Docker host and bridged networking. Running library/httpd on different ports

Docker provides different networking options. When using the Docker host networking, you don’t have the option to create port mappings. When using images like library/httpd:2.4, you don’t have the option to update the port on which it runs; it runs by default on port 80. Suppose you want to use the host networking feature and want to run library/httpd:2.4 on different ports, how would you do this?

In this blog I’ll explain 2 (more...)

PreBuilt Oracle Database 18c with Docker

In this post, we can use Docker service to pull the prebuilt Oracle Database 18c. Docker must be installed and running for this feature prerequisite.

In your VM or Bare Metal, check the status and version of Docker if it is installed.

[root@docker ~]# docker info
[root@docker ~]# docker version
 Version:           18.06.0-ce
 API version:       1.38
 Go version:        go1.10.3
 Git commit:        0ffa825
 Built:             Wed Jul 18 19:08:18 2018
 OS/Arch:           linux/amd64

Running Spring Tool Suite and other GUI applications from a Docker container

Running an application within a Docker container helps in isolating the application from the host OS. Running GUI applications like for example an IDE from a Docker container, can be challenging. I’ll explain several of the issues you might encounter and how to solve them. For this I will use Spring Tool Suite as an example. The code (Dockerfile and docker-compose.yml) can also be found here. Due to (several) security concerns, this is not (more...)

Could RedHat’s absolute commitment to OpenShift put them into difficult waters?

As a middleware (to use a fading term) or technical architect, I preferred not to get too involved in the detailed OS layer considerations when it can be helped (my Infrastructure Architect colleagues will always know more about NICs, port bonding, kernel versions etc etc than I ever will) and why I prefer to work with PaaS over IaaS.

But there is an undeniable trend where having a greater understanding of the OS is necessary, (more...)

Oracle Database 18.3.0 and Docker

Just a quick heads-up to let you know I’ve updated my Docker builds to use the new 18c on-prem software.

If you like to play around with Docker, here is some stuff you might want to check out. Remember, I’m not saying this is production ready. It’s just stuff I use for learning and demos…

  • My Docker GitHub Repo here.
  • The new 18c container build here.
  • The new Docker compose file here to fire up (more...)

Setting up Docker on Oracle Linux 7

Docker has become widely popular in the last couple of years. I use it on a regular basis these days for running Oracle databases on my laptop. Docker is available on all popular Linux distributions, as well as Mac and Windows, and of course Oracle Linux is no exception. Since a long time Docker ships … Continue reading "Setting up Docker on Oracle Linux 7"

Docker: Networking with docker swarm: creating new subnets/gateways/…

In this posting i explained how to configure the network for a container on a docker machine.
If you want to do this for a docker swarm, you have to change the commands. The network driver "bridge" does not work in swarm mode:
(How to run a container inside a swarm take a look here)

docker service create  --network mybrigde --name helloworld alpine ping

Error: No such network: mybrigde
Even (more...)

Docker on Fedora 27

This walks you through the steps to install the Community Edition of Docker on Fedora 27. If you’ve been living under a rock for a few years, Docker is an open source container virtualization software.

Docker or Docker Community Edition is a necessary step if you want to install something like Microsoft’s SQL Server on Fedora because only these are supported platforms:

  • Red Hat Enterprise Linux 7.3 or 7.4
  • SUSE Linux Enterprise Server (more...)

Docker: Network configuration: How to customize the network bridge and use my own subnet / netmask / CiDR

In my last posting i described how to configure the network settings of a container via docker command line:
--net none
--net bridge
Now i want to try to change the subnet from the standard to another ip range.

There are some tutorials out there which say:

docker run -it  --net bridge  --fixed-cidr ""  alpine /bin/ash
unknown flag: --fixed-cidr
but this doesa not work any more.

First you (more...)

Docker: Network configuration – none / brigde / hostname / dns entries

If you are starting your docker container you can add some network configuration details via command line.
Let's start with the easiest network setting:
docker run -it  --net none alpine /bin/ash
This setting starts the container without any connectivity to the network:
# ip addr show
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet scope host lo
       valid_lft forever preferred_lft forever

Docker: How to limit memory

By starting your container you can limit the RAM usage simply by adding
-m 4M

(this limits the memory to 4 megabytes).

