Setting up a Jenkinsfile to tar and commit a repo to S3

Notes on Jenkinsfile‘s

agenttells Jenkins to allocate an executor and workspace for the Pipeline.

More here:

https://jenkins.io/doc/book/pipeline/jenkinsfile/

First draft:

This creates Build, Test and Deploy stages.

 

Jenkins: Blue Ocean

Return to standard Jenkins interface – click on Administration button at top.

Notes: it’s not obvious how to Fetch from Git and Rebuild via Blue Ocean.

E.g.

http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.25-PM-300x115.png 300w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.25-PM-768x294.png 768w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.25-PM-588x225.png 588w" sizes="(max-width: 474px) 100vw, 474px" />

the circular icons to the right just rebuild the currently checked out code. See the Replayed entries (i.e. it uses the same commit as last time).

In Classic you have the Schedule a Scan button which does a rebuild (i.e. it takes the current commit in Github). See on the right here:

http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.59-PM-300x115.png 300w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.59-PM-768x295.png 768w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-3.56.59-PM-588x226.png 588w" sizes="(max-width: 474px) 100vw, 474px" />

The button says Scan scheduled and a job appears in Build Executor Status saying:

Building pipeline » Scan Repository

Oddly, this doesn’t happen immediately even on my instance where there are no other jobs running. It also seems a little intermittent. E.g. a few more clicks later sometimes trigger the job.

If there are no Github updates you get a Branch indexing in Blue Ocean.

 

In Blue Ocean you can do a Rebuild by going to the branch, hover over the row and a new Run icon should appear to the right

http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-4.47.05-PM-300x74.png 300w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-4.47.05-PM-768x189.png 768w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-4.47.05-PM-588x145.png 588w, http://www.snowcrash.eu/wp-content/uploads/2018/09/Screen-Shot-2018-09-28-at-4.47.05-PM.png 1062w" sizes="(max-width: 474px) 100vw, 474px" />

which, for maximum confusion, hides itself when your mouse is not near.

 

 

docker: Error response from daemon: driver failed programming external connectivity on endpoint …: Bind for 0.0.0.0:8080 failed: port is already allocated.

So, I’m trying to run Jenkins via Docker with:

docker run -d -v jenkins_home:/var/jenkins_home -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts

but getting:

Clearly the previous time I ran Jenkins the container hadn’t been cleanly stopped. Or there was another container using that port (it turned out to be the latter).

Here’s how to fix it.

  1. check port: netstat -nl -p tcp | grep 8080 (interestingly this didn’t show anything even though:
  2. docker ps(showed a container using this port)

docker stop <container name>

to solve the problem.

dig

Checking DNS:

dig

1. What’s the IP address for a domain?

Note: ping won’t necessarily work if ICMPpackets are refused but this does the job:

dig +short <domain name>

2. query a specific nameserver

e.g. your DNS might be OK with your internal DNS servers but not have propagated to public DNS servers like Google’s 8.8.8.8.

dig@<nameserver> <domain.com>

nslookup

 

docker port

Golden rule:


port1:port2 means you’re mapping port1on the host to port2on the container.

i.e. host:container


Say you run:

you’re mapping port 80 in the container to port 8080 on the host.

-p => publish a container’s port to the host

docker port web

gives
80/tcp -> 0.0.0.0:8080

which means:

80 on containermaps to 8080 on host

See also Tech Rant

https://docs.docker.com/engine/reference/commandline/run/#publish-or-expose-port–p—expose

https://docs.docker.com/engine/reference/commandline/port/

Tech Rant

Part of the problem with Tech is:

  • keeping so many things going in your brain at once
  • having to be an expert at so many things
  • the brain-crushing complexity

Example 1

I’m trying to figure out how docker port works. i.e. with this:

docker container run --rm -d --name web -p 8080:80 nginx

is 8080 on the host or the container?

E.g. I can run this: docker port web
80/tcp -> 0.0.0.0:8080

but I’m not clear on the mapping so I check the docs:

https://docs.docker.com/engine/reference/commandline/port/#description

which shows you an example:

but does not explain what the line actually means.

Is it container to host or host to container?

