[VDB-751 VDB-754] Bugfix null pointer panic and improve logging (#119)

* VDB-751 VDB-754 Bugfix null pointer panic and improve logging

* Fix typo

Gopkg.lock

@@ -2,39 +2,50 @@
 
 
 [[projects]]
+  digest = "1:48a213e9dc4880bbbd6999309a476fa4d3cc67560aa7127154cf8ea95bd464c2"
   name = "github.com/allegro/bigcache"
   packages = [
     ".",
-    "queue"
+    "queue",
   ]
+  pruneopts = ""
   revision = "f31987a23e44c5121ef8c8b2f2ea2e8ffa37b068"
   version = "v1.1.0"
 
 [[projects]]
   branch = "master"
+  digest = "1:a313376bcbcce8ae8bddb8089a7293e0473a0f8e9e3710d6244e09e81875ccf0"
   name = "github.com/aristanetworks/goarista"
   packages = ["monotime"]
+  pruneopts = ""
   revision = "ff33da284e760fcdb03c33d37a719e5ed30ba844"
 
 [[projects]]
   branch = "master"
+  digest = "1:c6bf1ac7bbc0fe51637bf54d5a88ff79b171b3b42dbc665dec98303c862d8662"
   name = "github.com/btcsuite/btcd"
   packages = ["btcec"]
+  pruneopts = ""
   revision = "cff30e1d23fc9e800b2b5b4b41ef1817dda07e9f"
 
 [[projects]]
+  digest = "1:5d47691333460db6ac83ced03c79b4bdb9aff3e322be24affb7855bed8affc6c"
   name = "github.com/dave/jennifer"
   packages = ["jen"]
+  pruneopts = ""
   revision = "14e399b6b5e8456c66c45c955fc27b568bacb5c9"
   version = "v1.3.0"
 
 [[projects]]
+  digest = "1:aaeffbff5bd24654cb4c190ed75d6c7b57b4f5d6741914c1a7a6bb7447e756c5"
   name = "github.com/deckarep/golang-set"
   packages = ["."]
+  pruneopts = ""
   revision = "cbaa98ba5575e67703b32b4b19f73c91f3c4159e"
   version = "v1.7.1"
 
 [[projects]]
+  digest = "1:90d36f5b581e95e00ced808cd48824ed6c320c25887828cce461bdef4cb7bc7c"
   name = "github.com/ethereum/go-ethereum"
   packages = [
     ".",
@@ -70,50 +81,64 @@
     "params",
     "rlp",
     "rpc",
-    "trie"
+    "trie",
   ]
+  pruneopts = ""
   revision = "cd79bc61a983d6482579d12cdd239b37bbfa12ef"
 
 [[projects]]
+  digest = "1:eb53021a8aa3f599d29c7102e65026242bdedce998a54837dc67f14b6a97c5fd"
   name = "github.com/fsnotify/fsnotify"
   packages = ["."]
+  pruneopts = ""
   revision = "c2828203cd70a50dcccfb2761f8b1f8ceef9a8e9"
   version = "v1.4.7"
 
 [[projects]]
+  digest = "1:a01080d20c45c031c13f3828c56e58f4f51d926a482ad10cc0316225097eb7ea"
   name = "github.com/go-stack/stack"
   packages = ["."]
+  pruneopts = ""
   revision = "2fee6af1a9795aafbe0253a0cfbdf668e1fb8a9a"
   version = "v1.8.0"
 
 [[projects]]
+  digest = "1:3dd078fda7500c341bc26cfbc6c6a34614f295a2457149fc1045cab767cbcf18"
   name = "github.com/golang/protobuf"
   packages = ["proto"]
+  pruneopts = ""
   revision = "aa810b61a9c79d51363740d207bb46cf8e620ed5"
   version = "v1.2.0"
 
 [[projects]]
   branch = "master"
+  digest = "1:2a5888946cdbc8aa360fd43301f9fc7869d663f60d5eedae7d4e6e5e4f06f2bf"
   name = "github.com/golang/snappy"
   packages = ["."]
+  pruneopts = ""
   revision = "2e65f85255dbc3072edf28d6b5b8efc472979f5a"
 
