3D printing comes to Saugatucket Rd

I succumbed. Exchanged cost (under $200) for some frustrating days ahead.

Red Chair Studio ceramics sale Saturday & Sunday

Red Chair Studio is having a studio sale today and tomorrow, Sat, Oct 13 and Sun, Oct 14, between the hours of 9 AM to 4 PM. The location is 574 Saugatucket Rd, South Kingstown, RI 02879 (map).


Who buys hundreds of dollars of used fencing sight unseen?

Experienced my first active phishing scam today. I posted to Craigslist the sale of some chainlink fence paneling I no longer need (and, frankly, want out of my yard). Within the hour I received a text message from Steven Anthony at 903-865-2390 saying he would buy it, pay with PayPal, and would arrange shipping. It seemed a little odd that someone in Texas would buy $600 of paneling sight-unseen. Nevertheless, I gave him my PayPal account name and my home address. Then the buyer wrote
"I will have to included the shipper funds with the payment so that you will pay them once you receive the payment." 
Now, I am not selling something that can be shipped USPS Priority mail for $8. The paneling is a few 100 pounds of metal and 100 or more square feet. The buyer is going to have to contract with a long distance hauler and, most likely prepay, some or all of the price. I passed on the sale. The buyer never texted back with a counter offer or a simple goodbye. Part of me wanted to see what would happen next. My expectation was that I would soon have received an email from "PayPal" having me login and collect the payment.

I have no way of knowing if Mr Anthony was or was not a legitimate buyer. But there were many signals of fraud in our interaction. If I do discover that Mr Anthony was, indeed, just trying to buy a bunch of cheap fencing quickly, then I will apologize to him and remove this posting.

We are all a seafaring people

Maps might not be the territory, they often define a world view. This Spilhaus Projection drawn by Clara Dealberto is a stunning example of such a map. We are all a seafaring people.

Incident Response Slack application series

I am have finished working on the Incident Response Slack application. It was a hobby project and I feel no need to take it any further, although, I would like to switch to RDS from SimpleDB. Here are the postings related to the project
  1. Incident Response Slack App 
  2. Adding persistence to the Incident Response Slack application 
  3. Who wants to perpetuate a flawed design when a proper one is just around the corner? 
  4. Incident Response and stating requirements
  5. Access AWS Secrets Manager from AWS Elastic Beanstalk

Access AWS Secrets Manager from AWS Elastic Beanstalk

I finally figured out how to connect my Incident Response Java application running in AWS Elastic Beanstalk with its associated secret in AWS Secrets Manager. As always, the solution is obvious once it is known. What is not so obvious to me as I write this, is how many of previous "solutions" were correct but the "system" had not yet become "eventually consistent?" Moreover, the current solution is very specific and that seems wrong. Nevertheless, here are the solution's parts.

Assume you have created an AWS Secrets Manager called S1 and an AWS Elastic Beanstalk called A1. What you now need to do is to
  1. Create an IAM Policy called P1 that enables access to S1.
  2. Attach policy P1 to the role aws-elasticbeanstalk-service-role.
  3. Attach policy P1 to the role aws-elasticbeanstalk-ec2-role.
When creating policy P1 give it all Secrets Manager's List and Read actions. I am sure some can be skipped and so you and I should go back and remove unneeded actions. You will also need to limit the actions to only the S1 resource, aka its ARN.

Once this is done, restart your application A1 and it will now have access the S1 secret and its keys and their values.

Since Incident Response needs to store its data in AWS SimpleDB, I extended the S1 policy to include all access to any AWS SimpleDB domain, but this did not work. I had to restrict access to a specific domain's ARN. What bothers me about this is that I have now specified the specific domain in both P1 and as a secret S1 key "aws.simpledb.domain" value. Perhaps there is a way I can read the domain from the policy; an exploration for another day.

The Father (Play)

Tonight (Oct 5) is the last performance of The Father, performed on the outside stage at the Contemporary Theater Company. The story is told from the point of view of a dementia patient. It had the same revelatory experience for me as did reading The Curious Incident of the Dog in the Night-Time for Aspergers. Highly recommended.

DevOps as a category will fade away

I do enjoy seeing all the work going into building out and solving the very real problems associated with running software in distributed systems. DevOps has embraced a lot of this work. I think this is a short term engagement. At its core, DevOps is about empowering developers to deploy and to watch their own applications in production. In the not too distant future, I see distributed systems design returning to its natural home as a part of operating systems design. And DevOps as a category will fade away and we will again focus on application design in a much richer systems environment.

Update, 2018-12-03: "Sorry, Linux. Kubernetes is now the OS that matters," by Matt Asay of InfoWorld.

Incident Response and stating requirements

In my Incident Response hobby project a user creates tasks in workspaces. The new task is given a unique id for the workspace it is in. Ideally, because these numbers are seen and used by people, the ids would be small integers that are strictly increasing. Most databases have some sequence or auto-increment feature, but AWS SimpleDB does not. You must create it yourself or use another mechanism.

Creating a globally consistent, strictly increasing, small integer number mechanism is very hard to do. A reason why ZooKeeper, atomix, etcd, consul, etc, are so widely used is because they do the hard work of implementing value consensus in distributed systems. For my hobby project these tools are overkill, but I still need the mechanism.

To restate the requirement, it is a mechanism enabling multiple processes (on a distributed set of machines) to add tasks to workspaces. But is that really the requirement? Isn't it a premature optimization to assume the need for multiple processes? Perhaps one process can handle all the task creation requests for a single workspace? [1] If I have 100 workspaces I can choose to enable task creation by distributing any request to any process, but I could also choose to distribute task creation to the workspace specific process. Choosing the second option vastly reduces the problem to enabling a single process to sequence the task ids. All I have to do now is direct the request to the right process and this is easily done at Slack with a different URL (option A) during application installation, or at an application layer gateway (option B).

So I am going with one process per workspace [2] with option A.

[1] An assumption is that one process is sufficient to manage the demand of a single workspace.
[2] Note that this does not preclude more than one workspace per process.

Strong consistency models

"Strong consistency models" is a very clear article on the problems of working with data, its all from the past, and collaborating with sometimes disconnected processes. The comments are good too.
Network partitions are going to happen. Switches, NICs, host hardware, operating systems, disks, virtualization layers, and language runtimes, not to mention program semantics themselves, all conspire to delay, drop, duplicate, or reorder our messages. In an uncertain world, we want our software to maintain some sense of intuitive correctness. 
Well, obviously we want intuitive correctness. Do The Right Thing™! But what exactly is the right thing? How might we describe it? In this essay, we’ll take a tour of some “strong” consistency models, and see how they fit together.