Check server version postgres=# select version(); version -------------------------------------------------------------------------------------------------------- PostgreSQL 12.3 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.3.1 20191121 (Red Hat 8.3.1-5), 64-bit (1 row) Check client version [postgres@postgres-lab ~]$ psql --version psql (PostgreSQL) 12.3 Check database version from PGDATA [postgres@postgres-lab ~]$ cat $PGDATA/PG_VERSION 12 PostgreSQL support table PostgreSQL Versioning Policy Check when database was started postgres=# select pg_postmaster_start_time(); pg_postmaster_start_ ..read more

Configure remote access - listen address By default after instalation and creting database cluster PostgreSQL will listner only on localhost. No remote access will be allowed. PostgreSQL installation on Linux - with database creation [postgres@postgres-lab ~]$ netstat -lptnu | grep post (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) tcp 0 0 127.0.0.1:5432 0 ..read more

PostgreSQL is open source software so we can install it wthout any limitation, including our personal code changes. It is distributed under own The PostgreSQL License(TPL). Installation of PostgreSQL is easy on Linux Distributions. For purpose of tutorial we use CentOS 8. We shuold get newest PostgreSQL from official repo - version in OS repos are mostly old - like for now when we get with CentOS 8 PostgreSQL 9.6 ..read more

In production environment we should care about security, also we want easy of usage. So, it is good to know docker security options and Docker Enterprise Edition. This guide assume that we have got Docker Enterprise Edition installed on three node cluster. Most of features described here are paid ones, but we can get a trial of Docker Enterprise Edition for free - 30 day period. How to do it ..read more

Containers need to communicate with each other and outside world. Docker has wide network capabilities. What we can do with docker network? How to use it? Docker Network Theory What elements we have in docker network? CNM libnetwork drivers Docker network concept is based on open-source design specification called Container Network Model(CNM). CNM assume that network drivers should be pluggable. Docker CNM implementation is in libnetwork library. What we can do with docker CNM ..read more

By default after installing docker on our host we have client and server(daemon) locally speaking to each other by IPC socket. On Linux - /var/run/docker.sock. So what we should do when our daemon is in remote location? How to make connection secure? Example environment Role Server IP Client docker-host1.lukas.int 10.10.10.20 CA docker-host2.lukas.int 10.10.10.21 Daemon docker-host3.lukas.int 10.10.10.22 All hosts can reach each other by hostname ..read more

Install and upgrade of Docker Engine is simple and straightforward process. In this post I will cover all important information in one place. Docker install requirements Minimum requirements 8GB RAM per manager node 4GB RAM per worker node 3GB of free disk space Recommended production requirements 16GB RAM per manager node 4 vCPUs per manager node 25-100GB of free disk space on each node Also you must have one of the following OS ..read more

For HA and easier management of our containers we can create swarm cluster. It is composed of couple nodes with docker engine installed. How to setup swarm and use it? Example configuration and prerequisites In my lab environment I used three nodes: Role in Swarm Server IP Manager docker-host1.lukas.int 10.10.10.20 Worker1 docker-host2.lukas.int 10.10.10.21 Worker2 docker-host3.lukas.int 10.10.10.22 Each node has got docker engine installed with standard procedure as for single node docker ..read more

Storing persistent data in containers needs special storage. There is two options - volumes or bind mounts. How to use them? Volume vs bind mounts Bind mounts: rely on docker host directory structure different behaviour for --mount and --volume parameters cant’ be control by docker CLI used mainly in development environments Volumes: can be control by docker CLI works in Linux and Windows hosts easier to backup because of central location /var/lib/docker/volumes easier to store in cloud provider infrastructure preferred method as docker documentation said give possibility to be shared between ..read more

A ..read more