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Justfiles
,Today I Learned
TIL Justfiles can also be Just Scripts
Please note: passing an argument like
--justfile
It only works on MacOS and on Linux.TIL that Justfiles can turn into Just Scripts by adding
#!/usr/bin/env just --justfile
to the top of the file and runningchmod +x
on the file.From the docs:
By adding a shebang line to the top of a
justfile
and making it executable,just
can be used as an interpreter for scripts: https://github.com/casey/just?tab=readme-ov-file#just-scriptsjust.sh
#!/usr/bin/env just --justfile @_default: just --justfile just.sh --list @lint *ARGS: uv --quiet run --with pre-commit-uv pre-commit run {{ ARGS }} --all-files
After you run
chmod +x just.sh
, this file may be run using./just.sh
, and sub-commands everythingjust <subcommand>
will just work.Please note that
--justfile just.sh
is needed if you want your Just Script to be able to introspect or call itself.Why?
More and more of my clients are using Justfiles, and occasionally, I want some other recipes that may belong outside the default workflows. These can also be reusable between projects for some of my other internal tooling, so it’s an excellent resource to learn about.
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Django
,Python
,Justfiles
,Docker
🐳 Using Just and Compose for interactive Django and Python debugging sessions
When I wrote REST APIs, I spent weeks and months writing tests and debugging without looking at the front end. It’s all JSON, after all.
For most of my projects, I will open two or three tabs. I’m running Docker Compose in tab one to see the logs as I work. I’ll use the following casey/just recipe to save some keystrokes and to standardize what running my project looks like:
# tab 1 $ just up
In my second tab, I’ll open a shell that is inside my main web or app container so that I can interact with the environment, run migrations, and run tests.
We can nitpick the meaning of “console” here, but I tend to have another just recipe for “shell” which will open a Django shell using shell_plus or something more interactive:
# tab 2 $ just console
In my third tab, I’ll run a shell session for creating git branches, switching git branches, stashing git changes, and running my linter, which I prefer to run by hand.
# tab 3 $ echo "I'm boring"
Over the last year or two, the web has returned to doing more frontend work with Django and less with REST. Using
ipdb
, in my view, to figure out what’s going on has been really helpful. Trying to getipdb
to “just work” takes a few steps in my normal workflow.# tab 1 (probably) # start everything $ just start # stop our web container $ just stop web # start our web container with "--service-ports" # just start-web-with-debug
The only real magic here is using Docker’s
--service-ports
, which opens ports so we may connect to the openipdb
session when we open one in our view code.My main
justfile
for all of these recipes/workflows looks very similar to this:# justfile set dotenv-load := false @build *ARGS: docker compose build {{ ARGS }} # opens a console @console: docker compose run --rm --no-deps utility/bin/bash @down: docker compose down @start *ARGS: just up --detach {{ ARGS }} @start-web-with-debug: docker compose run --service-ports --rm web python -m manage runserver 0.0.0.0:8000 @stop *ARGS: docker compose down {{ ARGS }} @up *ARGS: docker compose up {{ ARGS }}
If you work on multiple projects, I encourage you to find patterns you can scale across them. Using Just, Make, shell scripts or even Python lightens the cognitive load when switching between them.
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Justfiles
,Docker
,Postgres
🐘 A Just recipe to backup and restore a Postgres database
I have used this casey/just recipe to help backup and restore my Postgres databases from my Docker containers.
I work with a few machines, and it’s an excellent way to create a database dump from one machine and then restore it from another machine. I sometimes use it to test data migrations because restoring a database dump takes a few seconds.
I have been migrating from Docker to OrbStack, and the only real pain point is moving data from one volume to another. I sometimes need to switch between the two, so I have recipes set to back up and restore my database from one context to another.
# justfile DATABASE_URL := env_var_or_default('DATABASE_URL', 'postgres://postgres@db/postgres') # dump database to file @pg_dump file='db.dump': docker compose run \ --no-deps \ --rm \ db \ pg_dump \ --dbname "{{ DATABASE_URL }}" \ --file /code/{{ file }} \ --format=c \ --verbose # restore database dump from file @pg_restore file='db.dump': docker compose run \ --no-deps \ --rm \ db \ pg_restore \ --clean \ --dbname "{{ DATABASE_URL }}" \ --if-exists \ --no-owner \ --verbose \ /code/{{ file }}
Shoutout to Josh Thomas for help on this recipe since we both iterated on this for several projects.
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Justfiles
,Docker
🐳 Managing Docker Compose Profiles with Just: Switching Between Default and Celery Configurations
For a recent client project, we wanted to toggle between various Docker Compose profiles to run the project with or without Celery.
Using Compose’s
profiles
option, we can label services that we may not want to start by default a label. This might look something like this:services: beat: profiles: - celery ... celery: profiles: - celery ... web: ...
We use a casey/just justfile for some of our common workflows, and I realized I could set a
COMPOSE_PROFILES
environment variable to switch between running a “default” profile and a “celery” profile.Using just’s
env_var_or_default
feature, we can set both an ENV variable and a default value to fall back on for our project.# justfie export COMPOSE_PROFILES := env_var_or_default('COMPOSE_PROFILES', 'default') @up *ARGS: docker compose up {{ ARGS }} # ... the rest of your justfile...
To start our service without Celery, I would run:
$ just up
` To start our service with Celery, I would run:
$ export COMPOSE_PROFILES=celery $ just up
Our
COMPOSE_PROFILES
environment variable will get passed into ourjust up
recipe, and if we don’t include one, it will have a default value ofdefault
, which will skip running the Celery service.