Let's break this down step by step: first checking if your implementation approach makes sense, then troubleshooting the blobstore error you're encountering.

Is your current approach correct? #

Your core idea is valid—using the CF V3 API to package a Docker image, stage it into a droplet, then run it as a task is a supported workflow. However, there are a few tweaks that could make this smoother:

• You don't need to bind the package to your existing myspringboot-app unless you specifically want the task to inherit the app's environment/network settings. Tasks can be entirely independent, so creating a standalone package might avoid conflicts with your Java Buildpack app's configuration.
• Before running cf v3-stage, always confirm the package is in a READY state (use cf v3-packages <app-or-package-name> to check). If it's FAILED, CF couldn't pull your Docker image, which is likely tied to the error you're seeing.

Troubleshooting the "Failed to get blobstore download url" error #

This error almost always stems from CF being unable to access or pull your private Docker image. Here's how to fix it:

1. Validate your Docker credentials and image access #

First, rule out basic credential issues by testing locally:

docker login <private-repo> -u $CF_DOCKER_USERNAME -p $CF_DOCKER_PASSWORD
docker pull <private-repo>/eng-bdp_bdp-dev/etlwithpython:1

If this fails, your credentials are invalid, the image path is wrong, or your local machine can't reach the registry. Fix those issues first before trying again with CF.

2. Pass credentials directly when creating the package #

Sometimes environment variables don't propagate correctly to the CF CLI. Instead of relying on CF_DOCKER_USERNAME/CF_DOCKER_PASSWORD, pass them explicitly in the package creation command:

cf v3-create-package myspringboot-app --docker-image <private-repo>/eng-bdp_bdp-dev/etlwithpython:1 --docker-username $CF_DOCKER_USERNAME --docker-password $CF_DOCKER_PASSWORD

This ensures CF uses the correct credentials when pulling your image.

3. Check package status before staging #

Run cf v3-packages myspringboot-app and look for the package with GUID a3bd45cd-eb5f-4072-bee8-af0bd389f13a. If its status is FAILED, the registry access issue is confirmed. If it's PENDING, wait a minute for CF to finish pulling the image before staging.

4. Ensure CF can reach your private registry #

If your registry is in a private network, make sure the Cloud Foundry stager component has network access to it. You might need to configure network policies or VPN access for the CF infrastructure to reach the registry endpoint.

5. Use CF logs for deeper debugging #

If the above steps don't work, check the app logs (or stager logs if you have admin access) for more details:

cf logs myspringboot-app --recent

This might reveal specific issues like credential rejection, timeout errors, or invalid image tags.

A Simpler Alternative: Run the Task Directly from the Docker Image #

You don't actually need to stage a droplet to run a Docker-based task. The CF V3 API supports creating tasks directly from Docker images, which cuts out the package/stage steps entirely:

# Run a task tied to your Spring Boot app (inherits its environment)
cf v3-run-task myspringboot-app "<your-task-command>" --docker-image <private-repo>/eng-bdp_bdp-dev/etlwithpython:1 --docker-username $CF_DOCKER_USERNAME --docker-password $CF_DOCKER_PASSWORD

# Or create a standalone task (no app association)
cf v3-create-task --name my-etl-task --command "<your-task-command>" --docker-image <private-repo>/eng-bdp_bdp-dev/etlwithpython:1 --docker-username $CF_DOCKER_USERNAME --docker-password $CF_DOCKER_PASSWORD
cf v3-execute-task my-etl-task

This is a more straightforward workflow and avoids the blobstore error you're hitting.

内容的提问来源于stack exchange，提问作者Puvanenthiran Subbaraj