Configuring pREST

The prestd configuration is via an environment variable or toml file. Starting from version v1.2.0 it will be possible to use prestd without any environment variable or the toml file, but the configurations used will be the described in the default column bellow.

Environment variables

var default description

var	default	description
`PREST_VERSION`	`1`	version used for environment variables, v2 introduces better naming for SSL pg connection
`PREST_CONF`	`./prest.conf`
`PREST_MIGRATIONS`	`./migrations`
`PREST_QUERIES_LOCATION`	`./queries`
`PREST_HTTP_HOST`	`0.0.0.0`
`PREST_HTTP_PORT` or `PORT`	`3000`	`PORT` is for cloud factor, when declared this variable overwrittes `PREST_HTTP_PORT`
`PREST_PG_HOST`	`127.0.0.1`	host used to connect
`PREST_PG_USER`	`postgres`	user used to connect
`PREST_PG_PASS`	`postgres`	password used to connect
`PREST_PG_DATABASE`	`prest`	database name used to connect
`PREST_PG_PORT`	`5432`
`PREST_PG_URL` or `DATABASE_URL`		cloud factor, when declaring this variable all the previous connection fields are overwritten
`PREST_PG_SSL_MODE`	require	v2 of configuration envs, is the postgres connection SSL mode
`PREST_PG_SSL_CERT`		v2 of configuration envs, is the postgres connection SSL certificate
`PREST_PG_SSL_KEY`		v2 of configuration envs, is the postgres connection SSL key
`PREST_PG_SSL_ROOTCERT`		v2 of configuration envs, is the postgres connection SSL root certificate
`PREST_PG_SINGLE`	`true`	Serving multiple databases over the same API with `prestd` is doable
`PREST_CACHE_ENABLED`	false	embedded cache system
`PREST_CACHE_TIME`	10	TTL in minute (time to live)
`PREST_CACHE_STORAGEPATH`	./	path where the cache file will be created
`PREST_CACHE_SUFIXFILE`	.cache.prestd.db	suffix of the name of the file that is created
`PREST_JWT_KEY`
`PREST_JWT_ALGO`	HS256	(Deprecrated) Not used
`PREST_JWT_WELLKNOWNURL`		URL of .wellknown config of IDP used to fetch the JWKS used to verify token signature. Ignored if PREST_JWT_JWKS is set
`PREST_JWT_JWKS`		JWKS used to verify token signature. If set, PREST_JWT_WELLKNOWNURL is ignored
`PREST_JWT_WHITELIST`	`[/auth]`
`PREST_AUTH_ENABLED`	`false`
`PREST_AUTH_ENCRYPT`	`MD5`
`PREST_AUTH_TYPE`	`body`
`PREST_AUTH_SCHEMA`	`public`
`PREST_AUTH_TABLE`	`prest_users`
`PREST_AUTH_USERNAME`	`username`
`PREST_AUTH_PASSWORD`	`password`
`PREST_SSL_MODE`	`require`	SSL mode used to connect to postgres, not related to server SSL
`PREST_SSL_CERT`		SSL certificate used to connect to postgres, not related to server SSL
`PREST_SSL_KEY`		SSL key used to connect to postgres, not related to server SSL
`PREST_SSL_ROOTCERT`		SSL root certificate used to connect to postgres, not related to server SSL
`PREST_PLUGINPATH`	`./lib`	path to plugin storage `.so`
`PREST_EXPOSE_ENABLED`	`false`	expose data setting enables you to configure if you want users to be able to reach listing endpoints, read more here
`PREST_EXPOSE_TABLES`	`true`	expose the tables listing, read more here
`PREST_EXPOSE_SCHEMAS`	`true`	expose the schemas listing, read more here
`PREST_EXPOSE_DATABASES`	`true`	expose the databases listing, read more here
`PREST_JSON_AGG_TYPE`	`jsonb_agg`	changes how pREST encodes data from the database, can be set also to `json_agg`

PREST_VERSION

1

version used for environment variables, v2 introduces better naming for SSL pg connection

PREST_CONF

./prest.conf

PREST_MIGRATIONS

./migrations

PREST_QUERIES_LOCATION

./queries

PREST_HTTP_HOST

0.0.0.0

PREST_HTTP_PORT or PORT

3000

PORT is for cloud factor, when declared this variable overwrittes PREST_HTTP_PORT

PREST_PG_HOST

127.0.0.1

host used to connect

PREST_PG_USER

postgres

user used to connect

PREST_PG_PASS

postgres

password used to connect

PREST_PG_DATABASE

prest

database name used to connect

PREST_PG_PORT

5432

PREST_PG_URL or DATABASE_URL

cloud factor, when declaring this variable all the previous connection fields are overwritten

