I am trying to set up crontab to run two docker containers on system startup/reboot. The line I use to do this after entering the command crontab -e is:
#reboot sh folder_b/run_docker_containers.bash
The script run_docker_containers.bash has the following contents:
#!/bin/bash
# Run containers based on setup_image and main_image
sudo bash /home/user/folder_a/run_setup_docker_container.bash
sudo bash /home/user/folder_b/run_main_docker_container.bash
The scripts run_setup_docker_container.bash and run_main_docker_container.bash both have the following contents (where docker_image is setup_image and main_image, respectively):
#!/bin/bash
/snap/bin/docker run \
--rm \
--detach \
--privileged \
--net=host \
--device /dev/bus/usb \
docker_image:latest \
/bin/bash -c\
"
*SOME COMMANDS*
"
export containerId=$(/snap/bin/docker ps -l -q)
However, the containers are not run when the script is executed on reboot. I prove it finds the script folder_b/run_docker_containers.bash by adding the following code to it and seeing that the new file has been created after reboot.
touch proof_that_crontab_has_done_something.txt
It seems that crontab cannot find the scripts run_setup_docker_container.bash and run_main_docker_container.bash. Any ideas where I'm going wrong?
If you want to execute a shellscript with sudo rights I would recommend using the sudo crontab.
sudo crontab -e
Your personal cronjob should not be able to start a shell with sudo rights. Unless you do some weird modifications.
Use the absolute path
#reboot /...../folder_b/run_docker_containers.bash
I'm trying to execute shell command in docker-compose.yml. Code is:
command: bash -c mkdir /opt/wa/usr/install_templates
When I do:
sudo docker-compose up serviceA
it gives me :
serviceA | mkdir: missing operand
When you use bash -c, it runs the first string after the -c flag. See this SO answer for more information. Docker is reading your command bash -c mkdir /path/ and your bash command is just running mkdir in a bash subshell, causing that error.
You don't need to put bash -c before your commands in a docker-compose file. The Docker engine will handle running it in a shell for you and you can simply write the command you want to be run. I'd suggest replacing your command with this:
command: mkdir /opt/wa/usr/install_templates
Alternatively, you could try putting the entire command into a string if you want to force the command to be run in bash:
command: bash -c "mkdir /opt/wa/usr/install_templates"
For a daily database backup, I created the following cron job :
File : crontab -e
SHELL=/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin
* * * * * /bin/bash /var/path/deploy/database/scripts/backup.sh
File : /var/path/deploy/database/scripts/backup.sh
#!/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
cp -r /var/path/deploy/database/scripts /var/bricoolpathpostgresql/data
chmod 755 -R /var/path/postgresql/data
docker exec -it database /var/lib/postgresql/data/scripts/pg_backup_rotated.sh
When I execute the script directly it works well and the backup is created successfully. But the script is being excuted from the cron job the command docker exec -it database /var/lib/postgresql/data/scripts/pg_backup_rotated.sh does not seem to work.
I have no error output in /var/log/syslog
as Danny Ebbers mentioned in comment, the problem ws the -i argument in Docker command.
#!/bin/bash
docker exec -ti erpnext sh -c "cd /home/frappe/frappe-bench/ &&
/usr/local/bin/bench backup"
echo 'Hello, world.' >foo.txt
The above code is my bash file.
Here have two command
create txt file
execute docker container
If I run this command
cd /home/arifur/workspace_python/erpdatabasebackup && bash backup_database.sh
in terminal then it is working
But when I run in crontab
* * * * * cd /home/arifur/workspace_python/erpdatabasebackup && bash backup_database.sh
then only txt file creation is working but docker container is not working.
The -ti requests to use a pseudo-tty and run in interactive mode but cron does not attach to any TTY. Try removing -ti as in
docker exec erpnext sh -c "cd /home/frappe/frappe-bench/ && /usr/local/bin/bench backup"
I'm trying to run MULTIPLE commands like this.
docker run image cd /path/to/somewhere && python a.py
But this gives me "No such file or directory" error because it is interpreted as...
