with Virtualbox, and Virtualbox has something called snapshots. As far as I understand, when you take a snapshot, the main vdi file becomes read-only and all changes go into a new snapshot file. Several snapshots can be made and they can reference each other and branch, and be folded back into the main vdi file and into each other. I followed this guide:
# != 1 ]
"Usage: $0 VBoxName"
"Renaming old snapshot..."
edit previous --name deleteme
"Renaming current snapshot..."
edit current --name previous
"Taking new snapshot..."
"Deleting old snapshot..."
But I ended up with errors and inconsistent snapshots that were corrupt according to Virtualbox. Which is probably my fault somehow. Digging deeper I found a blog post referencing the same script, OSC — Backing up Virtual Machines in VirtualBox and that guy writes that he has gone back to shutting down the virtual machines and then back them up:
Sadly, for me personally, live VirtualBox snapshots haven’t been a terribly robust backup strategy. I’ve unfortunately seen several snapshots fail. Or, worse, had VirtualBox crash while a snapshot was taking place.
So next solution, why not put the virtual machine on a snapshotting file system, that is guaranteed to copy the vdi file in one fell swoop? This may not be enough, in the sense that there might be state stored in other files or in RAM. But it is worth a shot. One option could be btrfs, which I have been experimenting with and which has a very smooth snapshotting mechanism: You can snapshot any file or director on a btrfs volume. But timely enough, this was posted on Reddit's /r/linuxadmin:
which thread says things like:
Yes. I do not recommend this. I spent more time maintaining the one client I had running VMs on a BTRFS store than I did the fifty or so others I had running VMs on ZFS stores, for roughly a year. The replication is unreliable, the performance is incredibly hit-or-miss
The poster lauds ZFS though. ZFS is supported well in Ubuntu 15.10, but the ZFS snapshotting is not as simple as btrfs. Just using LVM should also be an option.
So, what about changing the virtual machine from Virtualbox to something else? Three options are:
VmWare costs money for the snapshotting version. I did however vaguely remember that Linode switched from one VM technology to another recently. A Google search turned up that they switched from Xen to KVM.
Ok KVM it is. What is available snapshot wise there then?
Well firstly there is a way of freezing the state of a VM, backup and then unfreeze it again Backup of running KVM qcow2 VPS - Server Fault.. Secondly it seems to have the same ability to do snapshots with mutable snapshot files as VirtualBox, but there is more documentation giving examples of what I think I want.
This is the best I have found so far [libvirt-users] Backup a VM (using live external snapshot and blockcommit:
# Create snapshot virsh snapshot-create-as --domain $VM_NAME snap --diskspec vda,file=$VM_DIR/"$VM_NAME"-snap.qcow2 --disk-only --atomic --no-metadata --quiesce # Copy frozen backing file cp $VM_DIR/"$VM_NAME".qcow2 $SNAP_FILEPATH # Blockcommit snapshot back into backing file virsh blockcommit $VM_NAME vda --active --pivot # Remove snapshot file rm $VM_DIR/"$VM_NAME"-snap.qcow2 # Variables should be self-explanatory: # - VM_DIR is the directory where the VM are stored # - VM_NAME is the name of the VM, and its qcow2 file is called # VM_NAME.qcow2 # - SNAP_FILEPATH is the full path (including name) where the backup # should be created
This seems to be essentially the same KVM – Live backups with qcow2 | Gonzalo Marcote | Open source, open mind.
Some more info here too: Live-disk-backup-with-active-blockcommit - Libvirt Wiki
The above script will only work if the following criteria are fulfilled:
- Apparmor does not interfere. One heavy handed option is to disable Apparmor altogether (I did this, see AppArmor for how-to)
- Qemu guest agent is installed in the guest
- There is a communications channel between the host and the qemu guest agent, see: QEMU Guest Agent | Gonzalo Marcote | Open source, open mind
- As of 2016-04-08 on Ubuntu 15.10, you need to manually download and update new versions of libvirt-bin and libvirt0, see discussion here: Bug #1517539 “Libvirt KVM can not create snapshot (with qemu-gue...” : Bugs : libvirt package : Ubuntu
Download links for amd64 are (to the best of my understanding and what I used):
Install with sudo dpkg -i libvirt*
(assuming you only have those two files in the directory)
Unfortunately, without tuning or disabling AppArmor there is currently no way to flatten the snapshot back into the image, as of the last comment currently at Bug #1517539 “Libvirt KVM can not create snapshot (with qemu-gue...” : Bugs : libvirt package : Ubuntu:
"Strictly speaking, the virsh command that prompted this ticket has been fixed. So, I can now successfully create a live snapshot using the proposed packages. Unfortunately, I have no way to flatten the snapshot back into the base image now."
However after having disabled AppArmor, it works, it seems.
Moving from VirtualBox to KVM
Was disarmingly simple. As long as you follow the up-to-date guides and use the virt-manager GUI, you can actually just use the vdi file directly in KVM. However then you will not get the snapshotting abilities. For that you need the qcow2 disk format. Which you can convert to directly from vdi like this:
...seems very difficult. I tried the script listed here:
but I end up with corrupt stuff, including the entire Virtual machine. VBoxManage says it cannot delete the deleteme copy and then it all goes downhill from there.
I am probably doing something wrong, but I am now looking at KVM or Xen to see if they can do snapshots. This is a lot trickier than I thought. Maybe I will need to settle for stopping the Virtualbox vm, back it up and then start it again, or somehow back up its entire state from within itself. But that does not feel right.
I'm also looking into using a snapshotting file system such as btrfs for snapshotting VM state, but btrfs has a lot of problems in this context according to this thread: