fix: allow host gateway traffic for localhost/Playwright#1435
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The `--allow-domains localhost` feature was broken because: 1. **Host-level iptables blocked gateway traffic**: The FW_WRAPPER chain in DOCKER-USER had no ACCEPT rules for the Docker bridge gateway IP, causing all traffic to host.docker.internal to hit the default REJECT rule. 2. **localhost resolved to container loopback**: The chroot /etc/hosts had `127.0.0.1 localhost` which made tools like Playwright connect to the container's own loopback instead of the host machine. 3. **AWF_ALLOW_HOST_PORTS not propagated**: The env var was missing from the iptables-init container, so custom port rules were never created. Changes: - Add HostAccessConfig to setupHostIptables() with gateway ACCEPT rules for both Docker bridge (172.17.0.1) and AWF network (172.30.0.1) gateways - Replace 127.0.0.1 localhost in chroot /etc/hosts with host gateway IP when localhostDetected (uses first-match semantics correctly) - Propagate AWF_ALLOW_HOST_PORTS to iptables-init container environment - Add port validation (isValidPortSpec) with dedup in host-iptables.ts - Add port validation (is_valid_port_spec) in setup-iptables.sh - Comprehensive test coverage for all new functionality Closes #1413 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Chroot Version Comparison Results
Result: Some versions differ between host and chroot. Go matches, but Python and Node.js are on different versions (chroot uses Ubuntu 22.04 system-installed runtimes while the host runner has newer versions via toolcache/nvm).
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Pull request overview
This PR fixes the “--allow-domains localhost” workflow so containers can reach dev servers running on the Docker host (not the container loopback), which is needed for Playwright/local testing and similar host-service access patterns.
Changes:
- Adds host-level iptables ACCEPT rules for host gateway traffic (including custom ports/ranges) when host access is enabled.
- Implements chroot
/etc/hostsrewriting solocalhostcan resolve to a host gateway IP whenlocalhostis detected in--allow-domains. - Propagates
AWF_ALLOW_HOST_PORTSinto the iptables-init container and adds port-spec validation in both TS and shell.
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| src/types.ts | Adds localhostDetected flag to WrapperConfig to drive localhost rewriting. |
| src/host-iptables.ts | Introduces host-access config, gateway discovery, and host-level iptables rules + port validation. |
| src/host-iptables.test.ts | Adds unit coverage for host-access iptables behavior and port-spec validation. |
| src/docker-manager.ts | Rewrites chroot hosts to map localhost to host gateway; propagates AWF_ALLOW_HOST_PORTS to iptables-init env. |
| src/cli.ts | Plumbs localhostDetected from localhost keyword processing into WrapperConfig. |
| src/cli-workflow.ts | Passes host-access config into setupHostIptables() when host access is enabled. |
| src/cli-workflow.test.ts | Verifies host-access config wiring into workflow dependency call. |
| containers/agent/setup-iptables.sh | Adds shell-side port spec validation before adding gateway accept/redirect rules. |
Comments suppressed due to low confidence (2)
src/docker-manager.ts:851
- This
hostsContent.replace()only updates127.0.0.1 localhost...lines and replaces the whole line with just"<gw>\tlocalhost", dropping any additional aliases that were on that line (e.g.localhost.localdomain). It also doesn’t address the common::1 localhost ...entry, solocalhostmay still resolve to IPv6 loopback first and continue pointing at the container. Consider preserving the suffix (capture group) in the replacement and also removing/replacinglocalhoston the::1line whenlocalhostDetectedis enabled.
hostsContent = hostsContent.replace(
/^127\.0\.0\.1\s+localhost(\s+.*)?$/gm,
`${hostGatewayIp}\tlocalhost`
);
src/host-iptables.ts:445
- When parsing
allowHostPorts, invalid specs are only logged and skipped. Since host iptables is set up before configs are generated (and before Squid validates ports), this can leave the host firewall partially configured and lead to confusing “port still blocked” failures. Consider treating an invalidallowHostPortsentry as a hard error (throw) so the run fails early and predictably, or validate--allow-host-portsin the CLI before any iptables side effects.
