Jsonnet

https://jsonnet.org/
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### std.slice examples

Source: https://jsonnet.org/ref/stdlib.html

Selects subarrays and substrings using start, end, and step parameters. Includes negative index example.

```jsonnet
std.slice([1, 2, 3, 4, 5, 6], 0, 4, 1)
```

```jsonnet
std.slice([1, 2, 3, 4, 5, 6], 1, 6, 2)
```

```jsonnet
std.slice("jsonnet", 0, 4, 1)
```

```jsonnet
std.slice("jsonnet", -3, null, null)
```

--------------------------------

### Jsonnet output.json from top-level arguments example

Source: https://jsonnet.org/learning/tutorial.html

The resulting output.json from the top-level arguments example, showing the generated cocktail menu with 'Happy Hour' prefix and brunch=true, including the Bloody Mary and Mimosa with 'Cheap Sparkling Wine'.

```json
{ "Happy Hour Bloody Mary": { "garnish": "Celery salt & pepper", "ingredients": [ { "kind": "Vodka", "qty": 1.5 }, { "kind": "Tomato Juice", "qty": 3 }, { "kind": "Lemon Juice", "qty": 1.5 }, { "kind": "Worcestershire", "qty": 0.25 }, { "kind": "Tobasco Sauce", "qty": 0.15 } ], "served": "Tall" }, "Happy Hour Mimosa": { "garnish": "Orange Slice", "ingredients": [ { "kind": "Cheap Sparkling Wine", "qty": 3 }, { "kind": "Orange Juice", "qty": 3 } ], "served": "Champagne Flute" }, "Happy Hour Pina Colada": { "garnish": "Pineapple slice", "ingredients": [ { "kind": "Rum", "qty": 3 }, { "kind": "Pineapple Juice", "qty": 6 }, { "kind": "Coconut Cream", "qty": 2 }, { "kind": "Ice", "qty": 12 } ], "served": "Frozen" } }
```

--------------------------------

### Object-orientation example

Source: https://jsonnet.org/

Shows how to eliminate duplication using object-orientation. The example defines two persons, where person2 inherits from person1 and overrides the name. The output is shown as JSON.

```jsonnet
// Edit me! {
  person1: {
    name: "Alice",
    welcome: "Hello " + self.name + "!",
  },
  person2: self.person1 { name: "Bob" },
}
```

```json
{
  "person1": {
    "name": "Alice",
    "welcome": "Hello Alice!"
  },
  "person2": {
    "name": "Bob",
    "welcome": "Hello Bob!"
  }
}
```

--------------------------------

### Jsonnet object inheritance example: templates.libsonnet with Sour template

Source: https://jsonnet.org/learning/tutorial.html

This example shows how to import a template library and create specialized cocktails by overriding fields of the Sour template. It demonstrates field overriding, using +: to modify fields, and adding to lists.

```jsonnet
local templates = import 'templates.libsonnet';
{
  // The template requires us to override
  // the 'spirit'.
  'Whiskey Sour': templates.Sour {
    spirit: 'Whiskey',
  },
  // Specialize it further.
  'Deluxe Sour': self['Whiskey Sour'] {
    // Don't replace the whole sweetner,
    // just change 'kind' within it.
    sweetener+: { kind: 'Gomme Syrup' },
  },
  Daiquiri: templates.Sour {
    spirit: 'Banks 7 Rum',
    citrus+: { kind: 'Lime' },
    // Any field can be overridden.
    garnish: 'Lime wedge',
  },
  "Nor'Easter": templates.Sour {
    spirit: 'Whiskey',
    citrus: { kind: 'Lime', qty: 0.5 },
    sweetener+: { kind: 'Maple Syrup' },
    // +: Can also add to a list.
    ingredients+: [
      { kind: 'Ginger Beer', qty: 1 },
    ],
  },
}
```

--------------------------------

### Jsonnet arithmetic and operations example

Source: https://jsonnet.org/learning/tutorial.html

Demonstrates arithmetic, bitwise, boolean, object merging, membership, and string formatting in Jsonnet. The example includes comments explaining each operation. The output is shown in the following block.

```jsonnet
{ concat\_array: \[1, 2, 3\] + \[4\], concat\_string: '123' + 4, equality1: 1 == '1', equality2: \[{}, { x: 3 - 1 }\] == \[{}, { x: 2 }\], ex1: 1 + 2 \* 3 / (4 + 5), // Bitwise operations first cast to int. ex2: self.ex1 | 3, // Modulo operator. ex3: self.ex1 % 2, // Boolean logic ex4: (4 > 3) && (1 <= 3) || false, // Mixing objects together obj: { a: 1, b: 2 } + { b: 3, c: 4 }, // Test if a field is in an object obj\_member: 'foo' in { foo: 1 }, // String formatting str1: 'The value of self.ex2 is ' + self.ex2 + '.', str2: 'The value of self.ex2 is %g.' % self.ex2, str3: 'ex1=%0.2f, ex2=%0.2f' % \[self.ex1, self.ex2\], // By passing self, we allow ex1 and ex2 to // be extracted internally. str4: 'ex1=%(ex1)0.2f, ex2=%(ex2)0.2f' % self, // Do textual templating of entire files: str5: ||| ex1=%(ex1)0.2f ex2=%(ex2)0.2f ||| % self, }
```

```json
{ "concat\_array": \[ 1, 2, 3, 4 \], "concat\_string": "1234", "equality1": false, "equality2": true, "ex1": 1.6666666666666665, "ex2": 3, "ex3": 1.6666666666666665, "ex4": true, "obj": { "a": 1, "b": 3, "c": 4 }, "obj\_member": true, "str1": "The value of self.ex2 is 3.", "str2": "The value of self.ex2 is 3.", "str3": "ex1=1.67, ex2=3.00", "str4": "ex1=1.67, ex2=3.00", "str5": "ex1=1.67\\nex2=3.00\\n" }
```

--------------------------------

### Jsonnet example with assertions and error handling

Source: https://jsonnet.org/learning/tutorial.html

An interactive Jsonnet example that extends a previous example to sanity check input. It defines functions with assertions and error checks, and includes an object with field assertions. The output is shown in the following block.

```jsonnet
// Extend above example to sanity check input.
local equal_parts(size, ingredients) =
  local qty = size / std.length(ingredients);
  // Check a pre-condition
  if std.length(ingredients) == 0 then
    error 'Empty ingredients.'
  else
    [ { kind: i, qty: qty } for i in ingredients ];
local subtract(a, b) =
  assert a > b : 'a must be bigger than b';
  a - b;
assert std.isFunction(subtract);
{
  test1: equal_parts(1, ['Whiskey']),
  test2: subtract(10, 3),
  object: {
    assert self.f < self.g : 'wat',
    f: 1,
    g: 2,
  },
  assert std.isObject(self.object),
}
```

```json
{
  "object": {
    "f": 1,
    "g": 2
  },
  "test1": [
    {
      "kind": "Whiskey",
      "qty": 1
    }
  ],
  "test2": 7
}
```

--------------------------------

### Run jsonnet -S ini.jsonnet

Source: https://jsonnet.org/articles/output-formats.html

Command to execute the INI example. The -S flag prints the string verbatim rather than as JSON.

```bash
$ jsonnet -S ini.jsonnet
```

--------------------------------

### std.trace example with conditional return

Source: https://jsonnet.org/ref/stdlib.html

Shows how to use std.trace to output a message to stderr and return a value. The example defines a local function conditionalReturn that uses std.trace to log which branch is taken. The output shows the trace message and the resulting JSON object.

```jsonnet
local conditionalReturn(cond, in1, in2) =
  if (cond) then
      std.trace('cond is true returning '
              + std.toString(in1), in1)
  else
      std.trace('cond is false returning '
              + std.toString(in2), in2);

{
    a: conditionalReturn(true, { b: true }, { c: false }),
}
```

```output
TRACE: test.jsonnet:3 cond is true returning {"b": true}
{
    "a": {
        "b": true
    }
}
```

--------------------------------

### std.repeat examples

Source: https://jsonnet.org/ref/stdlib.html

Repeats an array and a string a given number of times.

```jsonnet
std.repeat([1, 2, 3], 3)
```

```jsonnet
std.repeat("blah", 2)
```

