docs: add django example

[rdmolony]

Hey there,

I created an example of using devenv alongside Django via poetry including running unit tests by starting the database in the background.

I rely on start-postgres to spin up Postgres in the background (see here similarly to our chat on Discord on spinning up a database in GitHub Actions for testing Django projects

Let me know if you find this useful & if so, if you have any feedback

There's also a corresponding repo - https://github.com/rdmolony/devenv-django

[rdmolony]

I'm not sure if the start-postgres workaround is a good idea.

I'm having a bit of trouble trying to figure out how to run start-mysql or start-postgres outside of devenv up. Ideally, I'd like to run individual process like I might using docker-compose run postgres, so that I can just spin up the database in CI & run tests against it

If interested see example GitHub Action runs here https://github.com/rdmolony/devenv-django/pull/1 against branch https://github.com/rdmolony/devenv-django/tree/reproduce-github-actions-passing-on-failing-test

[rdmolony]

I refactored to use devenv up as per https://github.com/rdmolony/devenv-django/pull/2 as this generalises to services other than postgres required to spin up prior to running tests

[rdmolony]

Adapted https://github.com/cachix/devenv/blob/dfd9c4857c4e4b910b4270c6a35af9f9ba824917/examples/python-poetry/devenv.nix so using languages.python.poetry.enable to initialise poetry

[domenkozar]

I feel like we need to expose wait_for_db from devenv itself for this example to get really small.

I'd love to merge this, but I'd like to make it minimal.

Can we get rid of some of the stuff that's not really required (like gitignore, CI, etc).

[rdmolony]

Let me know if you need anything further here or upstream re wait_for_db!

[domenkozar]

We now have wait_for_port: https://devenv.sh/tests/

[rdmolony]

I simplified the example, it's much simpler via wait_for_port, however, it now throws ...

Having upgraded to devenv 1.0.2 (x86_64-linux)

rowan@Windows:/mnt/c/Users/New User/Code/third-party/devenv/examples/python-django$ devenv test
• Overriding .devenv to .devenv.dPJ3fscqlnMO
• Building tests ...
error:
       … while evaluating the attribute 'config'
         at «github:cachix/devenv-nixpkgs/06fb0f1c643aee3ae6838dda3b37ef0abc3c763b»/lib/modules.nix:322:9:
          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |         ^
          323|         _module = checked (config._module);

       … while calling the 'seq' builtin
         at «github:cachix/devenv-nixpkgs/06fb0f1c643aee3ae6838dda3b37ef0abc3c763b»/lib/modules.nix:322:18:
          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |                  ^
          323|         _module = checked (config._module);

       … while calling the 'throw' builtin
         at «github:cachix/devenv-nixpkgs/06fb0f1c643aee3ae6838dda3b37ef0abc3c763b»/lib/modules.nix:298:18:
          297|                     ''
          298|             else throw baseMsg
             |                  ^
          299|         else null;

       error:
       error: The option `devenv.dotfile' does not exist. Definition values:
       - In `<unknown-file>': "/mnt/c/Users/New User/Code/third-party/devenv/examples/python-django/.devenv.dPJ3fscqlnMO"

✖ Command produced the following output:

✔ Building tests in 15.2s.
Error:   × Command `/nix/store/l24rmcpdnachwhz4rjwb9d89m3gxfy5n-nix-2.21-devenv/bin/nix --show-trace --extra-experimental-features nix-command --extra-experimental-features flakes --option warn-dirty
  │ false --option eval-cache false --keep-going --max-jobs 2 build .#devenv.test --no-link --print-out-paths` failed with with exit code 1

I previously used .env to store SECRET_KEY for Django, however, I have since moved this to an environment variable in devenv.nix & still I see this thrown. I don't understand it.

[domenkozar]

You need to delete your devenv.lock in that folder

[rdmolony]

Thanks @domenkozar, the tests pass now, however, the behaviour doesn't match what I expect. I changed examples/python-django/myapp/test.py to a failing test & devenv test still shows Tests passed :) -

