ZX Spectrum BASIC Web Server

Finally, you can write your web sites in ZX Spectrum BASIC, using my new project, ZX Spectrum BASIC CGI server .

How it works

Here’s what happens when a request comes in:

  • Apache HTTPD receives the request, and runs the CGI script that does the magic.
  • The CGI script (written in Bash) generates some BASIC code that provides the HTTP meta-vars (e.g. PATH_INFO for the path of the request) as DATA statements and wraps some other boilerplate around the code of the .basic file asked for in the request, and writes out another .basic file which is ready to be executed.
  • Then it uses BAS2TAP (my mirror here) to create an audio tape file representing the program.
  • Next it launches the Fuse spectrum emulator (inside an Xvfb wrapper to make it think it has a display), telling it to load from the audio tape and run the program.
  • The program runs, and writes its HTTP responses to the Spectrum printer using LPRINT statements.
  • Fuse uses very basic OCR to understand what characters are printed, and writes them into a text file.
  • The CGI script monitors the output file, waiting for a line containing an end marker (“ENDSPECTRUMBASIC”). When it finds it, it kills the emulator (since it can’t made to auto-exit, I think).
  • The CGI script sends the contents of the output file (minus the end marker) back to Apache, which returns it as a response.

Simple.

Why?

Originally designed to demonstrate how Docker can help isolate other services from “interesting” dependencies, this became a bit of a labour of love.

I’ll never stop being grateful to the designers of the ZX Spectrum, or the authors of “Further Programming for the ZX Spectrum”.

Changing the Docker daemon options in systemd on Ubuntu 15.04

Update: now documenting the better way, as described in issue 14513.

Update 2: I think this way is even better (works in Ubuntu 16.04, Docker 1.12.2, Reference: dockerd command line):

sudo -s -H
echo '{"insecure-registries":["myreg.example.com:5000"]}' > /etc/docker/daemon.json
exit
sudo service docker restart

End of update 2

On earlier versions of Ubuntu (14.04 and before), changing the command line options to the Docker daemon (e.g. to allow using an insecure private registry) was just a matter of editing /etc/default/docker and uncommenting the line starting with #DOCKER_OPTS=.

On Ubuntu 15.04, even though that file still exists, editing it does not have any effect, and I found it quite tricky to work out how to change Docker’s command line, so I wrote it up here.

I wanted to use an insecure private docker registry for Docker on Ubuntu 15.04, which uses systemd.

Under systemd, we must create a config file that overrides the default Docker command line by typing sudo systemctl edit docker. In the editor which pops up, type:

[Service]
ExecStart=
ExecStart=/usr/bin/docker daemon -H fd:// --insecure-registry=myreg.example.com:5000

Note: the first “ExecStart=” line is necessary.

The second “ExecStart=” line should contain whatever command line options you want to include.

Note: for docker versions before 1.10, replace “daemon” with “-d”.

With this config in place, restart the Docker service:

$ sudo systemctl restart docker

Check everything looks right for the Docker service:

$ systemctl status docker

And confirm the command line arguments have been applied with:

$ ps axwww | grep /usr/bin/docker

The instructions here: Control and configure Docker with systemd and issues: 14513 and 15859 suggest that the Docker team are not planning to make this any easier in the short term.

Docker fails to start on Ubuntu 15.04

I installed Docker on Ubuntu 15.04 using:

wget -qO- https://get.docker.com/ | sh

as described at Install Docker on Ubuntu.

I added myself to the docker group:

sudo usermod -aG docker balaaman

Then I logged out and logged in again, and ran:

docker run hello-world

and saw this:

Cannot connect to the Docker daemon. Is 'docker -d' running on this host?

When I tried to start the Docker daemon like this:

sudo service docker start

I got this error:

Failed to start docker.service: Unit docker.service is masked.

Thanks to Yannick Lizzi on this thread I found this fix:

systemctl unmask docker.service
systemctl unmask docker.socket
systemctl start docker.service

After this, “docker run hello-world” worked fine, and all was well.