Aug 25, 2020

Review: Running Containers in Production for dummies

 Last evening i read the following booklet:

Here my review:

Chapter one gives within 7 pages an excellent introduction into "Containers & Orchestration Platforms". From Kubernetes over Openshift/Docker Swarm up to Amazon EKS - many services are described. In my opinion Azure AKS is missing, but it is clear, that every hyperscaler will provide you its managed Kubernetes environment. At the end even Apache Mesos is listed - which is out of scope for the most of us. 
Building & Deploying Containers is the headline of chapter 2 and a brief, solid description of these topics is given. If you want to know what all the buzzwords like CI/CD/CS, Pipelines, Container Registries are about: Read that chapter and you have a good starting point.

Nearly 33% of the book(let) is abount Monitoring Containers (chapter 3). This points in to the right directions. You have to know what your containers are doing and what you have to change with continuous delivery and continuous deployment. If you are running tens or hundreds of containers, the monitoring has to be  automatic as well - or you are lost. "A best practice for using containers is to isolate workloads by running only a single process per container.  Placing a monitoring agent — which amounts to a second process or service — in each container to get visibility risks destroying a key value of containers: simplicity." - So building up a monitoring is not such easy, as is was on full-stack servers...

Chapter 4 is about Security. This focuses on the following topics: Implementing container limits against resource abuse, how to avoid outdated container images, management of secrets and image authenticity.

The last chapter closes with "Ten Container Takeaways".


Within 43 pages a really nice starting point to learn about the world of docker and container orchestration.

Aug 7, 2020

openssl: strange error.... (at first glance) error:2008F002:BIO

Some days ago i wanted to do a check of a certificate of an ip address. No big deal - so i did:
schroff@zerberus:~$ openssl s_client -showcerts  -connect

140011908769088:error:2008F002:BIO routines:BIO_lookup_ex:system
lib:../crypto/bio/b_addr.c:726:Name or service not known
So i opened google to find a solution.
But on google i found nothing really helpful.


The answer was very easy:
If i read the command line carfully, i would have detected my error:


I wrote an ipv4 with 5 numbers and not with 4...

After using a correct ipv4 number the command worked like expected:
schroff@zerberus:~$ openssl s_client -showcerts -connect #
Can't use SSL_get_servername
depth=2 C = US, O = DigiCert Inc, OU =, CN = DigiCert Global Root CA
verify return:1
depth=1 C = US, O = DigiCert Inc, OU =, CN = GeoTrust RSA CA 2018
verify return:1
depth=0 C = DE, ST = Rheinland-Pfalz, L = Montabaur, O = 1&1 Mail & Media GmbH, CN =
verify return:1