Tag Archives: Unix

The command command

According to the 2018 edition of The Open Group Base Specifications (Issue 7), there’s a command named command which executes commands.

Wait, macOS is OpenGroup UNIX 03 certified, right?

command running uname -a

I tried tracing back the history, macOS is mostly based on FreeBSD, as we can see in their open-source code.

So I started tracing back the FreeBSD code, and I found the current one.

I found the oldest commit about command in FreeBSD’s source tree, but it said

Import the 4.4BSD-Lite2 /bin/sh sources

builtins.def

So I opened up the SVN tree of CSRG, and there I found this

date and time created 91/03/07 20:24:04 by bostic

builtins.def

However, if I knew how to use SVNWeb, I’m pretty sure I’d navigate around the /old/sh directory.

It’s funny, how this line
# NOTE: bltincmd must come first!
Is both in the macOS code AND the CSRG code from 30 years ago.

That’s all folks…

Linux is dead, long-live Docker monoculture

Full Discloser: While reading this blog post, please put yourself in my shoes. You’ve been looking around for a simple monitoring solution, you found some. None of the some are working because you use an Operating System that is used by Apple, WhatsApp, Netflix and many more, but developers think that everyone, everywhere, runs either macOS or Linux. And they all use Docker.

A while back Rubenerd wrote that he’s not sure that UNIX won and how Linux created a monoculture of assuming everything is supposed to run on Linux.

For me, this was not much of a problem, I can run Linux binaries on FreeBSD, I even watch Netflix using Linuxulator.

But now things are on another level, WAY another level.

I have a simple monitoring setup using cron, Grafana, InfluxDB and ping. It basically pings my servers and sends me a telegram message if they are down.

I set that up years ago, but now I have more public facing infrastructure that other people use as well, such as an Armenian Lobsters instance, Jabber.am, a WriteFreely instance and more.

As a self-respecting Ops, I wanted to make a simple dashboard for my users to see the uptime status of these services as well. First, they won’t bug me asking if something is not working; they will SEE, that, SSL/TLS certificate is expired, or the network is an issue, or that the server is down.

<rant>

So I started hunting on the internet for some software that do just that.

The first one that came to my mind was Gatus. I’ve used Gatus before for one of my clients, I like it a lot. It’s simple, it does what it’s supposed to do.

As a sane person, I fetched the code from GitHub using fetch, extracted the tarball and ran make. Nothing happens. Let’s see the Makefile, shall we?

Docker executed in Make

Oh boy, if only, only, I had Docker, all my problems would be solved. First of all, let’s talk about the fact that this Makefile is used as a… script. There’s no dependencies in the targets!

Okay, let’s read that Dockerfile. Executing the scripts inside it should help out, aye?

# Build the go application into a binary
FROM golang:alpine as builder
RUN apk --update add ca-certificates
WORKDIR /app
COPY . ./
RUN CGO_ENABLED=0 GOOS=linux go build -mod vendor -a -installsuffix cgo -o gatus .

# Run Tests inside docker image if you don't have a configured go environment
#RUN apk update && apk add --virtual build-dependencies build-base gcc
#RUN go test ./... -mod vendor

# Run the binary on an empty container
FROM scratch
COPY --from=builder /app/gatus .
COPY --from=builder /app/config.yaml ./config/config.yaml
COPY --from=builder /app/web/static ./web/static
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
ENV PORT=8080
EXPOSE ${PORT}

There are multiple things wrong in me this.

First, please stop putting your binaries in /app, please, pretty-please? We have /usr/local/bin/ for that.

Second, I thought that running go build without GOOS=linux would solve all of my problems. I was wrong, very wrong.

root@mon:~/gatus/gatus-2.8.1 # env CGO_ENABLED=0 go build -mod vendor -a -installsuffix cgo -o gatus .
package github.com/TwinProduction/gatus
        imports github.com/TwinProduction/gatus/config
        imports github.com/TwinProduction/gatus/storage
        imports github.com/TwinProduction/gatus/storage/store
        imports github.com/TwinProduction/gatus/storage/store/sqlite
        imports modernc.org/sqlite
        imports modernc.org/libc
        imports modernc.org/libc/errno: build constraints exclude all Go files in /root/gatus/gatus-2.8.1/vendor/modernc.org/libc/errno

Okay, check this out, the package is called modernc.org/sqlite and it says:

Package sqlite is a CGo-free port of SQLite.

