fetch

This is the HTTP client for Hackolade Studio and its plugins. It takes into account the proxies and the custom certificate authorities that are configured at the level of the operating system, which removes the need for the end user to deal with complex network settings in Hackolade Studio. It also supports configuring custom network settings in the desktop application if needed.

Context

Web browsers provide natively the Fetch API. In Electron, that API was originally only available in the renderer process (which is basically a browser). It is now also available in the main process and in utility processes via net.fetch. Since that function uses the Chrome's network stack, it also benefits from the integration with the OS trust store (for validating self-signed-certificates) and network settings (for detecting proxies).

Approach

This library returns the proper implementation of fetch() depending on the runtime context:

• it returns the native Fetch API in a browser, as well as in a Electron renderer process
• it returns net.fetch in the Electron main and utility processes

This library also provides extensions to modular SDK's that allow setting a custom HTTP client:

• it provides a custom HttpHandler for the aws-sdk (see example here)

Release process

1. Open a pull request to bump the semantic version in package.json.
2. Set the title of your pull request to Release v<major>.<minor>.<patch>.
3. Document the content of the release in the description of your pull request.
4. Merge the pull request into the branch that you plan to release (develop typically).
5. Trigger the release workflow from the GitHub Actions for that branch. It will publish the library to the NPM registry as @hackolade/fetch. It will also create a GitHub release with the same description as the pull request you created.

Tests components

We need to test that this library behaves as expected in various situations, whatever the OS of the user:

• in both the main process, a renderer process and a utility process
• when connecting directly to a server (aka when no proxy is involved)
• when connecting to a server that uses a self-signed certificate whose authority has been installed in the trust store of the OS
• when connecting to a server through a proxy that has been configured either at the level of the OS, either manually in the application
  • through a simple proxy
  • through a proxy that requires basic authentication
  • through the proxy returned by a PAC file
  • through a proxy that performs HTTPS inspection using a self-signed certificate

In order to perform those tests, we have prepared multiple components:

Component	URL	Description
server	On your host (direct access): http://127.0.0.1:8080 https://127.0.0.1:4443 In Docker network (access through proxy): http://server:8080 https://server:4443	This server exposes the following REST endpoint: PUT /initiators/:connectionType/:initiator It allows clients to register themselves using arbitrary routes: /initiators/direct/main, initiators/proxy/renderer, etc. This server also exposes the following REST endpoint: GET /initiators/:connectionType/:initiator It can be used to check if a given client managed to reach the server to register itself.
app	NA	This is an Electron application. It contacts the server from both the main process, a renderer process and a utility process. Each process registers itself as a distinct :initiator: main, renderer and utility respectively. The base URL of the endpoint - including the :connectionType - is passed to the application through an environment variable, making it possible to start different instances of the application to cover different cases (e.g. direct connection, connection through a proxy).
proxy	http://127.0.0.1:3128	This is a proxy that does not require authentication.
proxy-basic-auth	http://127.0.0.1:3129	This is a proxy that requires basic authentication. You can use user1 as both username and password.
proxy-https-inspection	http://127.0.0.1:3130	This is a proxy that performs HTTPS inspection using a self-signed certificate.
PAC file	http://127.0.0.1:8081/proxy.pac	This is a PAC file that leads to using the proxy that does not require authentication.
tests	NA	This is a set of tests that query the REST API of the server to verify that all clients could successfully register themselves, whatever the context of the connection.

Test pre-requisites

Follow the instructions below prior to executing the tests:

• Install the latest version of node: see instructions here.
• Install and start the docker engine for your operating system: see instructions here.
• Run npm install in this repository in order to install the dependencies.

Test automation

You can run the command below to execute the automated tests.

npm run docker:test

⚠️ Those tests validate the behavior of the library in Docker/Linux. Validating the behavior of the library in MacOS and Windows involve manual steps that are documented below.

Test overview

See next sections for more details...