 [[projects]]
+  digest = "1:5247b135b5492aa232a731acdcb52b08f32b874cb398f21ab460396eadbe866b"
   name = "github.com/google/uuid"
   packages = ["."]
+  pruneopts = ""
   revision = "d460ce9f8df2e77fb1ba55ca87fafed96c607494"
   version = "v1.0.0"
 
 [[projects]]
   branch = "master"
+  digest = "1:9c776d7d9c54b7ed89f119e449983c3f24c0023e75001d6092442412ebca6b94"
   name = "github.com/hashicorp/golang-lru"
   packages = [
     ".",
-    "simplelru"
+    "simplelru",
   ]
+  pruneopts = ""
   revision = "0fb14efe8c47ae851c0034ed7a448854d3d34cf3"
 
 [[projects]]
+  digest = "1:d14365c51dd1d34d5c79833ec91413bfbb166be978724f15701e17080dc06dec"
   name = "github.com/hashicorp/hcl"
   packages = [
     ".",
@@ -125,25 +150,29 @@
     "hcl/token",
     "json/parser",
     "json/scanner",
-    "json/token"
+    "json/token",
   ]
+  pruneopts = ""
   revision = "8cb6e5b959231cc1119e43259c4a608f9c51a241"
   version = "v1.0.0"
 
 [[projects]]
+  digest = "1:b3c5b95e56c06f5aa72cb2500e6ee5f44fcd122872d4fec2023a488e561218bc"
   name = "github.com/hpcloud/tail"
   packages = [
     ".",
     "ratelimiter",
     "util",
     "watch",
-    "winfile"
+    "winfile",
   ]
+  pruneopts = ""
   revision = "a30252cb686a21eb2d0b98132633053ec2f7f1e5"
   version = "v1.0.0"
 
 [[projects]]
   branch = "master"
+  digest = "1:b6e4cc26365c004808649862e22069de09594a9222143399a7a04904e9f7018c"
   name = "github.com/huin/goupnp"
   packages = [
     ".",
@@ -152,65 +181,83 @@
     "httpu",
     "scpd",
     "soap",
-    "ssdp"
+    "ssdp",
   ]
+  pruneopts = ""
   revision = "1395d1447324cbea88d249fbfcfd70ea878fdfca"
 
 [[projects]]
+  digest = "1:870d441fe217b8e689d7949fef6e43efbc787e50f200cb1e70dbca9204a1d6be"
   name = "github.com/inconshreveable/mousetrap"
   packages = ["."]
+  pruneopts = ""
   revision = "76626ae9c91c4f2a10f34cad8ce83ea42c93bb75"
   version = "v1.0"
 
 [[projects]]
+  digest = "1:76f836364ae83ed811c415aa92e1209ce49de9f62aad85b85fca749a8b96a110"
   name = "github.com/jackpal/go-nat-pmp"
   packages = ["."]
+  pruneopts = ""
   revision = "c9cfead9f2a36ddf3daa40ba269aa7f4bbba6b62"
   version = "v1.0.1"
 
 [[projects]]
   branch = "master"
+  digest = "1:617ee2434b77e911fa26b678730be9a617f75243b194eadc8201c8ac860844aa"
   name = "github.com/jmoiron/sqlx"
   packages = [
     ".",
-    "reflectx"
+    "reflectx",
   ]
+  pruneopts = ""
   revision = "0dae4fefe7c0e190f7b5a78dac28a1c82cc8d849"
 
 [[projects]]
+  digest = "1:6a874e3ddfb9db2b42bd8c85b6875407c702fa868eed20634ff489bc896ccfd3"
   name = "github.com/konsorten/go-windows-terminal-sequences"
   packages = ["."]
+  pruneopts = ""
   revision = "5c8c8bd35d3832f5d134ae1e1e375b69a4d25242"
   version = "v1.0.1"
 
 [[projects]]
   branch = "master"
+  digest = "1:29145d7af4adafd72a79df5e41456ac9e232d5a28c1cd4dacf3ff008a217fc10"
   name = "github.com/lib/pq"
   packages = [
     ".",
-    "oid"
+    "oid",
   ]
+  pruneopts = ""
   revision = "4ded0e9383f75c197b3a2aaa6d590ac52df6fd79"
 
 [[projects]]
+  digest = "1:961dc3b1d11f969370533390fdf203813162980c858e1dabe827b60940c909a5"
   name = "github.com/magiconair/properties"
   packages = ["."]
+  pruneopts = ""
   revision = "c2353362d570a7bfa228149c62842019201cfb71"
   version = "v1.8.0"
 
