Microservices Toolkit

Little library with a few "common" functionality that we use in our microservices.

Installation

``
npm i @bluealba/microservices-toolkit
`

Use Cases

$3

#### Pool

Pool is a wrapper on pg-pool that provides the possibility to query centralizing error handling
using retries and mapping responses

Pool provides:

* getPool: returns the pg-pool object for direct use.
* query: queries the database with the given statement and parameters logging any possible error before rethrowing the exception.
* recoverQuery: same as query but with retries (configured by maxQueryRetries).
* mappedQuery: same as recoverQuery but adding a mapping parameter that is used to map each value of the result set.

Code example

In order to create a connection pool you should use the following code.

`javascript
const config = ...;
const toolkit = require("@bluealba/microservices-toolkit");

const pgPool = toolkit.buildPGClient(config);

`

We use the config object to configure the pool expecting the following attributes.

`javascript
{
host: config.host,
database: config.dbName,
user: config.user,
password: config.password,
port: config.port,
max: config.maxPoolSize,
idleTimeoutMillis: config.idleTimeout,
connectionTimeoutMillis: config.dbTimeout,
maxUses: config.maxUses,
}
`

Also, the configuration should have the following value to specify the amount of retries

`
maxQueryRetries
`

$3

#### graphqlCustomErrorFn

Is a custom error handler for graphql that allows the user to provide errors with extensions that

Configure the custom error handling using:

`javascript
const toolkit = require("@bluealba/microservices-toolkit");

const graphqlCustomErrorFn = toolkit.graphqlCustomErrorFn;

app.use(
"/graphql",
graphqlHTTP({
schema,
pretty: true,
graphiql: true,
customFormatErrorFn: graphqlCustomErrorFn(),
})
);
`

Errors should be created adding an extension field like in this example:

`javascript
class StatusCodeError extends Error {

constructor(statusCode, errorCode, message) {
super(message);
this.extensions = { errorCode: errorCode, statusCode: statusCode, message: message };
}

}
`

$3

#### errorHandler

Simple error handler for express that catches any loose error and turns it into a well-formed JSON error with a 500 status code.

`javascript

const toolkit = require("@bluealba/microservices-toolkit");

const errorHandler = toolkit.errorHandler;
app.use(errorHandler(logger));
`
#### gatewayAuth

Filter that adds an auth object to the request using the x-forwarded-user-* headers added by the proxy
this object provides:

* username:
* displayName:
* operations:
* can: method that check if the user has the given operation
* matchesLoggedUser: checks if the parameter is the username

Code example

`javascript

const toolkit = require("@bluealba/microservices-toolkit");

const gatewayAuth = toolkit.gatewayAuth;
app.use(gatewayAuth());
`

#### getAuthHeaders

`javascript

const toolkit = require("@bluealba/microservices-toolkit");
const getAuthHeaders = toolkit.getAuthHeaders;

const authHeaders = getAuthHeaders(req);
`

$3

#### run

wraps any give call with a method that logs the time the method takes to run when called

`javascript

const toolkit = require("@bluealba/microservices-toolkit");
const run = toolkit.run;

module.exports = run(getSegments, "getSegments");
`

$3

Util class that provides methods to generate sql parts.

* formatDate,
* escapeQuotes,
* wrapInQuotes,
* wrapInDoublesQuotes,
* generateAnyClause,
* generateInClause,

Code example

`javascript

const toolkit = require("@bluealba/microservices-toolkit");
const { generateAnyClause } = toolkit.sqlUtils;
``