Event-driven fullstack architecture centered around JavaScript, AWS, and the JSON:API specification
"JavaScript on both sides and underneath"
Jaypie is an opinionated approach to application development centered around JavaScript and the JSON:API specification in an event-driven architecture.
Jaypie is suited for applications that require custom infrastructure beyond HTTP requests (e.g., message queues). Without custom infrastructure, fullstack hosts like Vercel or Netlify are recommended.
- AWS infrastructure managed by CDK in Node.js
- Express server running on AWS Lambda
- Node.js worker processes running on AWS Lambda
- MongoDB via Mongoose
- Vue ecosystem frontend: Vue 3 composition, Vuetify, Pinia
- Vitest for testing
- ES6 syntax enforced via ESLint
- Prettier formatting
- JSON logging with custom metadata
Jaypie is for building fullstack JavaScript applications.
Jaypie uses the AWS Cloud Development Kit (CDK) to manage infrastructure, which is written in Node.js. This makes managing infrastructure accessible to the fullstack developer without learning a new syntax and living without language constructs like loops and inheritance.
Does NOT use Kubernetes, Docker, Terraform, or the "Serverless" framework.
Jaypie embraces "ejectability," the philosophy that any part of the code can be removed (and therefore replaced) without disturbing the whole.
Jaypie strives to be "mockable-first" meaning all components should be easily tested via default or provided mocks.
npm install jaypie
@jaypie/core
is included in jaypie
. Almost every Jaypie package requires core.
These packages are included in jaypie
. They may be installed separately in the future.
Package | Exports | Description |
---|---|---|
@jaypie/aws |
getMessages , getSecret , sendBatchMessages , sendMessage
|
AWS helpers |
@jaypie/datadog |
submitMetric , submitMetricSet
|
Datadog helpers |
@jaypie/express |
expressHandler |
Express entry point |
@jaypie/lambda |
lambdaHandler |
Lambda entry point |
@jaypie/mongoose |
connect , connectFromSecretEnv , disconnect , mongoose
|
MongoDB management |
Matchers, mocks, and utilities to test Jaypie projects.
npm install --save-dev @jaypie/testkit
npm install jaypie @jaypie/lambda
const { InternalError, lambdaHandler, log } = require("jaypie");
export const handler = lambdaHandler(async({event}) => {
// await new Promise(r => setTimeout(r, 2000));
if (event.something === "problem") {
throw new InternalError();
}
// log.debug("Hello World");
return "Hello World";
}, { name: "example"});
This example would then be deployed to AWS via CDK or similar orchestration. See @jaypie/cdk.
import {
getMessages,
getSecret,
sendBatchMessages,
sendMessage,
} from "jaypie";
Return an array of message bodies from an SQS event.
import { getMessages } from '@jaypie/aws';
const messages = getMessages(event);
// messages = [{ salutation: "Hello, world!" }, { salutation: "Hola, dushi!" }]
Retrieve a secret from AWS Secrets Manager using the secret name.
import { getSecret } from '@jaypie/aws';
const secret = await getSecret("MongoConnectionStringN0NC3-nSg1bR1sh");
// secret = "mongodb+srv://username:password@env-project.n0nc3.mongodb.net/app?retryWrites=true&w=majority";
Batch and send messages to an SQS queue. If more than ten messages are provided, the function will batch them into groups of ten or less (per AWS).
import { sendBatchMessages } from '@jaypie/aws';
const messages = [
{ salutation: "Hello, world!" },
{ salutation: "Hola, dushi!" },
];
const queueUrl = "https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue";
await sendBatchMessages({ messages, queueUrl });
Parameter | Type | Required | Description |
---|---|---|---|
delaySeconds |
number |
No | Seconds to delay message delivery; default 0
|
messages |
Array |
Yes | Array of message objects (or strings) |
messageAttributes |
object |
No | Message attributes |
messageGroupId |
string |
No | Custom message group for FIFO queues; default provided |
queueUrl |
string |
Yes | URL of the SQS queue |
Send a single message to an SQS queue.