--------------------------------

### Python API example: evaluate_snippet with ext_vars

Source: https://jsonnet.org/ref/bindings.html

Example of using the Python API to evaluate a Jsonnet snippet. It imports the _jsonnet module, defines a Jsonnet string with external variables, calls evaluate_snippet with ext_vars, parses the JSON output, and prints the results. Requires the jsonnet package installed.

```python
import json
import _jsonnet

jsonnet_str = '''
{
  person1: {
    name: "Alice",
    welcome: "Hello " + self.name + "!",
  },
  person2: self.person1 {
    name: std.extVar("OTHER_NAME"),
  },
}
'''

json_str = _jsonnet.evaluate_snippet(
    "snippet", jsonnet_str,
    ext_vars={'OTHER_NAME': 'Bob'})

json_obj = json.loads(json_str)
for person_id, person in json_obj.items():
  print('%s is %s, greeted by "%s"' % (
      person_id,
      person['name'],
      person['welcome']))
```

--------------------------------

### Evaluate a Jsonnet file with output

Source: https://jsonnet.org/learning/getting_started.html

Run jsonnet on a file to evaluate it and print the resulting JSON to stdout. The example shows the output for landingpage.jsonnet.

```bash
$ jsonnet landingpage.jsonnet
{
   "person1": {
      "name": "Alice",
      "welcome": "Hello Alice!"
   },
   "person2": {
      "name": "Bob",
      "welcome": "Hello Bob!"
   }
}
```

--------------------------------

### Jsonnet abstract template example: Sour template definition

Source: https://jsonnet.org/learning/tutorial.html

This example defines an abstract template for a 'sour' cocktail. It uses hidden fields (::) for citrus, sweetener, and spirit, and requires the spirit to be overridden. The ingredients list is built from these fields.

```jsonnet
{
  // Abstract template of a "sour" cocktail.
  Sour: {
    local drink = self,
    // Hidden fields can be referred to
    // and overridden, but do not appear
    // in the JSON output.
    citrus:: { kind: 'Lemon Juice', qty: 1 },
    sweetener:: { kind: 'Simple Syrup', qty: 0.5 },
    // A field that must be overridden.
    spirit:: error 'Must override "spirit"',
    ingredients: [
      { kind: drink.spirit, qty: 2 },
      drink.citrus,
      drink.sweetener,
    ],
    garnish: self.citrus.kind + ' twist',
    served: 'Straight Up',
  },
}
```

--------------------------------

### Output JSON for external variables example

Source: https://jsonnet.org/learning/tutorial.html

The resulting JSON output when the external variables example is evaluated with the given command line. It shows the generated cocktail objects, including the conditional 'Bloody Mary' and the Mimosa using 'Cheap Sparkling Wine'.

```json
{
  "Happy Hour Bloody Mary": {
    "garnish": "Celery salt & pepper",
    "ingredients": [
      { "kind": "Vodka", "qty": 1.5 },
      { "kind": "Tomato Juice", "qty": 3 },
      { "kind": "Lemon Juice", "qty": 1.5 },
      { "kind": "Worcestershire", "qty": 0.25 },
      { "kind": "Tobasco Sauce", "qty": 0.15 }
    ],
    "served": "Tall"
  },
  "Happy Hour Mimosa": {
    "garnish": "Orange Slice",
    "ingredients": [
      { "kind": "Cheap Sparkling Wine", "qty": 3 },
      { "kind": "Orange Juice", "qty": 3 }
    ],
    "served": "Champagne Flute"
  },
  "Happy Hour Pina Colada": {
    "garnish": "Pineapple slice",
    "ingredients": [
      { "kind": "Rum", "qty": 3 },
      { "kind": "Pineapple Juice", "qty": 6 },
      { "kind": "Coconut Cream", "qty": 2 },
      { "kind": "Ice", "qty": 12 }
    ],
    "served": "Frozen"
  }
}
```

--------------------------------

### std.makeArray example

Source: https://jsonnet.org/ref/stdlib.html

Creates an array of 3 elements by squaring each index, yielding [ 0, 1, 4 ].

```jsonnet
std.makeArray(3,function(x) x * x)
```

--------------------------------

### std.flatMap examples

Source: https://jsonnet.org/ref/stdlib.html

Shows four uses of std.flatMap: duplicating elements, filtering with empty arrays, mapping with multiplication, and concatenating strings.

```jsonnet
std.flatMap(function(x) [x, x], [1, 2, 3])
```

```jsonnet
std.flatMap(function(x) if x == 2 then [] else [x], [1, 2, 3])
```

```jsonnet
std.flatMap(function(x) if x == 2 then [] else [x * 3, x * 2], [1, 2, 3])
```

```jsonnet
std.flatMap(function(x) x+x, "foo")
```

