I decided to compare if there will be significant differences between dockerized and non-dockerized Postgres.
Here is my test environment:
- rails 5 application with rich test suite, about 628 examples,
- macOS Sierra 10.12.6,
- Docker 17.06.0-ce-mac19.
I use Postgres docker version alpine 9.6 which is 37,7Mb and raw Postgres 9.6 with GUI for Mac which is 379Mb.
Rails run locally, database.yml connects to the localhost postgres with pool 5 using gem pg (0.21.0).
Here is my docker-compose config
db:
image: postgres:alpine
ports:
- 5432:5432
adminer:
image: adminer
ports:
- 8080:8080
links:
- db
With docker
Finished in 46.86 seconds (files took 17.77 seconds to load)
628 examples, 0 failures
Without docker,
Finished in 31.35 seconds (files took 8.38 seconds to load)
628 examples, 0 failures
And again withDocker
Finished in 41.64 seconds (files took 8.24 seconds to load)
628 examples, 0 failures
And again without Docker
Finished in 31.53 seconds (files took 8.01 seconds to load)
628 examples, 0 failure
And again with Docker
Finished in 41.77 seconds (files took 8.51 seconds to load)
628 examples, 0 failures
So its 41,5 seconds for Docker version and 31,53 seconds without Docker in average.
This is 24% difference in particular rails rspec case, which is quite significant as for comparison and IMHO is not so significant for the testing loop.
At least this is a price you pay for the container portability and convenience.