	Linux	MacOS	Windows	Notes
Direct connection	✅	✅	✅
OS SETTINGS				Test cases for proxy settings and certificate authorities from the OS
Self-signed certificate	✅	✅	✅
Proxy	✅	✅	✅
Proxy with basic auth	✅	⚠️	⚠️	'login' event not emitted for main process (see issue #44249)
PAC file	⚠️	✅	✅	Not natively supported by the Linux OS
Proxy with HTTPS inspection	✅	✅	✅
APP SETTINGS				Test cases for proxy settings and certificate authorities configured in the app
Self-signed certificate	✅	⚠️	⚠️	setCertificateVerifyProc() ignored by utility process (see issue #44264)
Proxy	✅	✅	✅
Proxy with basic auth	✅	⚠️	⚠️	'login' event not emitted for main process (see issue #44249)
PAC file	✅	✅	✅

Test direct connection

In this case, the app connects directly to the server. There is no intermediate proxy involved.

✅ Linux: this case is covered by the automated tests.

✅ MacOS, ✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Start the application with npm run test:app:direct. It should render all connections with a green background.

Test integration with OS settings

The test cases that are described in this section cover the integration with the OS trust store (for validating self-signed-certificates) and network settings (for detecting proxies).

[OS] Test connection involving a self-signed certificate

For a certificate to be considered valid, it must be signed by a trusted certificate authority (CA), such as GlobalSign or DigiCert. Obtaining such a certificate used to cost some money (this is not true anymore thanks to Let's Encrypt, a nonprofit certificate authority). That's why some organizations generated their own self-signed certificates, typically for internal use. Those certificates are free. However, they are unsafe and prevent HTTPS connections from being established. To be able to use self-signed certificates, an organization must add itself to the list of trusted certificate authorities in the OS of all its users.

✅ Linux: this case is covered by the automated tests. Note that the custom certificate authority must be added to the NSS Shared DB (see instructions here).

✅ MacOS: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the MacOS Keychain Access.
3. Click on File > Import Items.
4. Select the certificate ./test/resources/certs/gen/rootCA.crt.
5. Locate the certificate that you just imported in your keychain (search for Hackolade-Test-Root-CA) and double click on it.
6. Expand the Trust section of the details dialog and choose to Always Trust the certificate for SSL.
7. Close the details dialog to apply your changes.
8. Start the application with npm run test:app:cert. It should render all connections with a green background.
9. [Optional] You can remove the certificate from your keychain.

✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Using the file explorer, double click on the certificate ./test/resources/certs/gen/rootCA.crt.
3. Click on Install certificate in the details dialog.
4. Click on Next until you have the option to select a store. Browser the available stores and select Trusted Root Certification Authorities (Autorités de certification racines de confiance in French).
5. Click on Next until you complete the installation process.
6. Start the application with npm run test:app:cert. It should render all connections with a green background.
7. [Optional] You can remove the certificate using the Windows Certificate Manager (search for certmgr.msc in the Start menu).

[OS] Test connection through a proxy

In this case, the app connects to the server through a proxy that has been configured in the OS.

✅ Linux: this case is covered by the automated tests. Note that the proxy is configured through the environment variables HTTP_PROXY and HTTPS_PROXY, which is the standard way of configuring proxies in Linux.

✅ MacOS: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the MacOS System Settings.
3. Select Network in the left menu.
4. Navigate to the details of your network connection.
5. In the details dialog, select Proxies.
6. Enable Web proxy (HTTP) and provide the following settings:
   • Server: 127.0.0.1
   • Port: 3128
   • No authentication required
7. Click on OK to apply your changes.
8. Start the application with npm run test:app:proxy. It should render all connections with a green background.
9. Turn off the proxy.

✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the Settings app by pressing Windows+I.
3. Select Network & Internet in the left menu.
4. Navigate to the Proxy section.
5. Configure a proxy manually with the following settings:
   • Server: 127.0.0.1
   • Port: 3128
6. Click on Save to apply your changes.
7. Start the application with npm run test:app:proxy. It should render all connections with a green background.
8. Turn off the proxy.