--------------------------------

### std.manifestPython example

Source: https://jsonnet.org/ref/stdlib.html

Converts a Jsonnet value to a Python-compatible representation, using True/False/None instead of true/false/null. The input object is shown with its corresponding Python output.

```jsonnet
{
    b: ["foo", "bar"],
    c: true,
    d: null,
    e: { f1: false, f2: 42 },
}
```

```python
{
    "b": ["foo", "bar"],
    "c": True,
    "d": None,
    "e": {"f1": False, "f2": 42}
}
```

--------------------------------

### std.manifestPythonVars example

Source: https://jsonnet.org/ref/stdlib.html

Converts a Jsonnet object to a list of Python global variable assignments. The input object is the same as for manifestPython, but the output is a series of variable assignments.

```jsonnet
{
    b: ["foo", "bar"],
    c: true,
    d: null,
    e: { f1: false, f2: 42 },
}
```

```python
b = ["foo", "bar"]
c = True
d = None
e = {"f1": False, "f2": 42}
```

--------------------------------

### Field name expressions example

Source: https://jsonnet.org/ref/language.html

Shows dynamic field names computed at object creation. Field names cannot refer to object locals, self, or super.

```jsonnet
{
  a: 1,
  "a a": 2,
  "ąę": 3,
  ["aaa" + "bbb"]: 4,
}
```

--------------------------------

### Jsonnet referential transparency example

Source: https://jsonnet.org/ref/language.html

Shows a recursive function pow2 and its call. The call can be replaced with its definition without changing the program's meaning.

```jsonnet
local pow2(n) = if n == 0 then 1 else 2 * pow2(n - 1);
pow2(17)
```

--------------------------------

### Integrate with existing applications

Source: https://jsonnet.org/

Shows how to generate multiple configuration files (uwsgi.ini, init.sh, cassandra.conf) from a single Jsonnet script using std.manifestIni, text blocks, and std.manifestYamlDoc. The output is shown as the contents of the generated files.

```jsonnet
local application = 'my-app';
local module = 'uwsgi_module';
local dir = '/var/www';
local permission = 644;
{
  'uwsgi.ini': std.manifestIni({
    sections: {
      uwsgi: {
        module: module,
        pythonpath: dir,
        socket: dir + '/uwsgi.sock',
        'chmod-socket': permission,
        callable: application,
        logto: '/var/log/uwsgi/uwsgi.log',
      },
    },
  }),
  'init.sh': |||
    #!/usr/bin/env bash
    mkdir -p %(dir)s
    touch %(dir)s/initialized
    chmod %(perm)d %(dir)s/initialized
  ||| % {dir: dir, perm: permission},
  'cassandra.conf': std.manifestYamlDoc({
    cluster_name: application,
    seed_provider: [
      {
        class_name: 'SimpleSeedProvider',
        parameters: [{ seeds: '127.0.0.1' }],
      },
    ],
  }),
}
```

```text
"cluster_name": "my-app"
"seed_provider":
- "class_name": "SimpleSeedProvider"
  "parameters":
  - "seeds": "127.0.0.1"
#!/usr/bin/env bash
mkdir -p /var/www
touch /var/www/initialized
chmod 644 /var/www/initialized
[uwsgi]
callable = my-app
chmod-socket = 644
logto = /var/log/uwsgi/uwsgi.log
module = uwsgi_module
pythonpath = /var/www
socket = /var/www/uwsgi.sock
```

--------------------------------

### FractalInstance resource with configuration and startup script

Source: https://jsonnet.org/articles/fractal.2.html

Defines a FractalInstance resource with a conf object extending ApplicationConf and a startup_script that appends a line to add a file. The conf includes database settings and tilegen address.

```jsonnet
resource.FractalInstance(k) {
    ...
    conf:: ApplicationConf {
        database_name: cassandraKeyspace,
        database_user: cassandraUser,
        database_pass: credentials.cassandraUserPass,
        tilegen: "${google_compute_address.tilegen.address}",
        db_endpoints: cassandraNodes,
    },
    startup_script +: [self.addFile(self.conf, "/var/www/conf.json")],
}
```

--------------------------------

### Conditional fields example

Source: https://jsonnet.org/ref/language.html

If a field name evaluates to null, the field is discarded. This example evaluates to an empty object because the condition is false.

```jsonnet
{
  [if 1 == 2 then "foo"]: "bar",
}
```

