1 files changed, 45 insertions, 7 deletions
diff --git a/roles/openshift_health_checker/openshift_checks/mixins.py b/roles/openshift_health_checker/openshift_checks/mixins.py
index 20d160eaf..e9bae60a3 100644
--- a/roles/openshift_health_checker/openshift_checks/mixins.py
+++ b/roles/openshift_health_checker/openshift_checks/mixins.py
@@ -1,15 +1,53 @@
-# pylint: disable=missing-docstring,too-few-public-methods
 """
 Mixin classes meant to be used with subclasses of OpenShiftCheck.
 """
 
-from openshift_checks import get_var
-
 
 class NotContainerizedMixin(object):
     """Mixin for checks that are only active when not in containerized mode."""
+    # permanent # pylint: disable=too-few-public-methods
+    # Reason: The mixin is not intended to stand on its own as a class.
+
+    def is_active(self):
+        """Only run on non-containerized hosts."""
+        is_containerized = self.get_var("openshift", "common", "is_containerized")
+        return super(NotContainerizedMixin, self).is_active() and not is_containerized
+
+
+class DockerHostMixin(object):
+    """Mixin for checks that are only active on hosts that require Docker."""
+
+    dependencies = []
+
+    def is_active(self):
+        """Only run on hosts that depend on Docker."""
+        is_containerized = self.get_var("openshift", "common", "is_containerized")
+        is_node = "nodes" in self.get_var("group_names", default=[])
+        return super(DockerHostMixin, self).is_active() and (is_containerized or is_node)
+
+    def ensure_dependencies(self):
+        """
+        Ensure that docker-related packages exist, but not on atomic hosts
+        (which would not be able to install but should already have them).
+        Returns: msg, failed
+        """
+        if self.get_var("openshift", "common", "is_atomic"):
+            return "", False
 
-    @classmethod
-    def is_active(cls, task_vars):
-        is_containerized = get_var(task_vars, "openshift", "common", "is_containerized")
-        return super(NotContainerizedMixin, cls).is_active(task_vars) and not is_containerized
+        # NOTE: we would use the "package" module but it's actually an action plugin
+        # and it's not clear how to invoke one of those. This is about the same anyway:
+        result = self.execute_module(
+            self.get_var("ansible_pkg_mgr", default="yum"),
+            {"name": self.dependencies, "state": "present"},
+        )
+        msg = result.get("msg", "")
+        if result.get("failed"):
+            if "No package matching" in msg:
+                msg = "Ensure that all required dependencies can be installed via `yum`.\n"
+            msg = (
+                "Unable to install required packages on this host:\n"
+                "    {deps}\n{msg}"
+            ).format(deps=',\n    '.join(self.dependencies), msg=msg)
+        failed = result.get("failed", False) or result.get("rc", 0) != 0
+        self.changed = result.get("changed", False)
+        return msg, failed