Next doc is https://docs.docker.com/engine/reference/commandline/run/#publish-or-expose-port–p—expose

This explains that 80:8080is host -> container. Which would mean that  the initial mapping I used for nginxabove is mapping 80in the container to 8080on the host. i.e. the other way around.

Let’s test.

1. from the VM

Assuming nginx is outputting to 80 (seems reasonable!) then I’d get something back from 8080 on the host (i.e. in the VM – we haven’t even started with what’s happening on the actual host – i.e. my Mac!) so we should get some output on 8080  from the VM so

curl localhost:8080

(what’s the format for using curl – is it curl localhost:8080 or curl localhost 8080 – check some more docs: https://www.unix.com/shell-programming-and-scripting/241172-how-specify-port-curl.html  – not unreasonable given that telnet doesn’t use a colon – i.e. you’d do telnet localhost 8080 – https://www.acronis.com/en-us/articles/telnet/)

which thankfully gives us some nginx output.

So, going back to:

docker port web
80/tcp -> 0.0.0.0:8080

This is saying:

80 on containermaps to 8080 on host

Annoyingly, the other way round to the format used earlier (i.e. of host to container).

If I do docker ps I get:

i.e. 0.0.0.0:8080->80/tcp

which even more annoyingly is the other way around! i.e. host -> container. I guess the way to remember it is that it’s host -> container unless you examine the container itself – e.g. using docker port web.

 

Some gotchas here:

  • curl localhost 8080 would give connection refused ‘cos curl by default will test on port 80 – given that we’ve got the command wrong it’s testing 80
  • if we’d tested using the container IP address. e.g.

docker container inspect web

gives  “IPAddress”: “172.17.0.3”

curl 172.17.0.3:80

that gives us nginx output. ‘cos we’re using the container IP address and port.

and

curl 172.17.0.3:8080 would give:
curl: (7) Failed to connect to 172.17.0.3 port 8080: Connection refused

 

2. from the container

we need to execfrom the VM into the container. Another doc page: https://docs.docker.com/engine/reference/commandline/exec/

docker exec -it web /bin/bash

and

curl localhost:80
bash: curl: command not found

So we need to install curl. More docs (‘cos it’s different on the Mac (I use brew), on Debian (apt) and CentOS (yum) to find out the OS.

cat /etc/os-release
PRETTY_NAME=”Debian GNU/Linux 9 (stretch)”

so we’re using Debian.

It should be apt-get but I get:

More docs on how to install on Debian:

https://www.cyberciti.biz/faq/howto-install-curl-command-on-debian-linux-using-apt-get/

says apt install curlwhich gives me the same problem.

More docs – seems like you have to run apt-get update first.

https://stackoverflow.com/questions/27273412/cannot-install-packages-inside-docker-ubuntu-image

And finally I can verify that, in the container,

curl localhost:80

outputs nginx content.

 

Note also: I’ve got Ubuntu in the VM and Debian in the container.

VM: my Vagrantfile uses  config.vm.box = "ubuntu/bionic64"

Container: docker container run --rm -d --name web -p 8080:80 nginx uses a Debian based container.

 


Finally, I write a blog post so I can remember in future how it all works without having to spend an entire morning figuring it out. I open up WordPress and it’s using Gutenberg which I’ve been struggling with. Trying to disable it is a pain. This doesn’t work:

How to Disable Gutenberg & Return to the Classic WordPress Editor

Groan. I just pasted a link and don’t want the Auto Insert content feature however I can’t even be bothered to try and figure out how to disable the Auto Insert behaviour.

In the end, I posted a test post and went to All Posts and clicked Classic Editor under the post.

Another rant: WordPress’ backtick -> formatted code only occasionally works – very frustrating.

 

3. To close the loop let’s test from my Mac

As we’re using 8080on the host let’s forward to 8081 on the Mac. Add this to the Vagrantfile:

config.vm.network "forwarded_port", guest: 8080, host: 8081

https://www.vagrantup.com/docs/networking/forwarded_ports.html

Another rant – trying to reprovision the VM with this gave me a continuous loop of:

I couldn’t be bothered to debug this so just did vagrant destroy vm1 and started again.

https://www.vagrantup.com/intro/getting-started/teardown.html

Then some more Waiting. e.g.

