From 3d4896ddcf34f56f83b000eb1af689060f68a1f1 Mon Sep 17 00:00:00 2001
From: Urvi <urvi.savla@stellar.org>
Date: Fri, 18 Aug 2023 12:34:39 -0700
Subject: [PATCH] Add deprecation warning for --db-url commandline parameter.

---
 services/horizon/internal/flags.go      | 17 +++++++++++++-
 services/horizon/internal/flags_test.go | 30 +++++++++++++++++++++++++
 support/config/config_option.go         | 21 ++++++++++++-----
 3 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/services/horizon/internal/flags.go b/services/horizon/internal/flags.go
index 34d9314758..24a7c3f3e9 100644
--- a/services/horizon/internal/flags.go
+++ b/services/horizon/internal/flags.go
@@ -62,6 +62,10 @@ const (
 	StellarPubnet = "pubnet"
 	// StellarTestnet is a constant representing the Stellar test network
 	StellarTestnet = "testnet"
+
+	dbUrlDeprecationWarning = "DEPRECATION WARNING: --db-url is deprecated and will be removed in a future" +
+		" Horizon release. Please use the DATABASE_URL environment variable to configure Horizon's" +
+		" PostgreSQL database connection"
 )
 
 // validateBothOrNeither ensures that both options are provided, if either is provided.
@@ -132,7 +136,18 @@ func Flags() (*Config, support.ConfigOptions) {
 			ConfigKey: &config.DatabaseURL,
 			OptType:   types.String,
 			Required:  true,
-			Usage:     "horizon postgres database to connect with",
+			Usage:     dbUrlDeprecationWarning,
+			CustomSetValue: func(co *support.ConfigOption) error {
+				if val := viper.GetString(DatabaseURLFlagName); val != "" {
+					if co.IsSetViaCommandline() {
+						stdLog.Printf(dbUrlDeprecationWarning)
+
+					}
+					config.DatabaseURL = val
+				}
+				return nil
+			},
+			EnvOnly: false, // set this to true when removing this option from the commandline
 		},
 		&support.ConfigOption{
 			Name:      "ro-database-url",
diff --git a/services/horizon/internal/flags_test.go b/services/horizon/internal/flags_test.go
index 38e0c16bda..592e9d1ff9 100644
--- a/services/horizon/internal/flags_test.go
+++ b/services/horizon/internal/flags_test.go
@@ -1,9 +1,13 @@
 package horizon
 
 import (
+	"bytes"
 	"fmt"
+	"io"
+	stdLog "log"
 	"testing"
 
+	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -131,3 +135,29 @@ func Test_createCaptiveCoreConfig(t *testing.T) {
 		})
 	}
 }
+
+func TestDatabaseUrlDeprecationWarning(t *testing.T) {
+	origWriter := stdLog.Writer()
+	defer stdLog.SetOutput(origWriter)
+
+	config, flags := Flags()
+	horizonCmd := &cobra.Command{
+		Use: "horizon",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			err := ApplyFlags(config, flags, ApplyOptions{RequireCaptiveCoreConfig: true, AlwaysIngest: false})
+			return err
+		},
+	}
+
+	var writer io.Writer = &bytes.Buffer{}
+	stdLog.SetOutput(writer)
+	horizonCmd.SetArgs([]string{"--" + DatabaseURLFlagName + "=testUrl",
+		"--" + IngestFlagName + "=false",
+		"--" + EnableCaptiveCoreIngestionFlagName + "=false",
+		"--" + StellarCoreURLFlagName + "=testUrl",
+	})
+	_ = flags.Init(horizonCmd)
+	err := horizonCmd.Execute()
+	assert.NoError(t, err)
+	assert.Contains(t, writer.(*bytes.Buffer).String(), dbUrlDeprecationWarning)
+}
diff --git a/support/config/config_option.go b/support/config/config_option.go
index 29fa77af3b..28006d0e5f 100644
--- a/support/config/config_option.go
+++ b/support/config/config_option.go
@@ -70,6 +70,7 @@ type ConfigOption struct {
 	ConfigKey      interface{}               // Pointer to the final key in the linked Config struct
 	flag           *pflag.Flag               // The persistent flag that the config option is attached to
 	Hidden         bool                      // Indicates whether to hide the flag from --help output
+	EnvOnly        bool                      // Indicates the option is supported via environment variable only (no commandline)
 }
 
 // Init handles initialisation steps, including configuring and binding the env variable name.
@@ -79,20 +80,25 @@ func (co *ConfigOption) Init(cmd *cobra.Command) error {
 	if co.EnvVar == "" {
 		co.EnvVar = strutils.KebabToConstantCase(co.Name)
 	}
-	// Initialise and bind the persistent flags
-	return co.setFlag(cmd)
+	if !co.EnvOnly {
+		// Initialise and bind the persistent flags
+		return co.setFlag(cmd)
+	}
+	return nil
 }
 
 // SetDeprecated Hides the deprecated flag from --help output
 func (co *ConfigOption) SetDeprecated(cmd *cobra.Command) {
-	if co.Hidden {
+	if !co.EnvOnly && co.Hidden {
 		co.flag.Hidden = true
 	}
 }
 
 // Bind binds the config option to viper.
 func (co *ConfigOption) Bind() {
-	viper.BindPFlag(co.Name, co.flag)
+	if !co.EnvOnly {
+		viper.BindPFlag(co.Name, co.flag)
+	}
 	viper.BindEnv(co.Name, co.EnvVar)
 }
 
@@ -237,7 +243,12 @@ var envVars = parseEnvVars(os.Environ())
 func IsExplicitlySet(co *ConfigOption) bool {
 	// co.flag.Changed is only set to true when the configuration is set via command line parameter.
 	// In the case where a variable is configured via environment variable we need to check envVars.
-	return co.flag.Changed || envVars[co.EnvVar]
+	return (co.flag != nil && co.flag.Changed) || envVars[co.EnvVar]
+}
+
+// IsSetViaCommandline returns true if the config option was set via commandline
+func (co *ConfigOption) IsSetViaCommandline() bool {
+	return co.flag != nil && co.flag.Value.String() != ""
 }
 
 // SetOptionalString converts a command line uint to a *string where the nil