What could be the reson for piped answers (Yes/No) to a script failing in dockerfile but working in interactive bash on the container

Question

While trying to set up a docker container I stumbled across something I don't know how to solve, understand or google.

I have a Dockerfile where I run a script. One layer of the Dockerfile is:

RUN cd /app/spinnaker-1.23.0.27-amd64 && \
    printf 'y\nn\n' | sh install_spinnaker.sh

Basically I copied that line from some GitHub repo.

When I try to build this Dockerfile with docker build --tag=app . it will run the install_spinnaker.sh until the very end but then crash with:

[Y/n] $ The command '/bin/sh -c cd /app/spinnaker-1.23.0.27-amd64 &&     printf 'y\nn\n' | sh install_spinnaker.sh' returned a non-zero code: 1

On the other hand, when remove this line from the Dockerfile, build it, and then open a bash on the container with docker run -ti app bash and inside the container then run the same command, i.e.

cd /app/spinnaker-1.23.0.27-amd64 && printf 'y\nn\n' | sh install_spinnaker.sh

it will just work.

Now, there are actually three [Y/n] questions. So printf 'y\nn\n' | sh install_spinnaker.sh should not work, either in the dockerfile nor the interactive bash I guess?

So I tried with a few different ones. The following seemed most plausible to me:

RUN cd /app/spinnaker-1.23.0.27-amd64 && \
    printf 'y\nn\nn\n' | sh install_spinnaker.sh

which I expected to work because there are three questions. But it doesn't work and I don't know why. On building the Dockerfile it gives the following at the end:

Installation complete.
Would you like to register the installed software?
[Y/n] $ error: process ID out of range

Usage:
 ps [options]

 Try 'ps --help <simple|list|output|threads|misc|all>'
  or 'ps --help <s|l|o|t|m|a>'
 for additional help text.

For more details see ps(1).
The command '/bin/sh -c cd /app/spinnaker-1.23.0.27-amd64 &&     printf 'y\nn\nn\n' | sh install_spinnaker.sh' returned a non-zero code: 1

I don't see my mistake here. Please if you see anything obvious, let me know.

Answer 1

Turns out the error with the error: process ID out of range also came up when running it in the container with docker rum -ti bash. I just somehow didn't see the error and the installation was successful regardles. So I didn't notice and thought that the problem is somewhere with Docker which is not the case.

I managed to get what I want by removing all lines of the install_spinnaker.sh script I don't need, including the one which caused the error. It also removes a question, so there are now only two questions left in the script. To do that I do:

sed -i '50,101d' install_spinnaker.sh`

before running the script.

In the Dockerfile the layer now looks like:

RUN cd /app/spinnaker-1.23.0.27-amd64 && \
    sed -i '50,101d' install_spinnaker.sh && \
    printf 'y\nn\n' | sh install_spinnaker.sh