[#79] When calling /collaborators fails completely, fall back to /ping

This can happen for very old versions of micro-infra-spring that do not support /collaborators.
Closes #79

micro-infra-spring-base/src/main/groovy/com/ofg/infrastructure/healthcheck/CollaboratorsConnectivityController.groovy

@@ -48,7 +48,8 @@ class CollaboratorsConnectivityController {
     private Map<String, String> statusOfAllCollaboratorInstances(ServicePath service) {
         Set<URI> allUrisOfService = serviceResolver.fetchAllUris(service)
         return allUrisOfService.collectEntries { URI instanceUrl ->
-            return [instanceUrl, checkConnectionStatus(instanceUrl)]
+            boolean status = checkConnectionStatus(instanceUrl)
+            return [instanceUrl, CollaboratorStatus.of(status)]
         }
     }
 
@@ -68,15 +69,34 @@ class CollaboratorsConnectivityController {
     }
 
     private Map checkCollaborators(URI url) {
-        Optional<Map> collaborators = pingClient
-                .checkCollaborators(url)
-                .transform({tryAdjustLegacyCollaboratorsResponse(it)})
+        Optional<Map> collaborators = establishCollaboratorsStatus(url)
         return [
                 status: CollaboratorStatus.of(collaborators.isPresent()),
                 collaborators: collaborators.or([:])
         ]
     }
 
+    private Optional<Map> establishCollaboratorsStatus(URI url) {
+        Optional<Map> collaborators = tryCallingCollaborators(url)
+        return fallbackWithPingIfCollaboratorsFailed(collaborators, url)
+    }
+
+    Optional<Map> fallbackWithPingIfCollaboratorsFailed(Optional<Map> maybeCollaborators, URI url) {
+        if (maybeCollaborators.isPresent()) {
+            return maybeCollaborators
+        }
+        return checkConnectionStatus(url) ?
+                Optional.of([:]) :
+                Optional.absent()
+    }
+
+    private Optional<Map> tryCallingCollaborators(URI url) {
+        Optional<Map> collaborators = pingClient
+                .checkCollaborators(url)
+                .transform({ tryAdjustLegacyCollaboratorsResponse(it) })
+        return collaborators
+    }
+
     private Map tryAdjustLegacyCollaboratorsResponse(Map collaboratorsResponse) {
         if (isLegacyResponse(collaboratorsResponse)) {
             return adjustLegacyCollaboratorsResponse(collaboratorsResponse)
@@ -98,12 +118,12 @@ class CollaboratorsConnectivityController {
 
     private boolean isLegacyResponse(Map collaboratorsResponse) {
         return !collaboratorsResponse.empty &&
-                collaboratorsResponse.values().any{!it instanceof Map}
+                collaboratorsResponse.values().any{!(it instanceof Map)}
     }
 
-    private String checkConnectionStatus(URI url) {
+    private boolean checkConnectionStatus(URI url) {
         final GuavaOptional<String> pingResult = pingClient.ping(url)
-        return CollaboratorStatus.of(pingResult == GuavaOptional.of('OK'))
+        return pingResult == GuavaOptional.of('OK')
     }
 
 }

micro-infra-spring-base/src/test/groovy/com/ofg/infrastructure/healthcheck/CollaboratorsConnectivityControllerSpec.groovy

@@ -58,11 +58,11 @@ class CollaboratorsConnectivityControllerSpec extends Specification {
         then:
             info.size() == 2
             info['/com/micro1'] == [
-                    (MICRO_1A_URL): 'UP',
-                    (MICRO_1B_URL): 'DOWN'
+                    (MICRO_1A_URL): UP,
+                    (MICRO_1B_URL): DOWN
             ]
             info['/com/micro2'] == [
-                    (MICRO_2_URL): 'UP'
+                    (MICRO_2_URL): UP
             ]
     }
 
@@ -207,6 +207,24 @@ class CollaboratorsConnectivityControllerSpec extends Specification {
                             collaborators: [:]]]
     }
 
+    def 'when /collaborators is unavailable, try to at least call /ping and degrade response gracefully'() {
+        given:
+            instancesOfMicroservices(['/com/micro1': [MICRO_1A_URL]])
+            collaboratorsCheckFailed(MICRO_1A_URL)
+        and:
+            theseAreOk(MICRO_1A_URL)
+
+        when:
+            Map info = controller.allCollaboratorsConnectivityInfo
+
+        then:
+            info.size() == 1
+            info['/com/micro1'] == [
+                    (MICRO_1A_URL): [
+                            status       : UP,
+                            collaborators: [:]]]
+    }
+
     private serviceReturnsLegacyCollaboratorsFormat(URI uri) {
         collaboratorsStatusOf(uri, ['micro3': 'CONNECTED'])
     }