Docker Compose ANTHROPIC_API_KEY Not Forwarded to Web Container

What this error means

ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose is a Docker failure pattern reported for developers trying to fix anthropic_api_key not set error in docker compose web container. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

PR #199 (May 2026) fixes a Docker Compose issue where the web service’s environment block didn’t forward ANTHROPIC_API_KEY from the host. The web container had no Anthropic key, causing all LLM calls to fail with ‘ANTHROPIC_API_KEY is not set’. Surfaced during May 11 smoke test.

Common causes

• Developers running LLM-integrated applications in Docker Compose find that the web container fails with ‘ANTHROPIC_API_KEY is not set’ even though the host has the variable configured. The docker-compose.yml environment block doesn’t forward ANTHROPIC_API_KEY from the host, causing all LLM calls (prep brief, clinical analysis, protocol generation) to fail silently.
• PR #199 (May 2026) fixes a Docker Compose issue where the web service’s environment block didn’t forward ANTHROPIC_API_KEY from the host. The web container had no Anthropic key, causing all LLM calls to fail with ‘ANTHROPIC_API_KEY is not set’. Surfaced during May 11 smoke test.

Quick fixes

1. Confirm the exact error signature matches ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose.
2. Check the Docker account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/Clinical-Signal/clinical-signal-main/pull/199

Evidence note: PR #199 (May 2026) fixes a Docker Compose issue where the web service’s environment block didn’t forward ANTHROPIC_API_KEY from the host. The web container had no Anthropic key, causing all LLM calls to fail with ‘ANTHROPIC_API_KEY is not set’. Surfaced during May 11 smoke test.

Related errors

• Docker environment variable not passed to container
• Docker Compose secrets not forwarded
• Container missing API key environment variable

FAQ

What should I check first?

Start with the exact ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Docker workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose.