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bake: add unixtimestampparse function #3286

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56 changes: 55 additions & 1 deletion bake/hclparser/stdlib.go
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ var stdlibFunctions = []funcDef{
{name: "trimspace", fn: stdlib.TrimSpaceFunc},
{name: "trimsuffix", fn: stdlib.TrimSuffixFunc},
{name: "try", fn: tryfunc.TryFunc, descriptionAlt: `Variadic function that tries to evaluate all of is arguments in sequence until one succeeds, in which case it returns that result, or returns an error if none of them succeed.`},
{name: "unixtimestampparse", factory: unixtimestampParseFunc},
{name: "upper", fn: stdlib.UpperFunc},
{name: "urlencode", fn: encoding.URLEncodeFunc, descriptionAlt: `Applies URL encoding to a given string.`},
{name: "uuidv4", fn: uuid.V4Func, descriptionAlt: `Generates and returns a Type-4 UUID in the standard hexadecimal string format.`},
Expand Down Expand Up @@ -248,7 +249,7 @@ func sanitizeFunc() function.Function {

// timestampFunc constructs a function that returns a string representation of the current date and time.
//
// This function was imported from terraform's datetime utilities.
// This function was imported from Terraform's datetime utilities.
func timestampFunc() function.Function {
return function.New(&function.Spec{
Description: `Returns a string representation of the current date and time.`,
Expand Down Expand Up @@ -281,6 +282,59 @@ func homedirFunc() function.Function {
})
}

// unixtimestampParseFunc, given a unix timestamp integer, will parse and
// return an object representation of that date and time
//
// This function is similar to the `unix_timestamp_parse` function in Terraform:
// https://registry.terraform.io/providers/hashicorp/time/latest/docs/functions/unix_timestamp_parse
func unixtimestampParseFunc() function.Function {
return function.New(&function.Spec{
Description: `Given a unix timestamp integer, will parse and return an object representation of that date and time. A unix timestamp is the number of seconds elapsed since January 1, 1970 UTC.`,
Params: []function.Parameter{
{
Name: "unix_timestamp",
Description: "Unix Timestamp integer to parse",
Type: cty.Number,
},
},
Type: function.StaticReturnType(cty.Object(map[string]cty.Type{
"year": cty.Number,
"year_day": cty.Number,
"day": cty.Number,
"month": cty.Number,
"month_name": cty.String,
"weekday": cty.Number,
"weekday_name": cty.String,
"hour": cty.Number,
"minute": cty.Number,
"second": cty.Number,
"rfc3339": cty.String,
"iso_year": cty.Number,
"iso_week": cty.Number,
})),
Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
ts, _ := args[0].AsBigFloat().Int64()
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@sdavids sdavids Jul 13, 2025

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see above

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@sdavids sdavids Jul 13, 2025 •
edited
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You might want to also handle the error.

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@crazy-max crazy-max Jul 14, 2025

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You might want to also handle the error.

.Int64() does not return an error as second value but accuracy: https://pkg.go.dev/math/big#Float.Int64

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@sdavids sdavids Jul 14, 2025

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See my note for the tests … someone could conceivably supply the following values -1, 0, 1.2, and "0"

unixTime := time.Unix(ts, 0).UTC()
isoYear, isoWeek := unixTime.ISOWeek()
return cty.ObjectVal(map[string]cty.Value{
"year": cty.NumberIntVal(int64(unixTime.Year())),
"year_day": cty.NumberIntVal(int64(unixTime.YearDay())),
"day": cty.NumberIntVal(int64(unixTime.Day())),
"month": cty.NumberIntVal(int64(unixTime.Month())),
"month_name": cty.StringVal(unixTime.Month().String()),
"weekday": cty.NumberIntVal(int64(unixTime.Weekday())),
"weekday_name": cty.StringVal(unixTime.Weekday().String()),
"hour": cty.NumberIntVal(int64(unixTime.Hour())),
"minute": cty.NumberIntVal(int64(unixTime.Minute())),
"second": cty.NumberIntVal(int64(unixTime.Second())),
"rfc3339": cty.StringVal(unixTime.Format(time.RFC3339)),
"iso_year": cty.NumberIntVal(int64(isoYear)),
"iso_week": cty.NumberIntVal(int64(isoWeek)),
}), nil
},
})
}

func Stdlib() map[string]function.Function {
funcs := make(map[string]function.Function, len(stdlibFunctions))
for _, v := range stdlibFunctions {
Expand Down
26 changes: 26 additions & 0 deletions bake/hclparser/stdlib_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -205,3 +205,29 @@ func TestHomedir(t *testing.T) {
require.NotEmpty(t, home.AsString())
require.True(t, filepath.IsAbs(home.AsString()))
}

func TestUnixTimestampParseFunc(t *testing.T) {
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@sdavids sdavids Jul 13, 2025 •
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You might want to add tests for -1, 0, 1.2, and "0".

