Breaking changes in 2.0

[dberenbaum]

Need a list of all breaking changes in 2.0 to post with release

UPDATE: Jump to #2228 (comment) for summary.

[dberenbaum]

See https://github.com/iterative/dvc/pulls?q=is%3Apr+label%3Abreaking-change

[jorgeorpinel]

Will this be blogged?

[dberenbaum]

Probably so. Thoughts @dmpetrov ?

[dberenbaum]

Summary/questions on breaking changes:

treeverse/dvc#5187 @efiop
What is the breaking change? Did behavior change for stages without deps or outs?

treeverse/dvc#5128 @skshetry

Is this the only breaking change?

The only thing that makes v1 -> v2 incompatible is the parametrization syntax (foreach .. do and vars can be made compatible). As an example, if user were using ${TMPDIR} in the cmd, v2 will start complaining considering it as a parametrization syntax rather than an env var and they'd have to escape them with \ (as, ${TMPDIR}).

Let me know your feedback on this proposed summary: "Environment variables inside the cmd of a stage using ${VAR} syntax must be escaped as \${VAR} in 2.0 due to the use of ${} syntax for templating."

treeverse/dvc#5063 @skshetry
When was set supported? What was the syntax for it? Was this an "experimental" feature? I'm wondering if this actually needs to be documented as a breaking change for the release.

treeverse/dvc#4910 @pmrowla
Similar to the one above, since experiments have been only implemented so far as an experimental feature, do we need to document changes to them as "breaking" for the release?

[pmrowla]

I don't think the experiments change needs to be documented as breaking, that PR and the notes on the wiki page were flagged as breaking for any users that had been testing the experimental feature already

[isidentical]

treeverse/dvc#5527 dropped support for external outputs in google storage, and also changed the default checksum from md5 to etag.

treeverse/dvc#5485 dropped support for login with p12 files on service authentication for gdrive.

[dberenbaum]

iterative/dvc#5187 @efiop
What is the breaking change? Did behavior change for stages without deps or outs?

Stages without dependencies will not always run as if changed. Instead, use --always-changed.

Thoughts on the wording @efiop?

iterative/dvc#5063 @skshetry
When was set supported? What was the syntax for it? Was this an "experimental" feature? I'm wondering if this actually needs to be documented as a breaking change for the release.

Experimental feature - doesn't need to be documented.

[dberenbaum]

Updated breaking changes summary:

• Dropped support for external outputs in Google Cloud Storage and changed the default checksum from md5 to etag.
• Dropped support for login with p12 files on service authentication for Google Drive.
• Stages without dependencies will not always run as if changed. Instead, use --always-changed.
• Environment variables inside the cmd of a stage using ${VAR} syntax must be escaped as \${VAR} in 2.0 due to the use of ${} syntax for templating.