feat!: support for rolling back migrations by ElijahAhianyo · Pull Request #583 · cot-rs/cot

ElijahAhianyo · 2026-06-02T03:02:46Z

Related issue or discussion

fixes #547

Description

This allows rolling back migrations to the specified migration file.

Assuming the project has the following migration files in its migration dir:

├── migrations
 │   └── m_0001_initial.rs
 |   └── m_0002_second.rs

./target/debug/foo migration rollback m_0001_initial

The above command will roll back(unapply) the m_0002_second file, leaving m_0001_initial applied.
Alternatively, the migration file number can be used for convenience:

./target/debug/foo migration rollback 0001

Migrations are currently tied to a crate(the crate name is used), which means rolling back a migration in a project that imports apps from external crates will implicitly (and only) rollback migrations in the current project/crate. This might change when support for workspaces is added.

This PR also provides a dry-run command to preview migrations to be rolled back before they actually do:

./target/debug/foo migration rollback --dry-run

As a bonus, this PR also adds CLI Group tasks as a means to group nested related subcommands under a parent subcommand:

Eg.

     use async_trait::async_trait;
     use clap::{ArgMatches, Command};
     use cot::cli::{Cli, CliTask, CliTaskGroup};
     use cot::project::WithConfig;
     use cot::{Bootstrapper, Project};
    
     struct Frobnicate;
    
     #[async_trait(?Send)]
     impl CliTask for Frobnicate {
         fn subcommand(&self) -> Command {
             Command::new("frobnicate")
                  .about("Test frobnicate command")

         }
    
         async fn execute(
             &mut self,
             _matches: &ArgMatches,
             _bootstrapper: Bootstrapper<WithConfig>,
         ) -> cot::Result<()> {
             println!("Frobnicating...");
    
             Ok(())
         }
     }
    
     struct MyProject;
     impl Project for MyProject {
         fn register_tasks(&self, cli: &mut Cli) {
             let mut group_command = CliTaskGroup::new("foo").about("Foo related commands");
             group_command.add_task(Frobnicate);
             cli.add_task(group_command);
        }
   }

Type of change

github-actions · 2026-06-02T03:07:14Z

Bencher Report

Project	cot
Branch	elijah/migrations-rollback
Testbed	github-ubuntu-latest

Click to view all benchmark results

Benchmark	Latency	Benchmark Result microseconds (µs) (Result Δ%)	Upper Boundary microseconds (µs) (Limit %)
empty_router/empty_router	📈 view plot 🚷 view threshold	12,572.00 µs (+71.32%) Baseline: 7,338.41 µs	12,807.92 µs (98.16%)
json_api/json_api	📈 view plot 🚷 view threshold	1,003.30 µs (-6.89%) Baseline: 1,077.50 µs	1,368.44 µs (73.32%)
nested_routers/nested_routers	📈 view plot 🚷 view threshold	964.20 µs (-3.97%) Baseline: 1,004.10 µs	1,245.23 µs (77.43%)
single_root_route/single_root_route	📈 view plot 🚷 view threshold	926.74 µs (-4.18%) Baseline: 967.14 µs	1,208.85 µs (76.66%)
single_root_route_burst/single_root_route_burst	📈 view plot 🚷 view threshold	16,289.00 µs (-6.16%) Baseline: 17,357.78 µs	21,685.90 µs (75.11%)

🐰 View full continuous benchmarking report in Bencher

codecov · 2026-06-09T20:39:50Z

Codecov Report

❌ Patch coverage is 88.43188% with 45 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cot/src/db/migrations.rs	85.22%	21 Missing and 22 partials ⚠️
cot/src/cli.rs	97.70%	2 Missing ⚠️

Flag	Coverage Δ
rust	`90.22% <88.43%> (-0.03%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cot/src/db/migrations/sorter.rs	`93.59% <100.00%> (+0.12%)`	⬆️
cot/src/utils/graph.rs	`98.76% <100.00%> (+0.04%)`	⬆️
cot/src/cli.rs	`87.33% <97.70%> (+4.07%)`	⬆️
cot/src/db/migrations.rs	`84.20% <85.22%> (+0.72%)`	⬆️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

m4tx

Looks like a solid start, but we need more work on this before it can be merged.

m4tx · 2026-06-23T20:38:43Z

+    }
+}
+
+struct MigrationRollback;


I believe a few features would make it much more useful:

A subcommand that would list all available migrations

A dry run mode to see which migrations would actually be rolled back

Actual log lines being displayed. cot-cli just eprintlns the info when executing migration make, which I think we could replicate here.

For a subcommand to list all available migrations, I believe we already have that in cot-cli via cot migration list and I dont think we should duplicate that in cot crate. Perhaps this is where #587 can come in handy

Ah, fair, I forgot about this. In that case yes, I think that should suffice for now.

For the future, though, (outside of this PR) maybe it would be useful to have a separate command for listing applied and pending migrations (which would have to be implemented outside of cot-cli I believe).

