Spilo: HA PostgreSQL Clusters with Docker

Spilo is a Docker image that provides PostgreSQL and Patroni bundled together. Patroni is a template for PostgreSQL HA. Multiple Spilos can create a resilient High Available PostgreSQL cluster. For this, you'll need to start all participating Spilos with identical etcd addresses and cluster names.

Spilo's name derives from [spil], the Georgian word for "elephant."

Real-World Usage and Plans

Spilo is currently evolving: Its creators are working on a Postgres operator that would make it simpler to deploy scalable Postgres clusters in a Kubernetes environment, and also do maintenancetasks. Spilo would serve as an essential building block for this. There is already a Helm chart that relies on Spilo and Patroni to provision a five-node PostgreSQL HA cluster in a Kubernetes+Google Compute Engine environment. (The Helm chart deploys Spilo Docker images, not just "bare" Patroni.)

How to Use This Docker Image

Spilo's setup assumes that you've correctly configured a load balancer (HAProxy, ELB, Google load balancer) that directs client connections to the master. There are two ways to achieve this: A) if the load balancer relies on the status code to distinguish between the healthy and failed nodes (like ELB), then one needs to configure it to poll the API URL; otherwise, B) you can use callback scripts to change the load balancer configuration dynamically.

Available container registry and image architectures

Spilo images are made available in the GitHub container registry (ghcr.io). Images are build and published as linux/amd64 and linux/arm64 on tag. For PostgreSQL version 14 currently availble images can be found here: https://github.com/zalando/spilo/pkgs/container/spilo-14

How to Build This Docker Image

$ cd postgres-appliance

$ docker build --tag $YOUR_TAG .

There are a few build arguments defined in the Dockerfile and it is possible to change them by specifying --build-arg arguments:

• WITH_PERL=false # set to true if you want to install perl and plperl packages into image
• PGVERSION="12"
• PGOLDVERSIONS="9.5 9.6 10 11"
• DEMO=false # set to true to build the smallest possible image which will work only on Kubernetes
• TIMESCALEDB_APACHE_ONLY=true # set to false to build timescaledb community version (Timescale License)
• TIMESCALEDB_TOOLKIT=true # set to false to skip installing toolkit with timescaledb community edition. Only relevant when TIMESCALEDB_APACHE_ONLY=false
• ADDITIONAL_LOCALES= # additional UTF-8 locales to build into image (example: "de_DE pl_PL fr_FR")

Run the image locally after build:

$ docker run -it your-spilo-image:$YOUR_TAG

Have a look inside the container:

$ docker exec -it $CONTAINER_NAME bash

Connecting to PostgreSQL

Administrative Connections

PostgreSQL is configured by default to listen to port 5432. Spilo master initializes PostgreSQL and creates the superuser and replication user (postgres and standby by default).

You'll need to setup Spilo to create a database and roles for your application(s). For example:

psql -h myfirstspilo.example.com -p 5432 -U admin -d postgres

Application Connections

Once you have created a database and roles for your application, you can connect to Spilo just like you want to connect to any other PostgreSQL cluster:

psql -h myfirstspilo.example.com -p 5432 -U wow_app -d wow
psql -d "postgresql://myfirstspilo.example.com:5432/wow?user=wow_app"

Configuration

Spilo is configured via environment variables, the values of which are either supplied manually via the environment (whenever Spilo is launched as a set of Docker containers) or added in the configuration file or manifest (whenever Spilo is used in the Docker orchestration environment, such as Kubernetes or Docker Compose).

Please go here to see our list of environment variables.

To supply env variables manually via the environment for local testing:

docker run -it -e YOUR_ENV_VAR=test your-spilo-image:latest

Issues and Contributing

Spilo welcomes questions via our issues tracker. We also greatly appreciate fixes, feature requests, and updates; before submitting a pull request, please visit our contributor guidelines.

License

This project uses the Apache 2.0 license.