A classic example is java Jenkins applications. This is what you want for applications that fork and haven't been written with child reaping in mind as normally they would leave this up to the init system. A pid 1 process must reap forked child processes correctly, if it doesn't then bad things happen like resources get leaked and zombies appear. The docker run command must specify an IMAGE to derive the container from. Tini is a first class init process that can be run as pid 1 correctly. General form The basic docker run command takes this form: docker run OPTIONS IMAGE :TAGDIGEST COMMAND ARG. ENTRYPOINT should be defined when using the container as an executable. Dockerfile should specify at least one of CMD or ENTRYPOINT commands. There are few rules that describe their co-operation. Though the ENTRYPOINT and CMD instructions may seem similar at first glance, there are fundamental differences in how they build container images. Both CMD and ENTRYPOINT instructions define what command gets executed when running a container. Any Docker image must have an ENTRYPOINT or CMD declaration for a container to start. With -init, tini (/dev/init) becomes pid 1 docker run -ti -init -rm ubuntu:16.04 ps -fA Default parameters that cannot be overridden when Docker Containers run with CLI parameters. COPY./docker-entrypoint.sh / ENTRYPOINT '/docker-entrypoint. Please correct me if I misunderstood something or elaborate a little bite more where I should find the docker-entrypoint.sh file etc. Hence, I assume it should be copied to the right directory by the Dockerfile of the images I used (e.g. See the specific docker, rancher, or marathon documentation. In this case, /bin/bash docker run -ti -rm ubuntu:16.04 ps -fA Docker builds images automatically by reading the instructions from a Dockerfile - a text file that contains all commands. I don't create a docker-entrypoint.sh file myself. Specifiying the new docker -init option in the run command basically sets ENTRYPOINT to tini and passes the CMD to it or whatever you specify on the commandline.įor example, without init, CMD becomes pid 1.
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