Passing variables from sh to expect not working with docker-compose

Question

The Dockerfile contains:

ENV VAR 1
COPY ./setup.exp /tmp/
RUN chmod a+x /tmp/setup.exp

The expect file:

#!/usr/bin/expect
set timeout -1
spawn setup -v
expect "Enter variable: "
send -- "$env(VAR)\r"

The shell file (main.sh):

#!/bin/sh
/tmp/setup.exp $VAR

When I run ./main.sh from the shell inside the container, it works perfectly fine.

However, when I run docker-compose up with entrypoint: ./main.sh, it prints this error:

send: spawn id exp4 not open
    while executing
"send -- "$env(VAR)\r""
    (file "/tmp/setup.exp" line 5)

If I pass the variable directly as entrypoint: /tmp/setup.exp ${VAR}, it prints this warning:

WARNING: The VAR variable is not set. Defaulting to a blank string.

I also tried set VAR [lindex $argv 0]; and then send -- "$VAR\r" without any success.

Seems like from inside the container the script is able to load docker's env variables.

Any suggestions?

"spawn id exp4 not open" means the setup program has already exited. — glenn jackman, Feb 16 '21 at 02:39
That warning `The VAR variable has not been set` means you need to set that environment variable in your current shell environment before running docker-compose. Can you try `export VAR=1` and then re-running `docker-compose up`? — cam, Feb 16 '21 at 03:38
Yes you are right @meuh the syntax I posted is actually for docker-compose `environment: - VAR=1` — user13581602, Feb 16 '21 at 10:50

score 0 · Accepted Answer · answered Feb 16 '21 at 10:47

Thanks @glennjackman for pointing that out. I ran expect -d for a more verbose output.

It turns out the reason the program exited is because python was raising this exception:

ValueError: invalid width 0 (must be > 0)

Setting the variable say ENV COLUMNS 100 in the Dockerfile solved the issue for me.

1 Answers1