feat: Introduce an opt-in "error" deprecation notification mode

docs/deprecations.md

@@ -17,6 +17,21 @@ disabledDeprecations:
   - '*' # To disable all deprecation messages
 ```
 
+## Notifications mode
+
+By default deprecations are logged as warnings. If there's an intention to work with _deprecation_ free service, reporting mode can be switched so approached deprecation is reported with a thrown error.
+
+Mode can be set via environment variable: `SLS_DEPRECATION_NOTIFICATION_MODE=error` or via top level service configuration setting:
+
+```yaml
+deprecationNotificationMode: error
+```
+
+Note:
+
+- Configuration setting is ineffective for deprecations reported before service configuration is read.
+- `SLS_DEPRECATION_DISABLE` env var and `disabledDeprecations` configuration setting remain respected, and no errors will be thrown for mentioned deprecation coodes.
+
 <a name="CHANGE_OF_DEFAULT_RUNTIME_TO_NODEJS14X"><div>&nbsp;</div></a>
 
 ## Change of default runtime to `nodejs14.x`

docs/providers/aws/guide/serverless.yml.md

@@ -29,6 +29,7 @@ enableLocalInstallationFallback: false # If set to 'true', guarantees that it's
 useDotenv: false # If set to 'true', environment variables will be automatically loaded from .env files
 variablesResolutionMode: null # To crash on variable resolution errors (as coming from new resolver), set this value to "20210326"
 unresolvedVariablesNotificationMode: warn # If set to 'error', references to variables that cannot be resolved will result in an error being thrown (applies to legacy resolver)
+deprecationNotificationMode: warn # If set to 'error' any reported deprection will result in an error being thrown
 
 disabledDeprecations: # Disable deprecation logs by their codes. Default is empty.
   - DEP_CODE_1 # Deprecation code to disable

lib/classes/Service.js

@@ -150,6 +150,7 @@ class Service {
 
     this.plugins = configurationInput.plugins;
     this.disabledDeprecations = configurationInput.disabledDeprecations;
+    this.deprecationNotificationMode = configurationInput.deprecationNotificationMode;
 
     // `package.path` is read by few core plugins at initialization
     if (configurationInput.package) {

lib/configSchema.js

@@ -20,6 +20,9 @@ const schema = {
       required: [],
       // User is free to add any properties for its own purpose
     },
+    deprecationsNotificationMode: {
+      enum: ['error', 'warn'],
+    },
     disabledDeprecations: {
       anyOf: [
         { const: '*' },

lib/utils/logDeprecation.js

@@ -2,9 +2,13 @@
 
 const chalk = require('chalk');
 const weakMemoizee = require('memoizee/weak');
+const _ = require('lodash');
+const ServerlessError = require('../serverless-error');
 
 const disabledCodesByEnv = extractCodes(process.env.SLS_DEPRECATION_DISABLE);
 
+const notificationModeByEnv = process.env.SLS_DEPRECATION_NOTIFICATION_MODE;
+
 const triggeredDeprecations = new Set();
 
 function extractCodes(codesStr) {
@@ -24,6 +28,11 @@ const resolveDeprecatedByService = weakMemoizee((serviceConfig) => {
   return new Set(disabledDeprecations);
 });
 
+const isErrorNotificationMode = (serviceConfig) => {
+  if (notificationModeByEnv) return notificationModeByEnv === 'error';
+  return _.get(serviceConfig, 'deprecationNotificationMode') === 'error';
+};
+
 function writeDeprecation(code, message) {
   const prefix = 'Serverless: ';
   const messageLines = message.split('\n');
@@ -53,13 +62,21 @@ module.exports = (code, message, { serviceConfig } = {}) => {
     ) {
       return;
     }
+
     if (serviceConfig) {
       const serviceDisabledCodes = resolveDeprecatedByService(serviceConfig);
       if (serviceDisabledCodes.has(code) || serviceDisabledCodes.has('*')) {
         return;
       }
     }
 
+    if (isErrorNotificationMode(serviceConfig)) {
+      throw new ServerlessError(
+        `${message}\n  More Info: https://www.serverless.com/framework/docs/deprecations/#${code}`,
+        `REJECTED_DEPRECATION_${code}`
+      );
+    }
+
     writeDeprecation(code, message);
   } finally {
     triggeredDeprecations.add(code);

scripts/serverless.js

@@ -203,6 +203,7 @@ const processSpanPromise = (async () => {
           // variable resolution choices
           if (!ensureResolvedProperty('variablesResolutionMode')) return;
           if (!ensureResolvedProperty('disabledDeprecations')) return;
+          if (!ensureResolvedProperty('deprecationNotificationMode')) return;
 
           if (isPropertyResolved(variablesMeta, 'provider\0name')) {
             providerName = resolveProviderName(configuration);

test/unit/lib/utils/logDeprecation.test.js

@@ -6,6 +6,7 @@ const mockRequire = require('mock-require');
 const overrideEnv = require('process-utils/override-env');
 const overrideStdoutWrite = require('process-utils/override-stdout-write');
 const runServerless = require('../../../utils/run-serverless');
+const ServerlessError = require('../../../../lib/serverless-error');
 
 describe('#logDeprecation()', () => {
   let restoreEnv;
@@ -91,6 +92,25 @@ describe('#logDeprecation()', () => {
     });
   });
 
+  it('Should throw on deprecation if env.SLS_DEPRECATION_NOTIFICATION_MODE=error', () => {
+    process.env.SLS_DEPRECATION_NOTIFICATION_MODE = 'error';
+    logDeprecation = mockRequire.reRequire('../../../../lib/utils/logDeprecation');
+    expect(() => logDeprecation('CODE1', 'Start using deprecation log'))
+      .to.throw(ServerlessError)
+      .with.property('code', 'REJECTED_DEPRECATION_CODE1');
+  });
+
+  it('Should throw on deprecation if error notifications mode set in service config', () => {
+    logDeprecation = mockRequire.reRequire('../../../../lib/utils/logDeprecation');
+    expect(() =>
+      logDeprecation('CODE1', 'Start using deprecation log', {
+        serviceConfig: { deprecationNotificationMode: 'error' },
+      })
+    )
+      .to.throw(ServerlessError)
+      .with.property('code', 'REJECTED_DEPRECATION_CODE1');
+  });
+
   it('Should not log deprecation twice', () => {
     let stdoutData = '';
     overrideStdoutWrite(