This docker container should work out of the box but I built it for use on circleci.

I've included two utility binaries;

1. asdf-install-plugins - Goes through your .tool-versions and installs the plugin for each tool. Properly propagating exit codes so you can use it in a CI build script.
2. asdf-install-versions - Goes through your .tool-versions and installs the missing tools for you. Properly propagating exit codes so you can use it in a CI build script.

CircleCI for some reason doesn't load the ~/.bashrc file.
So it's important to point BASH_ENV to this file.

version: 2
jobs:
  build:
    docker:
      - image: lisinge/asdf:latest
        environment:
          BASH_ENV: "~/.bashrc" # IMPORTANT!

I recommend to utilize caching on CircleCI so asdf doesn't have to install all of your versions on each build.

steps:
  - checkout

  - restore_cache:
      keys:
        - v1-tools-cache-{{ checksum ".tool-versions" }}

  - run: asdf-install-plugins
  - run: asdf-install-versions

  - save_cache:
      key: v1-tools-cache-{{ checksum ".tool-versions" }}
      paths:
        - "~/.asdf/plugins"
        - "~/.asdf/installs"