Docker Port Exposed But Not Accessible From Host
A port that shows up in docker ps but doesn't respond when you try to connect from the host almost always means the application inside the container is bound...
Category
Docker
Troubleshooting Docker containers, images, networking and Compose.
Docker Environment Variables Not Loading From .env File
When environment variables from a .env file don't show up inside a container, the cause is usually a mismatch between what actually reads that file (Docker...
Docker Healthcheck Always Showing Unhealthy
A container marked "unhealthy" by Docker despite the application clearly working when tested manually almost always means the healthcheck command itself is...
Docker Image Size Too Large, How to Reduce It
A bloated Docker image isn't usually caused by your application code — it's almost always the base image choice, unnecessary build tools left in the final...
Docker Multi-Stage Build Not Copying Files Correctly
When files that clearly exist in an earlier build stage don't show up in the final image after a COPY --from, the cause is almost always a mismatch between the...
Docker "No Space Left on Device" Error Fix
Docker's "no space left on device" error almost always means Docker's own storage — accumulated images, stopped containers, unused volumes, and build cache —...
Docker Build Cache Not Invalidating After File Change
If you change a file in your project but docker build keeps producing an image with the old content, Docker isn't actually ignoring your change — it's reusing...
Docker Compose Network Not Resolving Between Containers
When containers in a Docker Compose setup can't reach each other by name — for example, your app container failing to connect to a database container using its...
Docker Container Can't Connect to Host PostgreSQL
When a containerized application needs to reach a PostgreSQL server running directly on your host machine (not inside another container), connection failures...