solution: health check endpoint

fix: #111

src/test/groovy/io/emeraldpay/dshackle/config/HealthConfigReaderSpec.groovy

@@ -0,0 +1,82 @@
+/**
+ * Copyright (c) 2021 EmeraldPay, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.emeraldpay.dshackle.config
+
+import io.emeraldpay.grpc.Chain
+import spock.lang.Specification
+
+class HealthConfigReaderSpec extends Specification {
+
+    HealthConfigReader reader = new HealthConfigReader()
+
+    def "Read empty"() {
+        setup:
+        def config = this.class.getClassLoader().getResourceAsStream("dshackle-health-empty.yaml")
+        when:
+        def act = reader.read(config)
+
+        then:
+        !act.enabled
+        act.port == 8082
+        act.host == "127.0.0.1"
+        act.path == "/health"
+        act.configs().size() == 0
+    }
+
+    def "Read single"() {
+        setup:
+        def config = this.class.getClassLoader().getResourceAsStream("dshackle-health-1.yaml")
+        when:
+        def act = reader.read(config)
+
+        then:
+        act.enabled
+        act.port == 8082
+        act.host == "127.0.0.1"
+        act.path == "/health"
+        with(act.configs()) {
+            size() == 1
+            with(it[0]) {
+                it.blockchain == Chain.ETHEREUM
+                it.minAvailable == 2
+            }
+        }
+    }
+
+    def "Read multiple"() {
+        setup:
+        def config = this.class.getClassLoader().getResourceAsStream("dshackle-health-2.yaml")
+        when:
+        def act = reader.read(config)
+
+        then:
+        act.enabled
+        act.port == 10003
+        act.host == "0.0.0.0"
+        act.path == "/healtz"
+        with(act.configs().toSorted { it.blockchain.id }) {
+            size() == 2
+            with(it[0]) {
+                it.blockchain == Chain.BITCOIN
+                it.minAvailable == 1
+            }
+            with(it[1]) {
+                it.blockchain == Chain.ETHEREUM
+                it.minAvailable == 2
+            }
+        }
+    }
+}

src/test/groovy/io/emeraldpay/dshackle/config/MainConfigReaderSpec.groovy

@@ -15,7 +15,7 @@
  */
 package io.emeraldpay.dshackle.config
 
-import io.emeraldpay.dshackle.FileResolver
+
 import io.emeraldpay.dshackle.test.TestingCommons
 import io.emeraldpay.grpc.Chain
 import spock.lang.Specification
@@ -73,6 +73,16 @@ class MainConfigReaderSpec extends Specification {
                 blockchain == Chain.TESTNET_RINKEBY
             }
         }
+        with(act.health) {
+            it.enabled
+            with(it.configs()) {
+                it.size() == 1
+                with(it[0]) {
+                    it.blockchain == Chain.ETHEREUM
+                    it.minAvailable == 1
+                }
+            }
+        }
         act.upstreams != null
         with(act.upstreams) {
             defaultOptions != null