 [[projects]]
+  digest = "1:096a8a9182648da3d00ff243b88407838902b6703fc12657f76890e08d1899bf"
   name = "github.com/mitchellh/go-homedir"
   packages = ["."]
+  pruneopts = ""
   revision = "ae18d6b8b3205b561c79e8e5f69bff09736185f4"
   version = "v1.0.0"
 
 [[projects]]
+  digest = "1:5219b4506253ccc598f9340677162a42d6a78f340a4cc6df2d62db4d0593c4e9"
   name = "github.com/mitchellh/mapstructure"
   packages = ["."]
+  pruneopts = ""
   revision = "fa473d140ef3c6adf42d6b391fe76707f1f243c8"
   version = "v1.0.0"
 
 [[projects]]
+  digest = "1:a7fd918fb5bd2188436785c0424f8a50b4addfedf37a2b14d796be2a927b8007"
   name = "github.com/onsi/ginkgo"
   packages = [
     ".",
@@ -230,12 +277,14 @@
     "reporters/stenographer",
     "reporters/stenographer/support/go-colorable",
     "reporters/stenographer/support/go-isatty",
-    "types"
+    "types",
   ]
+  pruneopts = ""
   revision = "3774a09d95489ccaa16032e0770d08ea77ba6184"
   version = "v1.6.0"
 
 [[projects]]
+  digest = "1:3ecd0a37c4a90c12a97e31c398cdbc173824351aa891898ee178120bfe71c478"
   name = "github.com/onsi/gomega"
   packages = [
     ".",
@@ -250,94 +299,122 @@
     "matchers/support/goraph/edge",
     "matchers/support/goraph/node",
     "matchers/support/goraph/util",
-    "types"
+    "types",
   ]
+  pruneopts = ""
   revision = "7615b9433f86a8bdf29709bf288bc4fd0636a369"
   version = "v1.4.2"
 
 [[projects]]
+  digest = "1:a5484d4fa43127138ae6e7b2299a6a52ae006c7f803d98d717f60abf3e97192e"
   name = "github.com/pborman/uuid"
   packages = ["."]
+  pruneopts = ""
   revision = "adf5a7427709b9deb95d29d3fa8a2bf9cfd388f1"
   version = "v1.2"
 
 [[projects]]
+  digest = "1:894aef961c056b6d85d12bac890bf60c44e99b46292888bfa66caf529f804457"
   name = "github.com/pelletier/go-toml"
   packages = ["."]
+  pruneopts = ""
   revision = "c01d1270ff3e442a8a57cddc1c92dc1138598194"
   version = "v1.2.0"
 
 [[projects]]
+  digest = "1:1d7e1867c49a6dd9856598ef7c3123604ea3daabf5b83f303ff457bcbc410b1d"
   name = "github.com/pkg/errors"
   packages = ["."]
+  pruneopts = ""
   revision = "ba968bfe8b2f7e042a574c888954fccecfa385b4"
   version = "v0.8.1"
 
 [[projects]]
+  digest = "1:fdbe7e05d74cc4d175cc4515a7807a5bb8b66ebe130da382b99713c9038648ae"
   name = "github.com/pressly/goose"
   packages = ["."]
+  pruneopts = ""
   revision = "e4b98955473e91a12fc7d8816c28d06376d1d92c"
   version = "v2.6.0"
 
 [[projects]]
+  digest = "1:7143292549152d009ca9e9c493b74736a2ebd93f921bea8a4b308d7cc5edc6b3"
   name = "github.com/rjeczalik/notify"
   packages = ["."]
+  pruneopts = ""
   revision = "0f065fa99b48b842c3fd3e2c8b194c6f2b69f6b8"
   version = "v0.9.1"
 
 [[projects]]
+  digest = "1:78c9cf43ddeacd0e472f412082227a0fac2ae107ee60e9112156f9371f9912cf"
   name = "github.com/rs/cors"
   packages = ["."]
+  pruneopts = ""
   revision = "3fb1b69b103a84de38a19c3c6ec073dd6caa4d3f"
   version = "v1.5.0"
 
