Develop Reference

How to make docker container running continuously?

I have a Docker image that is actually a server for a device. It is started from a Python script, and I made .sh to run it. However, whenever I run it, it says that it is executed and it ends (server exited with code 0). The only way I made it work is via docker-compose when I run it as detached container, then enter the container via bin/bash and execute the run script (beforementioned .sh) from it manually, then exit the container.
After that everything works as intended, but the issue arises when the server is rebooted. I have to do it manually all over again.
Did anyone else experience anything similar? If yes how can I fix this?
File that starts server (start.sh):
#!/bin/sh
python source/server/main.pyc &
python source/server/main_socket.pyc &
python source/server/main_monitor_server.pyc &
python source/server/main_status_server.pyc &
python source/server/main_events_server.pyc &
Dockerfile:
FROM ubuntu:trusty
RUN mkdir -p /home/server
COPY server /home/server/
EXPOSE 8854
CMD [ /home/server/start.sh ]
Docker Compose:
version: "3.9"
services:
server:
tty: yes
image: deviceserver:latest
container_name: server
restart: always
ports:
- "8854:8854"
deploy:
resources:
limits:
memory: 3072M

It's not a problem with docker-compose. Your docker container should not return (i.e block) even when launched with a simple docker run.
For that your CMD should run in the foreground.
I think the issue is that you're start.sh returns instead of blocking. Have you tried to remove the last '&' from your script (I'm not familiar with python and what these different processes are)?

In general you should run only one process per container. If you have five separate processes you need to run, you would typically run five separate containers.
The corollaries to this are that the main container command should be a foreground process; but also that you can run multiple containers off of the same image with different commands. In Compose you can override the command: separately for each container. So, for example, you can specify:
version: '3.8'
services:
main:
image: deviceserver:latest
command: ./main.py
socket:
image: deviceserver:latest
command: ./main_socket.py
et: cetera
If you're trying to copy-and-paste this exact docker-compose.yml file, make sure to set a WORKDIR in the Dockerfile so that the scripts are in the current directory, make sure the scripts are executable (chmod +x in your source repository), and make sure they start with a "shebang" line #!/usr/bin/env python3. You shouldn't need to explicitly say python anywhere.
FROM python:3.9 # not a bare Ubuntu image
WORKDIR /home/server # creates the directory too
COPY server ./ # don't need to duplicate the directory name here
RUN pip install -r requirements.txt
EXPOSE 8854 # optional, does almost nothing
CMD ["./main.py"] # valid JSON-array syntax; can be overridden
There are two major issues in the setup you show. The CMD is not a syntactically valid JSON array (the command itself is not "quoted") and so Docker will run it as a shell command; [ is an alias for test(1) and will exit immediately. If you do successfully run the script, the script launches a bunch of background processes and then exits, but since the script is the main container command, that will cause the container to exit as well. Running a set of single-process containers is generally easier to manage and scale than trying to squeeze multiple processes into a single container.

You can add sleep command in the end of your start.sh.
#!/bin/sh
python source/server/main.pyc &
python source/server/main_socket.pyc &
python source/server/main_monitor_server.pyc &
python source/server/main_status_server.pyc &
python source/server/main_events_server.pyc &
while true
do
sleep 1;
done