Ah, one problem with the current solution is that it really only lists the migrations found directly in the current workspace, and it ignores any migrations defined in the dependencies, because this can't really be figured out until runtime. Because of that, I think we will need a better list command in the future. But as I've mentioned, the PR is already big enough, so let's keep it for another one.

seqre

Apart from @m4tx comments, please add snapshot tests for the new commands

- add an app flag which defaults to the current running app

m4tx · 2026-07-22T13:43:11Z

+
+use anstyle::{AnsiColor, Color, Effects, Style};
+
+#[doc(hidden)] // Not part of Cot's public API; used by the CLI.


I'm wondering if it would make sense to take all the #[doc(hidden)] stuff and just move it into another crate. This shouldn't happen in this PR anyway, but this is just something that maybe we should do at some point.

Do you think the cot-core crate is a good place to move these?

I'm not sure, the idea behind cot-core is to only contain the bare, rock-solid minimum required to serve the core functionality (so mostly just HTTP stuff) with minimal number of dependencies. I'm not sure if adding pretty printing there (which is quite a high-level functionality) belongs there. We don't necessarily need to care about this right now, though.

ElijahAhianyo · 2026-07-27T14:40:38Z

Documentation included in #622

m4tx

Please fix the last issue and then it will Look Good To Me!

m4tx · 2026-07-27T16:50:34Z

+
+    #[cot::test]
+    async fn cli_task_group_dispatches_nested_task() {
+        use std::sync::atomic::{AtomicBool, Ordering};


I think this can be moved directly into mod tests.

m4tx · 2026-07-27T16:54:39Z

+    }
+}
+
+struct MigrationRollback;


Ah, one problem with the current solution is that it really only lists the migrations found directly in the current workspace, and it ignores any migrations defined in the dependencies, because this can't really be figured out until runtime. Because of that, I think we will need a better list command in the future. But as I've mentioned, the PR is already big enough, so let's keep it for another one.

feat!: Add support for rolling back migrations

edcd182

github-actions Bot added A-deps Area: Dependencies C-lib Crate: cot (main library crate) labels Jun 2, 2026

ElijahAhianyo and others added 11 commits June 4, 2026 23:00

add unit tests

d069460

chore(pre-commit.ci): auto fixes from pre-commit hooks

965f482

clippy fix

851faff

chore(pre-commit.ci): auto fixes from pre-commit hooks

921ef7b

Merge branch 'master' into elijah/migrations-rollback

4b90c80

fix doc tests

45ed531

update lock

92564de

Merge branch 'master' into elijah/migrations-rollback

6b4176d

remove unwanted test

787f31a

fix linting

d5445b9

shorten test name so mysql runs

d16c593

add some more comments and docs

aa5472c

ElijahAhianyo marked this pull request as ready for review June 9, 2026 20:46

ElijahAhianyo requested review from m4tx and seqre June 9, 2026 20:58

refactor function name

eeb4a62

m4tx requested changes Jun 23, 2026

View reviewed changes

ElijahAhianyo added 3 commits June 25, 2026 22:00

address low-hanging fruits in PR comments

4978351

Merge branch 'master' into elijah/migrations-rollback

65e48e7

remove unused dep

99da125

seqre requested changes Jun 26, 2026

View reviewed changes

ElijahAhianyo added 4 commits June 29, 2026 18:23

- add dry run

b34f193

- add an app flag which defaults to the current running app

Merge branch 'master' into elijah/migrations-rollback

fd959a5

Snapshot test for migration rollback dry run

982e83e

move snapshot testing into tests module

197bd5d

ElijahAhianyo added 2 commits July 17, 2026 21:25

Merge branch 'master' into elijah/migrations-rollback

5e8c26b

add logs to rollback cli and some refactor

ac361ea

github-actions Bot added the C-cli Crate: cot-cli (issues and Pull Requests related to Cot CLI) label Jul 17, 2026

ElijahAhianyo added 3 commits July 21, 2026 13:20

move snapshot tests back

1220134

add snapshot to rollback command

a5e11cd

Merge branch 'master' into elijah/migrations-rollback

2d94f86

ElijahAhianyo requested review from m4tx and seqre July 21, 2026 15:21

m4tx requested changes Jul 22, 2026

View reviewed changes

m4tx changed the title ~~feat!: Add support for rolling back migrations~~ feat!: support for rolling back migrations Jul 22, 2026

ElijahAhianyo added 3 commits July 26, 2026 22:12

Merge branch 'master' into elijah/migrations-rollback

8f13a07

move tests to tests dir

8cd5172

refactor tests

f1ac291

ElijahAhianyo requested a review from m4tx July 26, 2026 23:37

m4tx approved these changes Jul 27, 2026

View reviewed changes

move cli task group test into integration tests

b93f5d1

m4tx reviewed Jul 27, 2026

View reviewed changes

Comment thread cot/tests/cli.rs Outdated

ElijahAhianyo mentioned this pull request Jul 27, 2026

migration list command should list migrations in dependecies #624

Open

move tests back into cli.rs and move use statement to the top

0386701

seqre mentioned this pull request Jul 28, 2026

docs: Add Migration docs #622

Open

6 tasks


		use anstyle::{AnsiColor, Color, Effects, Style};

		#[doc(hidden)] // Not part of Cot's public API; used by the CLI.

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