DSCI series / Rakulang CI, part2. Cro Application

In this episode I talk about developing web application based on well known cro framework and specifically how to create CI pipeline using DSCI tool.

Here is example of very simple cro application (taken from cro web site):

use Cro::HTTP::Router;
use Cro::HTTP::Server;

my $application = route {
    get -> {
        content 'text/html', 'Hello Cro!';
    }
}

my Cro::Service $service = Cro::HTTP::Server.new:
    :host<localhost>, :port<10000>, :$application;

$service.start;

react whenever signal(SIGINT) {
    $service.stop;
    exit;
}

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---

First of all let's create jobs file .dsci/jobs.yaml that would contain list of jobs, in our case this is just a single job:

jobs:
  - 
    id: ci
    path: .

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In this case we would have just a single job that:

• installs apps dependencies
• runs web application in background
• runs some end to end tests using http client

---

.dsci/job.raku

run_task "install";
run_task "end-to-end";

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.dsci/tasks/install/task.bash

set -e
cd ../
ls -l
zef install . --deps-only
zef install .
echo "done"

nohup cro run 1>app.log 2>&1 & </dev/null

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The first task just installs application dependencies and runs web application in background, now we can create some end to end test. For simplicity I am going to use curl http client here, but feel free choose any languages you like, for example Raku's HTTP::Tiny client, DSCI is super flexible allowing to write tasks on different languages mixing then effectively.

.dsci/tasks/end-to-end/task.bash

I could have made this simple one line Bash task a part of initial install task, but for claritrty and demonstration of modularity I keep as a separate one. In the future more tests may come (rathe then this trivial one) and it reasonable separate installation and testing logic.

set -e
# the test should fail if HTTP response is not
# successful 
curl 127.0.0.1 127.0.0.1:10000 -f -L

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---

Ok, let's try this out. And the very first run results in ... error:

08:47:39 :: ===> Building: Digest::SHA1::Native:ver<1.0.1>:auth<zef:bduggan>
08:47:39 :: [Digest::SHA1::Native] /bin/sh: make: not found

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Which means we need to install make on our alpine worker, let's joust add this line to .dsci/tasks/install/task.bash

apk add --no-cache make

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And run again ... And bump into similar error:

[Digest::SHA1::Native] make: cc: No such file or directory

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So, we just this to .dsci/tasks/install/task.bash

apk add --no-cache make build-base

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To fix the issue of vanilla Alpine not having cc preinstalled.

Ok. After making few others tweaks the pipeline finally passes, bits I've missed:

• adding .cro.yml
• running cro full path /usr/share/rakudo/site/bin/cro

Here is the final ci code and it works!

12:13:02 :: 1 bin/ script [cro] installed to:
12:13:02 :: /usr/share/rakudo/site/bin
12:13:02 :: done
12:13:07 :: ▶ Starting Raku Cro Demo (hello)
[task run: task.bash - .]
[task stdout]
12:13:22 :: HTTP/1.1 200 OK
12:13:22 :: 
12:13:22 :: Content-type: text/html; charset=utf-8
12:13:22 :: Content-length: 10
12:13:22 :: 
12:13:22 :: Hello Cro!

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That's it for today. Thanks for reading and stay tuned for other episodes.