I'm trying to setup emacs in a docker image that I am creating. I would like to create the image with a particular melpa package installed.

This is my Dockerfile:

FROM ubuntu

RUN apt-get update
RUN apt-get install -y emacs
COPY setup.el /root/.emacs.d/
WORKDIR /root/.emacs.d/
RUN emacs --script setup.el

This is my setup.el file:

(require 'package)


(setq package-archives '(("melpa" . "http://melpa.org/packages/")))


(package-install 'racket-mode))

When I go to build the docker image, I get the following error:

Loading /etc/emacs/site-start.d/00debian.el (source)...
Contacting host: melpa.org:80
error in process filter: Could not create connection to melpa.org:443

I looked at the 00debian.el file to see if it had any effect on the docker build.

$ cat /etc/emacs/site-start.d/00debian.el

;; Set the default mail server and news server as specified by Debian
;; policy.

(setq gnus-nntpserver-file "/etc/news/server")

(setq mail-host-address (let ((name (expand-file-name "/etc/mailname")))
                          (if (not (file-readable-p name))
                              (insert-file-contents-literally name)
                              (while (search-forward "\n" nil t)
                                (replace-match "" nil t))

It doesn't seem to have any effect on the package system nor does it seem to be reaching out to Melpa or Elpa.

I made the package-archives point to http Melpa as opposed to https Melpa so that I wouldn't connect on port 443. However, my system still seems to be connecting to Melpa on port 443. I did this because when emacs tries to connect over port 443 it throws an unknown certificate authority error (the certificate authority is R3).

Does anyone have an idea how I might be able to fix the certificate authority error in my docker image or otherwise get Melpa to connect over port 80?

  • MELPA uses Let's Encrypt, so look for guides explaining how to fix certificate errors for it.
    – wasamasa
    Mar 19 at 8:05

I don't have complete answer, but few points which you have to take into consideration:

  1. It won't be possible to connect to Melpa.org over port 80, so it is better to switch to https (port 443)
  2. I don't have any debian to verify/falsify this guess, but most likely you are missing TLS library and certificates.

Ad1. As you can see below, any query to http melpa.org is moved permanently to https:

~  curl -v http://melpa.org/packages/
*   Trying
* Failed to set TCP_KEEPALIVE on fd 6
* Connected to melpa.org ( port 80 (#0)
> GET /packages/ HTTP/1.1
> Host: melpa.org
> User-Agent: curl/7.74.0
> Accept: */*
* Mark bundle as not supporting multiuse
< HTTP/1.1 301 Moved Permanently
< Server: nginx
< Date: Thu, 18 Mar 2021 21:25:41 GMT
< Content-Type: text/html
< Content-Length: 162
< Connection: keep-alive
< Location: https://melpa.org/packages/
<head><title>301 Moved Permanently</title></head>
<center><h1>301 Moved Permanently</h1></center>
* Connection #0 to host melpa.org left intact

Ad.2 Consider adding to your docker image package gnutls, openssl or libressl.

Good luck!


Create your own local ELPA mirror repo from installed packages and use that repo in docker.

See https://github.com/redguardtoo/elpa-mirror

Remote elpa repo might be blocked by corp firewall.


This is something of a workaround but if you create a docker image and install emacs on it and then connect it to melpa/elpa and then approve the connections to the package repositories, it will create a file network.data in root/.emacs.d/.

If you copy the text of that file and create a file named network.data and incorporate that into your docker build process in root/.emacs.d/, it will allow the connection to melpa in a non-interactive mode during the docker build process.

This isn't perfect but it worked for me!

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