Add documentation around using default Google application credentials,
along with a changelog extra that describes the feature and the
potential impact on existing restic uses (read: none).
This change removes the hardcoded Google auth mechanism for the GCS
backend, instead using Google's provided client library to discover and
generate credential material.
Google recommend that client libraries use their common auth mechanism
in order to authorise requests against Google services. Doing so means
you automatically support various types of authentication, from the
standard GOOGLE_APPLICATION_CREDENTIALS environment variable to making
use of Google's metadata API if running within Google Container Engine.
Before this change restic would attempt to JSON decode the error
message resulting in confusing `Decode: invalid character 'B' looking
for beginning of value` messages. Afterwards it will return `List
failed, server response: 400 Bad Request (400)`
This commit fixes a bug introduced in
e9ea268847: When an invalid lock is
encountered (e.g. if the file is empty), the code used to ignore that,
but now returns the error.
Now, invalid files are ignored for the normal lock check, and removed
when `restic unlock --remove-all` is run.
Closes #1652
As mentioned in issue [#1560](https://github.com/restic/restic/pull/1560#issuecomment-364689346)
this changes the signature for `backend.Save()`. It now takes a
parameter of interface type `RewindReader`, so that the backend
implementations or our `RetryBackend` middleware can reset the reader to
the beginning and then retry an upload operation.
The `RewindReader` interface also provides a `Length()` method, which is
used in the backend to get the size of the data to be saved. This
removes several ugly hacks we had to do to pull the size back out of the
`io.Reader` passed to `Save()` before. In the `s3` and `rest` backend
this is actively used.