--------------------------------

### std.substr(str, from, len)

Source: https://jsonnet.org/ref/stdlib.html

Returns a substring of str starting at offset from and len codepoints long. If the string is shorter than from+len, the suffix starting at from is returned.

```APIDOC
## std.substr(str, from, len)

### Description
Returns a string that is the part of `str` that starts at offset `from` and is `len` codepoints long. If the string `str` is shorter than `from+len`, the suffix starting at position `from` will be returned.

### Parameters
- **str** (string) - Required - The input string.
- **from** (integer) - Required - The starting offset (0-based).
- **len** (integer) - Required - The number of codepoints to include.

### Availability
Since version 0.10.0.

### Notes
The slice operator (e.g., `str[from:to]`) can also be used on strings, as an alternative to this function. However, note that the slice operator takes a start and an end index, but `std.substr` takes a start index and a length.
```

--------------------------------

### Functions example

Source: https://jsonnet.org/

Shows how to use functions to generate objects. The Person function has a default parameter 'Alice' and returns an object with a welcome message. The output is shown as JSON.

```jsonnet
// A function that returns an object.
local Person(name='Alice') = {
  name: name,
  welcome: 'Hello ' + name + '!',
};
{
  person1: Person(),
  person2: Person('Bob'),
}
```

```json
{
  "person1": {
    "name": "Alice",
    "welcome": "Hello Alice!"
  },
  "person2": {
    "name": "Bob",
    "welcome": "Hello Bob!"
  }
}
```

--------------------------------

### std.escapeStringJson example

Source: https://jsonnet.org/ref/stdlib.html

Shows how to embed a string with newlines and backslashes into a JSON string representation. The example uses the format operator %s with std.escapeStringJson to produce a quoted and escaped JSON string.

```jsonnet
local description = "Multiline\nc:\\path"; "{name: %s}" % std.escapeStringJson(description)
```

--------------------------------

### Jsonnet output example: output.json for cocktail mixins

Source: https://jsonnet.org/learning/tutorial.html

This is the JSON output produced by the mixin example. It shows the resulting objects for 'Virgin Daiquiri', 'Virgin Whiskey Sour', and 'Whiskey Sour' after applying the mixins.

```json
{
  "Virgin Daiquiri": {
    "garnish": "Lime wedge",
    "ingredients": [
      { "kind": "Water", "qty": 2 },
      { "kind": "Vanilla Essence", "qty": "dash" },
      { "kind": "Angustura Bitters", "qty": "dash" },
      { "kind": "Lime", "qty": 1 },
      { "kind": "Simple Syrup", "qty": 0.5 }
    ],
    "served": "Straight Up"
  },
  "Virgin Whiskey Sour": {
    "garnish": "Lemon Juice twist",
    "ingredients": [
      { "kind": "Water", "qty": 2 },
      { "kind": "Angustura Bitters", "qty": "tsp" },
      { "kind": "Lemon Juice", "qty": 1 },
      { "kind": "Simple Syrup", "qty": 0.5 }
    ],
    "served": "Straight Up"
  },
  "Whiskey Sour": {
    "ingredients": [
      { "kind": "Whiskey", "qty": 2 },
      { "kind": "Lemon Juice", "qty": 1 },
      { "kind": "Simple Syrup", "qty": 0.5 }
    ],
    "served": "In a plastic cup"
  }
}
```

--------------------------------

### Jsonnet: Importing and calling add.jsonnet as a function

Source: https://jsonnet.org/ref/language.html

Shows how to import a Jsonnet program that is a function and call it with arguments, demonstrating that TLA programs can be reused as normal functions.

```jsonnet
local add = import 'add.jsonnet';
add(1, 2)
```

