ci/cd: fix IPv6 timeout with force-ipv4 action

This commit introduces the `force-ipv4` GitHub action to address
connectivity issues caused by the lack of IPv6 support in GitHub
runners. Details:
- actions/runner$3138
- actions/runner-images$668

This change solves connection problems when Node's `fetch` API fails due
to `UND_ERR_CONNECT_TIMEOUT` errors. Details:
- actions/runner-images$9540
- actions/runner$3213

This action disables IPv6 at the system level, ensuring all outging
requests use IPv4. Resolving connectivity issues when running external
URL checks and Docker build checks.

This solution is a temporary workaround until GitHub runners support
IPv6 or Node `fetch` API has a working solution such as Happy Eyeball:
- nodejs/nodei$41625
- nodejs/undici$1531

.github/actions/force-ipv4/README.md

@@ -0,0 +1,31 @@
+# force-ipv4
+
+## Overview
+
+This GitHub action enforces IPv4 for all outgoing network requests. It addresses connectivity issues encountered in GitHub runners, where IPv6 requests may lead to timeouts due to the lack of IPv6 support [1] [2].
+
+## Background
+
+Some applications attempt network connections over IPv6.
+Such as requests made by Node's `fetch` API causes `UND_ERR_CONNECT_TIMEOUT` errors [3] [4].
+This happens when the software cannot handle this such as by using Happy Eyeballs [5] [6].
+
+## Usage
+
+To use this action in your GitHub workflow, add the following step before any job that requires network access:
+
+```yaml
+- name: Enforce IPv4 Connectivity
+  uses: ./.github/actions/force-ipv4
+```
+
+## Note
+
+This action is a workaround addressing specific IPv6-related connectivity issues on GitHub runners and may not be necessary if GitHub's infrastructure evolves to fully support IPv6 in the future.
+
+[1]: https://archive.ph/2024.03.28-185829/https://github.com/actions/runner/issues/3138 "Actions Runner fails on IPv6 only host · Issue #3138 · actions/runner · GitHub | github.com"
+[2]: https://archive.ph/2024.03.28-185838/https://github.com/actions/runner-images/issues/668 "IPv6 on GitHub-hosted runners · Issue #668 · actions/runner-images · GitHub | github.com"
+[3]: https://archive.ph/2024.03.28-185847/https://github.com/actions/runner/issues/3213 "GitHub runner cannot send `fetch` with `node`, failing with IPv6 DNS error `UND_ERR_CONNECT_TIMEOUT` · Issue #3213 · actions/runner · GitHub | github.com"
+[4]: https://archive.today/2024.03.28-185853/https://github.com/actions/runner-images/issues/9540 "Cannot send outbound requests using node fetch, failing with IPv6 DNS error UND_ERR_CONNECT_TIMEOUT · Issue #9540 · actions/runner-images · GitHub | github.com"
+[5]: https://archive.today/2024.03.28-185900/https://github.com/nodejs/node/issues/41625 "Happy Eyeballs support (address IPv6 issues in Node 17) · Issue #41625 · nodejs/node · GitHub | github.com"
+[6]: https://archive.today/2024.03.28-185910/https://github.com/nodejs/undici/issues/1531 "fetch times out in under 5 seconds · Issue #1531 · nodejs/undici · GitHub | github.com"

.github/actions/force-ipv4/action.yml

@@ -0,0 +1,12 @@
+inputs:
+  project-root:
+    required: false
+    default: '.'
+runs:
+  using: composite
+  steps:
+    -
+      name: Run prefer IPv4 script
+      shell: bash
+      run: ./.github/actions/force-ipv4/force-ipv4.sh
+      working-directory: ${{ inputs.project-root }}