PREST_PG_SSL_MODE

require

v2 of configuration envs, is the postgres connection SSL mode

PREST_PG_SSL_CERT

v2 of configuration envs, is the postgres connection SSL certificate

PREST_PG_SSL_KEY

v2 of configuration envs, is the postgres connection SSL key

PREST_PG_SSL_ROOTCERT

v2 of configuration envs, is the postgres connection SSL root certificate

PREST_PG_SINGLE

true

Serving multiple databases over the same API with prestd is doable

PREST_CACHE_ENABLED

false

embedded cache system

PREST_CACHE_TIME

TTL in minute (time to live)

PREST_CACHE_STORAGEPATH

path where the cache file will be created

PREST_CACHE_SUFIXFILE

.cache.prestd.db

suffix of the name of the file that is created

PREST_JWT_KEY

PREST_JWT_ALGO

HS256

(Deprecrated) Not used

PREST_JWT_WELLKNOWNURL

URL of .wellknown config of IDP used to fetch the JWKS used to verify token signature. Ignored if PREST_JWT_JWKS is set

PREST_JWT_JWKS

JWKS used to verify token signature. If set, PREST_JWT_WELLKNOWNURL is ignored

PREST_JWT_WHITELIST

[/auth]

PREST_AUTH_ENABLED

false

PREST_AUTH_ENCRYPT

MD5

PREST_AUTH_TYPE

body

PREST_AUTH_SCHEMA

public

PREST_AUTH_TABLE

prest_users

PREST_AUTH_USERNAME

username

PREST_AUTH_PASSWORD

password

PREST_SSL_MODE

require

SSL mode used to connect to postgres, not related to server SSL

PREST_SSL_CERT

SSL certificate used to connect to postgres, not related to server SSL

PREST_SSL_KEY

SSL key used to connect to postgres, not related to server SSL

PREST_SSL_ROOTCERT

SSL root certificate used to connect to postgres, not related to server SSL

PREST_PLUGINPATH

./lib

path to plugin storage .so

PREST_EXPOSE_ENABLED

false

expose data setting enables you to configure if you want users to be able to reach listing endpoints, read more here

PREST_EXPOSE_TABLES

true

expose the tables listing, read more here

PREST_EXPOSE_SCHEMAS

true

expose the schemas listing, read more here

PREST_EXPOSE_DATABASES

true

expose the databases listing, read more here

PREST_JSON_AGG_TYPE

jsonb_agg

changes how pREST encodes data from the database, can be set also to json_agg

TOML

Optionally the prestd can be configured by TOML file.

You can follow this sample and create your own prest.toml file and put this on the same folder that you run prestd command.

migrations = "./migrations"

# debug = true
# enabling debug mode will disable JWT authorization

[http]
port = 3000

[jwt]
key = "secret"
algo = "HS256"

[auth]
enabled = true
type = "body"
encrypt = "MD5"
table = "prest_users"
username = "username"
password = "password"

[pg]
host = "127.0.0.1"
user = "postgres"
pass = "mypass"
port = 5432
database = "prest"
single = true
## or used cloud factor
# URL = "postgresql://user:pass@localhost/mydatabase/?sslmode=disable"

[ssl]
mode = "disable"
sslcert = "./PATH"
sslkey = "./PATH"
sslrootcert = "./PATH"

[expose]
enabled = true
databases = true
schemas = true
tables = true

Authorization

JWT

JWT middleware is enabled by default. To disable JWT need to set default to false. Enabling debug mode will also disable it.

[jwt]
default = false

The algorithm used is the one contained in the header of the token. The token is then validated with the provided key or JWKS.

The supported signing algorithms are described in the documentation of the JWK package.

They include the following algorithms:

The HMAC signing method: HS256, HS384, HS512
The RSA signing method: RS256, RS384, RS512
The ECDSA signing method: ES256, ES384, ES512
The RSA signing method: RS256, RS384, RS512
The ECDSA signing method: ES256, ES384, ES512
The RSA signing method: RS256, RS384, RS512
The ECDSA signing method: ES256, ES384, ES512

Instead of the key, you could provide the URL of a .well-known OpenID configuration or the JWKS directly through PREST_JWT_WELLKNOWNURL or PREST_JWT_JWKS as environment variables or by using the TOML configuration file:

[jwt]
wellknownurl = https://accounts.google.com/.well-known/openid-configuration
jwks = {"keys": [{"kty": "RSA", "alg": "RS256", "kid": "93b495162af0c87cc7a51686294097040daf3b43", "n": "3NXwASNf_7-9hOWDKyZ39qgz-yl_npuIsBgxnhNoE7WyQQl-muajPsQRdFqM-HWsAAbS_WtLrmf2aRSmjXBm8wXHIeJjcrZiWeUnSyfZLDr13jxXhN0rDvdiZEsAlaKuh-iCgwC_pXd0TtWpaYlv5FFguuSitKTOiDR6z3eSZUd0XNxr8POCDQ7VlG_4HyzhsO7nOwgivO-PzekDEbcoLI93U8uzKZXYHSRxYWhoSp47PbM9D5WbuwXqbmXRp9TjiJUy6GqEOJ4K2FNvqe-g6C3BnpPVuHZNaVf8QGP806rWrWPdJ0irGBhg-EasC-sdFSrH3kxMxBFfVsuj69U-7Q", "use": "sig", "e": "AQAB" }]}

prestd will parse the JWKS to find the corresponding key from the token and fail if it does not find it.

White list

By default the endpoints /auth do not require JWT, the whitelist option serves to configure which endpoints will not ask for jwt token

[jwt]
default = true
whitelist = ["\/auth", "\/ping", "\/ping\/.*"]

Auth

pREST has support in jwt token generation based on two fields (example user and password), being possible to use an existing table from your database to login configuring some parameters in the configuration file (or environment variable), by default this feature is disabled.

[auth]
enabled = true
type = "body"
encrypt = "MD5"
table = "prest_users"
username = "username"
password = "password"

Name Description

Name	Description
`enabled`	Boolean field that activates or deactivates token generation endpoint support
`type`	Type that will receive the login, support for body and http basic authentication
`encrypt`	Type of encryption used in password field, support for `MD5` and `SHA1`
`table`	Table name we will consult (query)
`username`	User field that will be consulted - if your software uses email just abstract name username (at prestd code level it was necessary to define an internal standard)
`password`	Password field that will be consulted

enabled

Boolean field that activates or deactivates token generation endpoint support

type

Type that will receive the login, support for body and http basic authentication

encrypt

Type of encryption used in password field, support for MD5 and SHA1

table

Table name we will consult (query)

username

User field that will be consulted - if your software uses email just abstract name username (at prestd code level it was necessary to define an internal standard)

password

Password field that will be consulted

to validate all endpoints with generated jwt token must be activated jwt option

Expose Data

The expose data setting enables you to configure if you want users to be able to reach listing endpoints, such as:

/databases
/schemas
/tables

An example of a configuration file disabling all listings:

# previous toml content
[expose]
enabled = true

If you want to disable just the database listing:

# previous toml content
[expose]
databases = true

Name Description

Name	Description
`enabled`	Set this as `true` if you want to disable all listing endpoints available.
`databases`	Set this as `false` if you want to disable databases listing endpoints only.
`schemas`	Set this as `false` if you want to disable schemas listing endpoints only.
`tables`	Set this as `false` if you want to disable tables listing endpoints only.

enabled

Set this as true if you want to disable all listing endpoints available.

databases

Set this as false if you want to disable databases listing endpoints only.

schemas

Set this as false if you want to disable schemas listing endpoints only.

tables

Set this as false if you want to disable tables listing endpoints only.

Default values for Exposure Settings

Name Default Value

Name	Default Value
enabled	`false`
databases	`true`
schemas	`true`
tables	`true`

enabled

false

databases

true

schemas

true

tables

true

SSL

There are 4 options to set on ssl mode:

Name Description Comment

Name	Description	Comment
`require`	Always SSL, is the default value	skips SSL verification step
`disable`	SSL off	also used when prestd is started without a `toml` file
`verify-ca`	Always SSL	verifies that the certificate presented is signed by a trusted CA
`verify-full`	Always SSL	verifies that the certificate presented is signed by a trusted CA and the server host name matches the one in the certificate

require

Always SSL, is the default value

skips SSL verification step

disable

SSL off

also used when prestd is started without a toml file

verify-ca

Always SSL

verifies that the certificate presented is signed by a trusted CA

verify-full

Always SSL

verifies that the certificate presented is signed by a trusted CA and the server host name matches the one in the certificate

Debug Mode

Set environment variable PREST_DEBUG or debug=true on top of prest.toml file.

PREST_DEBUG=true

Single mode - multi database (PostgreSQL)

Serving multiple databases over the same API with prestd is doable, but it is not currently supported. Thus it was introduced by default the single configuration, it can be disabled by the following config in the toml file:

[pg]
single = false

Since v1.1.2 it is a lot safer to use multiple databases, but not yet in the ideal state of security that we want, so use it in your own risk.

CORS support

Cross-Origin Resource Sharing

Read the specific topic where we talk about CROS here.

Health check endpoint

If you need to setup a health check on your deployment (ECS/EKS or others), you can use /_health as a provider of this information.

The server will return 503 whenever a pREST is not working properly.

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