--------------------------------

### Importing a Jsonnet library and using importstr

Source: https://jsonnet.org/learning/tutorial.html

Shows how to import a Jsonnet library (martinis.libsonnet) and a text file (garnish.txt) using importstr. The example defines a local variable for the library and constructs an object with a Manhattan cocktail that uses the imported garnish.

```jsonnet
local martinis = import 'martinis.libsonnet'; { 'Vodka Martini': martinis\['Vodka Martini'\], Manhattan: { ingredients: [ { kind: 'Rye', qty: 2.5 }, { kind: 'Sweet Red Vermouth', qty: 1 }, { kind: 'Angostura', qty: 'dash' }, ], garnish: importstr 'garnish.txt', served: 'Straight Up', }, }
```

```jsonnet
{ 'Vodka Martini': { ingredients: [ { kind: 'Vodka', qty: 2 }, { kind: 'Dry White Vermouth', qty: 1 }, ], garnish: 'Olive', served: 'Straight Up', }, Cosmopolitan: { ingredients: [ { kind: 'Vodka', qty: 2 }, { kind: 'Triple Sec', qty: 0.5 }, { kind: 'Cranberry Juice', qty: 0.75 }, { kind: 'Lime Juice', qty: 0.5 }, ], garnish: 'Orange Peel', served: 'Straight Up', }, }
```

```json
{ "Manhattan": { "garnish": "Maraschino Cherry", "ingredients": [ { "kind": "Rye", "qty": 2.5 }, { "kind": "Sweet Red Vermouth", "qty": 1 }, { "kind": "Angostura", "qty": "dash" } ], "served": "Straight Up" }, "Vodka Martini": { "garnish": "Olive", "ingredients": [ { "kind": "Vodka", "qty": 2 }, { "kind": "Dry White Vermouth", "qty": 1 } ], "served": "Straight Up" } }
```

--------------------------------

### Jsonnet formatter demo: before and after

Source: https://jsonnet.org/learning/tools.html

Shows the input and output of the formatter demo. The input has unformatted code with comments, imports, a function, and a template object. The output is the formatted version with sorted imports, canonical string quotes, spacing, and trailing commas.

```jsonnet
# Edit me! local b = import "b.libsonnet"; # comment local a = import "a.libsonnet"; local f(x,y)=x+y; local Template = {z: "foo"}; Template + { "f": ((3)) , "g g": f(4,2), arr: [[ 1, 2, ], 3, ] }
```

```jsonnet
// Edit me! local a = import 'a.libsonnet'; local b = import 'b.libsonnet'; // comment local f(x, y) = x + y; local Template = { z: 'foo' }; Template { f: (3), 'g g': f(4, 2), arr: [ [ 1, 2, ], 3, ], }
```

--------------------------------

### Better solution using objects and utils.libsonnet

Source: https://jsonnet.org/articles/kubernetes.html

A better solution using an object to represent the mapping, converting to Kubernetes representation post-hoc. Includes the utils.libsonnet file with pairList and namedObjectList functions.

```jsonnet
local utils = import 'utils.libsonnet';
local PodSpec = {
  containersObj:: {
    foo: {
      envObj:: {
        var1: 'somevalue',
        var2: 'somevalue',
      },
      env: utils.pairList(self.envObj),
    },
    bar: {
      envObj:: {
        var2: 'somevalue',
        var3: 'somevalue',
      },
      env: utils.pairList(self.envObj),
    },
  },
  containers: utils.namedObjectList(self.containersObj),
};
PodSpec {
  containersObj+: {
    bar+: {
      envObj+: {
        var3: 'othervalue'
      }
    }
  }
}
```

```jsonnet
// utils.libsonnet
{
  pairList(tab, kfield='name', vfield='value'):: [
    { [kfield]: k, [vfield]: tab[k] } for k in std.objectFields(tab)
  ],
  namedObjectList(tab, name_field='name'):: [
    tab[name] + { [name_field]: name } for name in std.objectFields(tab)
  ],
}
```

--------------------------------

### Jsonnet mixins example: RemoveGarnish and NoAlcohol applied to sours

Source: https://jsonnet.org/learning/tutorial.html

This example demonstrates defining mixins in Jsonnet. RemoveGarnish hides the garnish field, and NoAlcohol substitutes ingredients for non-alcoholic versions. The final object applies these mixins to 'Whiskey Sour', 'Virgin Whiskey Sour', and 'Virgin Daiquiri'.

```jsonnet
local sours = import 'sours-oo.jsonnet';
local RemoveGarnish = {
  // Not technically removed, but made hidden.
  garnish:: super.garnish,
};
// Make virgin cocktails
local NoAlcohol = {
  local Substitute(ingredient) =
    local k = ingredient.kind;
    local bitters = 'Angustura Bitters';
    if k == 'Whiskey' then
      [
        { kind: 'Water', qty: ingredient.qty },
        { kind: bitters, qty: 'tsp' },
      ]
    else if k == 'Banks 7 Rum' then
      [
        { kind: 'Water', qty: ingredient.qty },
        { kind: 'Vanilla Essence', qty: 'dash' },
        { kind: bitters, qty: 'dash' },
      ]
    else
      [ ingredient ],
  ingredients: std.flattenArrays([ Substitute(i) for i in super.ingredients ]),
};
local PartyMode = {
  served: 'In a plastic cup',
};
{
  'Whiskey Sour': sours['Whiskey Sour'] + RemoveGarnish + PartyMode,
  'Virgin Whiskey Sour': sours['Whiskey Sour'] + NoAlcohol,
  'Virgin Daiquiri': sours.Daiquiri + NoAlcohol,
}
```