Python process never exits in Docker container during CircleCI workflow

I have a Dockerfile that looks like this:
FROM python:3.6
WORKDIR /app
ADD . /app/
# Install system requirements
RUN apt-get update && \
xargs -a requirements_apt.txt apt-get install -y
# Install Python requirements
RUN python -m pip install --upgrade pip
RUN python -m pip install -r requirements_pip.txt
# Circle CI ignores entrypoints by default
ENTRYPOINT ["dostuff"]
I have a CircleCI config that does:
version: 2.1
orbs:
aws-ecr: circleci/aws-ecr#6.15.3
jobs:
benchmark_tests_dev:
docker:
- image: blah_blah_image:test_dev
#auth
steps:
- checkout
- run:
name: Compile and run benchmarks
command: make bench
workflows:
workflow_test_and_deploy_dev:
jobs:
- aws-ecr/build-and-push-image:
name: build_test_dev
context: my_context
account-url: AWS_ECR_ACCOUNT_URL
region: AWS_REGION
repo: my_repo
aws-access-key-id: AWS_ACCESS_KEY_ID
aws-secret-access-key: AWS_SECRET_ACCESS_KEY
dockerfile: Dockerfile
tag: test_dev
filters:
branches:
only: my-test-branch
- benchmark_tests_dev:
requires: [build_test_dev]
context: my_context
filters:
branches:
only: my-test-branch
- aws-ecr/build-and-push-image:
name: deploy_dev
requires: [benchmark_tests_dev]
context: my_context
account-url: AWS_ECR_ACCOUNT_URL
region: AWS_REGION
repo: my_repo
aws-access-key-id: AWS_ACCESS_KEY_ID
aws-secret-access-key: AWS_SECRET_ACCESS_KEY
dockerfile: Dockerfile
tag: test2
filters:
branches:
only: my-test-branch
make bench looks like:
bench:
python tests/benchmarks/bench_1.py
python tests/benchmarks/bench_2.py
Both benchmark tests follow this pattern:
# imports
# define constants
# Define functions/classes
if __name__ == "__main__":
# Run those tests
If I build my Docker container on my-test-branch locally, override the entrypoint to get inside of it, and run make bench from inside the container, both Python scripts execute perfectly and exit.
If I commit to the same branch and trigger the CircleCI workflow, the bench_1.py runs and then never exits. I have tried switching the order of the Python scripts in the make command. In that case, bench_2.py runs and then never exits. I have tried putting a sys.exit() at the end of the if __name__ == "__main__": block of both scripts and that doesn't force an exit on CircleCI. I the first script to be run will run to completion because I have placed logs throughout the script to track progress. It just never exits.
Any idea why these scripts would run and exit in the container locally but not exit in the container on CircleCI?
EDIT
I just realized "never exits" is an assumption I'm making. It's possible the script exits but the CircleCI job hangs silently after that? The point is the script runs, finishes, and the CircleCI job continues to run until I get a timeout error at 10 minutes (Too long with no output (exceeded 10m0s): context deadline exceeded).

Turns out the snowflake.connector Python lib we were using has this issue where if an error occurs during an open Snowflake connection, the connection is not properly closed and the process hangs. There is also another issue where certain errors in that lib are being logged and not raised, causing the first issue to occur silently.
I updated our snowflake IO handler to explicitly open/close a connection for every read/execute so that this doesn't happen. Now my scripts run just fine in the container on CircleCI. I still don't know why they ran in the container locally and not remotely, but I'm going to leave that one for the dev ops gods.

Issues with using proper directory when running python script in gitlab-ci

I have a python script that I am trying to run as part of gitlab pages deployment of a jekyll site. My site has blog posts that have various tags, and the python script generates the .md files for the tag pages. The script works perfectly fine when I just manually run it in an IDE, however I want it to be part of the gitlab ci deployment process
here is what my gitlab-ci.yml setup looks like:
run:
image: python:latest
script:
- python tag_generator.py
artifacts:
paths:
- public
only:
- master
pages:
image: ruby:2.3
stage: deploy
script:
- bundle install
- bundle exec jekyll build -d public
artifacts:
paths:
- public
only:
- master
however, it doesn't actually create the files that it's supposed to create, here is the output from the job "run":
...
Cloning repository...
Cloning into '/builds/username/projectname'...
Checking out 4c8a47fe as master...
Skipping Git submodules setup
$ python tag_generator.py
Tags generated, count 23
Uploading artifacts...
WARNING: public: no matching files
ERROR: No files to upload
Job succeeded
the script reads out "tags generated, count ___" once it's executed, so it is running, however the files that it's supposed to create aren't being created/uploaded into the right directory. there is a /tag directory in the root project folder, that is where they are supposed to go.
I realize that the issue must have something to do with the public folder, however when I don't have
artifacts:
paths:
- public
it still doesn't create the files in the /tag directory, so it doesn't work whether I have -public or not, and I don't know what the problem is.

I FIGURED IT OUT!
the "build" for the project isn't made in the repo, gitlab clones the repo into another place, so I had to change the artifact path for the python job so that it's in the cloned "build" location, like so:
run:
image: python:latest
stage: test
before_script:
- python -V # Print out python version for debugging
- pip install virtualenv
script:
- python tag_generator.py
artifacts:
paths:
- /builds/username/projectname/tag
only:
- master

Returning log file from process run in docker

I'm a total newbie to docker, and am having trouble on how to approach this problem. Consider this super simplified cli tool that produces a log when ran with docker run.
import click
import logging
logging.basicConfig(filename='log.log')
logger = logging.getLogger(__name__)
#click.group()
#click.version_option('1.0')
def cli():
'''docker_cli with docker test'''
#cli.command('run')
#click.argument('name', default='my name')
def run(name):
logger.info("running 'run' within docker")
print('Hello {}'.format(name))
And my dockerfile is as follows:
FROM python:3.5-slim
LABEL maintainer="Boudewijn Aasman"
LABEL version="1.0"
ENV config production
RUN mkdir /docker_cli
COPY docker_cli ./docker_cli
COPY setup.py .
RUN python setup.py install
CMD ["cli", "run"]
If I execute the container using:
docker run cli_test cli run world
how do I retrieve the log file that gets created during the process? The container exits immediately after the command print out 'Hello world'. My assumption is using a volume, but not sure how to make it work.

