Igor Ciganovic Igor Ciganovic - 3 months ago 166
Linux Question

Docker image gives me "executable file not found in $PATH" when run from python

I'm trying to run some commands inside a docker image in python. When I do:

docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh -c "javac example.java && java example"


In console (kali linux) it runs fine and prints the result. When I try to run same command from python it gives me the error:

"Exception: docker: Error response from daemon: oci runtime error: exec: \"sh -c 'javac example.java && java example'\": executable file not found in $PATH.\n"


These lines work fine from python:

docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim javac
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim javac example.java


But these don't:

docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh javac
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh javac example.java
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh -c javac
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim sh -c "javac"


They all work from console. Just not from python. As soon as I add "sh -c" it gives me the error. I can run it as 2 separate commands like:

docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim javac example.java
docker run --rm -v <some_dir>:/mnt --workdir /mnt frolvlad/alpine-oraclejdk8:slim java example


But it's important that it runs all at once.

It all works fine from console, but in python as soon as I add "sh -c" it gives me the error. What am I doing wrong?

Here is the python code that I use:

BASE_CMD = [
'docker',
'run',
'--rm',
'-v'
]

def calculate_compile_and_execute_java_command(folder_name, file_name):
return BASE_CMD + [
folder_name + ":/mnt",
"--workdir",
"/mnt",
"frolvlad/alpine-oraclejdk8:slim",
"sh -c 'javac " + file_name + " && java " + file_name[:-5] + "'"
]
.
.
.
response = call_command(calculate_compile_and_execute_command(self.lang, file_path, file_name))
.
.
.
def call_command(cmd, timeout=float('inf'), cwd=None, decode=True, **subproc_options):
if cwd is None:
cwd = os.getcwd()

subproc = subprocess.Popen(
cmd,
cwd=cwd,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
**subproc_options
)
.
.
# code for timeout handling and result polling
.
.


I tried all possible combinations of string concatenation and quotes escaping in calculate method. Popen() sends the string to terminal as it should. It just doesn't work with "sh -c". It even works if I add more switches to the command. Like this:

def calculate_compile_and_execute_c_command(folder_name, file_name):
return BASE_CMD + [
folder_name + ':/mnt',
'frolvlad/alpine-gcc',
'gcc',
'--static',
'/mnt/' + file_name,
'-o',
'/mnt/qq'
]


Which gives the string like this:

docker run --rm -v "$(pwd)":/mnt --workdir /mnt frolvlad/alpine-gcc gcc --static qq.c -o qq

Answer

You are passing one big string as the last parameter to Docker. Docker is trying to run a binary called sh -c 'javac example.java && java example' which obviously doesn't exist.

You want to run the sh binary with 2 arguments. -c and the shell script you want sh to run.

return BASE_CMD + [
    folder_name + ":/mnt",
    "--workdir",
    "/mnt",
    "frolvlad/alpine-oraclejdk8:slim",
    "sh", 
    "-c",
    "javac " + file_name + " && java " + file_name[:-5]
]

If a command line script becomes too complex, you can hide it behind a shell script

#!/bin/sh
set -ue
javac $1
java ${1%.*}

Then

$ compile_and_run.sh whatever.java