Docker / Images, Dockerfiles & Build Reliability
Diagnose a Docker build that cannot see an expected source file
COPY reads from the selected build context or explicit build source, not arbitrary host paths. Ignore rules can exclude the file.
Environment and inputs: Docker Engine · Compose v2 and Buildx where specified; Linux containers unless noted. Verify daemon context, installed feature support and authorized host or Swarm manager access first.
Start with this check
Confirm the environment and replace sample objects, namespaces, images, paths and hosts with approved targets. Share only relevant, sanitized output. Follow the workload owner’s process for changes.
sed -n '1,120p' .dockerignoreRead the result
This shell example reads the local ignore file when present. Also verify the actual context directory and Dockerfile path used by the build command.
Resolve and verify
Compare the missing path with context boundaries, case sensitivity and ignore patterns. Correct the reviewed build input and rerun a controlled validation.
Before changing production
Do not send the entire home directory as context or remove secret-excluding patterns just to make COPY succeed.