 [[projects]]
+  digest = "1:9d57e200ef5ccc4217fe0a34287308bac652435e7c6513f6263e0493d2245c56"
   name = "github.com/sirupsen/logrus"
   packages = ["."]
+  pruneopts = ""
   revision = "bcd833dfe83d3cebad139e4a29ed79cb2318bf95"
   version = "v1.2.0"
 
 [[projects]]
+  digest = "1:d0431c2fd72e39ee43ea7742322abbc200c3e704c9102c5c3c2e2e667095b0ca"
   name = "github.com/spf13/afero"
   packages = [
     ".",
-    "mem"
+    "mem",
   ]
+  pruneopts = ""
   revision = "d40851caa0d747393da1ffb28f7f9d8b4eeffebd"
   version = "v1.1.2"
 
 [[projects]]
+  digest = "1:d0b38ba6da419a6d4380700218eeec8623841d44a856bb57369c172fbf692ab4"
   name = "github.com/spf13/cast"
   packages = ["."]
+  pruneopts = ""
   revision = "8965335b8c7107321228e3e3702cab9832751bac"
   version = "v1.2.0"
 
 [[projects]]
+  digest = "1:a1403cc8a94b8d7956ee5e9694badef0e7b051af289caad1cf668331e3ffa4f6"
   name = "github.com/spf13/cobra"
   packages = ["."]
+  pruneopts = ""
   revision = "ef82de70bb3f60c65fb8eebacbb2d122ef517385"
   version = "v0.0.3"
 
 [[projects]]
+  digest = "1:9ceffa4ab5f7195ecf18b3a7fff90c837a9ed5e22e66d18069e4bccfe1f52aa0"
   name = "github.com/spf13/jwalterweatherman"
   packages = ["."]
+  pruneopts = ""
   revision = "4a4406e478ca629068e7768fc33f3f044173c0a6"
   version = "v1.0.0"
 
 [[projects]]
+  digest = "1:0a52bcb568386d98f4894575d53ce3e456f56471de6897bb8b9de13c33d9340e"
   name = "github.com/spf13/pflag"
   packages = ["."]
+  pruneopts = ""
   revision = "9a97c102cda95a86cec2345a6f09f55a939babf5"
   version = "v1.0.2"
 
 [[projects]]
+  digest = "1:ac25ea6cc1156aca9611411274b4a0bdd83a623845df6985aab508253955cc66"
   name = "github.com/spf13/viper"
   packages = ["."]
+  pruneopts = ""
   revision = "8fb642006536c8d3760c99d4fa2389f5e2205631"
   version = "v1.2.0"
 
 [[projects]]
   branch = "master"
+  digest = "1:ce5194e5afac308cc34e500cab45b4ce88a0742d689e3cf7e37b607ad76bed2f"
   name = "github.com/syndtr/goleveldb"
   packages = [
     "leveldb",
@@ -351,49 +428,59 @@
     "leveldb/opt",
     "leveldb/storage",
     "leveldb/table",
-    "leveldb/util"
+    "leveldb/util",
   ]
+  pruneopts = ""
   revision = "ae2bd5eed72d46b28834ec3f60db3a3ebedd8dbd"
 
 [[projects]]
   branch = "master"
+  digest = "1:59b49c47c11a48f1054529207f65907c014ecf5f9a7c0d9c0f1616dec7b062ed"
   name = "golang.org/x/crypto"
   packages = [
     "pbkdf2",
     "scrypt",
     "sha3",
-    "ssh/terminal"
+    "ssh/terminal",
   ]
+  pruneopts = ""
   revision = "ff983b9c42bc9fbf91556e191cc8efb585c16908"
 
 [[projects]]
   branch = "master"
+  digest = "1:fbdbb6cf8db3278412c9425ad78b26bb8eb788181f26a3ffb3e4f216b314f86a"
   name = "golang.org/x/net"
   packages = [
     "context",
     "html",
     "html/atom",
     "html/charset",
-    "websocket"
+    "websocket",
   ]
+  pruneopts = ""
   revision = "26e67e76b6c3f6ce91f7c52def5af501b4e0f3a2"
 
 [[projects]]
   branch = "master"
+  digest = "1:b2ea75de0ccb2db2ac79356407f8a4cd8f798fe15d41b381c00abf3ae8e55ed1"
   name = "golang.org/x/sync"
   packages = ["errgroup"]
+  pruneopts = ""
   revision = "1d60e4601c6fd243af51cc01ddf169918a5407ca"
 