You can either share a local directory:
docker run -v full-path-your-local-dir:. cli_test cli run world
Or create a docker volume
docker volume create cli_test_volume
docker run -v cli-test_volume:. cli_test cli run world
docker volume inspect cli_test_volume # will show where the volume is located.
For both of these approaches you will need to write the logs in a different path than the application. Otherwise, app code will be overwritten by the shared volume.
There is another alternative, which is to copy files from the container using create and cp:
docker create --name cli_test_instance cli_test run world
docker start cli_test_instance
docker cp cli_test_instance:log.log .

Have you tried this?
docker logs cli_test
EDIT: Sorry, I missed this the first time, but in order for this to work, you'll have to log to STDERR, not to a log file. (Thanks #Gonzalo Matheu
for pointing this out.) To get it working, it should be as simple as making this small additional change:
logging.basicConfig() # note no file name

Execute Python script inside a given docker-compose container

I have made a little python script to create a DB and some tables inside a RethinkDB
But now I'm trying to launch this python script inside my rethink container launched with docker-compose.
This is my docker-compose.yml rethink container config
# Rethink DB
rethink:
image: rethinkdb:latest
container_name: rethink
ports:
- 58080:8080
- 58015:28015
- 59015:29015
I'm trying to execute the script with after launching my container
docker exec -it rethink python src/app/db-install.py
But I get this error
rpc error: code = 2 desc = oci runtime error: exec failed: exec: "python": executable file not found in $PATH
Python is not found in me container. Is this possible to execute a python script inside a given container with docker-compose or with docker exec ?

First find out if you have python executable in the container:
docker exec -it rethink which python
If it exists, Use the absolute path provided by which command in previous step:
docker exec -it rethink /absolute/path/to/python src/app/db-install.py
If not, you can convert your python script to bash script, so you can run it without extra executables and libraries.
Or you can create a dockerfile, use base image, and install python.
dockerfile:
FROM rethinkdb:latest
RUN apt-get update && apt-get install -y python
Docker Compose file:
rethink:
build : .
container_name: rethink
ports:
- 58080:8080
- 58015:28015
- 59015:29015

Docker-compose
Assuming that python is installed, try:
docker-compose run --rm MY_DOCKER_COMPOSE_SERVICE MY_PYTHON_COMMAND
For a start, you might also just go into the shell at first and run a python script from the command prompt.
docker-compose run --rm MY_DOCKER_COMPOSE_SERVICE bash
In your case, MY_DOCKER_COMPOSE_SERVICE is 'rethink', and that is not the container name here, but the name of the service (first line rethink:), and only the service is run with docker-compose run, not the container.
The MY_PYTHON_COMMAND is, in your case of Python2, python src/app/db-install.py, but in Python3 it is python -m src/app/db-install (without the ".py"), or, if you have Python3 and Python2 installed, python3 -m src/app/db-install.
Dockerfile
To be able to run this python command, the Python file needs to be in the container. Therefore, in your Dockerfile that you need to call with build: ., you need to copy your build directory to a directory in the container of your choice
COPY $PROJECT_PATH /tmp
This /tmp will be created in your build directory. If you just write ".", you do not have any subfolder and save it directly in the build directory.
When using /tmp as the subfolder, you might write at the end of your Dockerfile:
WORKDIR /tmp
Docker-compose
Or if you do not change the WORKDIR from the build (".") context to /tmp and you still want to reach /tmp, run your Python file like /tmp/db-install.py.

The rethinkdb image is based on the debian:jessie image :
https://github.com/rethinkdb/rethinkdb-dockerfiles/blob/da98484fc73485fe7780546903d01dcbcd931673/jessie/2.3.5/Dockerfile
The debian:jessie image does not come with python installed.
So you will need to create your own Dockerfile, something like :
FROM rethinkdb:latest
RUN apt-get update && apt-get install -y python
Then change your docker-compose :
# Rethink DB
rethink:
build : .
container_name: rethink
ports:
- 58080:8080
- 58015:28015
- 59015:29015
build : . is the path to your Dockerfile.