[OS] Test connection through a proxy that requires basic authentication

In this case, the app connects to the server through a proxy that has been configured in the OS. That proxy requires a username and a password. Even though the username and the password might have been set at the level of the operating system, the user needs to provide them interactively to the Electron application. It is also the case for other apps such as Slack or Docker Desktop.

The main process must handle the login event and prompt the user for the proxy credentials.

const { app } = require('electron');

app.on('login', (event, webContents, details, authInfo, callback) => {
  // Prevent the default behavior since it cancels all authentications.
  event.preventDefault();

  // Prompt the user for credentials
  // ...

  callback(username, password);
});

The login handler will be called automatically for both the main process and a renderer process. For a utility process, the option respondToAuthRequestsFromMainProcess must be set to true when creating it.

const { utilityProcess } = require('electron');

utilityProcess.fork(..., { respondToAuthRequestsFromMainProcess: true });

✅ Linux: this case is covered by the automated tests. Note that the proxy is configured through the environment variables HTTP_PROXY and HTTPS_PROXY, which is the standard way of configuring proxies in Linux.

⚠️ MacOS: follow the instructions below. Note that the server cannot be contacted from the main process because the 'login' event (see code snippet above) is not emitted for that process, which ultimately leads to a HTTP #407 Proxy Authentication Required.

1. Start the server with npm run docker:server.
2. Open the MacOS System Settings.
3. Select Network in the left menu.
4. Navigate to the details of your network connection.
5. In the details dialog, select Proxies.
6. Enable Web proxy (HTTP) and provide the following settings:
   • Server: 127.0.0.1
   • Port: 3129
   • Username: user1
   • Password: user1
7. Click on OK to apply your changes.
8. Start the application with npm run test:app:proxy-basic-auth. It should render all connections with a green background. Note that you won't be prompted for credentials because we hardcoded them.
9. Turn off the proxy.

✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the Settings app by pressing Windows+I.
3. Select Network & Internet in the left menu.
4. Navigate to the Proxy section.
5. Configure a proxy manually with the following settings:
   • Server: 127.0.0.1
   • Port: 3129
6. Click on Save to apply your changes.
7. Open the Windows Start menu and search for Credential Manager (Gestionnaire d'identification in French).
8. In the credential manager, click on Windows Credentials (Information d'identification Windows in French).
9. Click on Add a Windows credential (Ajouter des informations d'identification Windows) and provide the following settings:
   • Network address: 127.0.0.1:3129
   • User name: user1
   • Password: user1
10. Click on OK to apply your changes.
11. Start the application with npm run test:app:proxy-basic-auth. It should render all connections with a green background. Note that you won't be prompted for credentials because we hardcoded them.
12. Turn off the proxy. Delete the Windows credential that you created.

[OS] Test connection through a proxy configured via a PAC file

In this case, the app connects to the server through the proxy that is returned by a PAC file that has been configured in the OS.

⚠️ Linux: PAC files are not natively supported by Linux, aka you cannot set HTTP_PROXY or HTTPS_PROXY to the URL of a PAC file. Linux requires the application itself to provide support for PAC files. That's because PAC files were originally meant to be used by browsers (see here). That's why they are JavaScript files.

✅ MacOS: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the MacOS System Settings.
3. Select Network in the left menu.
4. Navigate to the details of your network connection.
5. In the details dialog, select Proxies.
6. Enable Auto proxy configuration and provide the following URL: http://127.0.0.1:8081/proxy.pac.
7. Click on OK to apply your changes.
8. Start the application with npm run test:app:proxy-pac-file. It should render all connections with a green background.
9. Turn off the proxy.

✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the Settings app by pressing Windows+I.
3. Select Network & Internet in the left menu.
4. Navigate to the Proxy section.
5. Choose to use an installation script and provide the following URL: http://127.0.0.1:8081/proxy.pac.
6. Click on Save to apply your changes.
7. Start the application with npm run test:app:proxy-pac-file. It should render all connections with a green background.
8. Turn off the proxy.

