(QENG-2636) Host snapshots #117

sschneid · 2015-07-14T18:09:57Z

This PR introduces host (VM) snapshotting support. Example workflow:

Request a VM

$ curl -d '{"debian-7-x86_64":"1"}' --url vmpooler-dev/vm
{
  "ok": true,
  "debian-7-x86_64": {
    "ok": true,
    "hostname": "cxd6n45t1pd5s4j"
  },
  "domain": "delivery.puppetlabs.net"
}

Take a snapshot

This command will return a snapshot ID ("fjgd9l9okym8647gmjnznky5sklji0r3")

$ curl -d --url vmpooler-dev/vm/cxd6n45t1pd5s4j/snapshot
{
  "ok": true,
  "cxd6n45t1pd5s4j": {
    "snapshot": "fjgd9l9okym8647gmjnznky5sklji0r3"
  }
}

The vmpooler pooler_manager component sees the snapshot-creation task, and snapshots the VM in the background

[2015-05-01 12:35:02] [ ] [snapshot_manager] 'cxd6n45t1pd5s4j' is being snapshotted
[2015-05-01 12:39:04] [+] [snapshot_manager] 'cxd6n45t1pd5s4j' snapshot created in 242.77 seconds

You can query the VM itself; the GET /vm/:hostname endpoint will show a snapshot once pool_manager has finished the snapshotting task

$ curl --url vmpooler-dev/vm/cxd6n45t1pd5s4j
{
  "ok": true,
  "cxd6n45t1pd5s4j": {
    "template": "debian-7-x86_64",
    "lifetime": 1,
    "running": 0.08,
    "snapshots": [
      "fjgd9l9okym8647gmjnznky5sklji0r3"
    ],
    "domain": "delivery.puppetlabs.net"
  }
}

Change something on the VM

$ ssh root@cxd6n45t1pd5s4j
root@cxd6n45t1pd5s4j's password:
Linux debian-7-64 3.2.0-4-amd64 #1 SMP Debian 3.2.65-1 x86_64 

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright. 

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Mar 31 08:33:05 2015
root@cxd6n45t1pd5s4j:~# echo "This VM has been modified." >/etc/motd
root@cxd6n45t1pd5s4j:~# cat /etc/motd
This VM has been modified.

Revert the VM back to the snapshot we took earlier

$ curl -d --url vmpooler-dev/vm/cxd6n45t1pd5s4j/snapshot/fjgd9l9okym8647gmjnznky5sklji0r3
{
  "ok": true
}

pool_manager reverts the VM

[2015-05-01 12:41:52] [ ] [snapshot_manager] 'cxd6n45t1pd5s4j' is being reverted to snapshot 'fjgd9l9okym8647gmjnznky5sklji0r3'
[2015-05-01 12:41:58] [<] [snapshot_manager] 'cxd6n45t1pd5s4j' reverted to snapshot in 6.86 seconds

Verify that the changes in step 4 do not persist

$ ssh root@cxd6n45t1pd5s4j
root@cxd6n45t1pd5s4j's password:
Linux debian-7-64 3.2.0-4-amd64 #1 SMP Debian 3.2.65-1 x86_64 

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright. 

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Mar 31 08:33:05 2015
root@cxd6n45t1pd5s4j:~# cat /etc/motd 

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright. 

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.

colinPL · 2015-07-14T19:03:51Z

How many snapshots can a VM have at one time?

colinPL · 2015-07-14T19:06:41Z

lib/vmpooler/api/v1.rb

+        result[params[:hostname]] = {}
+
+        o = [('a'..'z'), ('0'..'9')].map(&:to_a).flatten
+        result[params[:hostname]]['snapshot'] = o[rand(25)] + (0...31).map { o[rand(o.length)] }.join


There isn't a random name method available?

There isn't a random name method available?

Not currently.

Would definitely say this pair of lines is a candidate for extracting to a method with an intention-revealing name.

def random_snapshot_name o = [('a'..'z'), ('0'..'9')].map(&:to_a).flatten o[rand(25)] + (0...31).map { o[rand(o.length)] }.join end # ... post "#{api_prefix}/vm/:hostname/snapshot/?" do content_type :json status 404 result = { 'ok' => false } hostname = params[:hostname] = hostname_shorten(params[:hostname], config['domain']) if backend.exists("vmpooler__vm__#{hostname}") result[hostname] = {} result[hostname]['snapshot'] = random_snapshot_name backend.sadd('vmpooler__tasks__snapshot', hostname + ':' + result[hostname]['snapshot']) status 202 result['ok'] = true end JSON.pretty_generate(result) end

I agree with the usefulness of a create_a_random_string_of_N_characters method. Currenlty both pool_manager and api/v1 have randomization code in them, and unfortunately there isn't currently a helper library which is shared throughout the app. I can certainly refactor some code to accomplish this, but am unsure if it's out of the scope of the PR.