==> vm1: Waiting for machine to boot. This may take a few minutes…

Given how fast computers are it seems crazy how much Waiting we have to do for them. E.g. web browsers, phones, etc.

End of that rant.

 

So, testing from my Mac:

http://localhost:8081/

did not work.

I tried

http://localhost:8080/

which did work. Wtf?

I gave up here. Kind of felt that figuring out the problems here was a rabbit hole too far.

 

Example 2

You’ve got a million more important things to do but you suddenly find in your AWS console that:

Amazon EC2 Instance scheduled for retirement

Groan. This is part of an Elastic cluster.

So, should be a pretty standard process.

  • disable shard allocation
  • stop elasticsearch on that node
  • terminate the instance
  • bring up another instance using terraform
  • reenable shard allocation

but you find unassigned_shards is stuck at x.

So, now you’ve got to become an elasticsearch expert.

E.g. do a

curl -XGET localhost:9200/_cluster/allocation/explain?pretty

and work out why these shards aren’t being assigned.

There goes the rest of my day wading through reams of debugging output and documentation.

https://www.datadoghq.com/blog/elasticsearch-unassigned-shards/

 

Example 3

Finding information is so slow.

E.g. you want to know why Elasticsearch skipped from versions 2.x to versions 5.x.

And whether it’s important.

So you Google. Eventually, hiding amongst the Release Notes is a StackOverflow page (https://stackoverflow.com/questions/38404144/why-did-elasticsearch-skip-from-version-2-4-to-version-5-0 ) which says go look at this 1 hour 52 minute keynote for the answer.

Unless you’re an elasticsearch specialist, no-one wants to spend this time finding out that info (the answer, btw, is Elasticsearch: why the jump from 2.x to 5.x ).

 

Example 4

After you’ve spent days of time finding a solution, the answer is complex.

E.g. let say you have to do a Production restore of Elasticsearch.

Can you imagine the dismay you’d get when you have to face the complex snake’s nest contained here:

https://www.elastic.co/guide/en/elasticsearch/reference/1.7/modules-snapshots.html#_restore

The preconditions start with:

The restore operation can be performed on a functioning cluster. However, an existing index can be only restored if it’s closed and has the same number of shards as the index in the snapshot.

and continue for page after page.

There is no simple command like: elasticsearch restore data from backup A

 

Instead you have to restore an index from a snapshot. How do you work out whether a snapshot contains an index?

Easy! Just search dozens of Google results, wade through several hundred pages of Elasticsearch documentation and Stackoverflow questions for different versions of Elasticsearch and Curator. E.g.

Query Google for:

restore index from elasticsearch snapshot – https://www.google.com/search?q=restore+index+from+elasticsearch+snapshot&oq=restore+index+from+elasticsearch+snapshot&aqs=chrome..69i57j0.8028j0j4&sourceid=chrome&ie=UTF-8

and you get not much useful.

 

https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html

and

https://stackoverflow.com/questions/39968861/how-to-find-elasticsearch-index-in-snapshot

Funny – in the Stackoverflow the Answerer had the temerity to say:

I’m confused by your question as you have posted snapshot json which tells you exactly which indices are backed up in each snapshot.

I guess that exactly reflects the lack of understanding / empathy in the tech industry that someone can’t even make the leap to understand how to generalise the question to different indices and snapshots.

Example 5

Software that’s ridiculously complex to use.

E.g. take ElasticHQ – simple web GUI.

But how do you list snapshots?

Perhaps their documentation says something.

http://docs.elastichq.org/

No.

How about a search?

That returns 2 results. One about an API and another containing the word in code.

http://docs.elastichq.org/search.html?q=snapshot&check_keywords=yes&area=default

For anyone searching, it’s under Indices > Snapshots.

But if you’ve clicked on Indices, beware ‘cos you’re now in an infinite loop waiting for Indices to return.

Example 6: the acres of gibberish problem

Let’s say you’re learning a new technology.

The first thing you usually do is some Hello World system.

So, you try this with a Kubernetes pod. E.g.

and do

All seems pretty rosy? No!

Now you’re in acres of gibberish territory.

