Support flag conditions based on Vespa release

Supports a "relational" condition with a new dimension "vespa-version", that
can be satisfied with e.g. "predicate": ">= 7.120.5" as long as the condition is
evaluated in a JVM that has a Vtag at least high as 7.120.5.

The typical use-case for this condition would be: The developer has used the
flag to test and verify the feature is ready to roll out globally. The
developer can now roll the feature with the next release, and ORCHESTRATED,
halting if anything goes wrong like any normal rollout.

This also allows one-shot tests of a feature flag in integration tests: Just
enable it for an upcoming version with predicate "== 7.x.y".

2 files changed, 45 insertions, 7 deletions

diff --git a/flags/src/test/java/com/yahoo/vespa/flags/json/ConditionTest.java b/flags/src/test/java/com/yahoo/vespa/flags/json/ConditionTest.java
index d19442ae0f0..cf8d06fd312 100644
--- a/flags/src/test/java/com/yahoo/vespa/flags/json/ConditionTest.java
+++ b/flags/src/test/java/com/yahoo/vespa/flags/json/ConditionTest.java
@@ -4,9 +4,10 @@ package com.yahoo.vespa.flags.json;
 import com.yahoo.vespa.flags.FetchVector;
 import org.junit.Test;
 
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
+import java.util.List;
+import java.util.Optional;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -17,8 +18,8 @@ public class ConditionTest {
     @Test
     public void testWhitelist() {
         String hostname1 = "host1";
-        Condition condition = new Condition(Condition.Type.WHITELIST, FetchVector.Dimension.HOSTNAME,
-                Stream.of(hostname1).collect(Collectors.toList()));
+        var params = new Condition.CreateParams(FetchVector.Dimension.HOSTNAME, List.of(hostname1), Optional.empty());
+        Condition condition = new WhitelistCondition(params);
         assertFalse(condition.test(new FetchVector()));
         assertFalse(condition.test(new FetchVector().with(FetchVector.Dimension.APPLICATION_ID, "foo")));
         assertFalse(condition.test(new FetchVector().with(FetchVector.Dimension.HOSTNAME, "bar")));
@@ -28,11 +29,38 @@ public class ConditionTest {
     @Test
     public void testBlacklist() {
         String hostname1 = "host1";
-        Condition condition = new Condition(Condition.Type.BLACKLIST, FetchVector.Dimension.HOSTNAME,
-                Stream.of(hostname1).collect(Collectors.toList()));
+        var params = new Condition.CreateParams(FetchVector.Dimension.HOSTNAME, List.of(hostname1), Optional.empty());
+        Condition condition = new BlacklistCondition(params);
         assertTrue(condition.test(new FetchVector()));
         assertTrue(condition.test(new FetchVector().with(FetchVector.Dimension.APPLICATION_ID, "foo")));
         assertTrue(condition.test(new FetchVector().with(FetchVector.Dimension.HOSTNAME, "bar")));
         assertFalse(condition.test(new FetchVector().with(FetchVector.Dimension.HOSTNAME, hostname1)));
     }
+
+    @Test
+    public void testRelational() {
+        verifyVespaVersionFor("<", true, false, false);
+        verifyVespaVersionFor("<=", true, true, false);
+        verifyVespaVersionFor(">", false, false, true);
+        verifyVespaVersionFor(">=", false, true, true);
+
+        // Test with empty fetch vector along vespa version dimension (this should never happen as the
+        // version is always available through Vtag, although Vtag has a dummy version number for e.g.
+        // locally run unit tests that hasn't set the release Vespa version).
+        var params = new Condition.CreateParams(FetchVector.Dimension.VESPA_VERSION, List.of(), Optional.of(">=7.1.2"));
+        Condition condition = RelationalCondition.create(params);
+        assertFalse(condition.test(new FetchVector()));
+    }
+
+    private void verifyVespaVersionFor(String operator, boolean whenLess, boolean whenEqual, boolean whenGreater) {
+        assertEquals(whenLess, vespaVersionCondition("7.2.4", operator + "7.3.4"));
+        assertEquals(whenEqual, vespaVersionCondition("7.3.4", operator + "7.3.4"));
+        assertEquals(whenGreater, vespaVersionCondition("7.4.4", operator + "7.3.4"));
+    }
+
+    private boolean vespaVersionCondition(String vespaVersion, String predicate) {
+        var params = new Condition.CreateParams(FetchVector.Dimension.VESPA_VERSION, List.of(), Optional.of(predicate));
+        Condition condition = RelationalCondition.create(params);
+        return condition.test(new FetchVector().with(FetchVector.Dimension.VESPA_VERSION, vespaVersion));
+    }
 }
diff --git a/flags/src/test/java/com/yahoo/vespa/flags/json/SerializationTest.java b/flags/src/test/java/com/yahoo/vespa/flags/json/SerializationTest.java
index b0e4cd0f682..8326b14fcbf 100644
--- a/flags/src/test/java/com/yahoo/vespa/flags/json/SerializationTest.java
+++ b/flags/src/test/java/com/yahoo/vespa/flags/json/SerializationTest.java
@@ -48,6 +48,11 @@ public class SerializationTest {
                 "                    \"type\": \"blacklist\",\n" +
                 "                    \"dimension\": \"hostname\",\n" +
                 "                    \"values\": [ \"h1\" ]\n" +
+                "                },\n" +
+                "                {\n" +
+                "                    \"type\": \"relational\",\n" +
+                "                    \"dimension\": \"vespa-version\",\n" +
+                "                    \"predicate\": \">=7.3.4\"\n" +
                 "                }\n" +
                 "            ],\n" +
                 "            \"value\": true\n" +
@@ -66,7 +71,7 @@ public class SerializationTest {
         assertThat(wireData.id, equalTo("id2"));
         // rule
         assertThat(wireData.rules.size(), equalTo(1));
-        assertThat(wireData.rules.get(0).andConditions.size(), equalTo(2));
+        assertThat(wireData.rules.get(0).andConditions.size(), equalTo(3));
         assertThat(wireData.rules.get(0).value.getNodeType(), equalTo(JsonNodeType.BOOLEAN));
         assertThat(wireData.rules.get(0).value.asBoolean(), equalTo(true));
         // first condition
@@ -79,6 +84,11 @@ public class SerializationTest {
         assertThat(blacklistCondition.type, equalTo("blacklist"));
         assertThat(blacklistCondition.dimension, equalTo("hostname"));
         assertThat(blacklistCondition.values, equalTo(List.of("h1")));
+        // third condition
+        WireCondition relationalCondition = wireData.rules.get(0).andConditions.get(2);
+        assertThat(relationalCondition.type, equalTo("relational"));
+        assertThat(relationalCondition.dimension, equalTo("vespa-version"));
+        assertThat(relationalCondition.predicate, equalTo(">=7.3.4"));
 
         // attributes
         assertThat(wireData.defaultFetchVector, notNullValue());