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Alexey Melezhik
Alexey Melezhik

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Provision of Docker Containers with Sparrowdo

#docker #perl6 #linux #devops

Introduction

Sparrowdo is a configuration management tool written on Perl6, in this post I'm going to show you how one can configure ( provision ) Docker instances by Sparrowdo scenarios.

Install Sparrowdo

Install Perl6

There are many ways to install Perl6, here are couple of links you can start with:

Once you've finished installing Perl6, the rest is simple, you need to install Sparrowdo as Perl6 module:

$ zef install Sparrowdo
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Running Docker Container

Sparrowdo provisions live Docker containers so you need to run one. I'm going to use bitnami/minideb-extras, however you are free to choose your own one:

$ docker run -t -d bitnami/minideb-extras bash
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If we check our Docker containers, the output will be something like that:

$ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 99bc3937ea37 bitnami/minideb-extras "/entrypoint.sh bash" 2 seconds ago Up 1 second determined_montalcini
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As we've seen we succeeded in running our Docker instance.

Creating Sparrowdo Scenario

Sparrowdo exposes a neat DSL for servers configuration, so we are going to cover some Sparrowdo DSL to show how to use it.

The rest of this article will be related to how one can configure running Docker instances by the means of various Sparrowdo scenarios.

We are going to cover some typical use cases.

Sparrowfile

By default Sparrowdo looks for the scenario source code at the file named sparrowfile located in the current working directory. So we are going place scenario code here.

Consider the first simple use case of creating users and directories.

Creating users, files and directories

Probably most often thing you do setting up your server, so:

user "melezhik"; directory "/var/data/dir-one", %( owner => "melezhik" );
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And then give this scenario run by Sparrowdo:

$ sparrowdo --no_sudo --docker=determined_montalcini --format=production --bootstrap
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The first run will produce a lot of output, don't be confused - because it's fresh server and Sparrowdo first install implies (*) Sparrow client bootstrap on this server ( notice --bootstrap option ). It results on many supplemental operations to be carried out.

The second run will be much faster and will produce much terser output (**):

running sparrow tasks on 127.0.0.1 ... target OS is - ubuntu push [task] create user melezhik OK push [task] create directory /var/data/dir-one OK SPL file /opt/sparrow/sparrow.list is empty get index updates from SparrowHub ... OK set up task box file - /home/melezhik/.sparrowdo//opt/sparrow/task-box.json - OK public@user is uptodate (0.2.1) public@directory is uptodate (0.1.5) running task box from /opt/sparrow/sparrow-cache/task-box.json ... 2017-10-10 10:22:30 : [task] create user melezhik [path] modules/change/ 2017-10-10 10:22:30 : [task] create directory /var/data/dir-one [path] modules/create/
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(*) Sparrow client is used as Sparrowdo agent to execute scenario which gets complied into underlying Sparrow tasks

(**) BTW, Sparrowdo comes with options to set the reports up, please follow the documentation.

Installing system packages

It is also often need when you do server setup and configuration, so:

package-install ( 'nano', 'mc', 'ncdu', 'nginx' );
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And the output will be:

running sparrow tasks on 127.0.0.1 ... target OS is - ubuntu push [task] install packages: nano mc ncdu nginx OK SPL file /opt/sparrow/sparrow.list is empty get index updates from SparrowHub ... OK set up task box file - /home/melezhik/.sparrowdo//opt/sparrow/task-box.json - OK installing public@package-generic version 0.003007 ... Download https://sparrowhub.org/plugins/package-generic-v0.003007.tar.gz --- 200 running task box from /opt/sparrow/sparrow-cache/task-box.json ... 2017-10-10 10:35:54 : [task] install packages: nano mc ncdu nginx [path] modules/apt-get/ [params] action:install package:nano 2017-10-10 10:36:01 : [task] install packages: nano mc ncdu nginx [path] modules/apt-get/ [params] action:install package:mc 2017-10-10 10:36:53 : [task] install packages: nano mc ncdu nginx [path] modules/apt-get/ [params] action:install package:ncdu 2017-10-10 10:36:59 : [task] install packages: nano mc ncdu nginx [path] modules/apt-get/ [params] action:install package:nginx
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Running services