import { sendMessage } from '@jaypie/aws';
const body = "Hello, world!";
const queueUrl = "https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue";
const response = await sendMessage({ body, queueUrl });
Parameter | Type | Required | Description |
---|---|---|---|
body |
string |
Yes | Message body |
delaySeconds |
number |
No | Seconds to delay message delivery; default 0
|
messageAttributes |
object |
No | Message attributes |
messageGroupId |
string |
No | Custom message group for FIFO queues; default provided |
queueUrl |
string |
Yes | URL of the SQS queue |
import {
CDK,
DATADOG,
ERROR,
EXPRESS,
HTTP,
VALIDATE,
} from "jaypie";
CDK.ACCOUNT
CDK.ENV
CDK.ROLE
CDK.SERVICE
CDK.TAG
See constants.js in @jaypie/core.
DATADOG.METRIC.TYPE.UNKNOWN
DATADOG.METRIC.TYPE.COUNT
DATADOG.METRIC.TYPE.RATE
DATADOG.METRIC.TYPE.GAUGE
Default messages and titles for Jaypie errors.
ERROR.MESSAGE
ERROR.TITLE
See HTTP
for status codes.
-
EXPRESS.PATH.ANY
- String*
for any path -
EXPRESS.PATH.ID
- String/:id
for an ID path -
EXPRESS.PATH.ROOT
- Regular expression for root path
HTTP.ALLOW.ANY
-
HTTP.CODE
:OK
,CREATED
, ... HTTP.CONTENT.ANY
HTTP.CONTENT.HTML
HTTP.CONTENT.JSON
HTTP.CONTENT.TEXT
-
HTTP.HEADER
: ... -
HTTP.METHOD
:GET
,POST
, ...
-
VALIDATE.ANY
- Default VALIDATE.ARRAY
VALIDATE.CLASS
VALIDATE.FUNCTION
VALIDATE.NUMBER
VALIDATE.NULL
VALIDATE.OBJECT
VALIDATE.STRING
VALIDATE.UNDEFINED
-
JAYPIE
- for consistency across Jaypie -
PROJECT
- for consistency across projects
const {
submitMetric,
submitMetricSet
} = require("jaypie");
import { submitMetric } from "jaypie";
await submitMetric({
name: "jaypie.metric",
type: DATADOG.METRIC.TYPE.COUNT,
value: 1,
});
Parameter | Type | Required | Description |
---|---|---|---|
apiKey | string |
No | Datadog API key; checks process.env.DATADOG_API_KEY
|
apiSecret | string |
No | AWS Secret name holding Datadog API key; checks process.env.SECRET_DATADOG_API_KEY . Preferred method of retrieving key |
name | string |
Yes | Name of the metric |
type | string |
No | Defaults to DATADOG.METRIC.TYPE.UNKNOWN
|
value | number |
Yes | Value of the metric |
tags |
array , object
|
No | Tags for the metric. Accepts arrays ["key:value"] or objects {"key":"value"}
|
timestamp | number |
No | Unix timestamp; defaults to Date.now()
|
import { submitMetricSet } from "jaypie";
await submitMetricSet({
type: DATADOG.METRIC.TYPE.GAUGE,
valueSet: {
"jaypie.metric.a": 1,
"jaypie.metric.b": 2,
"jaypie.metric.c": 3,
},
});
Parameter | Type | Required | Description |
---|---|---|---|
apiKey | string |
No | Datadog API key; checks process.env.DATADOG_API_KEY
|
apiSecret | string |
No | AWS Secret name holding Datadog API key; checks process.env.SECRET_DATADOG_API_KEY . Preferred method of retrieving key |
type | string |
No | Defaults to DATADOG.METRIC.TYPE.UNKNOWN
|
valueSet | object |
Yes | Key-value pairs where the key is the metric name and the value is the metric value (number) |
tags |
array , object
|
No | Tags for the metric. Accepts arrays ["key:value"] or objects {"key":"value"}
|
timestamp | number |
No | Unix timestamp; defaults to Date.now()
|
// See `Error Reference` for full list
const { InternalError } = require("jaypie");
try {
// Code happens...
throw InternalError("Oh, I am slain!");
} catch (error) {
// Is this from a jaypie project?
if(error.isProjectError) {
{
name, // ProjectError
title, // "Internal Server Error"
detail, // "Oh, I am slain"
status, // 500 (HTTP code)
} = error;
} else {
// Not from jaypie
throw error;
}
}
if(error.isProjectError) {
return error.json();
}
const errors = [];
errors.push(BadGatewayError());
errors.push(NotFoundError());
throw MultiError(errors);
Error | Status | Notes |
---|---|---|
BadGatewayError |
502 | Something I need gave me an error |
BadRequestError |
400 | You did something wrong |
ConfigurationError |
500 | "The developer" (probably you) or an associate did something wrong |
ForbiddenError |
403 | You are not allowed |
GatewayTimeoutError |
504 | Something I need is taking too long |
GoneError |
410 | The thing you are looking for was here but is now gone forever |
IllogicalError |
500 | Code is in a state that "should never happen" |
InternalError |
500 | General "something went wrong" |
MethodNotAllowedError |
405 | You tried a good path but the wrong method |
MultiError |
Varies | Takes an array of errors |
NotFoundError |
404 | The thing you are looking for is not here and maybe never was |
NotImplementedError |
400 | "The developer" (you again?) didn't finish this part yet - hopefully a temporary message |
RejectedError |
403 | Request filtered prior to processing |
TeapotError |
418 | RFC 2324 section-2.3.2 |
UnavailableError |
503 | The thing you are looking for cannot come to the phone right now |
UnhandledError |
500 | An error that should have been handled wasn't |
UnreachableCodeError |
500 | Should not be possible |
ALWAYS internal to the app, NEVER something the client did
- Configuration
- "The person writing the code did something wrong" like forgot to pass or passed bad arguments
- "The person who configured the application made a mistake" like set mutually exclusive settings to true
- Illogical
- A combination of truth conditions occurred that should not be able to occur at the same time
- Not Implemented
- A marker to come back and finish this, but allows stubbing out HTTP endpoints
- Unhandled
- Internal to Jaypie, should not be thrown directly
- Jaypie expects code in handlers to handler errors and re-throw a Jaypie error
- If an unexpected error escapes the handler, Jaypie returns this when it is caught
- Unreachable
- In theory the block is literally not reachable and we want to put something there to make sure it stays that way
- For example, a complicated chain of
if
/else
that should always return and cover all cases, may throw this as the lastelse
- A configuration error means what happened was possible but should not have happened, an unreachable error means it should not have been possible
The Express handler wraps the Jaypie handler for Express running on AWS Lambda. It will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError
. It adds the locals
lifecycle call. It extends jaypieHandler
, not the lambda handler.
const { expressHandler } = require("jaypie");
const handler = expressHandler(async(req, res) => {
// await new Promise(r => setTimeout(r, 2000));
// log.debug("Hello World");
return { message: "Hello World" };
}, { name: "lambdaReference"});
The order of options and handler may be swapped to improve readability. Having lifecycle methods listed before the handler may read more intuitively.
const handler = expressHandler({
name: "expressOptions",
setup: [connect],
teardown: [disconnect],
}, async(req, res) => {
// await new Promise(r => setTimeout(r, 2000));
// log.debug("Hello World");
return { message: "Hello World" };
});
Do not use res.send
or res.json
in the handler. The return value of the handler is the response body. The status code is determined by the error thrown or the return value. Custom status codes can be set by calling res.status
in the handler.
Return Type | Status Code | Content-Type |
---|---|---|
Object, Array | 200 OK | application/json |
String | 200 OK | text/html |
true |
201 Created | None |
Falsy values | 204 No Content | None |
Errors can be returned by throwing the appropriate Jaypie error.
In addition to the Jaypie lifecycle methods, expressHandler
adds locals
, an object of scalars or functions that will be called at the end of setup
and available to the handler as req.locals
.
const handler = expressHandler(async(req) => {
// req.locals.asyncFn = "async"
// req.locals.fn = "function"
// req.locals.key = "static"
return { message: "Hello World" };
}, {
name: "expressReference",
locals: {
asyncFn: async() => "async",
fn: () => "function",
key: "static"
},
});
A "handler" returns a function that can be used as an Express route. A "route" does not require instantiation.
import {
echoRoute,
EXPRESS,
forbiddenRoute,
goneRoute,
noContentRoute,
notFoundRoute,
notImplementedRoute,
} from "jaypie";
app.get(EXPRESS.PATH.ROOT, noContentRoute); // 204 No Content
app.get(EXPRESS.PATH.ANY, echoRoute); // 200 OK returning the request
app.post(EXPRESS.PATH.ANY, forbiddenRoute); // 403 Forbidden
app.any("/future", notImplementedRoute); // 400 Bad Request
notImplementedRoute
returns "400 Bad Request" as a placeholder for future functionality. In this regard, calling it is a "user error." The "501 Not Implemented" status code is reserved for the server not supporting parts of the HTTP protocol such as POST
or PUT
.
lodash.clonedeep
from NPM
import { cloneDeep } from "jaypie";
const original = { a: 1, b: { c: 2 }};
const clone = cloneDeep(original);
Look up a key in process.env
and coerce it into a boolean.
Returns true
for true
(case-insensitive) and 1
for string, boolean, and numeric types.
Returns false
for false
(case-insensitive) and 0
for string, boolean, and numeric types.
Returns undefined
otherwise.
const { envBoolean } = require("jaypie");
process.env.AWESOME = true;
if (envBoolean("AWESOME")) {
console.log("Awesome!");
}
const { envBoolean } = require("jaypie");
if (envBoolean("AWESOME", { defaultValue: true })) {
console.log("Awesome!");
}
envsKey(key:string, { env:string = process.env.PROJECT_ENV || process.env.DEFAULT_ENV })
return process.env.${KEY} || ENV_${ENV}_${KEY} || false
DEFAULT_ENV=sandbox
MONGODB_URI=...
ENV_SANDBOX_MONGODB_URI=...
ENV_DEVELOPMENT_MONGODB_URI=...
PROJECT_ENV=development
Return order:
-
MONGODB_URI
- the exact key always takes precedence, if set -
ENV_DEVELOPMENT_MONGODB_URI
- thePROJECT_ENV
, if set. Usually this is set in the deploy workflow -
ENV_SANDBOX_MONGODB_URI
- theDEFAULT_ENV
, if set. Usually this is set in the local environment false
import { envsKey } from "jaypie";
const url = envsKey("MONGODB_URI");
Coerce a value into a type or throw an error. Forcing arrays is the primary use case.
import { force } from "jaypie";
argument = force(thing, Array);
argument = force([thing], Array);
// argument = [thing]
force
supports Array, Boolean, Number, Object, and String.
argument = force(argument, Array);
argument = force(argument, Boolean, "true");
argument = force(argument, Number, "12");
argument = force(argument, Object, "key");
argument = force(argument, String, "default");
// Convenience functions
argument = force.array(argument);
argument = force.boolean(argument);
argument = force.number(argument);
argument = force.object(argument, "key");
argument = force.string(argument);
getHeaderFrom(headerKey:string, searchObject:object)
Case-insensitive search inside searchObject
for headerKey
. Also looks in header
and headers
child object of searchObject
, if headerKey
not found at top-level.
Case-insensitive search for key
in object
. Returns the value of the key or undefined
.
Lightweight string interpolation
import { placeholders } from "jaypie";
const string = placeholders("Hello, {name}!", { name: "World" });
// string = "Hello, World!"
The code for placeholders was written by Chris Ferdinandi and distributed under the MIT License in 2018-2019. Their web site is https://gomakethings.com
parseFloat
that returns 0
for NaN
sleep
is a promise-based setTimeout
that resolves after a specified number of milliseconds. It will NOT run when NODE_ENV
is test
. See sleepAlways
for a version that will run in tests.
import { sleep } from "jaypie";
await sleep(2000);
This is "bad code" because it checks NODE_ENV
during runtime. The "right way" is to let sleep run and mock it in tests, in practice this is needless boilerplate. A fair compromise would be to mock sleep
with @jaypie/testkit
but not all projects include that dependency. Jaypie will trade academically incorrect for human convenience and simplicity.
