Add an 'ignorePendingMigrations' configuration option

[yjo]

Add an 'ignorePendingMigrations' option to suppress validation errors caused by the availability of not-yet-applied migrations.

My use case is for a CI/CD pipeline - while developers are working on a feature branch they should be able to create and modify migrations for that feature. However, we should be able to detect and break the build when changes are made to versioned migrations that have already been applied to (e.g.) our production database. Running flyway validate with ignorePendingMigrations=true would support this scenario and be consistent with the existing ignore*Migrations options.

[axelfontaine]

This is already possible by passing -target=current to the flyway validate command.

[yjo]

@axelfontaine -target=current doesn't seem to work in exactly the same way in the presence of out-of-order migrations. E.g. if I run flyway -target=current -ignoreIgnoredMigrations=true -ignoreFutureMigrations=true -outOfOrder=true validate then I can still get "Detected resolved migration not applied" errors. This happens when running with a migration set with a new migration ordered before the current DB version, which can occur when team members work on feature branches that overlap in time. When running with the proposed ignorePendingMigrations=true option the validation works as expected.

[yjo]

Hmm, the right configuration for my use case seems to be to use -ignoreIgnoredMigrations=true -outOfOrder=false which isn't super intuitive. I think one source of difficulty is that the documentation mostly assumes a very linear, serialised version history (corresponding to application release versions), and its examples don't often apply to scenarios where a team creates migrations in a distributed, parallel way (as application features are developed).

[yjo]

Versioned migrations aside, I can't find any combination of existing flags that will pass validation with changes to a repeatable migration. It seems that might only be achievable with an ignorePendingMigrations option, @axelfontaine?

[axelfontaine]

@yjo Thanks for the clarifications. I am starting to warm to the idea of adding this. Reopening.