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README.md

@@ -16,9 +16,10 @@ An overview of the proxy architecture and logical flow can be viewed [here](http
 
 ## Quick Start
 
-In order to run the proxy, you'll need to set some environment variables to configure it properly.
+In order to run the proxy, you'll need to set some environment variables or pass reference to YAML configuration file.
 Below you'll find a list with the most important variables along with their default values.
-The required ones are marked with a comment.
+The required ones are marked with a comment. Variable names for YAML configuration file do not have `ZDM_` prefix and
+are lower-cased.
 
 ```shell
 ZDM_ORIGIN_CONTACT_POINTS=10.0.0.1  #required
@@ -36,7 +37,7 @@ ZDM_READ_MODE=PRIMARY_ONLY
 ZDM_LOG_LEVEL=INFO
 ```
 
-The environment variables must be set and exported for the proxy to work.
+The environment variables (or YAM configuration file) must be set for the proxy to work.
 
 In order to get started quickly, in your local environment, grab a copy of the binary distribution in the
 [Releases](https://github.com/datastax/zdm-proxy/releases) page. For the recommended installation in a production
@@ -55,6 +56,19 @@ export ZDM_TARGET_PASSWORD=cassandra \
 ./zdm-proxy-v2.0.0 # run the ZDM proxy executable
 ```
 
+If you prefer to use YAML configuration file, analogical setup would look like:
+
+```shell
+$ cat zdm-config.yml
+origin_contact_points: 10.0.0.1
+target_contact_points: 10.0.0.2
+origin_username: cassandra
+origin_password: cassandra
+target_username: cassandra
+target_password: cassandra
+$ ./zdm-proxy-v2.0.0 --config=./zdm-config.yml # run the ZDM proxy executable
+```
+
 At this point, you should be able to connect some client such as [CQLSH](https://downloads.datastax.com/#cqlsh) to the proxy
 and write data to it and the proxy will take care of forwarding the requests to both clusters concurrently.
 

proxy/launch.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"flag"
+	"fmt"
 	"github.com/datastax/zdm-proxy/proxy/pkg/config"
 	"github.com/datastax/zdm-proxy/proxy/pkg/runner"
 	log "github.com/sirupsen/logrus"
@@ -10,6 +12,12 @@ import (
 	"syscall"
 )
 
+// TODO: to be managed externally
+const ZdmVersionString = "2.2.0"
+
+var displayVersionOpt = flag.Bool("version", false, "display the ZDM proxy version and exit")
+var configFileOpt = flag.String("config", "", "specify path to ZDM configuration file")
+
 func runSignalListener(cancelFunc context.CancelFunc) {
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
@@ -23,6 +31,16 @@ func runSignalListener(cancelFunc context.CancelFunc) {
 	}()
 }
 
+func displayVersion() {
+	if *displayVersionOpt {
+		fmt.Printf("ZDM proxy version %v\n", ZdmVersionString)
+		os.Exit(0)
+	}
+
+	// Always record version information (very) early in the log
+	log.Infof("Starting ZDM proxy version %v", ZdmVersionString)
+}
+
 func launchProxy(profilingSupported bool, configFile string) {
 	conf, err := config.New().LoadConfig(configFile)
 

proxy/main.go

@@ -7,28 +7,13 @@ package main
 
 import (
 	"flag"
-	"fmt"
-	"os"
-
-	log "github.com/sirupsen/logrus"
 )
 
-// TODO: to be managed externally
-const ZdmVersionString = "2.2.0"
-
-var displayVersion = flag.Bool("version", false, "display the ZDM proxy version and exit")
-var configFile = flag.String("config", "", "specify path to ZDM configuration file")
-
 func main() {
 
 	flag.Parse()
-	if *displayVersion {
-		fmt.Printf("ZDM proxy version %v\n", ZdmVersionString)
-		os.Exit(0)
-	}
 
-	// Always record version information (very) early in the log
-	log.Infof("Starting ZDM proxy version %v", ZdmVersionString)
+	displayVersion()
 
-	launchProxy(false, *configFile)
+	launchProxy(false, *configFileOpt)
 }

proxy/main_profiling.go

@@ -15,12 +15,13 @@ import (
 
 var cpuProfile = flag.String("cpu_profile", "", "write cpu profile to the specified file")
 var memProfile = flag.String("mem_profile", "", "write memory profile to the specified file")
-var configFile = flag.String("config", "", "specify path to ZDM configuration file")
 
 func main() {
 
 	flag.Parse()
 
+	displayVersion()
+
 	// the cpu profiling is enabled at startup and is periodically collected while the proxy is running
 	// if cpu profiling is requested, any error configuring or starting it will cause the proxy startup to fail
 	if *cpuProfile != "" {
@@ -62,5 +63,5 @@ func main() {
 		}()
 	}
 
-	launchProxy(true, configFile)
+	launchProxy(true, configFileOpt)
 }

proxy/pkg/config/config.go

@@ -181,7 +181,7 @@ func (c *Config) LoadConfig(configFile string) (*Config, error) {
 
 	log.Infof("Parsed configuration: %v", c)
 
-	return c, err
+	return c, nil
 }
 
 func lookupFirstIp4(host string) (net.IP, error) {