#9988 feature: Add Backblaze B2 as a first-class state backend (subclass of S3 manager) Issue created by goanpeca Feature scope Configuration (settings parsing, validation, etc.) Description Feature scope Configuration (settings parsing, validation, etc.) Description Proposal Summary Add native Backblaze B2 support as a state backend at

src/meltano/core/state_store/b2/

, registered as the entry point

b2 = meltano.core.state_store.b2.backend:B2StateStoreManager

in

pyproject.toml

. The implementation is a thin subclass of the existing

S3StateStoreManager

that defaults

endpoint_url

to a B2 region (

<https://s3.us-west-004.backblazeb2.com>

) and surfaces

B2_APPLICATION_KEY_ID

/

B2_APPLICATION_KEY

as the canonical credential env vars. Motivation B2 is wire-compatible with S3, and users can already set the

s3

backend with

s3_endpoint_url

pointing at B2 today. But: 1. There is no documented "Meltano + B2" path. New users following the docs configure AWS S3. 2. "Use the s3 backend, override endpoint_url" leaks an AWS-specific abstraction into a non-AWS deployment. Details Proposed layout, mirroring `src/meltano/core/state_store/s3/`: •

src/meltano/core/state_store/b2/__init__.py

•

src/meltano/core/state_store/b2/backend.py

—

B2StateStoreManager(S3StateStoreManager)

with B2 endpoint defaults, B2-flavored

MeltanoError

messages on auth failure. •

src/meltano/core/state_store/b2/settings.py

— declares

B2_APPLICATION_KEY_ID

,

B2_APPLICATION_KEY

,

B2_ENDPOINT_URL

,

B2_BUCKET

,

B2_PREFIX

. •

pyproject.toml

— register entry point under

[project.entry-points."meltano.state_backends"]

(alongside the existing

s3

,

azure

,

gs

,

file

) and the corresponding settings under

[tool.meltano.settings]

(mirroring the

s3_*

lines). •

tests/meltano/core/state_store/test_b2.py

— mirror the S3 tests using

moto

(already in test deps via the s3 backend). • Docs page on docs.meltano.com under "State Backends" with a

meltano.yml

snippet. No new runtime dependencies —

boto3>=1.35,<2

is already declared as the

s3

extra; the B2 backend reuses it. Users install with

meltano[s3]

(no separate

b2

extra needed). Backward compatibility Pure addition. Users currently using

state_backend.uri: s3://...

with

s3_endpoint_url

set to B2 keep working unchanged. Willingness to contribute Yes — I can prepare the PR. It will: • Follow

nox -t lint

,

nox -s typing

, and

nox -s pytest

(per AGENTS.md). • Use type hints throughout and raise

MeltanoError

for user-actionable failures. • Mirror the test structure under

tests/meltano/core/state_store/

. • Use the PR template, include the generative-AI disclosure if AI-assisted. File references •

src/meltano/core/state_store/base.py

—

StateStoreManager

ABC. •

src/meltano/core/state_store/s3/backend.py

— pattern to mirror. •

pyproject.toml

lines ~91–109 — settings + entry-point registration. meltano/meltano