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title Resource
draft false
slug Resource
url /reference/primitives/app/resource

Resource

A Resource is a network-accessible external service.

Definition

A Resource is defined in convox.yml and linked to one or more Services.

resources:
  main:
    type: postgres
services:
  web:
    resources:
      - main

Types

The following Resource types are currently available:

  • mariadb
  • memcached
  • mysql
  • postgis
  • postgres
  • redis

Linking

Linking a Resource to a Service causes an environment variable to be injected into Processes of that Service based on the name of the Resource.

The credential details will be stored in the environment variables, and you can use the FQDN (URL) or each credential separately.

For example, a postgres resource named main (as in the example above) would be injected like this:

MAIN_URL=postgres://username:password@host.name:port/database
MAIN_USER=username
MAIN_PASS=password
MAIN_HOST=host.name
MAIN_PORT=port
MAIN_NAME=database

Custom Images:

You can also pass a compatible custom image for all resource type.

To use a custom image, include the image field in your resource configuration:

resources:
  main:
    type: postgres
    image: pgvector/pgvector:pg16
services:
  web:
    resources:
      - main

Note:

  1. Always include the image tag when specifying a custom image. If no tag is provided, the latest tag will be used. Ensure that the specified image has a latest tag or provide a specific tag to avoid errors.
  2. The image field takes precedence over the version field. If both are specified, the version field will be ignored.

Example:

resources:
  myRedis:
    type: redis
    image: custom-redis-image:6.2
    options:
      version: 6.0

In this example, a custom Redis image named custom-redis-image with tag 6.2 will be used.

Overlays

By default, any Resources you define will be satisfied by starting a containerized version on your Rack. This allows you to get up and running as quickly as possible and provides a low-cost solution and more effective usage of your Rack.

In your production environment, or for particular usage requirements, you may wish to replace the containerized Resources with a managed cloud service for durability. For instance, on AWS you may wish to utilize RDS to provide you with a Database, or on GCP you may wish to use Memorystore in place of a containerized Redis instance.

Resource Overlays provide you with a simple and effective way to maintain the cheaper and efficient containerized Resources on the environments you wish, while easily switching them out for the cloud-provider managed services on those environments that require them.

If you wish to replace any of those containerized Resources on a Rack, to stop them being initiated, you can manually set a matching environment variable on your App. The corresponding Resource will then not be started by Convox on that Rack.

$ convox env set MAIN_URL=postgres://username:password@postgres-instance1.123456789012.us-east-1.rds.amazonaws.com:5432/database -r production-rack
Setting MAIN_URL... OK
Release: RABCDEFGHI

By doing this, a containerized main resource will now no longer be started on the production-rack for this app. The service will instead communicate with the managed database.

AWS RDS Managed Database Resources

In addition to containerized resources, Convox v3 allows the creation of database resources (mariadb, mysql, and postgres) via AWS RDS. This integration provides enhanced durability and managed service benefits. Below are the basic configurations required for using AWS RDS resources.

Defining AWS RDS Resources

AWS RDS resources are specified with a rds- prefix followed by the database type (e.g., rds-mariadb, rds-mysql, rds-postgres). Here is a general example of how to define AWS RDS resources:

resources:
  database:
    type: rds-postgres
    options:
      storage: 100
      class: db.t3.large
      version: 13
services:
  web:
    resources:
      - database

For detailed configuration options and defaults for each type of AWS RDS resource, refer to the specific resource documentation pages:

Advisory

If an application is deleted, it will delete its created RDS databases. We advise enabling deletionProtection for any production or critical databases to avoid any accidental removal. If a database is imported, the database will not be removed if the application is deleted and it will need to be manually deleted.

RDS Features

Read Replicas

Read replicas allow you to create read-only copies of your database to improve read scalability and reliability.