fn := unixtimestampParseFunc()
input := cty.NumberIntVal(1690328596)
got, err := fn.Call([]cty.Value{input})
require.NoError(t, err)

expected := map[string]cty.Value{
"year": cty.NumberIntVal(2023),
"year_day": cty.NumberIntVal(206),
"day": cty.NumberIntVal(25),
"month": cty.NumberIntVal(7),
"month_name": cty.StringVal("July"),
"weekday": cty.NumberIntVal(2),
"weekday_name": cty.StringVal("Tuesday"),
"hour": cty.NumberIntVal(23),
"minute": cty.NumberIntVal(43),
"second": cty.NumberIntVal(16),
"rfc3339": cty.StringVal("2023-07-25T23:43:16Z"),
"iso_year": cty.NumberIntVal(2023),
"iso_week": cty.NumberIntVal(30),
}
for k, v := range expected {
require.True(t, got.GetAttr(k).RawEquals(v), "field %s: got %v, want %v", k, got.GetAttr(k), v)
}
}
34 changes: 34 additions & 0 deletions docs/bake-stdlib.md
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,7 @@ title: Bake standard library functions
| [`trimspace`](#trimspace) | Removes any consecutive space characters (as defined by Unicode) from the start and end of the given string. |
| [`trimsuffix`](#trimsuffix) | Removes the given suffix from the start of the given string, if present. |
| [`try`](#try) | Variadic function that tries to evaluate all of is arguments in sequence until one succeeds, in which case it returns that result, or returns an error if none of them succeed. |
| [`unixtimestampparse`](#unixtimestampparse) | Given a unix timestamp integer, will parse and return an object representation of that date and time. A unix timestamp is the number of seconds elapsed since January 1, 1970 UTC. |
| [`upper`](#upper) | Returns the given string with all Unicode letters translated to their uppercase equivalents. |
| [`urlencode`](#urlencode) | Applies URL encoding to a given string. |
| [`uuidv4`](#uuidv4) | Generates and returns a Type-4 UUID in the standard hexadecimal string format. |
Expand Down Expand Up @@ -1385,6 +1386,39 @@ target "webapp-dev" {
}
```

### <a name="unixtimestampparse"></a> `unixtimestampparse`

The returned object has the following attributes:
* `year` (Number) The year for the unix timestamp.
* `year_day` (Number) The day of the year for the unix timestamp, in the range 1-365 for non-leap years, and 1-366 in leap years.
* `day` (Number) The day of the month for the unix timestamp.
* `month` (Number) The month of the year for the unix timestamp.
* `month_name` (String) The name of the month for the unix timestamp (ex. "January").
* `weekday` (Number) The day of the week for the unix timestamp.
* `weekday_name` (String) The name of the day for the unix timestamp (ex. "Sunday").
* `hour` (Number) The hour within the day for the unix timestamp, in the range 0-23.
* `minute` (Number) The minute offset within the hour for the unix timestamp, in the range 0-59.
* `second` (Number) The second offset within the minute for the unix timestamp, in the range 0-59.
* `rfc3339` (String) The RFC3339 format string.
* `iso_year` (Number) The ISO 8601 year number.
* `iso_week` (Number) The ISO 8601 week number.

```hcl
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@tonistiigi tonistiigi Jul 14, 2025

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how about

variable "SOURCE_DATE_EPOCH" {
  type    = number
  default = formattimestamp("X", "2015-10-21T00:00:00Z")
}

target "default" {
  args = {
    SOURCE_DATE_EPOCH = SOURCE_DATE_EPOCH
    BUILD_TIME = formattimestamp("YYYY-MM-DD'T'00:00:00Z", SOURCE_DATE_EPOCH)
  }
}

I'm also ok for special formatting for rfc3399 for less verbosity.

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@crazy-max crazy-max Jul 15, 2025

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I looked at forking FormatDateFunc func as they are not willing to accept timestamp format: zclconf/go-cty#130 (comment) but there's quite a lot to fork and it might be better to be aligned so users are not confused. So that's why I opted for the terraform unix_timestamp_parse function func instead.

# docker-bake.hcl
variable "SOURCE_DATE_EPOCH" {
type = number
default = 1690328596
}
target "default" {
args = {
SOURCE_DATE_EPOCH = SOURCE_DATE_EPOCH
}
labels = {
"org.opencontainers.image.created" = unixtimestampparse(SOURCE_DATE_EPOCH).rfc3339
}
}
```

### <a name="upper"></a> `upper`

```hcl
Expand Down