The v4
function from the uuid
package
import { uuid } from "jaypie";
const id = uuid();
import { validate, VALIDATE } from "jaypie";
validate(argument, {
type: VALIDATE.ANY,
falsy: false, // When `true`, allows "falsy" values that match the type (e.g., `0`, `""`)
required: true, // When `false`, allows `undefined` as a valid value
throws: true // When `false`, returns `false` instead of throwing error
});
import { validate } from "jaypie";
validate.array(argument);
validate.class(argument);
validate.function(argument);
validate.null(argument);
validate.number(argument);
validate.object(argument);
validate.string(argument);
validate.undefined(argument);
Does not include any, class, or undefined
validate(argument, {
// One of:
type: Array,
type: Function,
type: Number,
type: null,
type: Object,
type: String,
})
The Jaypie handler can be used directly but is more likely to be wrapped in a more specific handler. The Jaypie handler will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError
.
import { jaypieHandler } from "jaypie";
const handler = jaypieHandler(async(...args) => {
// await new Promise(r => setTimeout(r, 2000));
// log.var({ args });
return "Hello World";
}, { name: "jaypieReference"});
Each function receives the same arguments as the handler.
Returns true
to validate the request. Throw an error or return false
to reject the request.
Called before the handler (e.g., connect to a database). Throw an error to halt execution.
The main function to handle the request. Throw an error to halt execution.
Called after the handler (e.g., disconnect from a database). Runs even if setup or handler throws errors.
The Lambda handler wraps the Jaypie handler for AWS Lambda. It will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError
.
const { lambdaHandler } = require("jaypie");
const handler = lambdaHandler(async({event}) => {
// await new Promise(r => setTimeout(r, 2000));
// log.debug("Hello World");
return "Hello World";
}, { name: "lambdaReference"});
import {
log,
} from "jaypie";
import { log } from "jaypie";
log.trace();
log.debug();
log.info();
log.warn();
log.error();
log.fatal();
Uses silent
by default. if process.env.MODULE_LOG_LEVEL
is true
, follows process.env.LOG_LEVEL
. If process.env.MODULE_LOG_LEVEL
is also set, uses that log level.
import { log } from "jaypie";
log.lib().trace();
log.lib({ lib: "myLib" }).trace();
Permanently add the key-value pair to the logger's tags, or at least until log.untag(key)
is called.
import { log } from "jaypie";
log.tag("myTag", "myValue");
log.tag({ myTag: "myValue" });
Remove the key-value pair from the logger's tags.
import { log } from "jaypie";
log.untag("myTag");
log.untag(["myTag1", "myTag2"]);
Log a key-value pair. In the json
format, the key will be tagged as var
and the value will be the value. Logging marker variables this way can be useful for debugging.
import { log } from "jaypie";
log.var("message", "Hello, world");
log.var({ message: "Hello, world" });
const message = "Hello, world";
log.var({ message });
Create a new log object with additional tags
import { log as defaultLogger } from "jaypie";
const log = defaultLogger.with({ customProperty: "customValue" });
import {
connect,
connectFromSecretEnv,
disconnect,
mongoose,
} from "jaypie";
Jaypie lifecycle method to connect to MongoDB. Uses process.env.SECRET_MONGODB_URI
AWS Secret or process.env.MONGODB_URI
string to connect.
import { connect, disconnect, lambdaHandler, mongoose } from "jaypie";
const handler = lambdaHandler(async({event}) => {
// mongoose is already connected
return "Hello World";
}, {
name: "lambdaReference"
setup: [connect],
teardown: [disconnect],
});
Jaypie lifecycle method to connect to MongoDB using process.env.MONGO_CONNECTION_STRING
. Using the newer connect
is generally preferred.
import { connectFromSecretEnv, disconnect, lambdaHandler, mongoose } from "jaypie";
const handler = lambdaHandler(async({event}) => {
// mongoose is already connected
return "Hello World";
}, {
name: "lambdaReference"
setup: [connectFromSecretEnv],
teardown: [disconnect],
});
Jaypie lifecycle method to disconnect from MongoDB.
import { disconnect, lambdaHandler } from "jaypie";
const handler = lambdaHandler(async({event}) => {
// ...
