In a shell script I am building some docker images(in background), once done I am running them(in background) and then I have to wait for all of them to complete. The code looks like this:
for tag in "${tags[#]}"
do
docker build -f dockerFilePath -t $tag . &
done
wait
for tag in "${tags[#]}"
do
docker run $tag arg1 arg2 | tee logoutput &
done
wait
The problem is that not all the docker run commands in the second wait section are able to complete. And the docker run commands take different times to complete, and any one of them is always incomplete (among a total of 4).
Also, I read that wait only works for the direct children of the process calling wait, in this case I think all the docker build and docker run commands are the direct children of the script process. Or is that wrong to assume?
Related
I want a custom bash script in the container that is called automatically before the container stops (docker stop or ctrl + c).
According to this docker doc and multiple StackOverflow threads, I need to catch the SIGTERM signal in the container and then run my custom script when the event appears. As I know SIGTERM can be only used from a root process with PID 1.
Relevand part of my Dockerfile:
...
COPY container-scripts/entrypoint.sh /
ENTRYPOINT ["/entrypoint.sh"]
I use [] to define the entrypoint and as I know this will run my script directly, without having a /bin/sh -c wrapper (PID 1), and when the script eventually exec another process, that process becomes the main process and will receive the docker stop signal.
entrypoint.sh:
...
# run the external bash script if it exists
BOOT_SCRIPT="/boot.sh"
if [ -f "$BOOT_SCRIPT" ]; then
printf ">> executing the '%s' script\n" "$BOOT_SCRIPT"
source "$BOOT_SCRIPT"
fi
# start something here
...
The boot.sh is used by child containers to execute something else that the child container wants. Everything is fine, my containers work like a charm.
ps axu in a child container:
PID USER TIME COMMAND
1 root 0:00 {entrypoint.sh} /bin/bash /entrypoint.sh
134 root 0:25 /usr/lib/jvm/java-17-openjdk/bin/java -server -D...
...
421 root 0:00 ps axu
Before stopping the container I need to run some commands automatically so I created a shutdown.sh bash script. This script works fine and does what I need. But I execute the shutdown script manually this way:
$ docker exec -it my-container /bin/bash
# /shutdown.sh
# exit
$ docker container stop my-container
I would like to automate the execution of the shutdown.sh script.
I tried to add the following to the entrypoint.sh but it does not work:
trap "echo 'hello SIGTERM'; source /shutdown.sh; exit" SIGTERM
What is wrong with my code?
Your help and comments guided me in the right direction.
I went through again the official documentations here, here, and here and finally I found what was the problem.
The issue was the following:
My entrypoint.sh script, which kept alive the container executed the following command at the end:
# start the ssh server
ssh-keygen -A
/usr/sbin/sshd -D -e "$#"
The -D option runs the ssh daemon in a NOT detach mode and sshd does not become a daemon. Actually, that was my intention, this is the way how I kept alive the container.
But this foreground process prevented to be executed properly the trap command. I changed the way how I started the sshd app and now it runs as a normal background process.
Then, I added the following command to keep alive my docker container (this is a recommended best practice):
tail -f /dev/null
But of course, the same issue appeared. Tail runs as a foreground process and the trap command does not do its job.
The only way how I can keep alive the container and let the entrypoint.sh runs as a foreign process in docker is the following:
while true; do
sleep 1
done
This way the trap command works fine and my bash function that handles the SIGINT, etc. signals runs properly when the time comes.
But honestly, I do not like this solution. This endless loop with a sleep looks ugly, but I have no idea at the moment how to manage it in a nice way :(
But this is another question that not belongs to this thread (but could be great if you can suggest my a better solution).
I have two scripts that I would like to execute.
Script 1: A script that executes docker run (needs to stay active because if it is closed the docker container stops running)
Script 2: A script that runs docker exec and gets into the docker shell
Problem:
I need to run script 1 and script 2 in separate shells because script 1 needs to stay active and cannot be closed.
Separating the scripts into two separate files and then running both scripts from one file
sh script1.sh & sh script2.sh
Just run it as one big script.
When executing/running the docker container use the --detach or -d flag.
This ensures, that the container does not stay active in the terminal but moves into the background (it keeps running!).
The docker command would look something like
docker run -d ...
In my Travis CI, part of my verification is to start a docker container and verify that it doesn't fail within 10 seconds.
I have a yarn script docker:run:local that calls docker run -it <mytag> node app.js.
If I call the yarn script with timeout from a bash shell, it works fine:
$ timeout 10 yarn docker:run:local; test $? -eq 124 && echo "Container ran for 10 seconds without error"
This calls docker run, lets it run for 10 seconds, then kills it (if not already returned). If the exit code is 124, the timeout did expire, which means the container was still running. Exactly what I need to verify that my docker container is reasonably sane.
However, as soon as I run this same command from within a script, either in a test.sh file called from the shell, or if putting it in another yarn script and calling yarn test:docker, the behaviour is completely different. I get:
ERRO[0000] error waiting for container: context canceled
Then the command hangs forever, there's no 10 second timeout, I have to ctrl-Z it and then kill -9 the process. If I run top I now have a docker process using all my CPU forever. If using timeout with any other command like sleep 20 && echo "Finished sleeping", this does not happen, so I suspect it may have something to do with how docker works in interactive mode or something, but that's only my guess.
What's causing timeout docker:run to fail from a script but work fine from a shell and how do I make this work?
Looks like running docker in interactive mode is causing the issue.
Run docker in detached more by removing the -it and allowing it to run in default detached mode or specify -d instead of -it and so:
docker run -d <mytag> node
or
docker run <mytag> node
In Jenkins, I have created a job which runs many shell script commands:
command1
command2
...etc
command1 is an ssh command which calls a shell script file on another server machine. I have to wait until it is finished, and AFTER it, command2 should come.
So, how can I make sure that the script file on the other machine, started by command1, has already finished its jobs, when in the Jenkins job the next command (command2) is started?
Or, alternatively,how can I make sure that command2 won't be started until the shell script on the other machine (started by command1) has already finished?
You can check out "How to send many commands to shell and wait for the command behind ends" in order to chain commands and wait for their completion.
When you execute a command through an ssh session, you might have to wrap that command in a script able to loop/wait for the command completion.
See an example in "How can I make ssh wait until the command exits?".
Or (a simpler wraper): How do I know when a command run over ssh has finished?
#/bin/bash
$#
echo "==== Command Output Finished ===="
look for the string ==== Command Output Finished ==== in your I/O routines to determine where the boundary between command outputs are.
Or you can try isolate those commands in their own Jenkins shell build step.
(Not a different job, just a different build step within the same job)
I would like to run n processes (in my case simulations) simultaneously, using bash.
Right now this is what I'm running:
for file in $ini/SAN*.ini;
do
echo "Running $file...";
temp=$(basename $file .ini)
mosrun -G opp_run -r 0 -u Cmdenv -n ..:../../src -l ../../src/inet SAN.ini > $outputs/$temp.out;
done
Problem is, the loop only progresses to the next iteration after the simulation is done. Any suggestions? Thanks!
You should be able to run your command in the background by adding a & after it.
Should make them run in parallell, although in the background.
(Small side note: the processes will continue to run even if you abort the script, so you might want to add a trap to kill the processes if you hit for eg. ctrl-c when script is running. Look at bash manual.)