[WIP] - v4-alpha.1

[mfridman]

This is a continuation of #484, all commits have been squashed from that branch.

There will be a separate place to capture all the additions, changes, removals and fixes.

The goal of these alpha branches is to continue polishing up the PR, making sure the package is idiomatic, has good test coverage and supports the main features. There will be breaking changes along the alpha branches, less in the beta, and little in the release candidates.

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Here's the current plan for rollout:

alpha.N

• How to handle partial migration failures, see comment
• Re-add goose_test.go from the /v3 module
  • Add additional locking tests with built binaries
  • Use t.TempDir() instead of building to the local filesystem
• Add goose init command
• Make decision on whether to pass ctx to the Go register functions such as GoMigration and GoMigrationNoTx

beta.N

• Revisit method specific options vs provider options, see comment
• Add mutex to *goose.Provider (maybe?)
• Add back mysql-specific -certfile, -ssl-cert, and -ssl-key
• Fix CLI output and add JSON where appropriate

rc.N (release candidate)

• Add support for Grouped Migrations feature
• Add goose validate command

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Rationale

Make a decision on whether to pass ctx to the Go register functions such as GoMigration and GoMigrationNoTx

I think it makes sense to break the register functions and force the user to write context-aware functions. It's become a standard in the Go community to pass down the context for request-scoped values, cancelation signals, and deadlines.

In this case, goose may receive a termination signal and it should be possible for the registered Go function to respect this signal and gracefully handle it.

// GoMigration is a Go migration func that is run within a transaction.
- type GoMigration func(tx *sql.Tx) error
+ type GoMigration func(ctx context.Context, tx *sql.Tx) error

// GoMigrationNoTx is a Go migration func that is run outside a transaction.
- type GoMigrationNoTx func(db *sql.DB) error
+ type GoMigrationNoTx func(ctx context.Context, db *sql.DB) error

[mfridman]

Closing in favor of #507