Fix GCS credentials when no endpoint specified

[atombender]

Description

Fixes #137 by not overriding the HTTP client when not necessary.

Without this, GCS errors with 403:

<?xml version='1.0' encoding='UTF-8'?><Error><Code>AccessDenied</Code><Message>Access denied.</Message><Details>Anonymous caller does not have storage.objects.get access to the Google Cloud Storage object.</Details></Error>

This happens when GCS_ENDPOINT isn't set, and the Google SDK is called with option.WithHTTPClient() using a custom HTTP client that disables TLS verification.

Checklist

• Read the CONTRIBUTING document.
• Read the CODE OF CONDUCT document.
• Add tests to cover changes. [Not possible since this only happens with TLS.]
• Ensure your code follows the code style of this project.
• Ensure CI and all other PR checks are green OR
  • Code compiles correctly.
  • All new and existing tests passed.
• Add your changes to Unreleased section of CHANGELOG.

[kakkoyun]

🙈

[kakkoyun]

Thanks a lot for your contribution! Another great PR! Thanks a lot for fixing those mistakes ❤️

[danihodovic]

@kakkoyun could you please update the Docker hub image to include this patch?

[kakkoyun]

@danihodovic We should release a new version. It's been a while. @seandtaber What do you think? Can someone take look at it on your side?

[danihodovic]

Goreleaser has deprecated building Docker images, so you will have to change that too.

[kakkoyun]

Hey @danihodovic, would you be up for handling it? We always welcome to new contributors 🤗

[danihodovic]

I would, but I'm on a busy schedule for the next month. I've resolved the blocker for myself by modifying the Dockerfile, building manually and pushing to danihodovic/drone-cache. The image is rather large, but it works for me.

FROM golang:1.14.4-alpine3.12 AS builder
RUN apk add --update --no-cache ca-certificates tzdata && update-ca-certificates
COPY . /app/
WORKDIR /app/
RUN go build
RUN go install
ENTRYPOINT ["drone-cache"]

[seandtaber]

@danihodovic We should release a new version. It's been a while. @seandtaber What do you think? Can someone take look at it on your side?

We can take a look at this issue and will respond here when we identify the issue.