"flutter channel stable" failed in docker image: cirrusci when publish pages to gitlab

Question

I'm trying to publish my flutter page on gitlab which is the git host of my project. I'm using the ci configure like the following(from this post)

gitlab page CI configure

image: cirrusci/flutter:latest

before_script:
  - flutter channel stable
  - flutter upgrade
  - flutter config --enable-web
  - flutter pub get

pages:
  stage: deploy
  script:
    - flutter build web
    - cp -r build/web public
  artifacts:
    paths:
      - public
  only:
    - live

The ci job failed in an error like:

...
$ flutter channel stable
Switching to flutter channel 'stable'...
git: fatal: 'origin/stable' is not a commit and a branch 'stable' cannot be created from it
Switching channels failed with error code 128.
...

What's the problem?

One thing worth to note is my flutter project locate in a subdirectory(ie., my-flutter-dir) of the repository root. Is it the reason? How to configure the CI script in this situation?

I've tried to add a cd my-flutter-dir as the first command in the before_script, but it still result in the same error.

Solution

It's turn out being an issue of the docker image. After I removed the flutter channel and flutter upgrade command in the befor_script part, everything is ok now.

Note if you have the flutter project in a subdirectory under the repository root, still you need to add cd you-flutter-dir command in the before_script. Also don't forget to put the .gitlab-ci.yml file in the root of the repository.