fix(client): retry a read-only script with EVAL_RO after NOSCRIPT

packages/client/lib/client/index.spec.ts

@@ -1239,6 +1239,61 @@ describe('Client', () => {
     }
   });
 
+  describe('read-only scripts', () => {
+    testUtils.isVersionGreaterThanHook([7]);
+
+    const READ_ONLY_SQUARE_SCRIPT = defineScript({
+      ...SQUARE_SCRIPT,
+      IS_READ_ONLY: true
+    });
+
+    const options = {
+      ...GLOBAL.SERVERS.OPEN,
+      clientOptions: {
+        scripts: {
+          square: READ_ONLY_SQUARE_SCRIPT
+        }
+      }
+    };
+
+    // runs fn as a user that may run EVAL_RO and EVALSHA_RO but not EVAL or EVALSHA,
+    // after SCRIPT FLUSH, so the script has to be loaded again
+    async function asReadOnlyScriptsUser(
+      client: RedisClientType<{}, {}, { square: typeof READ_ONLY_SQUARE_SCRIPT }, 2>,
+      fn: (user: typeof client) => Promise<void>
+    ) {
+      await client.sendCommand([
+        'ACL', 'SETUSER', 'read-only-scripts', 'on', '>password', '~*', '+@all', '-eval', '-evalsha'
+      ]);
+      const user = client.duplicate({
+        username: 'read-only-scripts',
+        password: 'password'
+      });
+      await user.connect();
+
+      try {
+        await client.set('key', '2');
+        await client.scriptFlush();
+        await fn(user);
+      } finally {
+        user.destroy();
+        await client.sendCommand(['ACL', 'DELUSER', 'read-only-scripts']);
+      }
+    }
+
+    testUtils.testWithClient('loads a missing script with EVAL_RO', async client => {
+      await asReadOnlyScriptsUser(client, async user => {
+        assert.equal(await user.square('key'), 4);
+      });
+    }, options);
+
+    testUtils.testWithClient('uses EVAL_RO in MULTI', async client => {
+      await asReadOnlyScriptsUser(client, async user => {
+        assert.deepEqual(await user.multi().square('key').exec(), [4]);
+      });
+    }, options);
+  });
+
   const module = {
     echo: {
       parseCommand(parser: CommandParser, message: string) {

packages/client/lib/client/index.ts

@@ -1725,7 +1725,7 @@ export default class RedisClient<
     } catch (err) {
       if (!(err as Error)?.message?.startsWith?.('NOSCRIPT')) throw err;
 
-      args[0] = 'EVAL';
+      args[0] = script.IS_READ_ONLY ? 'EVAL_RO' : 'EVAL';
       args[1] = script.SCRIPT;
       reply = await this.sendCommand(args, options);
     }

packages/client/lib/multi-command.spec.ts

@@ -42,6 +42,24 @@ describe('Multi Command', () => {
         ['EVALSHA', SQUARE_SCRIPT.SHA1, '2']
       );
     });
+
+    it('should use EVAL_RO and EVALSHA_RO for a read-only script', () => {
+      const multi = new RedisMultiCommand(),
+        script = {
+          ...SQUARE_SCRIPT,
+          IS_READ_ONLY: true
+        };
+
+      multi.addScript(script, ['1']);
+      multi.addScript(script, ['2']);
+      assert.deepEqual(
+        multi.queue.map(({ args }) => Array.from(args)),
+        [
+          ['EVAL_RO', SQUARE_SCRIPT.SCRIPT, '1', '1'],
+          ['EVALSHA_RO', SQUARE_SCRIPT.SHA1, '1', '2']
+        ]
+      );
+    });
   });
 
   describe('exec', () => {

packages/client/lib/multi-command.ts

@@ -44,10 +44,10 @@ export default class RedisMultiCommand {
     const redisArgs: CommandArguments = [];
     redisArgs.preserve = args.preserve;
     if (this.scriptsInUse.has(script.SHA1)) {
-      redisArgs.push('EVALSHA', script.SHA1);
+      redisArgs.push(script.IS_READ_ONLY ? 'EVALSHA_RO' : 'EVALSHA', script.SHA1);
     } else {
       this.scriptsInUse.add(script.SHA1);
-      redisArgs.push('EVAL', script.SCRIPT);
+      redisArgs.push(script.IS_READ_ONLY ? 'EVAL_RO' : 'EVAL', script.SCRIPT);
     }
 
     if (script.NUMBER_OF_KEYS !== undefined) {