To configure a read replica, use the readSourceDB option to point to another database using the name you've chosen in the convox.yml:

resources:
  mydb:
    type: rds-postgres
    options:
      storage: 100
      class: db.t3.large
      version: 13
  dbrr:
    type: rds-postgres
    options:
      readSourceDB: "#convox.resources.mydb"
services:
  web:
    resources:
      - mydb
      - dbrr

Immutable Attributes for Read Replicas:

  • Engine version
  • Storage type
  • Storage encryption
  • Storage volume

To promote a read replica to an active primary DB, remove the readSourceDB option from the convox.yml and redeploy.

Resource linking works the same with read replicas, meaning environment variables for both primary and read replica databases will be created based on their respective YAML names.

Database Import

Database import allows you to integrate any RDS managed database or Elasticache into Convox, whether it was initially created by Convox or not.

resources:
  mydb-import:
    type: rds-postgres
    options:
      import: mydb-rtest-rc6-7924r-postgres-rds-check
      masterUserPassword: ${MYDBPASS}
services:
  web:
    resources:
      - mydb-import

Usage:

  • Set the import option with the masterUserPassword before deploying.
  • As long as the import option is set, the database will act as a passive linked access database.
  • Remove the import option and redeploy to manage the database through Convox.
  • While import is set, no other configured options will be considered. If import is removed, the application will have management control over the RDS database, and the masterUserPassword no longer needs to be configured.

You can set the master user password using convox env set before deploying:

$ convox env set MYDBPASS=my_secure_password -a myapp
Setting MYDBPASS... OK
Release: RABCDEFGHI

Snapshot Support

Snapshots allow you to restore a database from a specific point in time.

resources:
  db-from-snap:
    type: rds-postgres
    options:
      storage: 10
      snapshot: test-v3-rds-snapshot-postgres
      version: 13
services:
  web:
    resources:
      - db-from-snap

Usage:

  • Set the snapshot option with the snapshot identifier and ensure the version matches the engine version of the snapshot.
  • Remove the snapshot option and redeploy to enable options management from the convox.yml.

Immutable Attributes for Snapshots:

  • Storage encryption
  • Engine version
  • Storage volume

AWS ElastiCache Redis and Memcached Resources

Convox now supports native AWS ElastiCache Redis and Memcached instances for high-performance caching solutions. These managed cache instances can be defined and linked to services similarly to other managed resources.

Defining AWS ElastiCache Resources

AWS ElastiCache resources are specified with an elasticache- prefix followed by the cache type (redis or memcached). Below are examples of defining both Redis and Memcached resources:

Redis Example:

resources:
  cache:
    type: elasticache-redis
    options:
      class: cache.t3.micro
      version: 6.2
services:
  web:
    resources:
      - cache

Memcached Example (note that the nodes parameter must be set):

resources:
  cache:
    type: elasticache-memcached
    options:
      version: 1.6.6
      class: cache.t4g.micro
      nodes: 1
services:
  web:
    resources:
      - cache

Note: The nodes option is required for Memcached and must be set to the desired number of nodes for the Memcached cluster.

For detailed configuration options and examples for each type of AWS Elasticache resource, refer to the specific resource documentation pages:

Command Line Interface

Listing Resources

$ convox resources -a myapp
NAME  TYPE      URL
main  postgres  postgres://username:password@host.name:port/database

Getting Information about a Resource

$ convox resources info main -a myapp
Name  main
Type  postgres
URL   postgres://username:password@host.name:port/database

Getting the URL for a Resource

$ convox resources url main -a myapp
postgres://username:password@host.name:port/database

Launching a Console

$ convox resources console main -a myapp
psql (11.5 (Debian 11.5-1+deb10u1), server 10.5 (Debian 10.5-2.pgdg90+1))
Type "help" for help.
database=#

Starting a Proxy to a Resource

$ convox resources proxy main -a myapp
Proxying localhost:5432 to host.name:port

Proxying allows you to connect tools on your local machine to Resources running inside the Rack.

Exporting Data from a Resource

$ convox resources export main -f /tmp/db.sql
Exporting data from main... OK

Importing Data to a Resource

$ convox resources import main -f /tmp/db.sql
Importing data to main... OK