Docker compose upgrade to 2.17.0 breaks yaml config

Danynad · April 3, 2023, 2:57pm

Hello,

I’m running the docker compose installation on latest debian 11.
After upgrading docker-compose-plugin from 2.16.0 to 2.17.x, few errors popped up starting up the docker compose config:

yaml: unmarshal errors:
  line 72: mapping key "<<" already defined at line 70
  line 145: mapping key "image" already defined at line 139
  line 150: mapping key "restart" already defined at line 140
  line 217: mapping key "<<" already defined at line 215

I had to remove duplicate “image” and “restart” tags, and for the other lines I’ve followed this hint:

github.com/docker/compose

[BUG] using multiple yaml alias not working. mapping key "<<" already defined

opened 03:46AM - 29 Mar 23 UTC

closed 06:39AM - 29 Mar 23 UTC

arulrajnet

kind/bug

### Description docker-compose.yml ``` version: '3.9' # yml aliases and an…chors x-mysql: &mysqlenv MYSQL_ROOT_PASSWORD: root MYSQL_DATABASE: test MYSQL_USER: test MYSQL_PASSWORD: test x-mysql-extraenv: &mysqlextraenv MY_CUSTOM_VAR: mycustomvalue services: mysql: image: mysql:5.7 environment: <<: *mysqlenv <<: *mysqlextraenv volumes: - mysql-data:/var/lib/mysql volumes: mysql-data: ``` Try `docker-compose config`. Then getting the following error ``` yaml: unmarshal errors: line 18: mapping key "<<" already defined at line 17 ``` The version of my docker-compose is `2.17.2` The same is working in `2.15.1` , `2.16.0` and even release candidate version `2.17.0-rc.1`. This is broken from version `2.17.0` <img width="466" alt="2023-03-29_09-13" src="https://user-images.githubusercontent.com/834529/228421352-a6ed33ad-2c69-4f48-a1f1-fa8f1ea69760.png"> ### Steps To Reproduce 1. Windows 11 2. Docker compose v2.17.0 3. Copy the above docker-compose.yml 4. Then `docker-compose config` 5. You will see the error ### Compose Version ```Text Docker Compose version v2.17.0 ``` ### Docker Environment ```Text Client: Context: default Debug Mode: false Server: Containers: 9 Running: 1 Paused: 0 Stopped: 8 Images: 53 Server Version: 23.0.0 Storage Driver: overlay2 Backing Filesystem: extfs Supports d_type: true Using metacopy: false Native Overlay Diff: true userxattr: false Logging Driver: json-file Cgroup Driver: systemd Cgroup Version: 2 Plugins: Volume: local Network: bridge host ipvlan macvlan null overlay Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog Swarm: inactive Runtimes: io.containerd.runc.v2 runc Default Runtime: runc Init Binary: docker-init containerd version: 31aa4358a36870b21a992d3ad2bef29e1d693bec runc version: v1.1.4-0-g5fd4c4d init version: de40ad0 Security Options: apparmor seccomp Profile: builtin cgroupns Kernel Version: 5.15.0-67-generic Operating System: Ubuntu 22.04 LTS OSType: linux Architecture: x86_64 CPUs: 4 Total Memory: 8.736GiB Name: ubuntuserver2204 ID: c8839b3e-9c74-4cb6-9444-e5c979394be0 Docker Root Dir: /var/lib/docker Debug Mode: false Username: arulrajnet Registry: https://index.docker.io/v1/ Labels: Experimental: false Insecure Registries: 127.0.0.0/8 Live Restore Enabled: false WARNING: API is accessible on http://0.0.0.0:2375 without encryption. Access to the remote API is equivalent to root access on the host. Refer to the 'Docker daemon attack surface' section in the documentation for more information: https://docs.docker.com/go/attack-surface/ ``` ### Anything else? **Not Working in 2.17.0** ``` arul@windows ~/Downloads/dc-yaml-alias-bug$~/Downloads/docker-compose-windows-x86_64-2.17.0.exe config yaml: unmarshal errors: line 18: mapping key "<<" already defined at line 17 ``` **Working in 2.17.0-rc.1** ``` arul@windows ~/Downloads/dc-yaml-alias-bug$~/Downloads/docker-compose-windows-x86_64-2.17.0-rc.1.exe config name: dc-yaml-alias-bug services: mysql: environment: MY_CUSTOM_VAR: mycustomvalue MYSQL_DATABASE: test MYSQL_PASSWORD: test MYSQL_ROOT_PASSWORD: root MYSQL_USER: test image: mysql:5.7 networks: default: null volumes: - type: volume source: mysql-data target: /var/lib/mysql volume: {} networks: default: name: dc-yaml-alias-bug_default volumes: mysql-data: name: dc-yaml-alias-bug_mysql-data x-mysql: MYSQL_DATABASE: test MYSQL_PASSWORD: test MYSQL_ROOT_PASSWORD: root MYSQL_USER: test x-mysql-extraenv: MY_CUSTOM_VAR: mycustomvalue ```

the docker compose lines before:

    <<: *mayan-container
    <<: *mayan-frontend-ports

and after, this way it’s starting and working:
<<: [*mayan-container, *mayan-frontend-ports]

Hope this can help someone.

roberto.rosario · April 3, 2023, 5:38pm

Hi,

We encountered this recently while working on version 4.5. It took quite a while to figure out. This is independent confirmation that it is not a bug on our side.

I appreciate you taking the time to investigate this.

Thanks for the research and sharing your findings!