lang-ref-ytt.md

ytt Library

Following modules are included with ytt. Example usage:

#@ load("@ytt:regexp", "regexp")

regex: #@ regexp.match("[a-z]+[0-9]+", "__hello123__")

General modules

• load("@ytt:struct", "struct")

st = struct.make(field1=123, field2={"key": "val"})
st.field1 # 123
st.field2 # {"key": "val"}

def _add_method(num, right):
  return num.val + right
end

num123 = struct.make(val=123)

calc = struct.make(add=struct.bind(_add_method, num123))
calc.add(3) # 126

# make_and_bind automatically binds any callable value to given object
calc = struct.make_and_bind(num123, add=_add_method)
calc.add(3) # 126

struct.encode({"a": [1,2,3,{"c":456}], "b": "str"})      # struct with contents
struct.decode(struct.make(a=[1,2,3,{"c":456}], b="str")) # plain values extracted from struct

# plain values extracted from data.values struct
struct.decode(data.values) # {...}

• load("@ytt:assert", "assert")

assert.fail("expected value foo, but was {}".format(value)) # stops execution
x = data.values.env.mysql_password or assert.fail("missing env.mysql_password")

• load("@ytt:data", "data") (see ytt @data/values for more details)

data.values                # struct that has input values
data.list()                # ["template.yml", "data/data.txt"]
data.read("data/data.txt") # "data-txt contents"

• load("@ytt:regexp", "regexp")

regexp.match("[a-z]+[0-9]+", "__hello123__") # True

• load("@ytt:url", "url")

url.path_segment_encode("part part")   # "part%20part"
url.path_segment_decode("part%20part") # "part part"

url.query_param_value_encode("part part") # "part+part"
url.query_param_value_decode("part+part") # "part part"

url.query_params_encode({"x":["1"],"y":["2","3"],"z":[""]}) # "x=1&y=2&y=3&z="
url.query_params_decode("x=1&y=2&y=3;z")                    # {"x":["1"],"y":["2","3"],"z":[""]}

• load("@ytt:version", "version") (see version module doc)

Serialization modules

• load("@ytt:base64", "base64")

base64.encode("regular")      # "cmVndWxhcg=="
base64.decode("cmVndWxhcg==") # "regular"

• load("@ytt:json", "json")

json.encode({"a": [1,2,3,{"c":456}], "b": "str"})
json.decode('{"a":[1,2,3,{"c":456}],"b":"str"}')

• load("@ytt:yaml", "yaml")

yaml.encode({"a": [1,2,3,{"c":456}], "b": "str"})
yaml.decode('{"a":[1,2,3,{"c":456}],"b":"str"}')

Hashing modules

• load("@ytt:md5", "md5")

md5.sum("data") # "8d777f385d3dfec8815d20f7496026dc"

• load("@ytt:sha256", "sha256")

sha256.sum("data") # "3a6eb0790f39ac87c94f3856b2dd2c5d110e6811602261a9a923d3bb23adc8b7"

Overlay module

See Overlay specific docs.

Library module

See Library specific docs.