I would ticket the creation of the method and work on it separately. It is out-of-scope of this PR, IMO.

Agreed, defer for separate work.

sschneid · 2015-07-14T19:13:02Z

How many snapshots can a VM have at one time?

No limit defined by either vmpooler or vSphere.

colinPL · 2015-07-14T19:22:41Z

lib/vmpooler/pool_manager.rb

+      end
+    end
+
+    def _create_vm_snapshot(vm, snapshot_name)


This method should do some scrutiny of snapshot_name. Or is that left to CreateSnapshot_Task?

What sort of scrutiny do you have in mind? As-is the only method calling create_vm_snapshot is the API, which is generating the snapshot_name var right before calling this method.

Mostly a check that it is not nil or empty?.

stahnma · 2015-07-15T17:36:37Z

Random Question, will you have to be auth'ed to use snap shotting?

sschneid · 2015-07-15T18:15:00Z

Random Question, will you have to be auth'ed to use snap shotting?

That's actually something I started thinking about yesterday. This PR doesn't require auth at the moment, but as snapshotting is a relatively "expensive" vSphere task, I think it probably should.

sschneid · 2015-07-16T18:00:45Z

This is ready for re-review. Addressed applicable comments above and included an additional commit to support requiring authentication tokens when using snapshots.

sschneid · 2015-07-16T18:05:05Z

I've deployed this branch to vmpooler-dev for manual testing as well.

sschneid · 2015-07-16T18:52:33Z

Some UX things I haven't figured out how to solve yet:

no way for user to tell when snapshotting is complete other than to check /api/v1/vm/:vm until a snapshots section appears in the JSON response
no way for user to tell when a snapshot revert task has completed

colinPL · 2015-07-16T20:28:30Z

lib/vmpooler/api/v1.rb

@@ -413,6 +413,11 @@ def need_token!
            result[params[:hostname]]['tags'] ||= {}
            result[params[:hostname]]['tags'][$1] = rdata[key]
          end
+
+          if key.match('^snapshot\:(.+?)$')


This could be an elsif for the above if.

(QENG-2636) Host snapshots

sschneid added the awaiting review label Jul 14, 2015

colinPL reviewed Jul 14, 2015
View reviewed changes

sschneid force-pushed the host_snapshots branch from c106550 to 8a8f05f Compare July 16, 2015 17:21

Host snapshot functionality

1c3045f

sschneid force-pushed the host_snapshots branch from 8a8f05f to f474fc0 Compare July 16, 2015 17:30

Host snapshot rspec tests

93acc83

sschneid force-pushed the host_snapshots branch from f474fc0 to 93acc83 Compare July 16, 2015 17:35

sschneid added 2 commits July 16, 2015 10:42

Merge branch 'master' into host_snapshots

fe65d5b

Require an auth token to use snapshots

1689133

Fix snapshort revert functionality

85aad61

colinPL reviewed Jul 16, 2015
View reviewed changes

colinPL added a commit that referenced this pull request Jul 27, 2015

Merge pull request #117 from sschneid/host_snapshots

7fddaf8

(QENG-2636) Host snapshots

colinPL merged commit 7fddaf8 into puppetlabs:master Jul 27, 2015

sschneid deleted the host_snapshots branch July 28, 2015 15:28

sschneid added ready to merge and removed awaiting review labels Aug 18, 2015

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

(QENG-2636) Host snapshots #117

(QENG-2636) Host snapshots #117

sschneid commented Jul 14, 2015

colinPL commented Jul 14, 2015

colinPL Jul 14, 2015

sschneid Jul 14, 2015

rick Jul 14, 2015

sschneid Jul 14, 2015

colinPL Jul 14, 2015

rick Jul 14, 2015

sschneid commented Jul 14, 2015

colinPL Jul 14, 2015

sschneid Jul 14, 2015

colinPL Jul 14, 2015

stahnma commented Jul 15, 2015

sschneid commented Jul 15, 2015

sschneid commented Jul 16, 2015

sschneid commented Jul 16, 2015

sschneid commented Jul 16, 2015

colinPL Jul 16, 2015

(QENG-2636) Host snapshots #117

(QENG-2636) Host snapshots #117

Conversation

sschneid commented Jul 14, 2015

colinPL commented Jul 14, 2015

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

sschneid commented Jul 14, 2015

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

stahnma commented Jul 15, 2015

sschneid commented Jul 15, 2015

sschneid commented Jul 16, 2015

sschneid commented Jul 16, 2015

sschneid commented Jul 16, 2015

Choose a reason for hiding this comment