papr2kube: Experiment to convert papr to Kubernetes jobs

After setup:
```
oc cluster up
...
oc adm policy add-scc-to-group anyuid system:authenticated
```

```
./papr/papr2kube.py --limit 1 ostreedev/ostree 886a5d79280b92d336a4eecc9da287fa8b697542 ~/src/github/ostreedev/ostree/.papr.yml  > ostree-papr-kube.yml
oc create -f ostree-papr-kube.yml
```

Then I can e.g. watch a build with:
`oc logs -f jobs/papr-ostreedev-ostree-886a5d7928-0`

papr/papr2kube.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+
+# Convert a papr YAML file into a Kubernetes Job
+
+import os
+import sys
+import re
+import time
+import yaml
+import traceback
+import argparse
+import subprocess
+
+# XXX: switch to relative imports when we're a proper module
+from papr import PKG_DIR
+import papr.utils.parser as paprparser
+
+GH_NAME_REGEX = re.compile('^[A-Za-z0-9_.-]+$')
+
+def paprsuite2kubejob(gh_org, gh_repo, commitsha, suiteidx, suite):
+    commitsha_short = commitsha[0:10]
+    name = 'papr-{}-{}-{}-{}'.format(gh_org, gh_repo, commitsha_short, suiteidx)
+    metadata = {'name': name}
+    cmd = 'set -xeuo pipefail\n'
+    for test in suite['tests']:
+        cmd += test + '\n'
+    volumes = [
+        {'name': 'builddir', 'emptyDir': {}}
+    ]
+    containers = [{
+        'name': name,
+        'image': suite['container']['image'],
+        'volumeMounts': [
+            { 'name': 'builddir',
+              'mountPath': '/srv',
+            }
+        ],
+        'securityContext': {'runAsUser': 0},
+        'workingDir': '/srv/build',
+        'command': ["/usr/bin/bash", "-c", cmd],
+    }]
+    initContainers = [
+        { 'name': 'init-git',
+          'image': 'registry.centos.org/centos/centos:7',
+          'volumeMounts': [
+              { 'name': 'builddir',
+                'mountPath': '/srv',
+              }
+          ],
+          'securityContext': {'runAsUser': 0},
+          'workingDir': '/srv/',
+          'command': ['/bin/sh', '-c',
+                      '''set -xeuo pipefail; yum -y install git
+                      git clone --depth=100 https://github.com/{gh_org}/{gh_repo} build
+                      cd build
+                      git checkout {commitsha}'''.format(gh_org=gh_org, gh_repo=gh_repo, commitsha=commitsha)]
+        }
+    ]
+    r = {'apiVersion': 'batch/v1',
+         'kind': 'Job',
+         'metadata': metadata,
+         'spec': {
+             'template': {
+                 'metadata': dict(metadata),
+                 'spec': {
+                     'volumes': volumes,
+                     'initContainers': initContainers,
+                     'containers': containers,
+                     'restartPolicy': 'Never'
+                 },
+             },
+         },
+    }
+    return r
+
+def main():
+    "Main entry point."
+
+    parser = argparse.ArgumentParser(description='Convert .papr.yml to Kuberentes Jobs')
+    parser.add_argument('--limit', action='store', type=int, help='Emit at most N jobs')
+    parser.add_argument('ghid', action='store', help='github repo')
+    parser.add_argument('commitsha', action='store', help='commit sha')
+    parser.add_argument('path', action='store', help='Path to papr YAML (normally .papr.yml)')
+    args = parser.parse_args()
+
+    (org,proj) = args.ghid.split('/', 1)
+    assert GH_NAME_REGEX.match(org)
+    assert GH_NAME_REGEX.match(proj)
+
+    suite_parser = paprparser.SuiteParser(args.path)
+    suites = suite_parser.parse()
+
+    stream = sys.stdout
+    stream.write('# Generated from papr YAML: {}\n'.format(os.path.basename(args.path)))
+    jobs = []
+    joblist = {'apiVersion': 'v1',
+               'kind': 'List',
+               'items': jobs}
+    for i,suite in enumerate(suites):
+        if not suite.get('container'):
+            continue
+        jobs.append(paprsuite2kubejob(org, proj, args.commitsha, i, suite))
+        if len(jobs) == args.limit:
+            break
+    yaml.dump(joblist, stream=stream, explicit_start=True)
+
+if __name__ == '__main__':
+    sys.exit(main())