Mito

Mito is a message stream processing engine based on CEL. Mito provides tools in the lib directory to support collection processing, timestamp handling and other common tasks (see test snippets in testdata and docs at https://pkg.go.dev/github.com/elastic/mito/lib).

The mito command will apply CEL expressions to a JSON value input under the label state within the CEL environment. This is intended to be used as a debugging and playground tool.

For example the following CEL expression processes the stream below generating the Cartesian product of the num and let fields and retaining the original message and adding timestamp metadata.

state.map(e, has(e.other) && e.other != '',
	has(e.num) && size(e.num) != 0 && has(e.let) && size(e.let) != 0 ?
		// Handle Cartesian product.
		e.num.map(v1,
			e.let.map(v2,
				e.with({
					"@triggered": now,   // As a value, the start time.
					"@timestamp": now(), // As a function, the time the action happened.
					"original": e.encode_json(),
					"numlet": e.num+e.let,
					"num": v1,
					"let": v2,
				})
		))
	:
		// Handle cases where there is only one of num or let and so
		// the Cartesian product would be empty: S × Ø, S = num or let.
		//
		// This expression is nested to agree with the Cartesian
		// product (an alternative is to flatten that for each e).
		[[e.with({
			"@triggered": now,   // As a value, the start time.
			"@timestamp": now(), // As a function, the time the action happened.
			"original": e.encode_json(),
		})]] 
).flatten().drop_empty().as(res,
	{
		"events": res,
		// Get cursor summary.
		"cursor": res.collate('@timestamp').as(t, {"timestamps":{
			"first": t.min(),
			"last": t.max(),
			"list": t,
		}}),
	}
)

working on

[
	{
		"let": ["a", "b"],
		"num": ["1", "2"],
		"other": "random information for first"
	},
	{
		"let": ["aa", "bb"],
		"num": ["12", "22", "33"],
		"other": "random information for second"
	},
	{
		"let": ["a", "b"],
		"num": [],
		"other": "random information for third"
	},
	{
		"let": [], 
		"num": ["1", "2"],
		"other": "random information for fourth"
	},
	{
		"num": ["1", "2"],
		"other": "random information for fifth"
	},
	{
		"let": ["y", "z"],
		"num": ["-1", "-2", "-3"]
	}
]

gives

{
	"cursor": {
		"timestamps": {
			"first": "2022-04-04T04:28:00.36378Z",
			"last": "2022-04-04T04:28:00.364034Z",
			"list": [
				"2022-04-04T04:28:00.36378Z",
				"2022-04-04T04:28:00.36385Z",
				"2022-04-04T04:28:00.363863Z",
				"2022-04-04T04:28:00.363872Z",
				"2022-04-04T04:28:00.363885Z",
				"2022-04-04T04:28:00.363893Z",
				"2022-04-04T04:28:00.363947Z",
				"2022-04-04T04:28:00.363955Z",
				"2022-04-04T04:28:00.363981Z",
				"2022-04-04T04:28:00.364003Z",
				"2022-04-04T04:28:00.364012Z",
				"2022-04-04T04:28:00.364021Z",
				"2022-04-04T04:28:00.364034Z"
			]
		}
	},
	"events": [
		{
			"@timestamp": "2022-04-04T04:28:00.36378Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "a",
			"num": "1",
			"numlet": [
				"1",
				"2",
				"a",
				"b"
			],
			"original": "{\"let\":[\"a\",\"b\"],\"num\":[\"1\",\"2\"],\"other\":\"random information for first\"}",
			"other": "random information for first"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.36385Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "b",
			"num": "1",
			"numlet": [
				"1",
				"2",
				"a",
				"b"
			],
			"original": "{\"let\":[\"a\",\"b\"],\"num\":[\"1\",\"2\"],\"other\":\"random information for first\"}",
			"other": "random information for first"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363863Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "a",
			"num": "2",
			"numlet": [
				"1",
				"2",
				"a",
				"b"
			],
			"original": "{\"let\":[\"a\",\"b\"],\"num\":[\"1\",\"2\"],\"other\":\"random information for first\"}",
			"other": "random information for first"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363872Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "b",
			"num": "2",
			"numlet": [
				"1",
				"2",
				"a",
				"b"
			],
			"original": "{\"let\":[\"a\",\"b\"],\"num\":[\"1\",\"2\"],\"other\":\"random information for first\"}",
			"other": "random information for first"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363885Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "aa",
			"num": "12",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363893Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "bb",
			"num": "12",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363947Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "aa",
			"num": "22",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363955Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "bb",
			"num": "22",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.363981Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "aa",
			"num": "33",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.364003Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": "bb",
			"num": "33",
			"numlet": [
				"12",
				"22",
				"33",
				"aa",
				"bb"
			],
			"original": "{\"let\":[\"aa\",\"bb\"],\"num\":[\"12\",\"22\",\"33\"],\"other\":\"random information for second\"}",
			"other": "random information for second"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.364012Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"let": [
				"a",
				"b"
			],
			"original": "{\"let\":[\"a\",\"b\"],\"num\":[],\"other\":\"random information for third\"}",
			"other": "random information for third"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.364021Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"num": [
				"1",
				"2"
			],
			"original": "{\"let\":[],\"num\":[\"1\",\"2\"],\"other\":\"random information for fourth\"}",
			"other": "random information for fourth"
		},
		{
			"@timestamp": "2022-04-04T04:28:00.364034Z",
			"@triggered": "2022-04-04T04:28:00.363778Z",
			"num": [
				"1",
				"2"
			],
			"original": "{\"num\":[\"1\",\"2\"],\"other\":\"random information for fifth\"}",
			"other": "random information for fifth"
		}
	]
}

(Run mito -data example.json example.cel to see this locally.)