SQLite is an in-process implementation of a self-contained, serverless, zero-configuration, transactional SQL database engine.

Of course it is. Looks like I have to port all of this to FreeBSD. Which, don’t get me wrong, I’m okay with doing that, but I thought that we have POSIX for a reason. notsomuch.

Okay, I’m an open-source guy, I’ll spend some time this weekend to port this to FreeBSD. Let’s look for another solution!

Here’s another one, it’s called statping, also written in Go, the readme is so promising.

No Requirements

Statping is built in Go Language so all you need is the precompile binary based on your operating system. You won’t need to install anything extra once you have the Statping binary installed. You can even run Statping on a Raspberry Pi.

Sounds good! Let’s try it out.

Again, I fetch the tarball, I extract and I bake make.

apt executed in Make

Of course it requires apt! Because not only we all run Linux, be we all run a specific distribution of Linux with a specific package manager.

While tweeting with anger, Daniel pointed out that I should tell them kindly and it’ll work out. I’m sure it will. Let’s hope I can make it work first. I don’t like just opening issues. I’d rather send a patch directly.

</rant>

Overall, now I understand why most *BSD folks use, what’s the word here? ah, yes, old-school software on their systems, like Nagios and the rest.

The developers of the New World Order will assume, always, you are running Linux, as Ubuntu, and you always have Docker.

Hopefully this weekend I will be able to port these software to FreeBSD, otherwise I will just use the Linux layer.

Like Rubenerd said, I am thankful that the mainstream-ness of Linux helped other Unix systems as well, but monocultures are destroying what people have spent years to improve.

Hopefully, next week, I will write a blog post on how to fix these issues and how I got all of those up and running.

That’s all folks…

Two Colons Equals Modules

Days ago I tweeted a shell function which is part of jailio’s code base. Jailio is a project I’ve been working on for the last 6 months. As the name implies, it’s a container management software for FreeBSD Jails.

It has two unique things compared to other Jail management software. First of all, it has no dependencies, it’s written purely in Shell. You can say the same about BastilleBSD, however, Jailio’s second unique thing is that it uses base tools only and requires the base system only. For example, you need to have bastille_enable in BastilleBSD, it also uses its own config files, etc. In Jailio, you need to have jail_enable, because technically Jailio automates jail.conf files. It also uses my patch to automate the jail.confs in /etc/jail.conf.d.

Anyway, back to our topic about Colons and Modules.

I like modules, I got introduced to them when I started programming in school. In Syria, we learn programming at 7th grade but in our school we started a year early, so 6th grade. We always start with block diagrams and then Turbo Pascal!

Yes, 16-bit Turbo Pascal was my first programming language and it had the concept of modules which we called Units.

And then you have languages like C or Shell which don’t have modules. If you use modules you KNOW that it’s hard not to use modules after that.

While reading the source code of vm-bhyve I learned that you can use two colons (::) as part of the function name, which can give you an amazing new superpower to take over the world write cleaner code.

For me this was a life-changer. I write a LOT of Shell code. I ship them to production too. No, you don’t need to write everything in a fancy new language and run it on kubernetes, you can always use simple languages like Shell and run them in a FreeBSD Jail. Or in my case, write in Shell to automate FreeBSD Jails.

Here’s an example code with “modules” in Shell. Note, this works in FreeBSD’s shell, I have not tested other Shells yet.

main.sh

#!/bin/sh

. ./mod1.sh

mod1::func1

mod1.sh

#!/bin/sh

mod1::func1(){
  printf "Here I am, rock you like a hurricane\n"
}
antranigv@pingvinashen:~ % ./main.sh 
Here I am, Rock you like a hurricane

As you can see it all relies on the concept that the function name itself has two colons in its name.

Here’s the code from jailio that I tweeted.

jail::get_next_id(){
  expr $(
    ( grep -s '$id' /etc/jail.conf.d/* || echo '$id = "0";' ) |
    awk -F '[="]' '{print $3}' |
    sort -h |
    tail -1
  ) + 1
}

After tweeting the code above Annatar replied that this should NOT work elsewhere and that’s how I got introduced to The Heirloom Project which provides traditional implementations of the original Unix tools from the original Unix source code.

Hopefully, I will see more people using “modules” in Shell scripts. Hopefully this trick works in other Shell implementations like Bash and zsh.

That’s all folks.