still loving git (though it has corrupted repo)

Last day I’ve had my 5 minutes panic.

On two (2!) different repos git says that I’ve corrupted files in it.
A rapid googling showed me exotic fixes to the problem, actually removing empty files from inner git secret folders.

The question is…why?
I’m on git, I can clone it again and restart from there!
So..let’s go.

Here’s a picture of my broken repo. Isn’t it lovely?

# broken!
git status
error: object file .git/objects/ea/2dcd1b9994ec139cc1328c8c0f3d45b94be228 is empty
error: object file .git/objects/ea/2dcd1b9994ec139cc1328c8c0f3d45b94be228 is empty
fatal: loose object ea2dcd1b9994ec139cc1328c8c0f3d45b94be228 (stored in .git/objects/ea/2dcd1b9994ec139cc1328c8c0f3d45b94be228) is corrupt


Let’s start from a new cleaned folder, then I’ll inspect where are my changes:

# list what's new
mv folder/ folder.broken/
git clone
diff -q -r -x node_modules -x .git folder/ folder.broken/


After I’m confident of my changes I can copy new stuff into my new folder.

# realign code
rsync -av --exclude node_modules --exclude .git folder.broken/ folder/


…and remember: use many, small commits to keep your tree clean!

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Jenkins (on docker) <3 siblings docker images

I was studying jpetazzo’s docker-in-docker (dind) to manage Jenkins builds, annoyed by the fact that I wasn’s able to separate the build engine from my build artifacts.
While digging deeper I’ve found the two alternative options (read this):

• installing the Docker CLI using your base image’s packaging system (i.e. if your image is based on Debian, use .deb packages)

• using the Docker API

So I decided for the third option … 😎

TL;DR

Communicate with your host’s docker daemon through the docker API using docker-compose inside your jenkins image.
Remember that to make it works you have to bind the docker.sock file from-in-to-out (-v /var/run/docker.sock:/var/run/docker.sock)

Let’s go

Install docker-ce and docker-compose on your host

Create a folder that will contain the dockerized jenkins (server) stuff in your home (if you change this path please fix the following docker run command):
mkdir -p $HOME/jenkins/jenkins_home

Into jenkins/ create a Dockerfile that extends the jenkins/jenkins image and downloads+install the docker-compose executable:
FROM jenkins/jenkins
USER root
RUN curl -L https://github.com/docker/compose/releases/download/1.22.0/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose && chmod +x /usr/local/bin/docker-compose
USER jenkins

Finally you can run the built image, with some trick: run as a daemon, expose needed ports, mount a named volume for jenkins stuff (to save state) and share the docker.sock

docker run -it -d --name jenkins_docker -p 8080:8080 -p 50000:50000 -v $HOME/jenkins/jenkins_home:/var/jenkins_home -v /var/run/docker.sock:/var/run/docker.sock jenkins-docker
Or, if you prefer using compose:

version: '3'
services:
  jenkins:
    image: jenkins-docker
    build: .
    ports:
      - "8080:8080"
      - "50000:50000"
    volumes:
      - $HOME/jenkins/jenkins_home:/var/jenkins_home
      - /var/run/docker.sock:/var/run/docker.sock

Now, after configuring the first jenkins run, you are able to build your 1st pipeline.
As a test, you can enter the running image:
docker exec -it -u root jenkins-docker bash
and manually launch a build of a docker image using compose.

It will communicate through the container-host binding and the image will be built into our host.

 

git + dropbox = gitbox!

Let say you’d like to sync all your projects between different pcs you own. Surely you can put every project on GitHub but this is not good for closed source projects (not if you’re using their free plan).

You can put the entire project on DropBox, but it will fill your space with .obj, .dll, .tmp, /node_modules/, … stuff you really NOT need.

The trick is to keep just a bare repository into DropBox: a well formed gitignore file will prevent you to sync object files.
So I create a GitBox folder into my DropBox folder, then:

cd "c:\DropBox\GitBox"
mkdir MyAwesomeProject
cd MyAwesomeProject
git init --bare

cd "c:\MyDevPath\MyAwesomeProject"
git init
git remote add gitbox "c:\DropBox\GitBox\MyAwesomeProject"
git add *
git status
git commit -m "1st commit"
git push --set-upstream gitbox master


 

Inspect a list of filenames (js)

This shortcut demonstrates the power of some ES6 features.

Given a list of filenames, a map function is applied onto the array to generate (another) array of objects. Arrow functions and parentheses (to return JSON objects) are the trick used to add properties “on the fly”.
The resulting object will have the name, path and stats information resolved.

https://bitbucket.org/snippets/pirraste/8eG956/filesniffjs

 

SELECT latestversion FROM versionedRows: a comparative approach

Because there’s no “the best way to do things” but only the best way to do THIS thing (to read with Yoda voice).

 

GZip a file in memory (csharp)

It is a thing I ALWAYS forget: what’s the right piping sequence? How avoid errors? ..and so on…

Here’s the snippet

 

POST a file, read a JSON response

Here’s a trick to send a file to a server AND read a response from it, in the same context.
I used it with a Node.js server (Express + busboy) and it worked like a charm.

When using HTML forms, you can submit stuff to a server but you can’t read a response from it.
If you need some kind of “send data” → (do something server side) → “read response” it can be painful.

I wrote a workaround to manage this kind of situation. It is pretty simple:
– prepare a form as usual
– block the original event
– build an ajax request as a POST method

Here’s the code