src/test/groovy/io/emeraldpay/dshackle/monitoring/HealthCheckSetupSpec.groovy

@@ -0,0 +1,127 @@
+/**
+ * Copyright (c) 2021 EmeraldPay, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.emeraldpay.dshackle.monitoring
+
+import io.emeraldpay.dshackle.config.HealthConfig
+import io.emeraldpay.dshackle.upstream.Multistream
+import io.emeraldpay.dshackle.upstream.MultistreamHolder
+import io.emeraldpay.dshackle.upstream.Upstream
+import io.emeraldpay.dshackle.upstream.UpstreamAvailability
+import io.emeraldpay.grpc.Chain
+import spock.lang.Specification
+
+class HealthCheckSetupSpec extends Specification {
+
+    def "OK when meets availability - 1"() {
+        setup:
+        def config = new HealthConfig().tap {
+            it.chains[Chain.ETHEREUM] = new HealthConfig.ChainConfig(
+                    Chain.ETHEREUM, 1
+            )
+        }
+        def up1 = Mock(Upstream)
+        def ethereumUpstreams = Mock(Multistream)
+        def multistream = Mock(MultistreamHolder)
+        def check = new HealthCheckSetup(config, multistream)
+
+        when:
+        def act = check.health
+
+        then:
+        act == "OK"
+        1 * multistream.getUpstream(Chain.ETHEREUM) >> ethereumUpstreams
+        1 * ethereumUpstreams.available >> true
+        1 * ethereumUpstreams.getAll() >> [up1]
+        1 * up1.status >> UpstreamAvailability.OK
+    }
+
+    def "OK when meets availability - 1 - bitcoin"() {
+        setup:
+        def config = new HealthConfig().tap {
+            it.chains[Chain.BITCOIN] = new HealthConfig.ChainConfig(
+                    Chain.BITCOIN, 1
+            )
+        }
+        def up1 = Mock(Upstream)
+        def bitcoinUpstreams = Mock(Multistream)
+        def multistream = Mock(MultistreamHolder)
+        def check = new HealthCheckSetup(config, multistream)
+
+        when:
+        def act = check.health
+
+        then:
+        act == "OK"
+        1 * multistream.getUpstream(Chain.BITCOIN) >> bitcoinUpstreams
+        1 * bitcoinUpstreams.available >> true
+        1 * bitcoinUpstreams.getAll() >> [up1]
+        1 * up1.status >> UpstreamAvailability.OK
+    }
+
+    def "OK when meets availability - 2/3"() {
+        setup:
+        def config = new HealthConfig().tap {
+            it.chains[Chain.ETHEREUM] = new HealthConfig.ChainConfig(
+                    Chain.ETHEREUM, 2
+            )
+        }
+        def up1 = Mock(Upstream)
+        def up2 = Mock(Upstream)
+        def up3 = Mock(Upstream)
+        def ethereumUpstreams = Mock(Multistream)
+        def multistream = Mock(MultistreamHolder)
+        def check = new HealthCheckSetup(config, multistream)
+
+        when:
+        def act = check.health
+
+        then:
+        act == "OK"
+        1 * multistream.getUpstream(Chain.ETHEREUM) >> ethereumUpstreams
+        1 * ethereumUpstreams.available >> true
+        1 * ethereumUpstreams.getAll() >> [up1, up2, up3]
+        1 * up1.status >> UpstreamAvailability.OK
+        1 * up2.status >> UpstreamAvailability.SYNCING
+        1 * up3.status >> UpstreamAvailability.OK
+    }
+
+    def "OK when doesn't meet availability - 2/3"() {
+        setup:
+        def config = new HealthConfig().tap {
+            it.chains[Chain.ETHEREUM] = new HealthConfig.ChainConfig(
+                    Chain.ETHEREUM, 2
+            )
+        }
+        def up1 = Mock(Upstream)
+        def up2 = Mock(Upstream)
+        def up3 = Mock(Upstream)
+        def ethereumUpstreams = Mock(Multistream)
+        def multistream = Mock(MultistreamHolder)
+        def check = new HealthCheckSetup(config, multistream)
+
+        when:
+        def act = check.health
+
+        then:
+        act != "OK"
+        1 * multistream.getUpstream(Chain.ETHEREUM) >> ethereumUpstreams
+        1 * ethereumUpstreams.available >> true
+        1 * ethereumUpstreams.getAll() >> [up1, up2, up3]
+        1 * up1.status >> UpstreamAvailability.OK
+        1 * up2.status >> UpstreamAvailability.SYNCING
+        1 * up3.status >> UpstreamAvailability.LAGGING
+    }
+}

src/test/resources/dshackle-full.yaml

@@ -16,6 +16,12 @@ cache:
     enabled: true
     host: redis-master
 
+health:
+  port: 8083
+  blockchains:
+    - chain: ethereum
+      min-available: 1
+
 proxy:
   port: 8082
   tls:

src/test/resources/dshackle-health-1.yaml

@@ -0,0 +1,6 @@
+version: v1
+
+health:
+  blockchains:
+    - chain: ethereum
+      min-available: 2

src/test/resources/dshackle-health-2.yaml

@@ -0,0 +1,11 @@
+version: v1
+
+health:
+  port: 10003
+  host: 0.0.0.0
+  path: /healtz
+  blockchains:
+    - chain: ethereum
+      min-available: 2
+    - chain: bitcoin
+      min-available: 1

src/test/resources/dshackle-health-empty.yaml

@@ -0,0 +1,3 @@
+version: v1
+
+health: