pongo-blender

pongo-blender

Renders pongo2 templates from environmental variables. pongo2 is the successor of pongo, a Django-syntax like templating-language.

READ: pongo-blender lets me use jinja2 pongo2 templates inside docker containers and populate the values(secrets and configs) at container run time. One image, many containers, every container can have its own configs.

##pongo2 examples https://github.com/flosch/pongo2/blob/master/template_tests/filters.tpl

Requirements

• golang
• $GOPATH set

Set your $GOPATH

mkdir ~/.go
echo "GOPATH=$HOME/.go" >> ~/.bashrc
echo "export GOPATH" >> ~/.bashrc
echo "PATH=\$PATH:\$GOPATH/bin # Add GOPATH/bin to PATH for scripting" >> ~/.bashrc
source ~/.bashrc

For OSX you will also have to do

mkdir $GOPATH/bin
export GOBIN=$GOPATH/bin

Dependencies

• gopkg.in/alecthomas/kingpin.v2
• github.com/flosch/pongo2

Install pongo-blender

Install pongo-blender and dependencies.

cd $GOPATH/src && git clone https://github.com/madedotcom/pongo-blender && cd pongo-blender && go get && go install .
go build

You now have a static binary called pongo-blender, you can run it anywhere. You can even copy it to /bin/ . You can also add this binary to your docker image.

Using pongo-blender

To use pongo blender you need to have a template, pongo-blender will collect the environmental variables and will render the template using those variables. pongo-blender will output the rendered template to stdout. You can try pongo-blender like this:

• Create a vars file

vim vars

with something like this

export SHOES="green"
export CATS="cute"
export STATE="busy"

• Create a template file with something like this

my shoes are {{ SHOES }}
my cats are {{ CATS }}
my state is {{ STATE }}

• Run pongo-blender passing it values for variables you want set

. vars && pongo-blender template > output

• The output file is a complete with your variables and template stuff

egidijus@ub-sol:/tmp/pongos$ cat output 
my shoes are green
my cats are cute
my state is busy

• Using pongo-blender with docker-compose Docker-compose will add crappy affinity env vars to containers, these var are not very parsable because the keys have colons.

To fix this we unset all affinity vars in our entrypoint. Here is an example entrypoint for docker-registry, the var $PROJECT_NAME is set in the Dockerfile. Gosu let's you change which user the process is run as.

#!/bin/sh

unset `env | grep affinity | awk -F= '/^\w/ {print $1}' | xargs`
/usr/bin/pongo-blender /etc/pongo-blender/config.yml.tmpl > /etc/docker-registry/config.yml

chown -R $PROJECT_NAME:$PROJECT_NAME /etc/docker-registry
gosu $PROJECT_NAME docker-registry /etc/docker-registry/config.yml