toboid
Correlation id
Correlation id maintains a consistent id across asynchronous calls in node.js applications; this is especially useful for logging purposes.
For example within an API, each incoming request can be assigned an id that will be available in all function calls made processing that request, so we can see which requests caused errors.
100% test coverage, no prod dependencies.
Installation
yarn:
yarn add correlation-idnpm:
npm i correlation-id --saveCompatibility
From v5 onwards this library requires node >=14. For older node versions use v3.x or v4.x.
Simple example
As demonstrated by this example, all calls to getId() within the same withId() block will return the same id. The id can be supplied, otherwise a v4 uuid will be generated.
const correlator = require("correlation-id");
function printCurrentId(name) {
console.log("%s id: %s", name, correlator.getId());
}
correlator.withId(() => {
setTimeout(() => {
printCurrentId("withId block 1, call 1");
});
setTimeout(() => {
printCurrentId("withId block 1, call 2");
}, 1000);
});
correlator.withId("my-custom-id", () => {
setTimeout(() => {
printCurrentId("withId block 2, call 1");
}, 500);
});
// Output:
// withId block 1, call 1 id: 5816e2d3-6b90-43be-8738-f6e1b2654f39
// withId block 2, call 1 id: my-custom-id
// withId block 1, call 2 id: 5816e2d3-6b90-43be-8738-f6e1b2654f39API
withId([id,] work)
Executes function work within a correlation scope and returns any result returned from work. Within work and any other function executions (sync or async) calls to getId() will return the same id. The id for the context may be set explicitly with the optional id parameter, otherwise it will be a v4 uuid. Calls to withId() may be nested.
correlator.withId(() => {
console.log(correlator.getId()); // Writes a uuid to stdout
});
correlator.withId("my-custom-id", () => {
console.log(correlator.getId()); // Writes 'my-custom-id' to stdout
});bindId([id,] work)
Returns function work bound with a correlation scope. When work is executed all calls to getId() will return the same id. The id for the context may be set explicitly with the optional id parameter, otherwise it will be a v4 uuid. Arguments passed to the bound function will be applied to work.
const boundFunction = correlator.bindId((p1) => {
console.log("p1 is", p1);
console.log(correlator.getId());
});
boundFunction("foo"); // Writes 'p1 is foo' and then a uuid to stdout
const boundFunction2 = correlator.bindId("my-custom-id", (p1) => {
console.log("p1 is", p1);
console.log(correlator.getId());
});
boundFunction2("foo"); // Writes 'p1 is foo' and then 'my-custom-id' to stdoutgetId()
Returns the id for the current correlation scope (created via withId or bindId). If called outside of a correlation scope returns undefined.
correlator.getId(); // Returns the current id or undefinedsetId(id)
Sets the id for the current correlation scope (created via withId or bindId). If called outside of a correlation scope throws an error.
correlator.setId("my-correlation-id");Typescript
Type defs are included.
License
MIT