builders.py: Add canStartBuild disk space check

We need a way to limit the builds for when a given worker has less than
a certain amount of disk space available. This implements a
canStartBuild method based on the example in the Buildbot docs and
blocks a build if the worker has less than 60GB of disk space available.
Unlike the example code, we want the stdout of the command so that we
can calculate the amount of disk space, rather than just relying on the
remote command's return code.

Docs: https://docs.buildbot.net/latest/manual/customization.html#canstartbuild-functions

[YOCTO #14591]

Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>

builders.py

@@ -8,6 +8,7 @@ from yoctoabb import config
 from yoctoabb.steps.writelayerinfo import WriteLayerInfo
 from yoctoabb.steps.runconfig import get_publish_dest, get_publish_resultdir, get_publish_name, RunConfigCheckSteps, TargetPresent
 from buildbot.process.results import Results, SUCCESS, FAILURE, CANCELLED, WARNINGS, SKIPPED, EXCEPTION, RETRY
+from buildbot.process.remotecommand import RemoteCommand
 
 from twisted.python import log
 from twisted.internet import defer
@@ -45,6 +46,41 @@ def ensure_props_set(props):
         "publish_destination": props.getProperty("publish_destination", "")
     }
 
+@defer.inlineCallbacks
+def shell(command, worker, builder):
+    args = {
+        'command': command,
+        'workdir': worker.worker_basedir,
+        'logEnviron': False,
+        'want_stdout': True,
+        'want_stderr': False,
+    }
+
+    cmd = RemoteCommand('shell', args, collectStdout=True, stdioLogName="stdio")
+    cmd.worker = worker
+    yield cmd.run(None, worker.conn, builder.name)
+    return cmd
+
+@defer.inlineCallbacks
+def canStartBuild(builder, wfb, request):
+    log.msg("Checking available disk space...")
+
+    cmd = yield shell("df -BG | grep $(findmnt -T . | awk '{print $2}' | sed -n 2p) | awk '{print $4}' | sed 's/[^0-9]*//g'", wfb.worker, builder)
+    threshold = 60 # GB of space
+    if int(cmd.stdout) < threshold:
+        log.msg("Detected {0} GB of space available, less than threshold of {1} GB. Can't start build".format(cmd.stdout, threshold))
+        wfb.worker.putInQuarantine()
+        return False
+    else:
+        log.msg("Detected {0} GB of space available, more than threshold of {1} GB. OK to build".format(cmd.stdout, threshold))
+
+    wfb.worker.quarantine_timeout = 120
+    wfb.worker.putInQuarantine()
+
+    wfb.worker.resetQuarantine()
+
+    return True
+
 def create_builder_factory():
     f = util.BuildFactory()
 
@@ -136,7 +172,7 @@ for builder in config.subbuilders:
     if not workers:
         workers = config.builder_to_workers['default']
     builders.append(util.BuilderConfig(name=builder,
-                                       workernames=workers, nextWorker=nextWorker, nextBuild=nextBuild,
+                                       workernames=workers, canStartBuild=canStartBuild, nextWorker=nextWorker, nextBuild=nextBuild,
                                        factory=f, env=extra_env))
 
 # Prioritize assigning builders to available workers based on the length
@@ -300,8 +336,8 @@ def create_parent_builder_factory(buildername, waitname):
 
     return factory
 
-builders.append(util.BuilderConfig(name="a-quick", workernames=config.workers, factory=create_parent_builder_factory("a-quick", "wait-quick"), nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env))
-builders.append(util.BuilderConfig(name="a-full", workernames=config.workers, factory=create_parent_builder_factory("a-full", "wait-full"), nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env))
+builders.append(util.BuilderConfig(name="a-quick", workernames=config.workers, factory=create_parent_builder_factory("a-quick", "wait-quick"), canStartBuild=canStartBuild, nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env))
+builders.append(util.BuilderConfig(name="a-full", workernames=config.workers, factory=create_parent_builder_factory("a-full", "wait-full"), canStartBuild=canStartBuild,nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env))
 
 def create_doc_builder_factory():
     f = util.BuildFactory()
@@ -345,4 +381,4 @@ def create_doc_builder_factory():
 
 # Only run one docs build at a time
 docs_lock = util.MasterLock("docs_lock")
-builders.append(util.BuilderConfig(name="docs", workernames=config.workers, factory=create_doc_builder_factory(), nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env, locks=[docs_lock.access('exclusive')]))
+builders.append(util.BuilderConfig(name="docs", workernames=config.workers, factory=create_doc_builder_factory(), canStartBuild=canStartBuild, nextWorker=nextWorker, nextBuild=nextBuild, env=extra_env, locks=[docs_lock.access('exclusive')]))