Architecture

Modular Architecture and Declarative Interface!

• Pigsty deployment is described by config inventory and materialized with ansible playbooks.
• Pigsty works on Linux x86_64 common nodes, i.e., bare metals or virtual machines.
• Pigsty uses a modular design that can be freely composed for different scenarios.
• The config controls where & how to install modules with parameters
• The playbooks will adjust nodes into the desired status in an idempotent manner.

Modules

Pigsty uses a modular design, and there are six default modules: PGSQL, INFRA, NODE, ETCD, REDIS, and MINIO.

• PGSQL: Autonomous ha Postgres cluster powered by Patroni, Pgbouncer, HAproxy, PgBackrest, etc…
• INFRA: Local yum/apt repo, Prometheus, Grafana, Loki, AlertManager, PushGateway, Blackbox Exporter…
• NODE: Tune node to desired state, name, timezone, NTP, ssh, sudo, haproxy, docker, promtail, keepalived
• ETCD: Distributed key-value store will be used as DCS for high-available Postgres clusters.
• REDIS: Redis servers in standalone master-replica, sentinel, cluster mode with Redis exporter.
• MINIO: S3 compatible simple object storage server, can be used as an optional backup center for Postgres.

You can compose them freely in a declarative manner. If you want host monitoring, INFRA & NODE will suffice. Add additional ETCD and PGSQL are used for HA PG Clusters. Deploying them on multiple nodes will form a ha cluster. You can reuse pigsty infra and develop your modules, considering optional REDIS and MINIO as examples.

Singleton Meta

Pigsty will install on a single node (BareMetal / VirtualMachine) by default. The install.yml playbook will install INFRA, ETCD, PGSQL, and optional MINIO modules on the current node, which will give you a full-featured observability infrastructure (Prometheus, Grafana, Loki, AlertManager, PushGateway, BlackboxExporter, etc… ) and a battery-included PostgreSQL Singleton Instance (Named meta).

This node now has a self-monitoring system, visualization toolsets, and a Postgres database with autoconfigured PITR. You can use this node for devbox, testing, running demos, and doing data visualization & analysis. Or, furthermore, adding more nodes to it!

Monitoring

The installed Singleton Meta can be use as an admin node and monitoring center, to take more nodes & Database servers under it’s surveillance & control.

If you want to install the Prometheus / Grafana observability stack, Pigsty just deliver the best practice for you! It has fine-grained dashboards for Nodes & PostgreSQL, no matter these nodes or PostgreSQL servers are managed by Pigsty or not, you can have a production-grade monitoring & alerting immediately with simple configuration.

HA PG Cluster

With Pigsty, you can have your own local production-grade HA PostgreSQL RDS as much as you want.

And to create such a HA PostgreSQL cluster, All you have to do is describe it & run the playbook:

pg-test:
  hosts:
    10.10.10.11: { pg_seq: 1, pg_role: primary }
    10.10.10.12: { pg_seq: 2, pg_role: replica }
    10.10.10.13: { pg_seq: 3, pg_role: replica }
  vars: { pg_cluster: pg-test }

$ bin/pgsql-add pg-test  # init cluster 'pg-test'

Which will gives you a following cluster with monitoring , replica, backup all set.

Hardware failures are covered by self-healing HA architecture powered by patroni, etcd, and haproxy, which will perform auto failover in case of leader failure under 30 seconds. With the self-healing traffic control powered by haproxy, the client may not even notice there’s a failure at all, in case of a switchover or replica failure.

Software Failures, human errors, and DC Failure are covered by pgbackrest, and optional MinIO clusters. Which gives you the ability to perform point-in-time recovery to anytime (as long as your storage is capable)

Database as Code

Pigsty follows IaC & GitOPS philosophy: Pigsty deployment is described by declarative Config Inventory and materialized with idempotent playbooks.

The user describes the desired status with Parameters in a declarative manner, and the playbooks tune target nodes into that status in an idempotent manner. It’s like Kubernetes CRD & Operator but works on Bare Metals & Virtual Machines.

Take the default config snippet as an example, which describes a node 10.10.10.10 with modules INFRA, NODE, ETCD, and PGSQL installed.

# infra cluster for proxy, monitor, alert, etc...
infra: { hosts: { 10.10.10.10: { infra_seq: 1 } } }

# minio cluster, s3 compatible object storage
minio: { hosts: { 10.10.10.10: { minio_seq: 1 } }, vars: { minio_cluster: minio } }

# etcd cluster for ha postgres DCS
etcd: { hosts: { 10.10.10.10: { etcd_seq: 1 } }, vars: { etcd_cluster: etcd } }

# postgres example cluster: pg-meta
pg-meta: { hosts: { 10.10.10.10: { pg_seq: 1, pg_role: primary }, vars: { pg_cluster: pg-meta } }

To materialize it, use the following playbooks:

./infra.yml -l infra    # init infra module on group 'infra'
./etcd.yml  -l etcd     # init etcd module on group 'etcd'
./minio.yml -l minio    # init minio module on group 'minio'
./pgsql.yml -l pg-meta  # init pgsql module on group 'pgsql'

It would be straightforward to perform regular administration tasks. For example, if you wish to add a new replica/database/user to an existing HA PostgreSQL cluster, all you need to do is add a host in config & run that playbook on it, such as:

pg-test:
  hosts:
    10.10.10.11: { pg_seq: 1, pg_role: primary }
    10.10.10.12: { pg_seq: 2, pg_role: replica }
    10.10.10.13: { pg_seq: 3, pg_role: replica } # <-- add new instance
  vars: { pg_cluster: pg-test }

$ bin/pgsql-add  pg-test 10.10.10.13

You can even manage many PostgreSQL Entities using this approach: User/Role, Database, Service, HBA Rules, Extensions, Schemas, etc…

Check PGSQL Conf for details.