Vanilla Harbor has no Vertex AI support. This patch adds it.

Replaces claude_code.py in the installed Harbor package and patches docker-compose-base.yaml:

• Vertex AI env var passthrough: CLAUDE_CODE_USE_VERTEX, ANTHROPIC_VERTEX_PROJECT_ID, CLOUD_ML_REGION
• ADC credential upload: Automatically copies your local Google Cloud credentials into the Docker container
• iptables REJECT rule: Blocks connections to the GCP metadata server (169.254.169.254) so the native binary's auth probes fail instantly instead of timing out for ~300s per API call
• NET_ADMIN capability: Added to docker-compose-base.yaml (required for iptables)
• --dangerously-skip-permissions: Replaces --permission-mode=bypassPermissions

uv tool install harbor

cd ~/work/harbor
bash vertex-patch/apply.sh

# Authenticate (creates ~/.config/gcloud/application_default_credentials.json)
gcloud auth application-default login

# Or point to an existing service account key:
export GOOGLE_APPLICATION_CREDENTIALS=/path/to/credentials.json

export CLAUDE_CODE_USE_VERTEX=1
export ANTHROPIC_VERTEX_PROJECT_ID=your-gcp-project
export CLOUD_ML_REGION=us-east5  # or "global"

harbor run \
    -a claude-code \
    -m "claude-sonnet-4-6" \
    -p "tasks/your-task" \
    -n 1 \
    --force-build

Use --force-build the first time (or after upgrading Harbor) to rebuild Docker images.

uv tool upgrade harbor overwrites the patched files. Re-run the script:

uv tool upgrade harbor
bash vertex-patch/apply.sh

The native Claude Code binary bundles the Bun runtime, which has a ~75s socket connect timeout. When running in Docker, the Google/AWS/Azure auth libraries probe the GCP metadata server (169.254.169.254:80) on every API call. This endpoint doesn't exist in Docker, so each probe times out. With 4 retries, that's ~300s of dead time per API call.

The iptables rule (iptables -A OUTPUT -d 169.254.169.254 -j REJECT) makes these connections fail instantly with ECONNREFUSED instead of timing out. The auth libraries then fall through to the ADC credentials file without delay.

This is safe: 169.254.169.254 only exists on GCP VMs. In Docker, it's unreachable anyway -- this just makes the failure instant instead of slow.

• Harbor 0.3.0
• Claude Code 2.1.96 (native binary)
• Vertex AI, region global, project claude-code-prod
• macOS host (Darwin 24.6.0)
• Task: a-minimal-no-skills (ubuntu:24.04 base) -- 2:03 wall time, 12 steps, max gap 16s, zero metadata server delays