Unable to get docker-language-server to recognize compose files

[miversen33]

I recently found this project and figured I would see how well it works. Unfortunately it seems that I am unable to get the lsp to treat a docker compose file as that. For some reason it seems stuck on the idea that docker-compose.yml is actually a dockerfile.

I am not seeing any sort of switch I need to provide to tell the lsp that the file its looking at is a docker compose file, so I assume this is something that should be handled automagically.

I am using neovim with the inbuilt vim.lsp configuration. My configuration is pretty simple,

    config = {
        filetypes = { "dockerfile", "yaml" },
        cmd = { "docker-language-server", "start", "--stdio" },
    }

Note specifically I am not limiting this to docker-compose.yml files currently, just as a test.

Below is the example docker compose file I am trying to use

services:
  web:
    build: .
    ports:
      - "8000:5000"
  redis:
    image: "redis:alpine"

And as you can see in my screenshot, the lsp is confused

This is with version: docker-language-server version 2025-08-12-07d5add

Here is the output from the lsp log (I am assuming but not certain that neovim dumps stderr from the lsp to this file)

[START][2025-08-21 21:24:50] LSP logging initiated
[WARN][2025-08-21 21:24:50] .../lua/vim/lsp.lua:439     "docker does not have a configuration"
[WARN][2025-08-21 21:24:50] .../lua/vim/lsp.lua:439     "yamlls does not have a configuration"
[WARN][2025-08-21 21:24:50] ...m/lsp/client.lua:874     "The language server yamlls triggers a registerCapability handler for workspace/didChangeConfiguration despite dynamicRegistration set to false. Report upstream, this warning is harmless"
[ERROR][2025-08-21 21:24:51] ...m/lsp/client.lua:619    "LSP[docker]"   "Cannot find request with id 4 whilst attempting to cancel"
[ERROR][2025-08-21 21:24:51] ...p/_transport.lua:36     "rpc"   "/home/miversen/.local/share/nvim/miversen/lsps/docker/docker"  "stderr"   '2025/08/21 21:24:51 jsonrpc2 handler: notification "$/cancelRequest" handling error: jsonrpc2: code -32601 message: method not supported: $/cancelRequest\n'

One thing that is interesting is that this seems to only affect diagnostics. Completion recommendations appear to work just fine. I am not super versed in LSP stuff so I don't know what exactly that means

[rcjsuen]

Hi @miversen33, thank you for your interest in this project.

Could you take a look at neovim/nvim-lspconfig#3990? It seems to describe the problem you are experiencing. Perhaps the issue has already been fixed or the changes presented there may help you figure out a solution.

[miversen33]

That sounds like exactly what I was dealing with! I'll try it this evening and let you know :)