 [[projects]]
   branch = "master"
+  digest = "1:70d519d5cddeb60ceda2db88c24c340b1b2d7efb25ab54bacb38f57ea1998df7"
   name = "golang.org/x/sys"
   packages = [
     "unix",
-    "windows"
+    "windows",
   ]
+  pruneopts = ""
   revision = "d641721ec2dead6fe5ca284096fe4b1fcd49e427"
 
 [[projects]]
+  digest = "1:5acd3512b047305d49e8763eef7ba423901e85d5dd2fd1e71778a0ea8de10bd4"
   name = "golang.org/x/text"
   packages = [
     "encoding",
@@ -415,39 +502,79 @@
     "runes",
     "transform",
     "unicode/cldr",
-    "unicode/norm"
+    "unicode/norm",
   ]
+  pruneopts = ""
   revision = "f21a4dfb5e38f5895301dc265a8def02365cc3d0"
   version = "v0.3.0"
 
 [[projects]]
+  digest = "1:eb53021a8aa3f599d29c7102e65026242bdedce998a54837dc67f14b6a97c5fd"
   name = "gopkg.in/fsnotify.v1"
   packages = ["."]
+  pruneopts = ""
   revision = "c2828203cd70a50dcccfb2761f8b1f8ceef9a8e9"
   source = "gopkg.in/fsnotify/fsnotify.v1"
   version = "v1.4.7"
 
 [[projects]]
   branch = "v2"
+  digest = "1:4f830ee018eb8c56d0def653ad7c9a1d2a053f0cef2ac6b2200f73b98fa6a681"
   name = "gopkg.in/natefinch/npipe.v2"
   packages = ["."]
+  pruneopts = ""
   revision = "c1b8fa8bdccecb0b8db834ee0b92fdbcfa606dd6"
 
 [[projects]]
   branch = "v1"
+  digest = "1:a96d16bd088460f2e0685d46c39bcf1208ba46e0a977be2df49864ec7da447dd"
   name = "gopkg.in/tomb.v1"
   packages = ["."]
+  pruneopts = ""
   revision = "dd632973f1e7218eb1089048e0798ec9ae7dceb8"
 
 [[projects]]
+  digest = "1:f0620375dd1f6251d9973b5f2596228cc8042e887cd7f827e4220bc1ce8c30e2"
   name = "gopkg.in/yaml.v2"
   packages = ["."]
+  pruneopts = ""
   revision = "5420a8b6744d3b0345ab293f6fcba19c978f1183"
   version = "v2.2.1"
 
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "d41c963e87b06f7edd9135e30472894a114d0d8298454e6b2dae7ff25ac3c62a"
+  input-imports = [
+    "github.com/dave/jennifer/jen",
+    "github.com/ethereum/go-ethereum",
+    "github.com/ethereum/go-ethereum/accounts/abi",
+    "github.com/ethereum/go-ethereum/accounts/abi/bind",
+    "github.com/ethereum/go-ethereum/common",
+    "github.com/ethereum/go-ethereum/common/hexutil",
+    "github.com/ethereum/go-ethereum/core/rawdb",
+    "github.com/ethereum/go-ethereum/core/types",
+    "github.com/ethereum/go-ethereum/crypto",
+    "github.com/ethereum/go-ethereum/ethclient",
+    "github.com/ethereum/go-ethereum/ethdb",
+    "github.com/ethereum/go-ethereum/p2p",
+    "github.com/ethereum/go-ethereum/p2p/discv5",
+    "github.com/ethereum/go-ethereum/rlp",
+    "github.com/ethereum/go-ethereum/rpc",
+    "github.com/hashicorp/golang-lru",
+    "github.com/hpcloud/tail",
+    "github.com/jmoiron/sqlx",
+    "github.com/lib/pq",
+    "github.com/mitchellh/go-homedir",
+    "github.com/onsi/ginkgo",
+    "github.com/onsi/gomega",
+    "github.com/onsi/gomega/ghttp",
+    "github.com/pressly/goose",
+    "github.com/sirupsen/logrus",
+    "github.com/spf13/cobra",
+    "github.com/spf13/viper",
+    "golang.org/x/net/context",
+    "golang.org/x/sync/errgroup",
+    "gopkg.in/tomb.v1",
+  ]
   solver-name = "gps-cdcl"
   solver-version = 1

cmd/root.go

@@ -67,7 +67,11 @@ func Execute() {
 
 func initFuncs(cmd *cobra.Command, args []string) {
 	database(cmd, args)
-	logLevel(cmd, args)
+
+	logLvlErr := logLevel(cmd, args)
+	if logLvlErr != nil {
+		log.Fatal("Could not set log level: ", logLvlErr)
+	}
 
