Dev Container web terminal not working (unmarshaling issue on agent)

[mafredri]

Web Terminal is not working jumping into the devcontainer due to devcontainer.json unmarshaling issue.

2025-04-03 15:54:12.885 [erro]  reconnecting-pty: reconnecting pty failed with attach error  remote=[fd7a:115c:a1e0:4fcc:936f:eee3:3160:4d8e]:30937  local=[fd7a:115c:a1e0:4f79:ab27:2909:8264:7d43]:2  message_id=4b45e782-ade2-4c62-ba08-861305bd28ae  connection_id=442fc409-e396-4f28-a68c-e171d8f3c367  container=inspiring_diffie  container_user="" ...
    error= get container env info:
               github.com/coder/coder/v2/agent/reconnectingpty.(*Server).handleConn
                   /home/runner/work/coder/coder/agent/reconnectingpty/server.go:193
             - read devcontainer remoteEnv:
               github.com/coder/coder/v2/agent/agentcontainers.EnvInfo
                   /home/runner/work/coder/coder/agent/agentcontainers/containers_dockercli.go:122
             - unmarshal devcontainer.metadata:
               github.com/coder/coder/v2/agent/agentcontainers.devcontainerEnv
                   /home/runner/work/coder/coder/agent/agentcontainers/containers_dockercli.go:196
             - json: cannot unmarshal string into Go struct field DevContainer.postCreateCommand of type dcspec.Command

This happened using the https://github.com/devcontainers/template-starter project.

[mafredri]

Seems to be because quicktype isn't properly generating the types.

				"postCreateCommand": {
					"type": [
						"string",
						"array",
						"object"
					],
					// ...

The generated type Command struct doesn't have any custom JSON unmarshaling to handle the different types.

[mafredri]

I think just removing --just-types-and-package from gen.sh might do the trick. But needs validation.