strace reveals that the escaping I used may cause a problem compared to the shell form (shell form vs exec form see https://docs.docker.com/engine/reference/builder/ )
exec form with [/* 3 vars */] - breaks / makes trouble
ENTRYPOINT ["strace", "hugo", "server", "--watch=true", "--bind=0.0.0.0", "--source=\"/src\"", "--destination=\"/output\""]
execve("hugo", ["hugo", "server", "--watch=true", "--bind=0.0.0.0", "--source=\"/src\"", "--destination=\"/output\""], [/* 3 vars */]) = 0
shell form with [/* 4 vars */] - works fine
ENTRYPOINT strace hugo server --watch=true --bind=0.0.0.0 --source=""/src"" --destination=""/output""
execve("hugo", ["hugo", "server", "--watch=true", "--bind=0.0.0.0", "--source=/src", "--destination=/output"], [/* 4 vars */]) = 0"
Dockerfile: (used ubuntu as i wasn't able to run strace with alpine:latest.)
# escape=\
# first line can be removed and doesn't change the behavior of the described issue
FROM ubuntu:latest
RUN apt-get update && apt-get install hugo strace
RUN hugo new site src
WORKDIR /src
ENTRYPOINT ["strace", "hugo", "server", "--watch=true", "--bind=0.0.0.0", "--source=\"/src\"", "--destination=\"/output\""]
EXPOSE 1313
Command to run and save output:
sudo docker run --security-opt seccomp:unconfined docker-hugo &> docker-hugo.strace
(see https://github.com/moby/moby/issues/20064#issuecomment-291095117 for info regarding --security-opt )
Overview of possible scenarios:
+------------------+-------------------------------------------+------------------------+---------------------------------------------------+
| | No Entrypoint | Entrypoint (JSON-form) | Entrypoint (shell-form) |
+------------------+-------------------------------------------+------------------------+---------------------------------------------------+
| No CMD | HostConfig.Config.cmd=/bin/bash is called | breaks | ok |
| | (assumption as of docker inspect) | | |
+------------------+-------------------------------------------+------------------------+---------------------------------------------------+
| CMD (JSON-form) | breaks | breaks | breaks |
| | | | (other issue; not handled here |
+------------------+-------------------------------------------+------------------------+---------------------------------------------------+
| CMD (shell-form) | ok | ok | Breaks [seems to work as designed] |
| | | | (both are called with a shell concatinated) |
| | | | Example: /bin/sh -c <ENTRYPOINT> /bin/sh -c <CMD> |
+------------------+-------------------------------------------+------------------------+---------------------------------------------------+
So my question: Am I escaping the JSON Array not correctly?