Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/Falldog/dcinja

The smallest binary size of template engine, born for docker image
https://github.com/Falldog/dcinja

command-line-tool configuration docker template template-engine

Last synced: about 1 month ago
JSON representation

The smallest binary size of template engine, born for docker image

Lists

README 

        
# dcinja

------------

The smallest binary size of template engine, born for docker image



Generate template file by powerful template engine `inja`. This project wrap it in 

docker command line binary. 



For building docker image, smaller execution binary size should be better.

The project `dcinja` compile by c++ compiler, the binary size is only **500KB ~ 600KB**.

It's very suitable to use `dcinja` in container to dynamic generate configuration 

file at run-time.



## Dependency library

* [inja](https://github.com/pantor/inja)

* [cxxopts](https://github.com/jarro2783/cxxopts)

* [nlohmann/json](https://github.com/nlohmann/json)



## Binary size

arch | os      | dcinja size  | embedded libstdc++ 

-----|:--------|:------------:|--------------------

linux-amd64 | Ubuntu 16+, Debian stretch+ | 591KB | Y

alpine | alpine 3.9+ | 586KB | N (libstdc++.so 1.3MB+)



## Command line usage

Reference repo docker example to build `dcinja` and copy to `/bin/` as system command in docker image.



help description

```

  dcinja [OPTION...]



  -h, --help               print help

  -w, --cwd arg            change current working dir

  -s, --src arg            source template file path

  -d, --dest arg           dest template file path

  -e, --defines arg        define environment parameters, read system env when not assigned value, ex: `-e NAME=FOO -e NUM=1 -e MY_ENV`

      --force-system-envs  force to use system envs as final value

  -j, --json arg           define json content, ex: `-j {"NAME": "FOO"} -j {"PHONE": "123"}`

  -f, --json-file arg      load json content from file, ex: `-f p1.json -f p2.json`

  -v, --verbose            verbose mode

```



## Template document

[inja - document tutorial](https://github.com/pantor/inja#tutorial), It's compatiable with `Jinja2`.



* variables `{{ ... }}`

* statements `{% ... %}`

    * for loop `{% for key in data %} ... {% endfor %}`

    * condition `{% if value >= 1 %} ... {% else if value >= 0 %} ... {% endif %}`

    * include `{% include "xxx.template" %}`

    * assignment  `{% set name="test" %}`

* functions

    * upper `{{ upper("name") }}`

    * length `{{ length(data_list) }}`

    * ...

* comments  `{# ... #}`



## Example

input template from STDIN, output template to STDOUT

```

$ echo "TEST Name: {{ name }}" | dcinja -j '{"name": "Foo"}'

>>> TEST Name: Foo

```



input template from file, output template to file

```

$ dcinja -j '{"name": "Foo"}' -s input.template -d output.template

```



input json from file

```

$ dcinja -f param.json -s input.template -d output.template

```



define env from command line or system env

```

$ dcinja -e name=Foo -s input.template -d output.template

or

$ export name=Foo

$ dcinja -e name -s input.template -d output.template

```



parameter context priority:

`-e` >> `-j` >> `-f`

1. `-f`: json file

2. `-j`: json content defiend in command line

3. `-e`: environment parameter defeind in command line or system

4. `--force-system-envs`: force to use system envs as final value

```

$ cat name.json

>>> {"name": "P1"}

$ echo "Name: {{ name }}" | dcinja -f name.json

>>> Name: P1

$ echo "Name: {{ name }}" | dcinja -j '{"name": "P2"}' -e name=P3 -f name.json

>>> Name: P3

```



## Integration from release build

Dockerfile example, download `dcinja` into docker image /bin/ as command. The download path should follow Github release page to get latest release version.



**ubuntu**



```

FROM ubuntu:latest

RUN apt-get update && apt-get install -y wget

RUN cd /tmp \

        && wget https://github.com/Falldog/dcinja/releases/download/v1.3/dcinja-1.3.linux-amd64.tar.gz -O dcinja.tar.gz \

        && tar xzf dcinja.tar.gz \

        && cp dcinja /bin/



# testing, check dcinja working normal

RUN dcinja -h \

        && echo "Normal: {{ name }}" | dcinja -j '{"name": "TEST"}'



# ...

```



**ubuntu (multi-stage)**

```

FROM ubuntu:latest as dcinja-downloader

RUN apt-get update && apt-get install -y wget

RUN mkdir -p /app \

        && cd /app \

        && wget https://github.com/Falldog/dcinja/releases/download/v1.3/dcinja-1.3.linux-amd64.tar.gz -O dcinja.tar.gz \

        && tar xzf dcinja.tar.gz



FROM ubuntu:latest

COPY --from=dcinja-downloader /app/dcinja /bin/



# testing, check dcinja working normal

RUN dcinja -h \

        && echo "Normal: {{ name }}" | dcinja -j '{"name": "TEST"}'



# ...

```



**alpine**



```

FROM alpine:latest

RUN apk --no-cache add wget libstdc++

RUN cd /tmp \

        && wget https://github.com/Falldog/dcinja/releases/download/v1.3/dcinja-1.3.alpine.tar.gz -O dcinja.tar.gz \

        && tar xzf dcinja.tar.gz \

        && cp dcinja /bin/



# testing, check dcinja working normal

RUN dcinja -h \

        && echo "Normal: {{ name }}" | dcinja -j '{"name": "TEST"}'

# ...

```



## Note

The binary size build by c++ compiler, it's platform sensitive, the minimum c++ compiler support is C++11. It will dependent with `libstdc++.so`. 



ldd result at ubuntu 18.04

```

$ ldd dcinja

	linux-vdso.so.1 (0x00007ffe933a9000)

	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f376bc40000)

	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f376b8a2000)

	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f376b68a000)

	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f376b299000)

	/lib64/ld-linux-x86-64.so.2 (0x00007f376c220000)

```



Need to make sure your environment have the correct c++ runtime on

* Ubuntu

```

apt-get update

apt-get install libstdc++

```

(Only support ubuntu 16.04+)



* Alpine

```

apk add libstdc++

```