.github/actions/force-ipv4/force-ipv4.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+
+main() {
+  if is_linux; then
+    echo 'Configuring Linux...'
+    disable_ipv6_on_linux
+  elif is_macos; then
+    echo 'Configuring macOS...'
+    disable_ipv6_on_macos
+  fi
+  nslookup localhost # TODO: Delete
+}
+
+is_linux() {
+  [[ "$(uname -s)" == "Linux" ]]
+}
+
+is_macos() {
+  [[ "$(uname -s)" == "Darwin" ]]
+}
+
+disable_ipv6_on_linux() {
+  # Temporarily and immediately disable IPv6
+  echo '1' | sudo tee /proc/sys/net/ipv6/conf/all/disable_ipv6 > /dev/null
+  echo '1' | sudo tee /proc/sys/net/ipv6/conf/default/disable_ipv6 > /dev/null
+  # Other approaches considered:
+  # - Prefer IPv4 in `/etc/gai.conf`: Requires proper configuration (just `precedence ::ffff:0:0/96  100`) is not enough.
+  # - Using `sysctl` command: Results in Node 18 to exit with code `13`.
+  # - Writing to `/proc/sys/net/`: Results in Node 18 to exit with code `13`.
+  # - Writing to `/etc/sysctl.conf`: Results in Node 18 to exit with code `13`.
+  #     echo '1' | sudo tee /proc/sys/net/ipv6/conf/all/disable_ipv6 > /dev/null
+  #     echo '1' | sudo tee /proc/sys/net/ipv6/conf/default/disable_ipv6 > /dev/null
+  sleep 1
+  echo "IPv4: $(sudo curl -s4m8 --retry 3 -A Mozilla https://api.ip.sb/geoip)"
+  echo "IPv6: $(sudo curl -s6m8 --retry 3 -A Mozilla https://api.ip.sb/geoip)"
+  nslookup
+}
+
+prefer_ipv4_on_linux() {
+  local -r gai_conf="/etc/gai.conf"
+  if [ ! -f "$gai_conf" ]; then
+      echo "Creating $gai_conf since it doesn't exist..."
+      touch "$gai_conf"
+  fi
+  echo "precedence ::ffff:0:0/96  100" | sudo tee -a "$gai_conf" > /dev/null
+  echo "Configuration complete."
+}
+
+disable_ipv6_on_macos() {
+  networksetup -listallnetworkservices \
+    | tail -n +2 \
+    | while IFS= read -r interface; do
+        echo "Disabling IPv6 on: $interface"
+        networksetup -setv6off "$interface"
+      done
+}
+
+main

.github/workflows/checks.build.yaml

@@ -95,6 +95,9 @@ jobs:
       -
         name: Run Docker image on port 8080
         run: docker run -d -p 8080:80 --rm --name privacy.sexy undergroundwires/privacy.sexy:latest
+      -
+        name: Enforce IPv4 Connectivity # Used due to GitHub runners' lack of IPv6 support, preventing request timeouts.
+        uses: ./.github/actions/force-ipv4
       -
         name: Check server is up and returns HTTP 200
         run: >-

.github/workflows/checks.external-urls.yaml

@@ -17,6 +17,9 @@ jobs:
       -
         name: Install dependencies
         uses: ./.github/actions/npm-install-dependencies
+      -
+        name: Enforce IPv4 Connectivity # Used due to GitHub runners' lack of IPv6 support, preventing request timeouts.
+        uses: ./.github/actions/force-ipv4
       -
         name: Test
         run: npm run check:external-urls

scripts/verify-web-server-status.js

@@ -20,6 +20,15 @@ const RETRY_DELAY_IN_SECONDS = 3;
 const PARAMETER_NAME_URL = '--url';
 const PARAMETER_NAME_MAX_RETRIES = '--max-retries';
 
+async function main() {
+  try {
+    await checkServer();
+  } catch (error) {
+    exitWithError('Uncaught exception:', error);
+    exitWithError('Verification failed with unexpected error.');
+  }
+}
+
 async function checkServer(currentRetryCount = 1) {
   const serverUrl = readRequiredParameterValue(PARAMETER_NAME_URL);
   const maxRetries = parseNumber(
@@ -84,4 +93,12 @@ function exitWithError(message) {
   process.exit(1);
 }
 
-await checkServer();
+await main();
+
+process.on('uncaughtException', (error) => {
+  console.error('Uncaught Exception:', error);
+});
+
+process.on('unhandledRejection', (reason, promise) => {
+  console.error('Unhandled Rejection at:', promise, 'reason:', reason);
+});