(I switched self.assertEquals(1,1) to self.assertEquals(1,2))

```sh • Overriding .devenv to .devenv.bwFPAwU1VW4y • Building tests ... • Using Cachix: devenv ✔ Building tests in 6.0s. • Building processes ... ✔ Building processes in 3.7s. • Starting processes ...• Building shell ... ✔ Building shell in 3.8s. • PID is 256663 • Stop: $ devenv processes stop ✔ Starting processes in 3.8s. • Running tests ... • Building shell ... evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'warning: unknown setting 'upgrade-nix-store-path-url' warning: unknown setting 'upgrade-nix-store-path-url' evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'Installing dependencies from lock file evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default' No dependencies to install or update evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'[runserver ] • Building shell ... [postgres ] The files belonging to this database system will be owned by user "rowan". [postgres ] This user must also own the server process. [postgres ] [postgres ] The database cluster will be initialized with locale "C". [postgres ] The default text search configuration will be set to "english". [postgres ] [postgres ] Data page checksums are disabled. [postgres ] [postgres ] creating directory /home/rowan/code/devenv/examples/python-django/.devenv.bwFPAwU1VW4y/state/postgres ... ok [postgres ] creating subdirectories ... ok [postgres ] selecting dynamic shared memory implementation ... posix [postgres ] selecting default max_connections ... 100 [postgres ] selecting default shared_buffers ... 128MB evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'[postgres ] selecting default time zone ... Europe/London [postgres ] creating configuration files ... ok evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'[postgres ] running bootstrap script ... ok evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'[runserver ] • Using Cachix: devenv evaluating derivation 'git+file:///home/rowan/code/devenv?dir=examples/python-django#devShells.x86_64-linux.default'[postgres ] performing post-bootstrap initialization ... ok [postgres ] syncing data to disk ... ok [postgres ] [postgres ] [postgres ] Success. You can now start the database server using: [postgres ] [postgres ] /nix/store/ph0bg8kq0g47h6rczgifrrbnag1isb56-postgresql-15.6/bin/pg_ctl -D /home/rowan/code/devenv/examples/python-django/.devenv.bwFPAwU1VW4y/state/postgres -l logfile start [postgres ] [postgres ] initdb: warning: enabling "trust" authentication for local connections [postgres ] initdb: hint: You can change this by editing pg_hba.conf or using the option -A, or --auth-local and --auth-host, the next time you run initdb. [postgres ] [postgres ] PostgreSQL initdb process complete. [postgres ] [postgres ] [postgres ] PostgreSQL is setting up the initial database. [postgres ] ✔ Building shell in 3.2s. [postgres ] waiting for server to start....2024-04-04 08:59:21.033 GMT [261579] LOG: starting PostgreSQL 15.6 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 13.2.0, 64-bit [postgres ] 2024-04-04 08:59:21.041 GMT [261579] LOG: listening on Unix socket "/tmp/devenv-0480122/postgres/.s.PGSQL.5432" [postgres ] 2024-04-04 08:59:21.051 GMT [261601] LOG: database system was shut down at 2024-04-04 08:59:20 GMT [postgres ] 2024-04-04 08:59:21.063 GMT [261579] LOG: database system is ready to accept connections evaluating derivation 'flake:nixpkgs#bashInteractive'[postgres ] done [postgres ] server started [postgres ] Checking presence of database: db [postgres ] 0 [postgres ] Creating database: db evaluating derivation 'flake:nixpkgs#bashInteractive'[postgres ] CREATE DATABASE [postgres ] CREATE ROLE [postgres ] waiting for server to shut down....2024-04-04 08:59:21.202 GMT [261579] LOG: received fast shutdown request [postgres ] 2024-04-04 08:59:21.206 GMT [261579] LOG: aborting any active transactions [postgres ] 2024-04-04 08:59:21.208 GMT [261579] LOG: background worker "logical replication launcher" (PID 261604) exited with exit code 1 [postgres ] 2024-04-04 08:59:21.212 GMT [261599] LOG: shutting down [postgres ] 2024-04-04 08:59:21.216 GMT [261599] LOG: checkpoint starting: shutdown immediate evaluating derivation 'flake:nixpkgs#bashInteractive'[postgres ] 2024-04-04 08:59:21.384 GMT [261599] LOG: checkpoint complete: wrote 922 buffers (5.6%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.024 s, sync=0.120 s, total=0.173 s; sync files=305, longest=0.051 s, average=0.001 s; distance=4226 kB, estimate=4226 kB [postgres ] 2024-04-04 08:59:21.389 GMT [261579] LOG: database system is shut down [postgres ] done [postgres ] server stopped evaluating derivation 'flake:nixpkgs#bashInteractive'[postgres ] 2024-04-04 08:59:21.465 GMT [259877] LOG: starting PostgreSQL 15.6 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 13.2.0, 64-bit [postgres ] 2024-04-04 08:59:21.466 GMT [259877] LOG: listening on IPv4 address "127.0.0.1", port 5432 evaluating derivation 'flake:nixpkgs#bashInteractive'[postgres ] 2024-04-04 08:59:21.482 GMT [259877] LOG: listening on Unix socket "/tmp/devenv-0480122/postgres/.s.PGSQL.5432" [postgres ] 2024-04-04 08:59:21.502 GMT [262148] LOG: database system was shut down at 2024-04-04 08:59:21 GMT [postgres ] 2024-04-04 08:59:21.512 GMT [259877] LOG: database system is ready to accept connections warning: unknown setting 'upgrade-nix-store-path-url' warning: unknown setting 'upgrade-nix-store-path-url' • Setting up shell environment ... warning: unknown setting 'upgrade-nix-store-path-url' warning: unknown setting 'upgrade-nix-store-path-url' • Testing ... ✔ Running tests in 5.4s. • Stopping process with PID 256663 Stopping processes... • Tests passed :) [postgres ] 2024-04-04 08:59:23.189 GMT [259877] LOG: received fast shutdown request [postgres ] 2024-04-04 08:59:23.202 GMT [259877] LOG: aborting any active transactions [postgres ] 2024-04-04 08:59:23.205 GMT [259877] LOG: background worker "logical replication launcher" (PID 262173) exited with exit code 1 [postgres ] 2024-04-04 08:59:23.205 GMT [262146] LOG: shutting down [postgres ] 2024-04-04 08:59:23.221 GMT [262146] LOG: checkpoint starting: shutdown immediate [postgres ] 2024-04-04 08:59:23.236 GMT [262146] PANIC: could not rename file "pg_logical/replorigin_checkpoint.tmp" to "pg_logical/replorigin_checkpoint": No such file or directory ```

[domenkozar]

Can you fix conflicts?

[rdmolony]

I rebased on main (dangerous tool!) & then realised that it was my bad that devenv.lock was out of sync. All good now

[domenkozar]

Thank you!