YAMLsubst

Takes YAML from a specified file and substitutes into a template from stdin, output is sent to stdout.

Templates are written in Go's text/template.

Example Usage:

yamlsubst -yaml nginx.conf.yml < nginx.conf.template > /etc/nginx/nginx.conf

Template Functions

datetime

Alias for time.Now

# Generated at {{datetime}}

Outputs:

# Generated at 2015-01-23 13:34:56.093250283 -0800 PST

# Generated at {datetime.Format("Jan 2, 2006 at 3:04pm (MST)")}

Outputs:

# Generated at Jan 23, 2015 at 1:34pm (EST)

See the time package for more usage: http://golang.org/pkg/time/

split

Wrapper for strings.Split. Splits the input string on the separating string and returns a slice of substrings.

{{ $url := .StringToSplit ":" }}
    host: {{index $url 0}}
    port: {{index $url 1}}

toUpper

Alias for strings.ToUpper Returns uppercased string.

key: {{toUpper "value"}}

toLower

Alias for strings.ToLower. Returns lowercased string.

key: {{toLower "Value"}}

join

Alias for the strings.Join function to work with YAML arrays.

{{join .Array ","}}

replace

Alias for the strings.Replace function.

{{replace .replaceExample "-" "_" -1}}

Example Usage

Located at ./test.yml

---
place: World
foods:
  - apples
  - bananas
  - avocados
  - pears
  - carrots

items: foo,bar,baz
replaceExample: qux-bar-bat

Located at ./test.template

Hello {{ .place }} it's {{datetime}}.

My favorite foods are {{join .foods ", "}}.

{{$items := split .items ","}}
{{range $index, $element := $items}}{{$index}}: {{$element}}
{{end}}

Upper: {{toUpper .place}}

Lower: {{toLower .place}}

{{replace .replaceExample "-" "_" -1}}

Usage: yamlsubst -yaml test.yml < test.template

Output:

Hello World it's 2016-03-29 18:28:05.793361229 +1300 NZDT.

My favorite foods are apples, bananas, avocados, pears, carrots.


0: foo
1: bar
2: baz


Upper: WORLD

Lower: world

qux_bar_bat

Go's text/template package is very powerful. For more details on it's capabilities see its documentation.

rjocoleman/yamlsubst