Issue
when I run "docker exec -it docker-name bash" on centOS7 service ,it will go into docker container and can run " python xx.py config.yaml " to execute some works . but if I use Jenkins shell run "docker exec -it docker-name bash" ,it will have no response ,I write "python xx.py config.yaml " behind ,Jenkins show [ python: can't open file 'xxx.py': [Errno 2] No such file or directory ] ,I think this error is not into the docker container ,so can't find the python file that in the docker container .How can I enter the docker container with Jenkins shell .
Solution
When you run docker exec -it docker-name bash, you get an interactive shell inside the container that gets connected to your console and the next command you type to the console is executed in that shell.
But Jenkins has no console. It is executing a script, with the standard input connected to a null device (which always returns end of file on read). So in effect it is executing the equivalent of
docker exec -it docker-name bash </dev/null (the /dev/null is the null device and < connects it to standard input of the command). And if you do that on your console, nothing happens and you'll get your original prompt again.
But you don't have to, and shouldn't be, running bash in this case at all. You give docker exec the command you want to run in the container and it runs it there. So you just do
docker exec -i docker-name python xx.py config.yaml
and that runs the python command, prints any output and when the command ends, disconnects from the container again.
I've omitted the -t because that instructs docker to use the terminal (console), but Jenkins does not have any console, just the -i, instructing it to connect the stdin, stdout and stderr, is good enough.
Now there is also a way to send the commands on the standard input of the bash similar to what the console would do, but I strongly recommend reading the documentation of bash before attempting that.
Answered By - Jan Hudec
Answer Checked By - Timothy Miller (JavaFixing Admin)
