Add endsWith, startsWith, utcNow, and uniqueString functions

dsc/tests/dsc_functions.tests.ps1

@@ -244,4 +244,80 @@ Describe 'tests for function expressions' {
         $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw)
         ($out.results[0].result.actualState.output | Out-String) | Should -BeExactly ($expected | Out-String)
     }
+
+    It 'utcNow function works for: utcNow(<format>)' -TestCases @(
+        @{ format = $null}
+        @{ format = "yyyy-MM-dd"}
+        @{ format = "yyyy-MM-ddTHH"}
+        @{ format = "yyyy-MM-ddTHHZ"}
+        @{ format = "MMM dd, yyyy HH"}
+        @{ format = "yy-MMMM-dddd tt H" }
+        @{ format = "MMM ddd zzz" }
+        @{ format = "YY YYYY MM MMM MMMM" }
+    ) {
+        param($format)
+
+        if ($null -eq $format) {
+            $expected = (Get-Date -AsUTC).ToString("o")
+        } else {
+            $expected = (Get-Date -AsUTC).ToString($format)
+            $format = "'$format'"
+        }
+
+        $config_yaml = @"
+            `$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+            parameters:
+              test:
+                type: string
+                defaultValue: "[utcNow($format)]"
+            resources:
+            - name: Echo
+              type: Microsoft.DSC.Debug/Echo
+              properties:
+                output: "[parameters('test')]"
+"@
+        $out = dsc -l trace config get -i $config_yaml 2>$TestDrive/error.log
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw)
+        # ConvertFrom-Json will convert the date to a DateTime object, so we use regex to capture the string
+        $out -match '"output":"(?<date>.*?)"' | Should -BeTrue -Because "Output should contain a date"
+        $actual = $matches['date']
+        # since the datetimes might slightly differ, we remove the seconds and milliseconds
+        $expected = $expected -replace ':\d+\.\d+Z$', 'Z'
+        $actual = $actual -replace ':\d+\.\d+Z$', 'Z'
+        $actual | Should -BeExactly $expected -Because "Expected: '$expected', Actual: '$actual'"
+    }
+
+    It 'utcNow errors if used not as a parameter default' {
+        $config_yaml = @"
+            `$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+            resources:
+            - name: Echo
+              type: Microsoft.DSC.Debug/Echo
+              properties:
+                output: "[utcNow()]"
+"@
+        $out = dsc -l trace config get -i $config_yaml 2>$TestDrive/error.log | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 2 -Because (Get-Content $TestDrive/error.log -Raw)
+        (Get-Content $TestDrive/error.log -Raw) | Should -Match 'utcNow function can only be used as a parameter default'
+    }
+
+    It 'uniqueString function works for: <expression>' -TestCases @(
+        @{ expression = "[uniqueString('a')]" ; expected = 'cfvwxu6sc4lqo' }
+        @{ expression = "[uniqueString('a', 'b', 'c')]" ; expected = 'bhw7m6t6ntwd6' }
+        @{ expression = "[uniqueString('a', 'b', 'c', 'd')]" ; expected = 'yxzg7ur4qetcy' }
+    ) {
+        param($expression, $expected)
+
+        $config_yaml = @"
+            `$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+            resources:
+            - name: Echo
+              type: Microsoft.DSC.Debug/Echo
+              properties:
+                output: "$expression"
+"@
+        $out = dsc -l trace config get -i $config_yaml 2>$TestDrive/error.log | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw)
+        $out.results[0].result.actualState.output | Should -BeExactly $expected
+    }
 }

dsc_lib/Cargo.toml

@@ -13,13 +13,15 @@ split-debuginfo = "packed"  # generates a seperate *.dwp/*.dSYM so the binary ca
 strip = "symbols"           # See split-debuginfo - allows us to drop the size by ~65%
 
 [dependencies]
+base32 = "0.5"
 base64 = "0.22"
-chrono = "0.4"
+chrono = { version = "0.4", features = ["alloc"] }
 clap = { version = "4.5", features = ["derive"] }
 derive_builder ="0.20"
 indicatif = "0.18"
 jsonschema = { version = "0.30", default-features = false }
 linked-hash-map = "0.5"
+murmurhash64 = "0.3"
 num-traits = "0.2"
 path-absolutize = { version = "3.1" }
 regex = "1.11"

dsc_lib/locales/en-us.toml

@@ -265,6 +265,10 @@ description = "Checks if an array, object, or string is empty"
 invoked = "empty function"
 invalidArgType = "Invalid argument type, argument must be an array, object, or string"
 
+[functions.endsWith]
+description = "Checks if a string ends with a specific suffix"
+invoked = "endsWith function"
+
 [functions.envvar]
 description = "Retrieves the value of an environment variable"
 notFound = "Environment variable not found"
@@ -381,6 +385,10 @@ extensionReturnedError = "Extension '%{extension}': %{error}"
 noExtensions = "No extensions supporting secrets was found"
 secretNotFound = "Secret '%{name}' not found"
 
+[functions.startsWith]
+description = "Checks if a string starts with a specific prefix"
+invoked = "startsWith function"
+
 [functions.sub]
 description = "Subtracts the second number from the first"
 invoked = "sub function"
@@ -398,6 +406,15 @@ description = "Returns a single array or object with all elements from the param
 invoked = "union function"
 invalidArgType = "All arguments must either be arrays or objects"
 
+[functions.uniqueString]
+description = "Returns a deterministic unique string from the given strings"
+invoked = "uniqueString function"
+
+[functions.utcNow]
+description = "Returns the current UTC time"
+invoked = "utcNow function"
+onlyUsedAsParameterDefault = "utcNow function can only be used as a parameter default"
+
 [functions.variables]
 description = "Retrieves the value of a variable"
 invoked = "variables function"

dsc_lib/src/configure/context.rs

@@ -20,6 +20,7 @@ pub struct Context {
     pub start_datetime: DateTime<Local>,
     pub restart_required: Option<Vec<RestartRequired>>,
     pub process_expressions: bool,
+    pub processing_parameter_defaults: bool,
 }
 
 impl Context {
@@ -39,6 +40,7 @@ impl Context {
             start_datetime: chrono::Local::now(),
             restart_required: None,
             process_expressions: true,
+            processing_parameter_defaults: false,
         }
     }
 }

dsc_lib/src/configure/mod.rs

@@ -722,7 +722,10 @@ impl Configurator {
                 // default values can be expressions
                 let value = if default_value.is_string() {
                     if let Some(value) = default_value.as_str() {
-                        self.statement_parser.parse_and_execute(value, &self.context)?
+                        self.context.processing_parameter_defaults = true;
+                        let result = self.statement_parser.parse_and_execute(value, &self.context)?;
+                        self.context.processing_parameter_defaults = false;
+                        result
                     } else {
                         return Err(DscError::Parser(t!("configure.mod.defaultStringNotDefined").to_string()));
                     }