Add setting graphql server endpoint via environment variable.

go.mod

@@ -4,6 +4,7 @@ go 1.16
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/lukaszraczylo/zero v0.0.0-20160322155811-4a4535dd56e7 // indirect
 	github.com/stretchr/testify v1.7.0
 	github.com/tidwall/gjson v1.7.3
 	github.com/valyala/fasthttp v1.22.0

go.sum

@@ -5,6 +5,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/klauspost/compress v1.11.8 h1:difgzQsp5mdAz9v8lm3P/I+EpDKMU/6uTMw1y1FObuo=
 github.com/klauspost/compress v1.11.8/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
+github.com/lukaszraczylo/zero v0.0.0-20160322155811-4a4535dd56e7 h1:9l31ZdbJuSK5sQH4hldeHB/ulflee5srCFzT4Oxm65Q=
+github.com/lukaszraczylo/zero v0.0.0-20160322155811-4a4535dd56e7/go.mod h1:UOwgylrs4V/Vzo1KfbjhzU+iB/5Pu4HnSpgE8WI14gs=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=

gql.go

@@ -9,12 +9,16 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
 
+	"github.com/lukaszraczylo/zero"
 	"github.com/tidwall/gjson"
 	"github.com/valyala/fasthttp"
 )
 
 // Endpoint of your GraphQL server to query
+// this variable can be overwritten by setting env variable, for example:
+// GRAPHQL_ENDPOINT=http://hasura.local/v1/graphql
 var GraphQLUrl = "http://127.0.0.1:9090/v1/graphql"
 
 type requestBase struct {
@@ -22,6 +26,12 @@ type requestBase struct {
 	Variables interface{} `json:"variables"`
 }
 
+func init() {
+	if !zero.IsZero(os.Getenv("GRAPHQL_ENDPOINT")) {
+		GraphQLUrl = os.Getenv("GRAPHQL_ENDPOINT")
+	}
+}
+
 // queryBuilder takes query data (string) and variables (interface) as a parameter and assembles
 // graphQL query. It also compacts the JSON result. Function returns query as []byte and error if anything went wrong.
 func queryBuilder(data string, variables interface{}) ([]byte, error) {