feat(postgres): use faster sql.DB instead of docker exec psql for snapshot/restore [rebased for main]

[cfstras]

See description of #2599

This is the same PR, but rebased for main.

The original description follows, just with latest benchmarks

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What does this PR do?

The postgres module has functions for saving snapshots and restoring them later.
This feature is helpful for integration testing without having to manually clear the database.

This PR speeds up the snapshot/restore functionality by executing the necessary SQL commands via a regular sql.DB connection.

If the driver is not available in the test environment, or the commands fail for some other reason (SSL config, etc), it falls back to the old variant of calling docker exec.

Why is it important?

docker exec can be unnecessarily slow, especially when using docker in a VM with Docker Desktop or colima.

On my laptop (MacBook Air M1), each call to Container.Restore() takes about 150~200ms.
In a small subset of 20 of our tests, where each test restores the database before starting, with creating the initial container, this brings the total time up to 12 seconds, which is quite a lot for a few small database tests.

After these changes, the same subset of tests now takes 6 seconds.

Related issues

• Relates to feat (postgres): support for creating and restoring Snapshots #2199
• Relates to feat(postgres): use faster sql.DB instead of docker exec psql for snapshot/restore #2599

How to test this PR

cd modules/postgres
go test ./...

Follow-ups

I've also considered caching the DB pool that is created to manage the databases.
After running some benchmark with this code (from branch X), I noticed it does not have a big impact on the whole test suite - my internal test suite does not change in execution time (since the time is dominated by re-connecting the actual test client, which will be terminated when the database gets deleted during the restore).
The module/postgres test suite even gets slower:

cached: main...cfstras:postgres-snapshot-sql-cached-rebased-main
not cached: this PR

testcontainers main, sql, not cached: 42.227 s ± 0.635

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     42.227 s ±  0.635 s    [User: 1.213 s, System: 1.034 s]
  Range (min … max):   41.832 s … 44.006 s    10 runs

testcontainers main, sql, cached: 43.207 s ± 1.549

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     43.207 s ±  1.549 s    [User: 1.247 s, System: 1.057 s]
  Range (min … max):   41.745 s … 45.664 s    10 runs

testcontainers main, without PR (but amended tests): 45.298 s ± 5.610 s

Branch: cfstras:testcontainers-go:main-with-postgres-sql-test-fixes

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     45.298 s ±  5.610 s    [User: 1.218 s, System: 1.005 s]
  Range (min … max):   41.243 s … 57.096 s    10 runs

internal testsuite, with testcontainers main, sql, cached, with ryuk: 14.123 s ± 1.795 s

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     14.123 s ±  1.795 s    [User: 9.589 s, System: 2.749 s]
  Range (min … max):   11.407 s … 16.748 s    10 runs

internal testsuite, with testcontainers main, sql, cached, without ryuk: 11.299 s ± 1.503 s

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     11.299 s ±  1.503 s    [User: 9.818 s, System: 2.728 s]
  Range (min … max):    9.928 s … 13.781 s    10 runs

internal testsuite, with testcontainers main, sql, not cached, without ryuk: 10.597 s ± 0.641 s

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     10.597 s ±  0.641 s    [User: 9.812 s, System: 2.820 s]
  Range (min … max):    9.894 s … 12.029 s    10 runs

internal testsuite, with testcontainers main, without my PR, not cached, without ryuk: 14.245 s ± 0.639 s

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     14.245 s ±  0.639 s    [User: 9.671 s, System: 2.760 s]
  Range (min … max):   13.742 s … 15.980 s    10 runs

internal testsuite, with testcontainers main, docker-exec fallback, not cached, without ryuk: 14.216 s ± 0.450 s

➜ hyperfine "go test ./... -count 1"
Benchmark 1: go test ./... -count 1
  Time (mean ± σ):     14.216 s ±  0.450 s    [User: 9.566 s, System: 2.654 s]
  Range (min … max):   13.735 s … 15.278 s    10 runs

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[mdelapenya]

Let's update the docs path:

Suggested change

	[Example Wait Strategies](../../modules/postgres/postgres_test.go) inside_block:waitStrategy
	[Example Wait Strategies](../../modules/postgres/wait_strategies.go) inside_block:waitStrategy

Once this is done and the CI passes, I think we can merge this one 🚀

[cfstras]

Cool! Fixed those two nits, LMK how it goes.

FYI going on holiday in a few hours, so if there's more things you want me to change it'll have to wait until next week.

Thanks so much for engaging with this :)

[mdelapenya]

@cfstras @ash2k I went ahead and added d8468ec converting the global variable into a container option. PLMK what you think.

Cheers!

[cfstras]

Looks good to me! :) Thanks for making the change.

[mdelapenya]

LGTM, thanks!