 }
 
@@ -147,7 +151,7 @@ func getBlockChain() *geth.BlockChain {
 	rawRpcClient, err := rpc.Dial(ipc)
 
 	if err != nil {
-		log.Fatal(err)
+		log.Fatal("Could not dial client: ", err)
 	}
 	rpcClient := client.NewRpcClient(rawRpcClient, ipc)
 	ethClient := ethclient.NewClient(rawRpcClient)

libraries/shared/watcher/event_watcher.go

@@ -100,7 +100,7 @@ func (watcher *EventWatcher) Execute(recheckHeaders constants.TransformerExecuti
 
 	missingHeaders, err := repository.MissingHeaders(*watcher.StartingBlock, -1, watcher.DB, notCheckedSQL)
 	if err != nil {
-		logrus.Error("Fetching of missing headers failed in watcher!")
+		logrus.Error("Couldn't fetch missing headers in watcher: ", err)
 		return err
 	}
 
@@ -108,7 +108,11 @@ func (watcher *EventWatcher) Execute(recheckHeaders constants.TransformerExecuti
 		// TODO Extend FetchLogs for doing several blocks at a time
 		logs, err := watcher.Fetcher.FetchLogs(watcher.Addresses, watcher.Topics, header)
 		if err != nil {
-			logrus.Errorf("Error while fetching logs for header %v in watcher", header.Id)
+			logrus.WithFields(logrus.Fields{
+				"headerId":    header.Id,
+				"headerHash":  header.Hash,
+				"blockNumber": header.BlockNumber,
+			}).Errorf("Couldn't fetch logs for header: %v", err)
 			return err
 		}
 
@@ -120,6 +124,7 @@ func (watcher *EventWatcher) Execute(recheckHeaders constants.TransformerExecuti
 
 		transformErr := watcher.transformLogs(logs, header)
 		if transformErr != nil {
+			logrus.Error("Could not transform logs: ", transformErr)
 			return transformErr
 		}
 	}

main.go

@@ -8,7 +8,10 @@ import (
 )
 
 func main() {
-	log.SetFormatter(&log.JSONFormatter{})
+	log.SetFormatter(&log.JSONFormatter{
+		PrettyPrint: true,
+	})
+	log.SetReportCaller(true)
 	file, err := os.OpenFile("vulcanizedb.log",
 		os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
 	if err == nil {

pkg/geth/blockchain.go

@@ -129,6 +129,9 @@ func (blockChain *BlockChain) GetTransactions(transactionHashes []common.Hash) (
 
 func (blockChain *BlockChain) LastBlock() (*big.Int, error) {
 	block, err := blockChain.ethClient.HeaderByNumber(context.Background(), nil)
+	if err != nil {
+		return big.NewInt(0), err
+	}
 	return block.Number, err
 }
 

pkg/history/populate_headers.go

@@ -61,4 +61,3 @@ func RetrieveAndUpdateHeaders(blockChain core.BlockChain, headerRepository datas
 	}
 	return len(blockNumbers), nil
 }
-

utils/utils.go

@@ -31,7 +31,7 @@ import (
 func LoadPostgres(database config.Database, node core.Node) postgres.DB {
 	db, err := postgres.NewDB(database, node)
 	if err != nil {
-		log.Fatalf("Error loading postgres\n%v", err)
+		log.Fatal("Error loading postgres: ", err)
 	}
 	return *db
 }
@@ -65,7 +65,7 @@ func GetAbi(abiFilepath string, contractHash string, network string) string {
 	}
 	_, err := geth.ParseAbi(contractAbiString)
 	if err != nil {
-		log.Fatalln("Invalid ABI")
+		log.Fatalln("Invalid ABI: ", err)
 	}
 	return contractAbiString
 }