TL;DR Dockerfile: ENV sets a variable for the build and the container; ARG exists only during the build and is gone at run time. export inside a RUN line dies with that line. Run time: docker run -e KEY=value and --env-file app.env. Flags override ENV from the image, and -e KEY with no value copies the variable from …

TL;DR "failed to compute cache key ... not found" is COPY telling you the source path is not in the build context. It happens before any layer is built, which is why --no-cache changes nothing. The context is the last argument of docker build, not the folder with the Dockerfile. cd docker && docker …

TL;DR Meaning: the host port in your -p HOST:CONTAINER is already in use. Docker could not bind it, so the container was created but never started (docker ps -a shows it as Created). Two wordings, same cause. Bind for 0.0.0.0:8080 failed: port is already allocated means another container publishes that port. failed to …

TL;DR Read the line before the error. OCI runtime create failed ... exec: "bash" is inside the container: the image cannot find that program. error: exec: "docker", "docker-compose" or "docker-credential-desktop" is on your host: a tool cannot find a Docker binary. Inside the …

As DevOps, we often make quite a lot of mistakes and one of the most oversight mistakes we generally do is forget to expose a port for the container. When you realize that you have not exposed any port for the container then you start looking for ways to change the port mapping of a live container or in other words, …

When we package any application using Docker then either we create Dockerfile or docker-compose.yaml, even you can create both the files and share the files with others. There is one important aspect in both the files .i.e. PORT. Any container which you build and ship to other developers has to have one or more …

TL;DR One container: docker restart <name-or-id>. Only that container stops and starts again; the others keep running. Reproduced below with nginx, redis and postgres side by side. Grace period: docker restart --timeout 30 <name> waits up to 30 seconds for the process to exit cleanly before killing it. The …

While working on my Spring Boot Microservices with Docker I felt a need to edit some of the files present under my docker container. But when I tried to edit the file nano application.yaml it throws me an error bash: nano: command not found. So I was not able to edit the file which is present inside my running docker …

TL;DR The message is literal. Failed to start docker.service: Unit docker.service not found. means there is no file called docker.service under /usr/lib/systemd/system/. Docker Engine is not installed, however many docker commands you have run. dnf install docker does not install Docker on CentOS, Rocky or RHEL 9. It …

There are times in a project where you have been working for quite a long time and you create and tag docker images on daily basis but after some time it is generally observed that we tend to forget how many docker images we have build and tagged. I do not see a problem in building and tagging a new docker image …