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https://github.com/bitnami/render-template

CLI tool for rendering templates with custom data
https://github.com/bitnami/render-template

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CLI tool for rendering templates with custom data

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# render-template



This tool allows rendering Handlebars 3.0 templates, using as context data the current environment variables or a provided data file.



# Basic usage



```console

$ render-template --help

Usage:

  render-template [OPTIONS] [template-file]



Application Options:

  -f, --data-file=DATA_FILE    Properties file containing the replacements for the template



Help Options:

  -h, --help                   Show this help message



Arguments:

  template-file:               File containing the template to render. Its contents can be also passed through stdin

```



The tool supports rendering templates from a file or stdin (for convenience).



The source data is taken from the environment variables or a data file, with properties-file format (key=value, a line for each pair). When a variable is defined both as an environment variable and in the data file, the latter will take precedence.



# Examples



## Render data from a template file with environment variables



```console

# Create the template

$ echo 'hello {{who}}' > template.tpl

# Render it without 'who' variable

$ render-template template.tpl

hello 

# Render it with 'who' variable defined

$ who=bitnami render-template template.tpl

hello bitnami

```



## Render data from stdin with environment variables



```console

$ log_file=/tmp/stout.log port=8080 pid_file=/tmp/my.pid render-template <<"EOF"

# My service log file

log_file "{{log_file}}"



# HTTP port

port {{port}}



# My service pid file

pid_file "{{pid_file}}"

EOF

```



Outputs:



```

# My servide log file

log_file "/tmp/stout.log"



# HTTP port

port 8080



# My service pid file

pid_file "/tmp/my.pid"

```



## Render data from stdin with data file



```console

# write data file

$ cat > data.properties <<"EOF"

log_file=/tmp/stout.log

port=8080

pid_file=/tmp/my.pid 

EOF



$ render-template --data-file ./data.properties <<"EOF"

# My servide log file

log_file "{{log_file}}"



# HTTP port

port {{port}}



# My service pid file

pid_file "{{pid_file}}"

EOF

```



Outputs:



```

# My service log file

log_file "/tmp/stout.log"



# HTTP port

port 8080



# My service pid file

pid_file "/tmp/my.pid"

```



## Overriding environment variables in a data file



```console

# Let's define some environment variables

$ export name=foo

$ export company=bar

$ export year=3000



# And write a template

$ cat > data.tpl <<"EOF"

{{name}} works at {{company}}

since {{year}}

EOF



# Rendering from the environment would yield

$ render-template data.tpl

foo works at bar

since 3000



# But we can override it from a data file, either partially, to get a mix:



$ echo "name=mike" > data.properties

$ render-template --data-file data.properties data.tpl

mike works at bar

since 3000



# Or completely:



$ cat > data.properties <<"EOF"

name=mike

company=Bitnami

year=2010

EOF



$ render-template --data-file data.properties data.tpl

mike works at Bitnami

since 2010

```



## Using helpers



The tool supports all the standard handlebar helpers: https://handlebarsjs.com/builtin_helpers.html



```console

$ render-template <<"EOF" 

 {{#if author}}

{{firstName}} {{lastName}}

 {{else}}

Unknown Author

 {{/if}}

EOF



# Which outputs

Unknown Author



$ author=me firsName=foo lastName=bar render-template <<"EOF" 

 {{#if author}}

{{firstName}} {{lastName}}

 {{else}}

Unknown Author

 {{/if}}

EOF



# Outputs:

foo bar

```



In addition, it includes a few custom helpers:



### json_escape



The json_escape helper converts the  provided value into a valid JSON string

```console

$ export VALUE='this is "a string", with quoting



and some line breaks'

```

Without the helper:



```console

$ render-template <<<'VALUE={{VALUE}}'

VALUE=this is "a string", with quoting



and some line breaks

```



Using the helper:

```console

$ render-template <<<'VALUE={{json_escape VALUE}}'

VALUE="this is \"a string\", with quoting\n\nand some line breaks"

```



### quote



The quote helper Quotes a string



Without the helper:

```console

$ ARG1="some arg" ARG2="some other \"arg\"" render-template <<"EOF"

ARG1={{ARG1}} ARG2={{ARG2}}

EOF

ARG1=some arg ARG2=some other "arg"

```



With the helper



```console

ARG1="some arg" ARG2="some other \"arg\"" render-template <<"EOF"

ARG1={{quote ARG1}} ARG2={{quote ARG2}}

EOF

ARG1="some arg" ARG2="some other \"arg\""

```



### or



This helper allows using the "or" logical operation over two values (a value will be true if not empty)



To render a block when either "firstName" or "lastName" values are not empty:



```console

$ cat > data.tpl <<"EOF" 

{{#if (or firstName lastName)}}

{{firstName}} {{lastName}}

{{else}}

Unknown Author

{{/if}}

EOF



$ render-template data.tpl

Unknown Author



$ firstName=foo render-template data.tpl

foo



$ lastName=bar render-template data.tpl

bar

 

$ firstName=foo lastName=bar render-template data.tpl

foo bar

```



This helper can also be used to provide defaults for your template variables:



```console

# No value provided, so we fallback to the second "or" argument

$ render-template <<<'VALUE={{or ENV_VALUE "default value"}}'

VALUE=default value



# ENV_VALUE is defined, so we take it

$ ENV_VALUE="customized value" render-template <<<'VALUE={{or ENV_VALUE "default value"}}'

VALUE=customized value

```



## License



Copyright © 2024 Broadcom. The term "Broadcom" refers to Broadcom Inc. and/or its subsidiaries.



Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.



You may obtain a copy of the License at



    http://www.apache.org/licenses/LICENSE-2.0



Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and limitations under the License.