t-template

README

t-template

A string interpolator and template processor cli tool.

Why

t-template was conceived to solve transforming strings in a flexible way. In our CI system we have JSON/YAML being generated by various system and needs to be consumed in different styles/format. It was also designed to run from within containers to do simple application config.

so simply t-template is a contained binary that consumes variables from stdin/file(s) as JSON and/or yaml and output templated file.

example input yaml file

- Username: "user1"
  Name: "User One"
- Username: "user2"
  Name: "User Two"
- Username: "user3"
  Name: "User Three"

example template

{{ range .}}{{ range .}}
Username: {{.Username}} Name: {{.Name}}{{ end }}
{{ end }}

Running the example

cd test/examples/simple
t-template ./simple.ctmp --yaml users.yml

Output

Username: user1 Name: User One
Username: user2 Name: User Two
Username: user3 Name: User Three

Download

t-template is a go application you can compile it or use latest releases in github.

Inputs

t-template support various input method

Stdin input

You can pass JSON or yaml via stdin.

yaml

cd test/examples/simple
cat users.yml | ./simple.ctmp --stdin-yaml

JSON

cd test/examples/simple
cat users.json | ./simple.ctmp --stdin-json

Files/Directories as input

You can pass both JSON and yaml files as an arguments in a mixed mode -j FILE --json=FILE -y FILE --yaml=FILE. You can repeat them for each file.

cd test/examples/usernames
./userReport.tmp -j ht.json -j pk.json -j ra.json -y cj.yml -y jp.yml -y yo.yml

You can also pass directories and mix with files.

cd test/examples/dir
./dir.tmp -j ./dir_json -j ./a.json -j -y ./dir_yaml -y a.yml

Note

You can also pass stdin and files together

cd test/examples/simple
cat users.json | ./simple.ctmp --stdin-json -j users.json

Output

By default the template is printed to stdout and error, warning and info to stderr.

So you can use normal unix pipe or redirects. i.e. ./simple.ctmp -y input.yml | other_program

You can also use -o FILE --output=FILE for outputting to a file.

Template

t-template supports standard go template syntax and function It also has loads of other functions ">100" for full list please check sprig

Your . is a slice

t-template passes variables within a slice. so your root is always a slice. Most probably your template will always start with

{{ range . }}
SOME SORT OF TEMPLATE
{{ end }}

White spaces control

White spaces are always tricky this might help

Running

You can run t-template by executing the binary and giving it arguments.

cd test/examples/simple
t-template ./simple.ctmp --json users.json

hashbang

You can make your template executable and add a hashbang in the first line #!/usr/bin/env t-template

cd test/examples/simple
./simple.ctmp --json users.json

by default t-template checks for #! in the beginning of file and removes the first line. If you still want the hashbang to be templated. you can pass -i or --ignore-hashbang

If your running MAC you can pass arguments in the hashbang, but this will fail for linux and it is not POSIX #!/usr/bin/env t-template --json users.json And if you decided to do that you have a limit of 127 chars for the entire hashbang line.

Delimiters

By default t-template support the standard go {{ }} delimiters you can change this by passing --left-delimiter="[[" --right-delimiter="]]" Note: depending on your delimiters you might need to escape it with quotes to avoid your shell from interpreting it

cd test/examples/delim
t-template delim.ctmp -j test1.json -j test2.json -j test3.json -y test4.yml -l "<%" -r "%>"

Arguments

To list supported arguments run t-template --help

Examples

Check the examples dir

TODO

• Output bug fix
• More tests
• Support HCL syntax https://www.terraform.io/docs/configuration/syntax.html

License

MIT