Services are vital part of infrastructure and configuration. Sparrowdo provides a desired set of functions to deal with this task. Let's install Nginx web server and the add it to run levels and then start it. The scenario will be:

package-install 'nginx'; service-enable 'nginx'; service-start 'nginx';
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And the Sparrowdo report looks like this:

running sparrow tasks on 127.0.0.1 ... target OS is - ubuntu push [task] install packages: nginx OK push [task] enable service nginx OK push [task] start service nginx OK SPL file /opt/sparrow/sparrow.list is empty get index updates from SparrowHub ... OK set up task box file - /home/melezhik/.sparrowdo//opt/sparrow/task-box.json - OK public@package-generic is uptodate (0.3.7) installing public@service version 0.001015 ... Download https://sparrowhub.org/plugins/service-v0.001015.tar.gz --- 200 running task box from /opt/sparrow/sparrow-cache/task-box.json ... 2017-10-10 10:42:33 : [task] install packages: nginx [path] modules/apt-get/ [params] action:install package:nginx 2017-10-10 10:42:33 : [task] enable service nginx [path] modules/enable/ [params] os:debian service:nginx 2017-10-10 10:42:33 : [task] start service nginx [path] modules/start/ [params] os:debian service:nginx
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BTW Sparrowdo provides some nifty functions to check services health, so let's use somes to check Nginx server availability:

proc-exists 'nginx'; http-ok;
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In this case we change --format to default value to see more details:

$ sparrowdo --no_sudo --docker=determined_montalcini --format=default
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running sparrow tasks on 127.0.0.1 ... target OS is - ubuntu push [task] check nginx process OK push [task] run bash: curl -fsSLk -D - --retry 3 127.0.0.1 -o /dev/null ... OK SPL file /opt/sparrow/sparrow.list is empty get index updates from SparrowHub ... OK set up task box file - /home/melezhik/.sparrowdo//opt/sparrow/task-box.json - OK installing public@proc-validate version 0.001003 ... Download https://sparrowhub.org/plugins/proc-validate-v0.001003.tar.gz --- 200 installing public@bash version 0.001006 ... Download https://sparrowhub.org/plugins/bash-v0.001006.tar.gz --- 200 running task box from /opt/sparrow/sparrow-cache/task-box.json ... 2017-10-10 11:26:28 : [task] check nginx process [path] / check by pid file pid found at /var/run/nginx.pid:11114 11114 nginx: master process /usr/ 43:54 ok scenario succeeded ok text match /.*/ ok '11114 nginx: master process /usr/ 43:54' match /.*/ STATUS SUCCEED @ runs bash command 2017-10-10 11:26:28 : [task] run bash: curl -fsSLk -D - --retry 3 127.0.0.1 -o /dev/null ... [path] modules/bash-command/ [params] envvars: ++ test -z ++ bash -c ' curl -fsSLk -D - --retry 3 127.0.0.1 -o /dev/null' HTTP/1.1 200 OK Server: nginx/1.6.2 Date: Tue, 10 Oct 2017 11:26:28 GMT Content-Type: text/html Content-Length: 867 Last-Modified: Tue, 10 Oct 2017 10:37:28 GMT Connection: keep-alive ETag: "59dca2e8-363" Accept-Ranges: bytes ok scenario succeeded STATUS SUCCEED
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And finally, if those high level abstractions are not enough you can always execute an arbitrary Bash code, see next section.

Executing Bash Code

Bash function makes it possible to insert snippets of Bash code and execute them, there are many ways to call it and various parameters you may add, the simple form is just a bash $command, like this:

bash('echo hello world');
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Conclusion

Sparrowdo is a modern, all batteries included toolkit to configure servers remotely. As we've seen, it plays nice with Docker.

There is a lot of ground to cover, like ssh/scp commands invocation, fetching Git repositories, population of configuration files by templates and more, I'd encourage you to delve the details at Sparrowdo GitHub documentation pages or at Sparrowdo dedicated blog site - http://sparrowdo.wordepress.com

As usual - ideas, comments and questions are welcome.

Regards.

The author of Sparrowdo.

Top comments (2)

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aptituz profile image
Patrick Schönfeld •

What I'm missing from the article: If you write "Sparrowdo provisions live Docker containers" do you mean that you are actually provisioning docker containers like they are normal systems?

Otherwise I'm missing the parts that talk about how the workflow looks like to actually built images (for ephemeral containers), since that is usually what we want to do if we use docker, isn't it?

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melezhik profile image
Alexey Melezhik •

Sure, Sparrowdo configures running Docker containers, it does not fit for building images.