changes from PR review

docs/settings/alert-action-settings.asciidoc

@@ -60,10 +60,10 @@ You can configure the following settings in the `kibana.yml` file.
   | Specifies the proxy URL to use, if using a proxy for actions. By default, no proxy is used.
 
 | `xpack.actions.proxyBypassHosts` {ess-icon}
-  | Specifies hostnames which should not use the proxy, if using a proxy for actions. The value is an array of hostnames as strings.  By default, all hosts will use the proxy.  The settings `xpack.actions.proxyBypassHosts` and `xpack.actions.proxyOnlyHosts` cannot be used at the same time.
+  | Specifies hostnames which should not use the proxy, if using a proxy for actions. The value is an array of hostnames as strings.  By default, all hosts will use the proxy, but if an action's hostname is in this list, the proxy will not be used.  The settings `xpack.actions.proxyBypassHosts` and `xpack.actions.proxyOnlyHosts` cannot be used at the same time.
 
 | `xpack.actions.proxyOnlyHosts` {ess-icon}
-  | Specifies hostnames which should only use the proxy, if using a proxy for actions. The value is an array of hostnames as strings.  By default, all hosts will use the proxy.  The settings `xpack.actions.proxyBypassHosts` and `xpack.actions.proxyOnlyHosts` cannot be used at the same time.
+  | Specifies hostnames which should only use the proxy, if using a proxy for actions. The value is an array of hostnames as strings.  By default, no hosts will use the proxy, but if an action's hostname is in this list, the proxy will be used.  The settings `xpack.actions.proxyBypassHosts` and `xpack.actions.proxyOnlyHosts` cannot be used at the same time.
 
 | `xpack.actions.proxyHeaders` {ess-icon}
   | Specifies HTTP headers for the proxy, if using a proxy for actions. Defaults to {}.

x-pack/plugins/actions/server/builtin_action_types/lib/get_custom_agents.test.ts

@@ -16,6 +16,7 @@ const logger = loggingSystemMock.create().get() as jest.Mocked<Logger>;
 
 const targetHost = 'elastic.co';
 const targetUrl = `https://${targetHost}/foo/bar/baz`;
+const nonMatchingUrl = `https://${targetHost}m/foo/bar/baz`;
 
 describe('getCustomAgents', () => {
   const configurationUtilities = actionsConfigMock.create();
@@ -62,6 +63,22 @@ describe('getCustomAgents', () => {
     expect(httpsAgent instanceof HttpsProxyAgent).toBeFalsy();
   });
 
+  test('returns proxy agents for non-matching proxyBypassHosts', () => {
+    configurationUtilities.getProxySettings.mockReturnValue({
+      proxyUrl: 'https://someproxyhost',
+      proxyRejectUnauthorizedCertificates: false,
+      proxyBypassHosts: new Set([targetHost]),
+      proxyOnlyHosts: undefined,
+    });
+    const { httpAgent, httpsAgent } = getCustomAgents(
+      configurationUtilities,
+      logger,
+      nonMatchingUrl
+    );
+    expect(httpAgent instanceof HttpProxyAgent).toBeTruthy();
+    expect(httpsAgent instanceof HttpsProxyAgent).toBeTruthy();
+  });
+
   test('returns proxy agents for matching proxyOnlyHosts', () => {
     configurationUtilities.getProxySettings.mockReturnValue({
       proxyUrl: 'https://someproxyhost',
@@ -73,4 +90,20 @@ describe('getCustomAgents', () => {
     expect(httpAgent instanceof HttpProxyAgent).toBeTruthy();
     expect(httpsAgent instanceof HttpsProxyAgent).toBeTruthy();
   });
+
+  test('returns non-proxy agents for non-matching proxyOnlyHosts', () => {
+    configurationUtilities.getProxySettings.mockReturnValue({
+      proxyUrl: 'https://someproxyhost',
+      proxyRejectUnauthorizedCertificates: false,
+      proxyBypassHosts: undefined,
+      proxyOnlyHosts: new Set([targetHost]),
+    });
+    const { httpAgent, httpsAgent } = getCustomAgents(
+      configurationUtilities,
+      logger,
+      nonMatchingUrl
+    );
+    expect(httpAgent instanceof HttpProxyAgent).toBeFalsy();
+    expect(httpsAgent instanceof HttpsProxyAgent).toBeFalsy();
+  });
 });