for (const entry of hostAccess.allowHostPorts.split(',')) {
const trimmed = entry.trim();
if (trimmed) {
if (!isValidPortSpec(trimmed)) {
logger.warn(`Skipping invalid port spec: ${trimmed}`);
continue;
}
customPorts.push(trimmed);
}
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| if (String(start) !== rangeMatch[1] || String(end) !== rangeMatch[2]) return false; | ||
| return start >= 1 && start <= 65535 && end >= 1 && end <= 65535 && start <= end; | ||
| } | ||
| const port = parseInt(spec, 10); | ||
| return !isNaN(port) && String(port) === spec && port >= 1 && port <= 65535; |
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isValidPortSpec() rejects leading zeros by comparing String(parseInt(...)) with the original token. That’s fine, but it creates inconsistent behavior with other layers: containers/agent/setup-iptables.sh and src/squid-config.ts currently accept leading-zero port specs, so a value like 080-090 could be allowed by Squid/NAT but silently skipped here at the host firewall layer (breaking connectivity). Recommend aligning validation across host iptables + agent iptables + Squid (either reject leading zeros everywhere and fail fast in CLI, or accept them everywhere).
This issue also appears on line 437 of the same file.
| if (String(start) !== rangeMatch[1] || String(end) !== rangeMatch[2]) return false; | |
| return start >= 1 && start <= 65535 && end >= 1 && end <= 65535 && start <= end; | |
| } | |
| const port = parseInt(spec, 10); | |
| return !isNaN(port) && String(port) === spec && port >= 1 && port <= 65535; | |
| return start >= 1 && start <= 65535 && end >= 1 && end <= 65535 && start <= end; | |
| } | |
| if (!/^\d+$/.test(spec)) return false; | |
| const port = parseInt(spec, 10); | |
| return port >= 1 && port <= 65535; |
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Thanks for the catch. The leading-zero rejection is intentional for consistency — I've aligned the bash is_valid_port_spec() in setup-iptables.sh to also reject leading zeros (using [1-9][0-9]{0,4} pattern instead of [0-9]+). This makes all three layers (host iptables, container iptables, Squid config) consistent: leading zeros are rejected everywhere and the CLI fails fast.
containers/agent/setup-iptables.sh
Outdated
| if echo "$spec" | grep -qE '^[0-9]+-[0-9]+$'; then | ||
| local start=$(echo "$spec" | cut -d- -f1) | ||
| local end=$(echo "$spec" | cut -d- -f2) | ||
| [ "$start" -ge 1 ] && [ "$start" -le 65535 ] && [ "$end" -ge 1 ] && [ "$end" -le 65535 ] && [ "$start" -le "$end" ] | ||
| elif echo "$spec" | grep -qE '^[0-9]+$'; then |
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is_valid_port_spec allows leading-zero port numbers/ranges (e.g. 080-090), while the new TypeScript isValidPortSpec() explicitly rejects them. This inconsistency can cause ports to be accepted in one layer but rejected/ignored in another. If the intent is “leading-zero rejection for port ranges”, update this shell validation to also reject leading zeros (and keep behavior consistent across host + agent + Squid).
| if echo "$spec" | grep -qE '^[0-9]+-[0-9]+$'; then | |
| local start=$(echo "$spec" | cut -d- -f1) | |
| local end=$(echo "$spec" | cut -d- -f2) | |
| [ "$start" -ge 1 ] && [ "$start" -le 65535 ] && [ "$end" -ge 1 ] && [ "$end" -le 65535 ] && [ "$start" -le "$end" ] | |
| elif echo "$spec" | grep -qE '^[0-9]+$'; then | |
| # Disallow leading zeros in both single ports and ranges to align with TypeScript validation. | |
| if echo "$spec" | grep -qE '^[1-9][0-9]{0,4}-[1-9][0-9]{0,4}$'; then | |
| local start=$(echo "$spec" | cut -d- -f1) | |
| local end=$(echo "$spec" | cut -d- -f2) | |
| [ "$start" -ge 1 ] && [ "$start" -le 65535 ] && [ "$end" -ge 1 ] && [ "$end" -le 65535 ] && [ "$start" -le "$end" ] | |
| elif echo "$spec" | grep -qE '^[1-9][0-9]{0,4}$'; then |
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Fixed in 347c112. The bash is_valid_port_spec() now uses ^[1-9][0-9]{0,4} patterns (both for single ports and ranges), matching the TypeScript String(parseInt(x)) === x round-trip check. Leading-zero ports like 080 or 080-090 are now rejected in both layers.
