Built-in Functions

ubx provides 30 built-in functions usable in any attribute expression. When any argument is Pending<T>, the result is automatically wrapped in .apply().

Interactive Testing

ubx console
> lower("HELLO")
"hello"
> cidrsubnet("10.0.0.0/16", 8, 2)
"10.0.2.0/24"

String Functions

Function	Description	Example
`lower(s)`	Lowercase	`lower("PROD")` → `"prod"`
`upper(s)`	Uppercase	`upper("dev")` → `"DEV"`
`replace(s, old, new)`	Replace all	`replace("a-b", "-", "_")` → `"a_b"`
`trim(s)`	Strip whitespace	`trim(" x ")` → `"x"`
`trimprefix(s, prefix)`	Remove prefix	`trimprefix("pre-x", "pre-")` → `"x"`
`trimsuffix(s, suffix)`	Remove suffix	`trimsuffix("x-suf", "-suf")` → `"x"`
`split(sep, s)`	Split to list	`split(",", "a,b")` → `["a","b"]`
`join(sep, list)`	Join list	`join("-", ["a","b"])` → `"a-b"`
`format(fmt, ...args)`	sprintf	`format("%s-%s", "a", "b")` → `"a-b"`
`strlen(s)`	Length	`strlen("hello")` → `5`

Collection Functions

Function	Description	Example
`length(list)`	Count items	`length(["a","b"])` → `2`
`keys(obj)`	Object keys	`keys({a="1"})` → `["a"]`
`values(obj)`	Object values	`values({a="1"})` → `["1"]`
`merge(obj1, obj2)`	Merge objects	`merge({a="1"},{b="2"})` → `{a="1",b="2"}`
`contains(list, val)`	Membership	`contains(["a","b"],"a")` → `true`
`lookup(obj, key, def)`	Key + fallback	`lookup({a="1"},"b","x")` → `"x"`
`flatten(list)`	Flatten nested	`flatten([["a"],["b"]])` → `["a","b"]`
`distinct(list)`	Remove dupes	`distinct(["a","a","b"])` → `["a","b"]`

Type Conversion

Function	Description	Example
`tostring(v)`	To string	`tostring(42)` → `"42"`
`tonumber(v)`	To number	`tonumber("42")` → `42`
`tobool(v)`	To boolean	`tobool(1)` → `true`

Numeric Functions

Function	Description	Example
`min(a, b)`	Smaller	`min(3, 5)` → `3`
`max(a, b)`	Larger	`max(3, 5)` → `5`
`abs(n)`	Absolute value	`abs(-7)` → `7`
`ceil(n)`	Round up	`ceil(1.3)` → `2`
`floor(n)`	Round down	`floor(1.9)` → `1`

Encoding Functions

Function	Description	Example
`jsonencode(v)`	To JSON	`jsonencode({a="1"})` → `'{"a":"1"}'`
`jsondecode(s)`	Parse JSON	`jsondecode("{}")` → `{}`
`base64encode(s)`	Base64 encode	`base64encode("hi")` → `"aGk="`
`base64decode(s)`	Base64 decode	`base64decode("aGk=")` → `"hi"`

IP/CIDR Functions

Function	Description	Example
`cidrsubnet(cidr, bits, idx)`	Subnet CIDR	`cidrsubnet("10.0.0.0/16", 8, 1)` → `"10.0.1.0/24"`
`cidrhost(cidr, idx)`	Host IP	`cidrhost("10.0.0.0/24", 5)` → `"10.0.0.5"`
`cidrnetmask(cidr)`	Netmask	`cidrnetmask("10.0.0.0/24")` → `"255.255.255.0"`
`cidrprefix(cidr)`	Prefix length	`cidrprefix("10.0.0.0/24")` → `24`

`Pending<T>` Propagation

# Resolved — emitted inline
bucket = lower("PROD")
# → ("PROD").toLowerCase()

# Pending — single arg wraps in .apply()
bucket = lower(~unit.aws_s3_bucket_v2.src.bucket)
# → src.bucket.apply(_dep0 => (_dep0).toLowerCase())

# Multiple pending args — uses pulumi.all()
bucket = join("-", [~unit.x.y.name, ~unit.z.w.id])
# → pulumi.all([x.name, z.id]).apply(([_dep0, _dep1]) => [_dep0, _dep1].join("-"))

​Interactive Testing

​String Functions

​Collection Functions

​Type Conversion

​Numeric Functions

​Encoding Functions

​IP/CIDR Functions

​Pending&lt;T&gt; Propagation

Interactive Testing

String Functions

Collection Functions

Type Conversion

Numeric Functions

Encoding Functions

IP/CIDR Functions

`Pending<T>` Propagation