j2_render

j2_render is a static binary CLI tool to render jinja 2 templates, it can load the context from different sources.

j2_render is writen in rust and uses tera as jinja 2 engine, may be some differences between implementations, so look at tera's documentation for reference

Installation

export J2_RENDER_VERSION=v0.0.1 
sudo curl -L "https://github.com/lumasepa/j2_render/releases/download/${J2_RENDER_VERSION}/j2_render_$(uname | tr '[:upper:]' '[:lower:]')_amd64" -o /usr/local/bin/j2_render
sudo chmod +x /usr/local/bin/j2_render

Working with the Context

The context in j2_render is a json. The context can be loaded from different formats and ways. The context is populated in args order so last arg overwrites keys of previous ones

Supported Context formats

• json
• yaml
• toml
• hcl/tf/tfvars
• key=value

Future Supported

• http/s + json/yaml/toml/hcl/tf/tfvars format+https?://...

Supported Context Inputs

• context file --file -f file_path or format+file_path
• environment variables --env -e
• arguments --var -v key=value or format+key=value
• stdin --stdin -i json/yaml/toml/hcl/tf/tfvars

Working with templates

Templates are jinja 2 templates implemented by tera, for reference of the jinja 2 template lenguaje go to tera doc

Supported Templates Inputs

• Template file --file -f file_path
• stdin --stdin -i template

Usage

j2_render [FLAGS]

    OPTIONS:

        FORMATS = json,yaml,hcl,tfvars,tf,template,j2,tpl
        FILE_PATH = file_path.FORMAT or FORMAT+file_path   -- path to a file ctx, template or output
        VAR = key=value or FORMAT+key=value   -- if format provided value will be parsed as format

    FLAGS:

    --stdin/-i FORMAT   -- read from stdin context or template
    --out/-o file_path   -- output file for rendered template, default stdout
    --env/-e    -- load env vars in ctx
    --file/-f FILE_PATH   -- loads a file as context or template depending on extension or format
    --var/-v VAR   -- adds a pair key value to the context or a template depending on format
    --print-ctx/-p   -- print the context as json and exits
    --help/-h   -- shows this help

Usage Examples

Render a template using a context file

j2_render -f ctx.yaml -f template.j2 > result

Render a template using environment variables

j2_render --env -f template.j2 > result

Render a template using context from stdin

cat ctx.yaml | j2_render -i yaml -f template.j2 > result

Render a template using context from var

echo "Hello {{name}}" | j2_render --var "name=world" -i j2 > result

Render a template from stdin

cat template.j2 | j2_render -i j2 -f ctx.yaml > result

Render a template from vars

TEMPLATE=$(cat template.j2)
j2_render --var "j2+=${TEMPLATE}" -f ctx.yaml > result

Render a template using context mixed by different inputs

cat ctx.json | j2_render --var "name=batman" -i json --env -f ctx.yaml --var "json+list=[1,2,3]" -f template.j2 > result

Abuse to convert to json

j2_render -f file.yaml --print-ctx > file.json

j2_render -f file.tfvars --print-ctx > file.json

j2_render -f file.toml --print-ctx > file.json

Extensions to jinja 2

filters

• "bash"
• "sed"
• "glob"
• "read_file"
• "file_name"
• "file_dir"
• "strip_line_breaks"
• "remove_extension"
• "b64decode"
• "b64encode"
• "str"
• "to_json"
• "from_json"

functions

• "tab_all_lines"
• "tab_all_lines_except_first"
• "bash"
• "str"
• "to_json"
• "from_json"

testers

• "file"
• "directory"