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How to use Docker to Develop - a guide

This guide is for developers and newcomers to help them debug and explore Docker.

This page describes how to test and debug your changes once you have set up the project, Product Opener with Docker using dev environment quick start guide.

Checking logs

Tail Docker Compose logs

make log

You will get logs from nginx, mongodb, postgres, etc.

Tail other logs

Most logs from perl are not (yet ?) displayed on the docker logs, but are instead available in specific directories.

To see them use:

make tail

It will tail -f all the files present in the logs/ directory:

  • apache2/error.log
  • apache2/log4perl.log
  • apache2/modperl_error.log
  • apache2/other_vhosts_access.log
  • nginx/access.log
  • nginx/error.log

You can also simply run:

tail -f <FILEPATH>

to check a specific log.

One of the most important is log4perl.log.

Increasing log verbosity

By default, the log4perl configuration conf/log.conf matches production settings. You can tweak that file with your own dev configuration settings and run make restart to reload the changes.

A setting useful for local environments is to set TRACE log level:

log4perl.rootLogger=TRACE, LOGFILE

Opening a shell in a Docker container

Run the following to open a bash shell within the backend container:

docker compose exec backend bash

You should see root@<CONTAINER_ID>:/# (opened root shell): you are now within the Docker container and can begin typing some commands!

Checking permissions

Navigate to the specific directory and run

ls -lrt

It will list all directories and their permissions.

Creating directory

Navigate to your specific directory using cd and run

mkdir directory-name

Running minion jobs

Minion is a high-performance job queue for Perl, used in openfoodfacts-server for time-consuming import and export tasks. These tasks are processed and queued using the minion jobs queue. Therefore, they are called minion jobs.

Go to /opt/product-opener/scripts and run

./minion_producers.pl minion job

The above command will show the status of minion jobs. Run the following command to launch the minion jobs.

./minion_producers.pl minion worker -m production -q pro.openfoodfacts.org

Restarting Apache

Sometimes restarting the whole backend container is overkill, and you can just restart Apache from inside the container:

apache2ctl -k restart

Exiting the container

Use exit to exit the container.

Making code changes

In the dev environment, any code change to the local directory will be written to the container. That said, some code changes require a restart of the backend container, or rebuilding the NPM assets.

Getting away from make up

make up is a good command for starters, but it's not the right one to use if you develop on a daily basis, because it may be slow, as it does a full rebuild, which, in dev mode, should only be necessary in a few cases.

On a daily basis you could better run those:

  • docker compose up to start and monitor the stack.
  • docker compose restart backend to account for a code change in a .pm file (cgi pl files do not need a restart)
  • docker compose stop to stop them all

If some important file changed (like Dockerfile or cpanfile, etc.), or if in doubt, you can run docker compose build (or maybe it's a good time to use make up once)

You should explore the docker compose commands. Most are useful!

Live reload

To automate the live reload on code changes, you can install the Python package when-changed:

pip3 install when-changed
when-changed -r docker/ docker-compose.yml .env -c "make restart"                                         # restart backend container on compose changes
when-changed -r lib/ -r docker/ docker-compose.yml -c "docker compose backend restart" # restart Apache on code changes
when-changed -r html/ Dockerfile Dockerfile.frontend package.json -c "make up" # rebuild containers on asset or Dockerfile changes

An alternative to when-changed is inotifywait.

Run queries on MongoDB database

docker compose exec mongodb mongo

The above command will open a MongoDB shell, allowing you to use all the mongo commands to interact with the database:

show dbs
use off
db.products.count()
db.products.find({_id: "5053990155354"})
db.products.deleteOne({_id: "5053990155354"})

See the mongo shell docs for more commands.

Adding environment variables

If you need some value to be configurable, it is best to set it as an environment variable.

To add a new environment variable TEST:

  • In a .env file, add TEST=test_val [local].
  • In .github/workflows/container-deploy.yml, add echo "TEST=${{ secrets.TEST }}" >> .env to the "Set environment variables" build step [remote]. Also add the corresponding GitHub secret TEST=test_val.
  • In docker-compose.yml file, add it under the backend > environment section.
  • In conf/apache.conf file, add PerlPassEnv TEST.
  • In lib/Config2.pm, add $test = $ENV{TEST};. Also add $test to the EXPORT_OK list at the top of the file to avoid a compilation error.

The call stack goes like this:

make up > docker compose > loads .env > pass env variables to the backend container > pass to mod_perl > initialized in Config2.pm.

Managing multiple deployments

To juggle between multiple local deployments (e.g: to run different flavors of Open Food Facts on the same host), there are different possible strategies.

a set env script

docker compose takes its settings from, in decreasing priority:

  • the environment
  • the .env file

So one strategy to have a different instance, can be to keep the same .env file, but override some env variables to tweak the configuration. This is a good strategy for the pro platform.

For this case we have a setenv.sh script.

To use it, open a terminal, where you want to be in pro environment and simply use:

. setenv.sh off-pro

then you can use whatever docker compose command.

Note: This terminal will remain in pro mode until you end its session.

See also Developing on the producers platform

different .env file

This strategy might be the right one if your settings differ a lot.

You will need:

  • Multiple .env files (one per deployment), such as:

    • .env.off : configuration for Open Food Facts dev env.
    • .env.off-pro : configuration for Open Food Facts Producer's Platform dev env.
    • .env.obf: configuration for Open Beauty Facts dev env.
    • .env.opff: configuration for Open Ped Food Facts dev env.

  • COMPOSE_PROJECT_NAME set to different values in each .env file, so that container names across deployments are unique.

  • FRONTEND_PORT and MONGODB_PORT set to different values in each .env file, so that frontend containers don't port-conflict with each other.

To switch between configurations, set ENV_FILE before running make commands, (or docker compose command):

ENV_FILE=.env.off-pro make up # starts the OFF Producer's Platform containers.
ENV_FILE=.env.obf     make up # starts the OBF containers.
ENV_FILE=.env.opff    make up # starts the OPFF containers.

or export it to keep it for a while:

export ENV_FILE=.env.off # going to work on OFF for a while
make up
make restart
make down
make log

A good strategy is to have multiple terminals open, one for each deployment:

  • off [Terminal 1]:

    export ENV_FILE=.env.off
make up

  • off-pro [Terminal 2]:

    export ENV_FILE=.env.off-pro
make up

  • obf [Terminal 3]:

    export ENV_FILE=.env.obf
make up

  • opff [Terminal 3]:

    export ENV_FILE=.env.opff
make up

Note: the above case of 4 deployments is a bit ambitious, since ProductOpener's backend container takes about ~6GB of RAM to run, meaning that the above 4 deployments would require a total of 24GB of RAM available.