Summary:
This was the major goal of D3859/D3855, and to a lesser degree D3854/D3852.
As Drydock is allocating a resource, it may need to allocate other resources first. For example, if it's allocating a working copy, it may need to allocate a host first.
Currently, we have the process basically queue up the allocation (insert a task into the queue) and sleep() until it finishes. This is problematic for a bunch of reasons, but the major one is that if allocation takes more resources (host, port, machine, DNS) than you have daemons, they could all end up sleeping and waiting for some other daemon to do their work. This is really stupid. Even if you only take up some of them, you're spending slots sleeping when you could be doing useful work.
To partially get around this and make the CLI experience less dumb, there's this goofy `synchronous` flag that gets passed around everywhere and pushes the workflow through a pile of special cases. Basically the `synchronous` flag causes us to do everything in-process. But this is dumb too because we'd rather do things in parallel if we can, and we have to have a lot of special case code to make it work at all.
Get rid of all of this. Instead of sleep()ing, try to work on the tasks that need to be worked on. If another daemon grabbed them already that's fine, but in the worst case we just gracefully degrade and do everything in process. So we get the best of both worlds: if we have parallelizable tasks and free daemons, things will execute in parallel. If we have nonparallelizable tasks or no free daemons, things will execute in process.
Test Plan: Ran `drydock_control.php --trace` and saw it perform cascading allocations without sleeping or special casing.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T2015
Differential Revision: https://secure.phabricator.com/D3861
Summary:
- Still really really rough.
- Adds a full synchronous mode for debugging.
- Adds some logging.
- It can now allocate EC2 machines and put webroots on them in a hacky, terrible way.
- Adds a base query class.
Test Plan: oh hey look a test page? http://ec2-50-18-65-151.us-west-1.compute.amazonaws.com:2011/
Reviewers: btrahan
Reviewed By: btrahan
CC: aran, epriestley
Maniphest Tasks: T1049
Differential Revision: https://secure.phabricator.com/D2026
Summary: Run the actual resource allocation for Drydock out-of-process via the
task queue.
Test Plan: Ran "drydock_control.php", saw it insert a task and wait for task
completion. Ran "phd debug taskmaster" and saw it run the task.
Reviewers: btrahan, jungejason
Reviewed By: btrahan
CC: aran, epriestley
Differential Revision: https://secure.phabricator.com/D1470
Summary:
Rough cut of Drydock. This is very basic and doesn't do much of use yet (it
//does// allocate EC2 machines as host resources and expose interfaces to them),
but I think the overall structure is more or less reasonable.
== Interfaces
Vision: Applications interact with Drydock resources through DrydockInterfaces,
like **command**, **filesystem** and **httpd** interfaces. Each interface allows
applications to perform some kind of operation on the resource, like executing
commands, reading/writing files, or configuring a web server. Interfaces have a
concrete, specific API:
// Filesystem Interface
$fs = $lease->getInterface('filesystem'); // Constants, some day?
$fs->writeFile('index.html', 'hello world!');
// Command Interface
$cmd = $lease->getInterface('command');
echo $cmd->execx('uptime');
// HTTPD Interface
$httpd = $lease->getInterface('httpd');
$httpd->restart();
Interfaces are mostly just stock, although installs might add new interfaces if
they expose different ways to interact with resources (for instance, a resource
might want to expose a new 'MongoDB' interface or whatever).
Currently: We have like part of a command interface.
== Leases
Vision: Leases keep track of which resources are in use, and what they're being
used for. They allow us to know when we need to allocate more resources (too
many sandcastles on the existing hosts, e.g.) and when we can release resources
(because they are no longer being used). They also give applications something
to hold while resources are being allocated.
// EXAMPLE: How this should work some day.
$allocator = new DrydockAllocator();
$allocator->setResourceType('sandcastle');
$allocator->setAttributes(
array(
'diffID' => $diff->getID(),
));
$lease = $allocator->allocate();
$diff->setSandcastleLeaseID($lease->getID());
// ...
if ($lease->getStatus() == DrydockLeaseStatus::STATUS_ACTIVE) {
$sandcastle_link = $lease->getInterface('httpd')->getURI('/');
} else {
$sandcastle_link = 'Still building your sandcastle...';
}
echo "Sandcastle for this diff: ".$sandcastle_link;
// EXAMPLE: How this actually works now.
$allocator = new DrydockAllocator();
$allocator->setResourceType('host');
// NOTE: Allocation is currently synchronous but will be task-driven soon.
$lease = $allocator->allocate();
Leases are completely stock, installs will not define new lease types.
Currently: Leases exist and work but are very very basic.
== Resources
Vision: Resources represent some actual thing we've put somewhere, whether it's
a host, a block of storage, a webroot, or whatever else. Applications interact
through resources by acquiring leases to them, and then getting interfaces
through these leases. The lease acquisition process has a side effect of
allocating new resources if a lease can't be acquired on existing resources
(e.g., the application wants storage but all storage resources are full) and
things are configured to autoscale.
Resources may themselves acquire leases in order to allocate. For instance, a
storage resource might first acquire a lease to a host resource. A 'test
scaffold' resource might lease a storage resource and a mysql resource.
Not all resources are auto-allocate: the entry-level version of Drydock is that
you manually allocate a couple boxes and configure them through the web console.
Then, e.g., 'storage' / 'webroot' resources allocate on top of them, but the
host pool itself does not autoscale.
Resources are completely stock, they are abstract shells representing any
arbitrary thing.
Currently: Resource exist ('host' only) but are very very basic.
== Blueprints
Vision: Blueprints contain instructions for building interfaces to, (possibly)
allocating, updating, managing, and destroying a specific type of resource in a
specific location. One way to think of them is that they are scripts for
creating and deleting resources. For example, the LocalHost, RemoteHost and
EC2Host blueprints can all manage 'host' resources.
Eventually, we will support more types of resources (storage, webroot,
sandcastle, test scaffold, phacility deployment) and more providers for resource
types, some of which will be in the Phabricator mainline and some of which will
be custom.
Blueprints are very custom and specific to application types, so installs will
define new blueprints if they are making significant use of Drydock.
Currently: They exist but have few capabilities. The stock blueprints do nearly
nothing useful. There is a technically functional blueprint for host allocation
in EC2.
== Allocator
This is just the actual code to execute the lease acquisition process.
Test Plan: Ran "drydock_control.php" script, it allocated a machine in EC2,
acquired a lease on it, interfaced with it, and then released the lease. Ran it
again, got a fresh lease on the existing resource.
Reviewers: btrahan, jungejason
Reviewed By: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D1454
