Docker
A build can finish with cache-only or remote registry output, depending on driver and export settings. Identify output intent before rebuilding.
Images, Dockerfiles & Build Reliability1 min read
Read article : Diagnose a successful Buildx build whose image is not in local Engine
Docker
A final stage can unintentionally reset the runtime user and file ownership assumptions from an earlier stage. Inspect final-image metadata.
Images, Dockerfiles & Build Reliability1 min read
Read article : Check the final runtime user after a multi-stage image build
Docker
A rebuild can reuse an older base locally even when application sources are unchanged. Release provenance should identify the actual base digest.
Images, Dockerfiles & Build Reliability1 min read
Read article : Review base-image refresh independently from application source changes
Docker
An image tag and a passing application test do not record all source, builder and dependency inputs. Inspect the published artifact identity first.
Images, Dockerfiles & Build Reliability1 min read
Read article : Use artifact provenance to explain which build produced an image
Docker
A container can listen internally without publishing a host port, or publish a different port than the caller expects. Inspect the mapping.
Networking, Ports & Service Connectivity1 min read
Read article : Check Docker's actual host-to-container port mapping
Docker
Publishing a port cannot generally reach a process bound only to the container's loopback address. Inspect the real listener when approved tools exist.
Networking, Ports & Service Connectivity1 min read
Read article : Investigate an application listening only on loopback inside its container
Docker
Containers attached to the same user-defined bridge can use its supported name-resolution behavior. Being on the same host alone is insufficient.
Networking, Ports & Service Connectivity1 min read
Read article : Use a user-defined Docker network for intended name-based discovery
Docker
The legacy default bridge and user-defined bridges have different name-discovery behavior. Inspect the network actually used.
Networking, Ports & Service Connectivity1 min read
Read article : Explain why a container name does not resolve on Docker's default bridge
Docker
Inside an ordinary container, localhost refers to that container's network namespace, not another container or the Docker host.
Networking, Ports & Service Connectivity1 min read
Read article : Understand why localhost reaches the wrong backend in a container
Docker
Docker can generate resolver settings and use an embedded DNS service on certain networks. Host lookup success does not prove the container's path.
Networking, Ports & Service Connectivity1 min read
Read article : Inspect a container's actual DNS configuration without assuming host equivalence
Docker
A container subnet can conflict with an external route and send traffic toward the wrong destination. Inspect allocated ranges.
Networking, Ports & Service Connectivity1 min read
Read article : Find a Docker network subnet overlapping the office or VPN network
Docker
An overlay, VPN or host-path MTU mismatch can allow small requests while larger transfers stall. Record network configuration before changing it.
Networking, Ports & Service Connectivity1 min read
Read article : Inspect Docker network MTU context during large-transfer failures