| if (config.localhostDetected) { | ||
| // Replace 127.0.0.1 localhost entries with the host gateway IP | ||
| // /etc/hosts uses first-match semantics, so we must replace rather than append | ||
| hostsContent = hostsContent.replace( | ||
| /^127\.0\.0\.1\s+localhost(\s+.*)?$/gm, | ||
| `${hostGatewayIp}\tlocalhost` | ||
| ); | ||
| logger.info('localhost inside container resolves to host machine (localhost keyword active)'); | ||
| } |
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In chroot mode, this rewrites localhost to hostGatewayIp that was computed via docker network inspect bridge. That IP may not match the host.docker.internal:host-gateway value for the AWF network (often the awf-net gateway, e.g. 172.30.0.1), which is what setup-iptables.sh uses when adding NAT RETURN/ACCEPT rules. If these differ, chrooted processes will connect to an IP that is still DNAT’d to Squid (or blocked), so localhost/host access remains broken. Consider deriving the gateway from the actual AWF network (docker network inspect awf-net ... Gateway) or otherwise using the same IP that Docker will inject for host-gateway on the awf-net network.
This issue also appears on line 848 of the same file.
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Good observation, but this is already handled. The host-iptables.ts FW_WRAPPER chain adds ACCEPT rules for both gateway IPs:
- Docker bridge gateway (172.17.0.1) — from
getDockerBridgeGateway()(line 410) - AWF network gateway (172.30.0.1) — hardcoded as
AWF_NETWORK_GATEWAY(line 414)
Similarly, setup-iptables.sh adds NAT RETURN + FILTER ACCEPT for both the host.docker.internal IP (resolved via getent hosts, typically 172.17.0.1) AND the network gateway (172.30.0.1, resolved via route -n).
The /etc/hosts uses the Docker bridge gateway IP (172.17.0.1) for the localhost entry, which matches the host.docker.internal IP that Docker injects via extra_hosts: host-gateway. Traffic to this IP is allowed by both the container-level and host-level rules. The dual-gateway approach ensures it works regardless of which IP the tool resolves to.
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Aligns is_valid_port_spec() in setup-iptables.sh with the TypeScript
isValidPortSpec() by rejecting leading-zero port specs (e.g., 080-090).
Uses [1-9][0-9]{0,4} regex pattern instead of [0-9]+ to ensure
consistent validation across all layers (host iptables, container
iptables, Squid config).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Smoke Test Results — PASS
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Smoke Test Results — ✅ GitHub MCP: #1420 Overall: PASS
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Chroot Version Comparison Results
Overall: Not all tests passed — Python and Node.js versions differ between host and chroot environments.
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🏗️ Build Test Suite Results
Overall: 8/8 ecosystems passed — ✅ PASS
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- Validate Docker bridge gateway IP as IPv4 before using in iptables rules or /etc/hosts injection (defense-in-depth) - Preserve localhost.localdomain and other aliases when replacing 127.0.0.1 localhost in /etc/hosts Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Smoke Test Results
Overall: PASS
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Smoke Test Results ✅ PASS
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Chroot Version Comparison Results
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Summary
Fixes the
--allow-domains localhostfeature which was completely broken — agents inside AWF containers could not reach dev servers running on the host machine, breaking Playwright testing workflows.Three root causes fixed:
Host-level FW_WRAPPER iptables chain blocked gateway traffic: The
DOCKER-USER → FW_WRAPPERchain had no ACCEPT rules for the Docker bridge gateway IP (172.17.0.1), so all traffic tohost.docker.internalhit the default REJECT. AddedHostAccessConfigparameter tosetupHostIptables()with per-port ACCEPT rules for both Docker bridge and AWF network gateways.localhostresolved to container loopback: The chroot/etc/hostshad127.0.0.1 localhost, making Playwright connect to the container's own loopback. Now replaces the entry with the host gateway IP when--allow-domains localhostis used (first-match semantics).AWF_ALLOW_HOST_PORTSnot propagated to iptables-init: The env var was missing from the iptables-init container environment, so custom port ACCEPT rules were never created at the container level.Additional hardening:
isValidPortSpec) in TypeScript with dedup viaSetis_valid_port_spec) insetup-iptables.sh(defense-in-depth)Test plan
npm test— 1180 tests passnpm run lint— 0 errorshost.docker.internal:8080reachable with--allow-domains localhost--allow-host-portsworkslocalhostkeyword, host unreachablelocalhostto host gatewaycurlon Ubuntu 22.04 has hardcoded localhost resolution bypassing/etc/hosts— this is a known curl behavior, not our bug. Playwright (Node.js) usesgetaddrinfo()which works correctly.Closes #1413
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