[OS] Test connection through a proxy that performs HTTPS inspection

HTTPS inspection is the process of checking encrypted web traffic. It relies on a proxy that sets up two separate encrypted connections:

• there is a first HTTPS connection between the client and the proxy where the proxy impersonates the server
• there is a second HTTPS connection between the proxy and the server where the proxy impersonates the client

Note that the proxy can use a self-signed certificate. This means that establishing the connection with a server can require a custom certificate authority even though the server uses a valid certificate.

✅ Linux: this case is covered by the automated tests.

✅ MacOS: follow the instructions below.

1. Start the server with npm run docker:server.
2. Open the MacOS Keychain Access.
3. Click on File > Import Items.
4. Select the certificate ./test/resources/certs/gen/rootCA.crt.
5. Locate the certificate that you just imported in your keychain (search for Hackolade-Test-Root-CA) and double click on it.
6. Expand the Trust section of the details dialog and choose to Always Trust the certificate for SSL.
7. Close the details dialog to apply your changes.
8. Start the application with test:app:proxy-https-inspection. It should render all connections with a green background.
9. [Optional] You can remove the certificate from your keychain.

✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Using the file explorer, double click on the certificate ./test/resources/certs/gen/rootCA.crt.
3. Click on Install certificate in the details dialog.
4. Click on Next until you have the option to select a store. Browser the available stores and select Trusted Root Certification Authorities (Autorités de certification racines de confiance in French).
5. Click on Next until you complete the installation process.
6. Start the application with test:app:proxy-https-inspection. It should render all connections with a green background.
7. [Optional] You can remove the certificate using the Windows Certificate Manager (search for certmgr.msc in the Start menu).

Test custom application settings

The test cases that are described in this section cover the configuration of custom network settings in the application itself.

[APP] Test connection involving a self-signed certificate

In this case, the app connects to a server that uses a self-signed certificate. The corresponding certificate authority has not been installed in the trust store of the operating system: it is configured directly in the application. You can find here the code that installs that certificate authority in the application.

✅ Linux: this case is covered by the automated tests.

⚠️ MacOS, ⚠️ Windows: follow the instructions below. Note that the server cannot be contacted from the utility process because it ignores the custom procedure that we set for verifying the certificate (see session.setCertificateVerifyProc()).

1. Start the server with npm run docker:server.
2. Start the application with npm run test:app:custom-cert. It should render all connections with a green background, except for the utility process.

[APP] Test connection through a proxy

In this case, the app connects to the server through a proxy that has been configured in the app itself. You can find here the code that applies the given proxy settings.

✅ Linux: this case is covered by the automated tests.

✅ MacOS, ✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Start the application with npm run test:app:custom-proxy. It should render all connections with a green background.

[APP] Test connection through a proxy that requires basic authentication

In this case, the app connects to the server through a proxy that has been configured in the app itself. That proxy requires a username and a password.

✅ Linux: this case is covered by the automated tests.

⚠️ MacOS, ⚠️ Windows: follow the instructions below. Note that the server cannot be contacted from the main process because the 'login' event is not emitted for that process, which ultimately leads to a HTTP #407 Proxy Authentication Required.

1. Start the server with npm run docker:server.
2. Start the application with npm run test:app:custom-proxy-basic-auth. It should render all connections with a green background, except for the main process.

[APP] Test connection through a proxy configured via a PAC file

In this case, the app connects to the server through the proxy that is returned by a PAC file that has been configured in the app itself.

✅ Linux: this case is covered by the automated tests.

✅ MacOS, ✅ Windows: follow the instructions below.

1. Start the server with npm run docker:server.
2. Start the application with npm run test:app:custom-proxy-pac-file. It should render all connections with a green background.

Known Issues

I am on Windows and I get the error "$'\r': command not found"

This problem is related to line break differences between operating systems. To fix it, just save the Dockerfile using the LF line break (e.g. from the status bar in Visual Studio Code).

Bug report

When reporting an issue in the Electron repository, you need to provide a standalone test case that reproduces the problem. You can do this easily by using Electron Fiddle. You can connect it to your GitHub account and easily upload a test case as a public gist that you can then link from the GitHub issue that you are creating.

Examples:

• Issue #44249
• Issue #44264