To check this simply run:

docker run -it -m=4M  --rm alpine /bin/ash

and on your docker machine check the following entry:

alpine:~# cat /sys/fs/cgroup/memory/docker/4ce0403caf667e7a6d446eac3820373aefafe4e73463357f680d7b38a392ba62/memory.limit_in_bytes 

Docker: Lessons learned – Logging

After some time working with docker here my experiences:

Some days ago i created my own container with a minimal web service.

Here the
sed -i  's/Hostname:.*/Hostname: '$HOSTNAME'/g' index.html
while true; do { echo -e 'HTTP/1.1 200 OK\r\n'; cat index.html;}  | nc  -l -p 8080  2>&1 >> logfile; done
This is the Dockerfile:
FROM alpine


RUN mkdir ncweb

ADD .  /tmp

ENTRYPOINT [ "/tmp/" (more...)

Creating an Oracle Rest Data Services Docker image

Oracle has added Oracle Rest Data Services (ORDS) to the Docker build files family on GitHub, which means that you can now easily dockerize ORDS. If you don’t know yet what ORDS is, it’s a free technology from Oracle that allows you to REST-enable your Oracle databases. More specifically, with ORDS you can just fire … Continue reading "Creating an Oracle Rest Data Services Docker image"

Docker: How to build you own container with your own application

atThere are many tutorials out there, how to create a docker container with a apache webserver inside or a nginx.
But you can hardly find a manual how to build your own docker container without pulling everything from a foreign repository.
Why should you not pull everything from foreign repositories?

You should read this article or this:
But since each phase of the development pipeline is built at a different time, …
…you can’t (more...)

UKOUG Technology Day


We have organized a UKOUG Technology Summit in Leeds on 16th May.

It’s really a small Conference!

This is available to UKOUG Members and will cost 1 SIG Pass – even Bronze memberships come with 1 SIG pass, so all members could attend at no cost.
Non-members can pay to attend, but you should take out a Bronze Membership instead as it’s about the same price!

Come along, network with your peers, and listen to (more...)

ADF on Docker – Java Memory Limit Tuning for JVM

It might look like a challenge to run Java in Docker environment, by default Java is not aware of Docker memory limits. Check this article for example - Java inside docker: What you must know to not FAIL.  I was able to run WebLogic and ADF (Essential WebLogic Tuning to Run on Docker and Avoid OOM) on Docker previously without Java memory issues, using JAVA_OPTIONS=-XX:+UnlockCommercialFeatures -XX:+ResourceManagement -XX:+UseG1GC. However after Docker upgrade (more...)

Docker Oracle and local installs

| Mar 14, 2018
So you want Docker and to install and Oracle Database locally.  So did I and while I have VirtualBox and the Oracle Developer Day VM, I wanted to setup docker and the Oracle Database
Well Colm Divilly (@cdivilly) has cleared it up for me.  His Gist on on Github had me up and running. Very little work on my part here, following Colm's detailed instructions, (barring time for downloads) I had docker (more...)

Get going with Project Fn on a remote Kubernetes Cluster from a Windows laptop–using Vagrant, VirtualBox, Docker, Helm and kubectl

| Mar 4, 2018


The challenge I describe in this article is quite specific. I have a Windows laptop. I have access to a remote Kubernetes cluster (on Oracle Cloud Infrastructure). I want to create Fn functions and deploy them to an Fn server running on that Kubernetes (k8s from now on) environment and I want to be able to execute functions running on k8s from my laptop. That’s it.

In this article I will take you on a (more…)

Using SQL*Plus to Seed your Dockerized Oracle Database

In my last blog, you learned  to create a containerized Oracle database for your development/testing purpose. You also know how to connect to your container and run command in the container.

Most applications require some reference data e.g. example,my  OrderApp application based on Apache Tom EE  requires catalog data to be pre-populated before I can test my application. 

One of the readers asked me how can we run a SQL (more...)

Dockerizing Your Development and Test Oracle databases

You are probably reading this blog because your application depends on Oracle database. Most enterprises in the world depend on Oracle database to run their business. If you are a developer using Oracle database and getting started with Docker, you must be wondering how can you use a containerized Oracle database. 

In my last blog, I outlined how you can use a Dockerized Tomcat /Tom EE with an Oracle database. In this blog, (more...)