}, {
teardown: [disconnect],
});
mongoose
from NPM
import { mongoose } from "jaypie";
npm install --save-dev @jaypie/testkit
import { restoreLog, spyLog } from "@jaypie/testkit";
import { log } from "@jaypie/core";
beforeEach(() => {
spyLog(log);
});
afterEach(() => {
restoreLog(log);
vi.clearAllMocks();
});
test("log", () => {
log.warn("Danger");
expect(log.warn).toHaveBeenCalled();
expect(log.error).not.toHaveBeenCalled();
});
👺 Logging Conventions:
- Only use
log.trace
orlog.var
during "happy path" - Use
log.debug
for edge cases - Now you can add an "observability" test that will fail as soon as new code triggers an unexpected edge condition
describe("Observability", () => {
it("Does not log above trace", async () => {
// Arrange
// TODO: "happy path" setup
// Act
await myNewFunction(); // TODO: add any "happy path" parameters
// Assert
expect(log.debug).not.toHaveBeenCalled();
expect(log.info).not.toHaveBeenCalled();
expect(log.warn).not.toHaveBeenCalled();
expect(log.error).not.toHaveBeenCalled();
expect(log.fatal).not.toHaveBeenCalled();
});
});
👺 Follow the "arrange, act, assert" pattern
testSetup.js
import { matchers as jaypieMatchers } from "@jaypie/testkit";
import * as extendedMatchers from "jest-extended";
import { expect } from "vitest";
expect.extend(extendedMatchers);
expect.extend(jaypieMatchers);
test.spec.js
import { ConfigurationError } from "@jaypie/core";
const error = new ConfigurationError();
const json = error.json();
expect(error).toBeJaypieError();
expect(json).toBeJaypieError();
Validates instance objects:
try {
throw new Error("Sorpresa!");
} catch (error) {
expect(error).not.toBeJaypieError();
}
Validates plain old JSON:
expect({ errors: [ { status, title, detail } ] }).toBeJaypieError();
Jaypie errors, which are ProjectErrors
, all have a .json()
to convert
import { jsonApiErrorSchema, jsonApiSchema } from "@jaypie/testkit";
expect(jsonApiErrorSchema).toBeValidSchema();
expect(jsonApiSchema).toBeValidSchema();
expect({ project: "mayhem" }).not.toBeValidSchema();
From jest-json-schema
toBeValidSchema.js (not documented in README)
import { jsonApiErrorSchema, jsonApiSchema } from "@jaypie/testkit";
import { ConfigurationError } from "@jaypie/core";
const error = new ConfigurationError();
const json = error.json();
expect(json).toMatchSchema(jsonApiErrorSchema);
expect(json).not.toMatchSchema(jsonApiSchema);
From jest-json-schema
; see README
import {
jsonApiErrorSchema,
jsonApiSchema,
mockLogFactory,
} from '@jaypie/testkit'
A JSON Schema validator for the JSON:API error schema. Powers the toBeJaypieError
matcher (via toMatchSchema
).
A JSON Schema validator for the JSON:API data schema.
Creates a mock of the log
provided by @jaypie/core
.
import { mockLogFactory } from "@jaypie/testkit";
const log = mockLogFactory();
log.warn("Danger");
expect(log.warn).toHaveBeenCalled();
expect(log.error).not.toHaveBeenCalled();
Restores the log
provided by @jaypie/core
, commonly performed afterEach
with spyLog
in beforeEach
. See example with spyLog
.
Spies on the log
provided by @jaypie/core
, commonly performed beforeEach
with restoreLog
in afterEach
.
import { restoreLog, spyLog } from "@jaypie/testkit";
import { log } from "@jaypie/core";
beforeEach(() => {
spyLog(log);
});
afterEach(() => {
restoreLog(log);
vi.clearAllMocks();
});
test("log", () => {
log.warn("Danger");
expect(log.warn).toHaveBeenCalled();
expect(log.error).not.toHaveBeenCalled();
});
- Optional loading of Jaypie side packages
- ...Nicely organized VitePress documentation 😅
Date | Version | Summary |
---|---|---|
5/4/2024 | 1.0.24 | Adds @jaypie/datadog
|
3/19/2024 | 1.0.0 | First publish with @jaypie/core@1.0.0
|
3/15/2024 | 0.1.0 | Initial deploy |
3/15/2024 | 0.0.1 | Initial commit |
Published by Finlayson Studio. All rights reserved