Prevent malformed config from being overwritten

src/datastore/DataStore.ts

@@ -38,6 +38,24 @@ const CURRENT_THEME = 'currentTheme'
 
 const DEFAULT_CAPTAIN_ROOT_DOMAIN = 'captain.localhost'
 
+export function validateConfigFile(configPath: string) {
+    if (!fs.pathExistsSync(configPath)) {
+        return
+    }
+
+    try {
+        JSON.parse(fs.readFileSync(configPath, 'utf8'))
+    } catch (error) {
+        if (error instanceof SyntaxError) {
+            throw new Error(
+                `Cannot start CapRover because ${configPath} contains invalid JSON. Fix the file or restore it from a backup, then restart CapRover.`
+            )
+        }
+
+        throw error
+    }
+}
+
 const DEFAULT_NGINX_BASE_CONFIG = fs
     .readFileSync(__dirname + '/../../template/base-nginx-conf.ejs')
     .toString()
@@ -69,11 +87,14 @@ class DataStore {
     private projectsDataStore: ProjectsDataStore
 
     constructor(namespace: string) {
+        const configPath = `${CaptainConstants.captainDataDirectory}/config-${namespace}.json`
+        validateConfigFile(configPath)
+
         const data = new Configstore(
             `captain-store-${namespace}`, // This value seems to be unused
             {},
             {
-                configPath: `${CaptainConstants.captainDataDirectory}/config-${namespace}.json`,
+                configPath,
             }
         )
 

tests/DataStore.test.ts

@@ -0,0 +1,42 @@
+import fs = require('fs-extra')
+import os = require('os')
+import path = require('path')
+import { validateConfigFile } from '../src/datastore/DataStore'
+
+describe('DataStore config validation', () => {
+    let tempDirectory: string
+
+    beforeEach(() => {
+        tempDirectory = fs.mkdtempSync(
+            path.join(os.tmpdir(), 'caprover-config-')
+        )
+    })
+
+    afterEach(() => {
+        fs.removeSync(tempDirectory)
+    })
+
+    test('does not modify a malformed config file', () => {
+        const configPath = path.join(tempDirectory, 'config-captain.json')
+        const malformedConfig = '{"namespace":"captain",}'
+        fs.writeFileSync(configPath, malformedConfig)
+
+        expect(() => validateConfigFile(configPath)).toThrow(
+            `Cannot start CapRover because ${configPath} contains invalid JSON.`
+        )
+        expect(fs.readFileSync(configPath, 'utf8')).toBe(malformedConfig)
+    })
+
+    test('accepts a valid config file', () => {
+        const configPath = path.join(tempDirectory, 'config-captain.json')
+        fs.writeJsonSync(configPath, { namespace: 'captain' })
+
+        expect(() => validateConfigFile(configPath)).not.toThrow()
+    })
+
+    test('accepts a missing config file on first startup', () => {
+        const configPath = path.join(tempDirectory, 'config-captain.json')
+
+        expect(() => validateConfigFile(configPath)).not.toThrow()
+    })
+})