"docker run image cd /path/to/somewhere" && "python a.py"
It seems that some ESCAPE characters like "" or () are needed.
So I also tried
docker run image "cd /path/to/somewhere && python a.py"
docker run image (cd /path/to/somewhere && python a.py)
but these didn't work.
I have searched for Docker Run Reference but have not find any hints about ESCAPE characters.
To run multiple commands in docker, use /bin/bash -c and semicolon ;
docker run image_name /bin/bash -c "cd /path/to/somewhere; python a.py"
In case we need command2 (python) will be executed if and only if command1 (cd) returned zero (no error) exit status, use && instead of ;
docker run image_name /bin/bash -c "cd /path/to/somewhere && python a.py"
You can do this a couple of ways:
Use the -w option to change the working directory:
-w, --workdir="" Working directory inside the container
https://docs.docker.com/engine/reference/commandline/run/#set-working-directory--w
Pass the entire argument to /bin/bash:
docker run image /bin/bash -c "cd /path/to/somewhere; python a.py"
You can also pipe commands inside Docker container, bash -c "<command1> | <command2>" for example:
docker run img /bin/bash -c "ls -1 | wc -l"
But, without invoking the shell in the remote the output will be redirected to the local terminal.
bash -c works well if the commands you are running are relatively simple. However, if you're trying to run a long series of commands full of control characters, it can get complex.
I successfully got around this by piping my commands into the process from the outside, i.e.
cat script.sh | docker run -i <image> /bin/bash
Just to make a proper answer from the #Eddy Hernandez's comment and which is very correct since Alpine comes with ash not bash.
The question now referes to Starting a shell in the Docker Alpine container which implies using sh or ash or /bin/sh or /bin/ash/.
Based on the OP's question:
docker run image sh -c "cd /path/to/somewhere && python a.py"
If you want to store the result in one file outside the container, in your local machine, you can do something like this.
RES_FILE=$(readlink -f /tmp/result.txt)
docker run --rm -v ${RES_FILE}:/result.txt img bash -c "grep root /etc/passwd > /result.txt"
The result of your commands will be available in /tmp/result.txt in your local machine.
For anyone else who came here looking to do the same with docker-compose you just need to prepend bash -c and enclose multiple commands in quotes, joined together with &&.
So in the OPs example docker-compose run image bash -c "cd /path/to/somewhere && python a.py"
If you don't mind the commands running in a subshell, just put a set of outer parentheses around the multiple commands to run:
docker run image (cd /path/to/somewhere && python a.py)
TL;DR;
$ docker run --entrypoint /bin/sh image_name -c "command1 && command2 && command3"
A concern regarding the accepted answer is below.
Nobody has mentioned that docker run image_name /bin/bash -c just appends a command to the entrypoint. Some popular images are smart enough to process this correctly, but some are not.
Imagine the following Dockerfile:
FROM alpine
ENTRYPOINT ["echo"]
If you try building it as echo and running:
$ docker run echo /bin/sh -c date
You will get your command appended to the entrypoint, so that result would be echo "/bin/sh -c date".
Instead, you need to override the entrypoint:
$ docker run --entrypoint /bin/sh echo -c date
Docker run reference
In case it's not obvious, if a.py always needs to run in a particular directory, create a simple wrapper script which does the cd and then runs the script.
In your Dockerfile, replace
CMD [ 'python', 'a.py' ]
or whatever with
CMD [ '/wrapper' ]
and create a script wrapper in your root directory (or wherever it's convenient for you) with contents like
#!/bin/sh
set -e
cd /path/to/somewhere
python a.py
In many situations, perhaps also consider rewriting a.py so that it doesn't need a wrapper. Either make it os.chdir() where it needs to be, or have it look for its data files in a directory you configure in its environment or similar.