feat: Error if purge request made with dev mode disabled (#3295)

## Relevant issue(s)

Resolves #3140

## Description

The issue was that if a purge request was made when the database was not
in development mode, it would fail, and an error would be output on the
node side of things. However, on the client side nothing indicated that
the process had failed. Whether the purge was successful, or it failed,
there would be no output.

I have created a new variable in the http package called `IsDevMode`,
which is checked in the `http/handler_extras.go/Purge` function. If dev
mode is enabled then `htttp.StatusOK` is written to the response header.
If it is not enabled, then `http.StatusBadRequest` is written to the
header instead, with a message indicating what happened.

## Tasks

- [x] I made sure the code is well commented, particularly
hard-to-understand areas.
- [x] I made sure the repository-held documentation is changed
accordingly.
- [x] I made sure the pull request title adheres to the conventional
commit style (the subset used in the project can be found in
[tools/configs/chglog/config.yml](tools/configs/chglog/config.yml)).
- [x] I made sure to discuss its limitations such as threats to
validity, vulnerability to mistake and misuse, robustness to
invalidation of assumptions, resource requirements, ...

## How has this been tested?

The platform(s) on which this was tested:
- Windows

cli/start.go

@@ -135,6 +135,7 @@ func MakeStartCommand() *cobra.Command {
 			}
 
 			isDevMode := cfg.GetBool("development")
+			http.IsDevMode = isDevMode
 			if isDevMode {
 				cmd.Printf(devModeBanner)
 				if cfg.GetBool("keyring.disabled") {

http/errors.go

@@ -19,9 +19,10 @@ import (
 )
 
 const (
-	errFailedToLoadKeys       string = "failed to load given keys"
-	errMethodIsNotImplemented string = "the method is not implemented"
-	errFailedToGetContext     string = "failed to get context"
+	errFailedToLoadKeys             string = "failed to load given keys"
+	errMethodIsNotImplemented       string = "the method is not implemented"
+	errFailedToGetContext           string = "failed to get context"
+	errPurgeRequestNonDeveloperMode string = "cannot purge database when development mode is disabled"
 )
 
 // Errors returnable from this package.

http/handler.go

@@ -21,6 +21,10 @@ import (
 	"github.com/go-chi/chi/v5"
 )
 
+// Global variable for the development mode flag
+// This is checked by the http/handler_extras.go/Purge function to determine which response to send
+var IsDevMode bool = false
+
 // Version is the identifier for the current API version.
 var Version string = "v0"
 

http/handler_extras.go

@@ -23,7 +23,14 @@ type extrasHandler struct{}
 
 func (s *extrasHandler) Purge(rw http.ResponseWriter, req *http.Request) {
 	db := mustGetContextClientDB(req)
-	rw.WriteHeader(http.StatusOK) // write the response before we restart to purge
+
+	// Send either 200 or 400 response based on whether the server is in dev mode
+	if IsDevMode {
+		rw.WriteHeader(http.StatusOK)
+	} else {
+		responseJSON(rw, http.StatusBadRequest, errPurgeRequestNonDeveloperMode)
+	}
+
 	db.Events().Publish(event.NewMessage(event.PurgeName, nil))
 }
 

http/handler_extras_test.go

@@ -20,8 +20,11 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestPurge(t *testing.T) {
+func TestPurgeDevModeTrue(t *testing.T) {
 	cdb := setupDatabase(t)
+
+	IsDevMode = true
+
 	url := "http://localhost:9181/api/v0/purge"
 
 	req := httptest.NewRequest(http.MethodPost, url, nil)
@@ -40,3 +43,27 @@ func TestPurge(t *testing.T) {
 	// test will timeout if purge never received
 	<-purgeSub.Message()
 }
+
+func TestPurgeDevModeFalse(t *testing.T) {
+	cdb := setupDatabase(t)
+
+	IsDevMode = false
+
+	url := "http://localhost:9181/api/v0/purge"
+
+	req := httptest.NewRequest(http.MethodPost, url, nil)
+	rec := httptest.NewRecorder()
+
+	purgeSub, err := cdb.Events().Subscribe(event.PurgeName)
+	require.NoError(t, err)
+
+	handler, err := NewHandler(cdb)
+	require.NoError(t, err)
+	handler.ServeHTTP(rec, req)
+
+	res := rec.Result()
+	require.Equal(t, 400, res.StatusCode)
+
+	// test will timeout if purge never received
+	<-purgeSub.Message()
+}