Alpine Container Running Tiny Proxy on GCP Cloud Run Returns 404 when Sending Request from Local Machine
Google Cloud Run is a managed compute platform that enables you to run stateless containers that are invocable via HTTP requests. It is a powerful tool for deploying applications, but occasionally, issues can arise that require troubleshooting. In this article, we will explore a particular issue that occurs when sending a request from a local machine to an Alpine container running Tiny Proxy on GCP Cloud Run, which results in a 404 error.
Tiny Proxy and Alpine Container
Tiny Proxy is a lightweight, forward-proxy server that is often used in testing and debugging scenarios. Alpine is a security-oriented, lightweight Linux distribution that is often used as a base image for containers. When combined, an Alpine container running Tiny Proxy can provide a convenient testing environment.
Issue: 404 Error when Sending Request from Local Machine
When sending a request from a local machine to an Alpine container running Tiny Proxy on GCP Cloud Run, a 404 error may occur. This is unexpected, as the Alpine container and Tiny Proxy are both running and functioning correctly. To troubleshoot this issue, let's explore some key concepts related to the topic.
Key Concepts
- Container Ports: A container exposes ports to enable communication between the container and the host machine. These ports must be mapped correctly between the container and the host machine for communication to occur.
- Firewall Rules: Firewall rules on GCP must be configured correctly to allow incoming traffic on specific ports.
- Cloud Run Services: Cloud Run services must be configured correctly to expose containers and ports for external communication.
Troubleshooting the Issue
To troubleshoot the issue of a 404 error occurring when sending a request from a local machine to an Alpine container running Tiny Proxy on GCP Cloud Run, let's explore each of the key concepts in more detail.
Step 1: Check Container Ports
The first step in troubleshooting the issue is to ensure that the container ports are mapped correctly. In this example, we are using port 8080 for communication.
docker run -p 8080:8080 my-alpine-tinyproxy-image
This maps the container's port 8080 to the host's port 8080, enabling communication between the two.
Step 2: Check Firewall Rules
The next step is to ensure that the firewall rules on GCP are configured correctly. By default, GCP blocks all incoming traffic. To enable incoming traffic on port 8080, a firewall rule must be created.
gcloud compute firewall-rules create allow-8080 --allow tcp:8080 --target-tags=my-container-tag
This creates a firewall rule that allows incoming traffic on port 8080 for containers with the tag "my-container-tag".
Step 3: Check Cloud Run Services
The final step is to ensure that the Cloud Run services are configured correctly. In Cloud Run, a service maps a container image to a URI that can be accessed via HTTP requests. To expose the container and ports for external communication, the service must be configured correctly.
gcloud run deploy tinyproxy \
--image=gcr.io/my-project-id/my-alpine-tinyproxy-image \
--platform managed \
--port 8080 \
--region us-central1 \
--allow-unauthenticated \
--tags=my-container-tag
This deploys the container image to Cloud Run and exposes port 8080 for external communication. The tag "my-container-tag" enables the firewall rule created in step 2 to allow incoming traffic on port 8080.
When sending a request from a local machine to an Alpine container running Tiny Proxy on GCP Cloud Run and receiving a 404 error, it is important to check the container ports, firewall rules, and Cloud Run services. By ensuring that these are configured correctly, communication can be established successfully.
References
- Google Cloud Run: https://tinyproxy.github.io/
- Alpine Linux: https://www.alpinelinux.org/