[Discuss] How to let CIDER make use of Clojure docker image?

[stardiviner]

This is a discuss, but in order to keep records down, and might help other people. So I record it here. I know there is a channel #cider/#emacs on Slack. I will post this link over there.

I want to use different version and environment of Clojure. There is an official Clojure Docker image. https://hub.docker.com/_/clojure

I'm thinking how to use Clojure image's binary and REPL in Emacs, and CIDER.

There are some ways can access Docker image as I know:

• running container which started Clojure REPL, user can attach it with Emacs package docker.el.
• use Emacs package docker-tramp.el and docker.el to access clojure container binary commands like clojure, clj etc. So that Emacs use them as executable command path. Like CIDER has customize option cider-clojure-cli-command. I tried following, but failed.

(add-to-list 'exec-path "/docker:clojure:/usr/local/bin/")
(setq cider-clojure-cli-command "/docker:clojure:/usr/local/bin/clojure")

• run the clojure image to expose the ip:port to host system. So that Emacs can access the Docker container just like host system local. I don't know how to do that yet.

Anyone have suggestion and solution? Welcome to add. (This might could add to Wiki, when the discussion is almost) Thanks for viewing.

[stardiviner]

I found CIDER has an variable to keep connection records. Could be used in upper mentioned case.

Like this:

(setq cider-known-endpoints
  '(("host-a" "10.10.10.1" "7888")
    ("host-b" "7888")))

[stardiviner]

• use CIDER remote host SSH support to SSH into Docker container
• Use CIDER transparent TRAMP support to use Emacs package docker-tramp.el to open files on container, then cider-jack-in-*, CIDER could transparently handling this.

[darkleaf]

I use docker-compose and volumes:

# docker-compose.yml
version: '3'

volumes:
  m2:
  gitlibs:

services:
  app:
    image: clojure:tools-deps-alpine
    working_dir: "${PWD}"
    command: "true"
    ports:
      - "4444:4444" # nrepl
      - "4445:4445" # http
    environment:
      - "CLJ_CONFIG=${PWD}/.docker-clojure"
      - DATABASE_URL=postgres://postgres:password@db:5432/postgres
      - TEST_DATABASE_URL=postgres://postgres:password@test-db:5432/postgres
      - PORT=4446
    volumes:
      - ".:${PWD}:cached" # cached - MacOS option
      - m2:/root/.m2
      - gitlibs:/root/.gitlibs
    links:
      - db
      - test-db
  db: &db
    image: postgres:10.4-alpine
    environment:
      - POSTGRES_PASSWORD=password
  test-db:
    <<: *db

;; .docker-clojure/deps.edn
{:aliases {:cider {:extra-deps {darkleaf/cider-tools-desp
                                {:git/url "https://github.com/darkleaf/cider-tools-deps.git"
                                 :sha     "1025b510db24b36ab741bc5599e36806eec904ec"}}
                   :main-opts  ["-m" "darkleaf.cider-tools-deps"
                                "port" "4444" "host" "0.0.0.0"]}
           :repl  {:extra-deps {darkleaf/repl-tools-deps
                                {:git/url "https://github.com/darkleaf/repl-tools-deps.git"
                                 :sha     "04e128ca67785e4eb7ccaecfdaffa3054442358c"}}
                   :main-opts  ["-m" "darkleaf.repl-tools-deps"]}

           :run-tests {:extra-deps {com.cognitect/test-runner
                                    {:git/url "https://github.com/cognitect-labs/test-runner.git"
                                     :sha     "028a6d41ac9ac5d5c405dfc38e4da6b4cc1255d5"}}
                       :main-opts  ["-m" "cognitect.test-runner"]}

           :coverage {:extra-deps {cloverage {:mvn/version "1.0.13"}}
                      :main-opts  ["-m" "cloverage.coverage" "-p" "src"  "-s" "test"]}}}

I run docker-compose run --rm --service-port app bash and than clojure -Acider.
In emacs I press C-c M-c and connect to localhost:4444.

Dependencies are installed into volumes. So Emacs can't have access to them.

[stardiviner]

Dependencies are installed into volumes. So Emacs can't have access to them.

I'm confused on this. Dependencies are installed into volumes, but Emacs CIDER connect to container started clojure -Acider alias. So if clojure -Acider should be able to access all dependencies in container. Add project dependencies into a container deps.edn file?

Can Docker access host system's .m2/ dependencies? So that Docker will be a bridge between Emacs CIDER and host system dependencies.

[zilti]

We have Maven and tools like Boot and Leiningen, why on earth would Docker be even necessary here? Just because it's trendy?

[darkleaf]

@stardiviner

I'm confused on this.

REPL is started inside a docker container. This process have access to container file system
with container related paths. Lock at volumes section:

    volumes:
      - ".:${PWD}:cached" # cached - MacOS option
      - m2:/root/.m2
      - gitlibs:/root/.gitlibs

$PWD is /User/darkleaf/projects/project for example. So the project sources are
available in the same path inside container .
It's make sense. REPL can send to Emacs some path and that path is container related.
Emacs can't get a file on host file system if paths are inconsistent.
So I use ${PWD}.

Later I used to mount .m2 and .gitlibs from host file system.
I use Docker for Mac and it's host volumes are slow. So I switched to container volumes.

[stardiviner]

@darkleaf I see. Thanks.

@zilti switch Java version, Clojure version is simpler on Docker? and It's cleaner. Easy to package image then share, simpler to reproduce environment issue. I admit Leiningen and Boot (I have not use it myself) is great. Still thanks for your advice.

[bbatsov]

Seems you've sorted this out, so I'll close this ticket.