--------------------------------

### Jsonnet: Add new instance with new image to google_compute_instance

Source: https://jsonnet.org/articles/fractal.3.html

Shows the configuration after adding a new instance (k=4) with the new image 'appserv-v20150102-1200' while keeping the old instances (k=1,2,3) with the old image. The duplication is temporary to allow easy rollback.

```jsonnet
google_compute_instance: {

    ["appserv" + k]: resource.FractalInstance(k) {
        name: "appserv" + k,
        image: "appserv-v20141222-0300",
        ...
    }
    for k in [1, 2, 3]

} + {

    ["appserv" + k]: resource.FractalInstance(k) {
        name: "appserv" + k,
        image: "appserv-v20150102-1200",
        ...
    }
    for k in [4]

} + ...
```

--------------------------------

### Jsonnet syntax example with cocktails

Source: https://jsonnet.org/learning/tutorial.html

Interactive example showing Jsonnet syntax: unquoted field names, trailing commas, comments, single/double quoted strings, text blocks (|||), verbatim strings (@'...'), and numeric underscores. The output shows the evaluated JSON with escaped characters and newlines.

```jsonnet
/* A C-style comment. */ # A Python-style comment. {
  cocktails: {
    // Ingredient quantities are in fl oz.
    'Tom Collins': {
      ingredients: [
        { kind: "Farmer's Gin", qty: 1.5 },
        { kind: 'Lemon', qty: 1 },
        { kind: 'Simple Syrup', qty: 0.5 },
        { kind: 'Soda', qty: 2 },
        { kind: 'Angostura', qty: 'dash' },
      ],
      garnish: 'Maraschino Cherry',
      served: 'Tall',
      description: |||
        The Tom Collins is essentially gin and lemonade.
        The bitters add complexity.
      |||,
    },
    Manhattan: {
      ingredients: [
        { kind: 'Rye', qty: 2.5 },
        { kind: 'Sweet Red Vermouth', qty: 1 },
        { kind: 'Angostura', qty: 'dash' },
      ],
      garnish: 'Maraschino Cherry',
      served: 'Straight Up',
      description: @'A clear \ red drink.',
    },
  },
}
```

```json
{
  "cocktails": {
    "Manhattan": {
      "description": "A clear \\ red drink.",
      "garnish": "Maraschino Cherry",
      "ingredients": [
        { "kind": "Rye", "qty": 2.5 },
        { "kind": "Sweet Red Vermouth", "qty": 1 },
        { "kind": "Angostura", "qty": "dash" }
      ],
      "served": "Straight Up"
    },
    "Tom Collins": {
      "description": "The Tom Collins is essentially gin and\nlemonade. The bitters add complexity.\n",
      "garnish": "Maraschino Cherry",
      "ingredients": [
        { "kind": "Farmer's Gin", "qty": 1.5 },
        { "kind": "Lemon", "qty": 1 },
        { "kind": "Simple Syrup", "qty": 0.5 },
        { "kind": "Soda", "qty": 2 },
        { "kind": "Angostura", "qty": "dash" }
      ],
      "served": "Tall"
    }
  }
}
```

--------------------------------

### Base and Derived object example with self, super, and hidden fields

Source: https://jsonnet.org/learning/tutorial.html

Shows how to derive an object from a base using the + operator, access base fields with super, and use hidden fields (::) that do not appear in output. The output shows the resulting JSON with overridden and inherited fields.

```jsonnet
local Base = { f: 2, g: self.f + 100, };
local WrapperBase = { Base: Base, };
{
  Derived: Base + {
    f: 5,
    old_f: super.f,
    old_g: super.g,
  },
  WrapperDerived: WrapperBase + {
    Base+: { f: 5 },
  },
}
```

```json
{
  "Derived": {
    "f": 5,
    "g": 105,
    "old_f": 2,
    "old_g": 105
  },
  "WrapperDerived": {
    "Base": {
      "f": 5,
      "g": 105
    }
  }
}
```

