Generate test engines list dynamically

Signed-off-by: Joffrey F <joffrey@docker.com>

Jenkinsfile

@@ -5,13 +5,6 @@ def imageNamePy2
 def imageNamePy3
 def images = [:]
 
-def dockerVersions = [
-  "17.06.2-ce",  // Latest EE
-  "17.12.1-ce",  // Latest CE stable
-  "18.02.0-ce",  // Latest CE edge
-  "18.03.0-ce-rc4" // Latest CE RC
-]
-
 def buildImage = { name, buildargs, pyTag ->
   img = docker.image(name)
   try {
@@ -37,9 +30,27 @@ def buildImages = { ->
   }
 }
 
+def getDockerVersions = { ->
+  def dockerVersions = ["17.06.2-ce"]
+  wrappedNode(label: "ubuntu && !zfs") {
+    def result = sh(script: """docker run --rm \\
+        --entrypoint=python \\
+        ${imageNamePy3} \\
+        /src/scripts/versions.py
+      """, returnStdout: true
+    )
+    dockerVersions = dockerVersions + result.trim().tokenize(' ')
+  }
+  return dockerVersions
+}
+
 def getAPIVersion = { engineVersion ->
   def versionMap = ['17.06': '1.30', '17.12': '1.35', '18.02': '1.36', '18.03': '1.37']
-  return versionMap[engineVersion.substring(0, 5)]
+  def result = versionMap[engineVersion.substring(0, 5)]
+  if (!result) {
+    return '1.37'
+  }
+  return result
 }
 
 def runTests = { Map settings ->
@@ -94,6 +105,8 @@ def runTests = { Map settings ->
 
 buildImages()
 
+def dockerVersions = getDockerVersions()
+
 def testMatrix = [failFast: false]
 
 for (imgKey in new ArrayList(images.keySet())) {

scripts/versions.py

+import operator
+import re
+from collections import namedtuple
+
+import requests
+
+base_url = 'https://download.docker.com/linux/static/{0}/x86_64/'
+categories = [
+    'edge',
+    'stable',
+    'test'
+]
+
+
+class Version(namedtuple('_Version', 'major minor patch rc edition')):
+
+    @classmethod
+    def parse(cls, version):
+        edition = None
+        version = version.lstrip('v')
+        version, _, rc = version.partition('-')
+        if rc:
+            if 'rc' not in rc:
+                edition = rc
+                rc = None
+            elif '-' in rc:
+                edition, rc = rc.split('-')
+
+        major, minor, patch = version.split('.', 3)
+        return cls(major, minor, patch, rc, edition)
+
+    @property
+    def major_minor(self):
+        return self.major, self.minor
+
+    @property
+    def order(self):
+        """Return a representation that allows this object to be sorted
+        correctly with the default comparator.
+        """
+        # rc releases should appear before official releases
+        rc = (0, self.rc) if self.rc else (1, )
+        return (int(self.major), int(self.minor), int(self.patch)) + rc
+
+    def __str__(self):
+        rc = '-{}'.format(self.rc) if self.rc else ''
+        edition = '-{}'.format(self.edition) if self.edition else ''
+        return '.'.join(map(str, self[:3])) + edition + rc
+
+
+def main():
+    results = set()
+    for url in [base_url.format(cat) for cat in categories]:
+        res = requests.get(url)
+        content = res.text
+        versions = [
+            Version.parse(
+                v.strip('"').lstrip('docker-').rstrip('.tgz').rstrip('-x86_64')
+            ) for v in re.findall(
+                r'"docker-[0-9]+\.[0-9]+\.[0-9]+-.*tgz"', content
+            )
+        ]
+        sorted_versions = sorted(
+            versions, reverse=True, key=operator.attrgetter('order')
+        )
+        latest = sorted_versions[0]
+        results.add(str(latest))
+    print(' '.join(results))
+
+if __name__ == '__main__':
+    main()