Add ability to provide only start or end time

This makes it so it is not necessary to provide both start and end
times. Instead you can provide either the start or end time.

ee/app/services/pod_logs_service.rb

@@ -74,10 +74,8 @@ class PodLogsService < ::BaseService
   end
 
   def check_times(result)
-    if params['start'] && params['end']
-      Time.iso8601(params['start'])
-      Time.iso8601(params['end'])
-    end
+    Time.iso8601(params['start']) if params['start']
+    Time.iso8601(params['end']) if params['end']
 
     success(result)
   rescue ArgumentError

ee/lib/gitlab/elasticsearch/logs.rb

@@ -89,16 +89,14 @@ module Gitlab
       end
 
       def filter_times(query, start_time, end_time)
-        return unless start_time && end_time
+        return unless start_time || end_time
 
-        query[:bool][:filter] = [
-          range: {
-           :@timestamp => {
-              gte: start_time,
-              lt: end_time
-            }
-          }
-        ]
+        time_range = { range: { :@timestamp => {} } }.tap do |tr|
+          tr[:range][:@timestamp][:gte] = start_time if start_time
+          tr[:range][:@timestamp][:lt] = end_time if end_time
+        end
+
+        query[:bool][:filter] = [time_range]
       end
 
       def format_response(response)

ee/spec/fixtures/lib/elasticsearch/query_with_end_time.json

+{
+  "query": {
+    "bool": {
+      "must": [
+        {
+          "match_phrase": {
+            "kubernetes.pod.name": {
+              "query": "production-6866bc8974-m4sk4"
+            }
+          }
+        },
+        {
+          "match_phrase": {
+            "kubernetes.namespace": {
+              "query": "autodevops-deploy-9-production"
+            }
+          }
+        }
+      ],
+      "filter": [
+        {
+          "range": {
+            "@timestamp": {
+              "lt": "2019-12-13T14:35:34.034Z"
+            }
+          }
+        }
+      ]
+    }
+  },
+  "sort": [
+    {
+      "@timestamp": {
+        "order": "desc"
+      }
+    },
+    {
+      "offset": {
+        "order": "desc"
+      }
+    }
+  ],
+  "_source": [
+    "@timestamp",
+    "message"
+  ],
+  "size": 500
+}

ee/spec/fixtures/lib/elasticsearch/query_with_start_time.json

+{
+  "query": {
+    "bool": {
+      "must": [
+        {
+          "match_phrase": {
+            "kubernetes.pod.name": {
+              "query": "production-6866bc8974-m4sk4"
+            }
+          }
+        },
+        {
+          "match_phrase": {
+            "kubernetes.namespace": {
+              "query": "autodevops-deploy-9-production"
+            }
+          }
+        }
+      ],
+      "filter": [
+        {
+          "range": {
+            "@timestamp": {
+              "gte": "2019-12-13T14:35:34.034Z"
+            }
+          }
+        }
+      ]
+    }
+  },
+  "sort": [
+    {
+      "@timestamp": {
+        "order": "desc"
+      }
+    },
+    {
+      "offset": {
+        "order": "desc"
+      }
+    }
+  ],
+  "_source": [
+    "@timestamp",
+    "message"
+  ],
+  "size": 500
+}

ee/spec/lib/gitlab/elasticsearch/logs_spec.rb

@@ -25,6 +25,8 @@ describe Gitlab::Elasticsearch::Logs do
   let(:body_with_container) { JSON.parse(fixture_file('lib/elasticsearch/query_with_container.json', dir: 'ee')) }
   let(:body_with_search) { JSON.parse(fixture_file('lib/elasticsearch/query_with_search.json', dir: 'ee')) }
   let(:body_with_times) { JSON.parse(fixture_file('lib/elasticsearch/query_with_times.json', dir: 'ee')) }
+  let(:body_with_start_time) { JSON.parse(fixture_file('lib/elasticsearch/query_with_start_time.json', dir: 'ee')) }
+  let(:body_with_end_time) { JSON.parse(fixture_file('lib/elasticsearch/query_with_end_time.json', dir: 'ee')) }
 
   RSpec::Matchers.define :a_hash_equal_to_json do |expected|
     match do |actual|
@@ -60,5 +62,19 @@ describe Gitlab::Elasticsearch::Logs do
       result = subject.pod_logs(namespace, pod_name, nil, nil, start_time, end_time)
       expect(result).to eq([es_message_4, es_message_3, es_message_2, es_message_1])
     end
+
+    it 'can further filter the logs by only start_time' do
+      expect(client).to receive(:search).with(body: a_hash_equal_to_json(body_with_start_time)).and_return(es_response)
+
+      result = subject.pod_logs(namespace, pod_name, nil, nil, start_time)
+      expect(result).to eq([es_message_4, es_message_3, es_message_2, es_message_1])
+    end
+
+    it 'can further filter the logs by only end_time' do
+      expect(client).to receive(:search).with(body: a_hash_equal_to_json(body_with_end_time)).and_return(es_response)
+
+      result = subject.pod_logs(namespace, pod_name, nil, nil, nil, end_time)
+      expect(result).to eq([es_message_4, es_message_3, es_message_2, es_message_1])
+    end
   end
 end