--------------------------------

### Object literal example

Source: https://jsonnet.org/ref/language.html

Shows a basic Jsonnet object with nested objects and arithmetic expressions.

```jsonnet
{
  "foo": 1,
  "bar": {
    "arr": [1, 2, 3],
    "number": 10 + 7,
  }
}
```

--------------------------------

### std.startsWith(a, b)

Source: https://jsonnet.org/ref/stdlib.html

Returns whether the string a is prefixed by the string b.

```APIDOC
## std.startsWith(a, b)

### Description
Returns whether the string `a` is prefixed by the string `b`.

### Parameters
- **a** (string) - Required - The string to check.
- **b** (string) - Required - The prefix to look for.

### Returns
Boolean - `true` if `a` starts with `b`, `false` otherwise.

### Availability
Since version 0.10.0.
```

--------------------------------

### output.svg

Source: https://jsonnet.org/articles/output-formats.html

The SVG output generated by the custom manifestation example. Shows the resulting XML structure.

```xml
<svg version="1.1" viewBox="0 0 180 180" x="0" xmlns="http://www.w3.org/2000/svg" y="0">
  <linearGradient gradientUnits="userSpaceOnUse" id="bg" x1="53" x2="126" y1="19" y2="162">
    <stop offset="0" stop-color="#0091AD"></stop>
    <stop offset="1" stop-color="#00728F"></stop>
  </linearGradient>
  <polygon fill="white" points="0,38 90,-14 180,38 180,142 90,194 0,142"></polygon>
  <path d="M168,49 v86 L129,82 L168,49 zM90,98 l67-59 L90,0 V98 zM73,10 L12,45 v90 l61,35 V10 zM117,94 L90,116 v63 l63-36 L117,94 z" fill="url(#bg)"></path>
</svg>
```

--------------------------------

### output.ini

Source: https://jsonnet.org/articles/output-formats.html

The INI output produced by the std.manifestIni example. Note the escaping of section names with backslashes.

```ini
a = 1 \[bar\] x = text \[foo\] a = 1 b = 2
```

--------------------------------

### std.manifestTomlEx example with TOML output

Source: https://jsonnet.org/ref/stdlib.html

Converts a Jsonnet object to TOML using two-space indentation. The output shows the resulting TOML file, including arrays and nested sections.

```jsonnet
std.manifestTomlEx({
  key1: "value",
  key2: 1,
  section: {
    a: 1,
    b: "str",
    c: false,
    d: [1, "s", [2, 3]],
    subsection: {
      k: "v",
    },
  },
  sectionArray: [
    { k: "v1", v: 123 },
    { k: "v2", c: "value2" },
  ],
}, "  ")
```

```toml
key1 = "value"
key2 = 1

[section]
  a = 1
  b = "str"
  c = false
  d = [
    1,
    "s",
    [ 2, 3 ]
  ]

  [section.subsection]
    k = "v"

[[sectionArray]]
  k = "v1"
  v = 123

[[sectionArray]]
  c = "value2"
  k = "v2"
```

--------------------------------

### Set external variables with jsonnet --ext-str and --ext-code

Source: https://jsonnet.org/learning/tutorial.html

Command line to bind the external variables 'prefix' and 'brunch' when initializing the Jsonnet virtual machine. 'prefix' is bound to the string 'Happy Hour ' and 'brunch' to true. The --ext-str flag passes a raw string, while --ext-code passes Jsonnet code.

```bash
jsonnet --ext-str prefix="Happy Hour " \
        --ext-code brunch=true ...
```

--------------------------------

### std.manifestJsonMinified output

Source: https://jsonnet.org/ref/stdlib.html

Converts an object to minified JSON. The example shows the input and the resulting single-line JSON output.

```jsonnet
std.manifestJsonMinified(
{
    x: [1, 2, 3, true, false, null,
        "string\nstring"],
    y: { a: 1, b: 2, c: [1, 2] },
})
```

```json
{"x":[1,2,3,true,false,null,"string\nstring"],"y":{"a":1,"b":2,"c":[1,2]}}
```

--------------------------------

### Jsonnet error and assert syntax examples

Source: https://jsonnet.org/learning/tutorial.html

Shows the basic syntax for raising errors and asserting conditions in Jsonnet, including custom failure messages and assertions on object fields.

```jsonnet
error "foo"
```

```jsonnet
assert "foo";
```

```jsonnet
assert "foo" : "message";
```

```jsonnet
assert self.f == 10,
```

```jsonnet
assert self.f == 10 : "message",
```
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