You’ve gone from trying to do a simple Hello World app to having to figure stuff out like:

  • NodeHasSufficientDisk
  • NodeHasNoDiskPressure
  • rpc error: code = Unknown desc = Error response from daemon

It’s the equivalent of learning to drive but, on trying to signal left, finding you have to replace the electrical circuitry of the car to get it working correctly.

This seemed to fix the problem:

e.g.

Example 7: Complexity

Example

Say I want to find out a version of a piece of software. This should be something even a beginner can do. E.g. it usually goes something like this:

app-name version

Now, however, it’s vastly more complex.

Let’s try helm version.

This is all real output I got.

Day 1:

Fortunately I know this is ‘cos I don’t have Kubernetes running on my local system which I can do with:

minikube start

Now, however,

So, now, when you’re not even at the level of running a hello world app you’re having to debug why you can’t even find out the version of your application!

I could go on with this. E.g. see the post Kubernetes: helm

Kind of frustrating when, at the most basic level, you reach a completely impassable roadblock. E.g.

And then you get:

which you have to spend a day Google’ing a solution.

E.g. on Stackoverflow you get obscure stuff like:

with no explanations why you need it or what it does and that doesn’t work anyway.
Day 3
This was a few days later. When I thought I’d sorted something simple like outputting the version.
helm version

Fortunately, I figured this out in a few minutes. But with less Kubernetes knowledge it could take you several days of effort – it shouldn’t take that long to work out what version of software you’re using.

By the way, this last one turned out to be because my default cluster turned out to be the one in EKS.

Need another example?

Ha ha. I could go on for days.

Let’s say you’ve committed some files using git. Now you realise you committed them on the wrong branch.

OK, if you were using Word or Google Docs, it would be pretty simple.

Select your changes, copy, Cmd Z until you got to the original state, paste.

With git it’s fucking complex.

I dare anyone with less than 3 years experience of git to do something this simple in under an hour.

 

More examples

https://github.com/kubernetes/dashboard

offers a dashboard. Great!

Seems to be a single line install. But just before the single line install you read:

IMPORTANT: Read the Access Control guide before performing any further steps. The default Dashboard deployment contains a minimal set of RBAC privileges needed to run.

That sounds ominous. Whilst I assume I don’t need to worry about that as I’m just testing on a local minikube I should read on just in case.

I start scanning through https://github.com/kubernetes/dashboard/wiki/Access-control

I get to:

Kubernetes supports few ways of authenticating and authorizing users. You can read about them here and here.

and I’m starting to worry about going down a rabbit hole here. Will I ever get this dashboard installed? Or will I just have to keep reading more and more documentation?

I decide to brave it and go with the single line install:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml

and get:

The Deployment "kubernetes-dashboard" is invalid: spec.selector: Invalid value: v1.LabelSelector{MatchLabels:map[string]string{"k8s-app":"kubernetes-dashboard"}, MatchExpressions:[]v1.LabelSelectorRequirement(nil)}: field is immutable

which seems pretty obvious. Clearly the Kubernetes authors have spent a lot of time making sure their output error messages are nice, clear and to the point. I’m not sure why they couldn’t have included a few more paragraphs of gibberish just to make things more obscure.

I try the suggested URL anyway

http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/

and get:

Again, clearly plenty of time spent creating nice, clear debug output.

 

What’s the solution?

Ignore all of the detailed advice on the Kubernetes Dashboard github page – i.e. https://github.com/kubernetes/dashboard

and, kudos to the Kubernetes documentation team (they outdid themselves here), buried nicely in issue 2898 is the answer:

minikube dashboard

So, translating, what the Kubernetes team mean by:

The Deployment "kubernetes-dashboard" is invalid: spec.selector: Invalid value: v1.LabelSelector{MatchLabels:map[string]string{"k8s-app":"kubernetes-dashboard"}, MatchExpressions:[]v1.LabelSelectorRequirement(nil)}: field is immutable

is

The dashboard is already running. Access it using <put URL in here>.

Someone needs to work on a Google Translate engine that maps Kubernetes to English.

https://github.com/kubernetes/dashboard/issues/2898

 

More examples

I want to run go on the Mac.

Example 8: Latency

It shouldn’t take 10 seconds to load up a web page.

Every time you click on a link it’s another 10 seconds. Get to the wrong web page? Click back and go to the next. That’s half a minute.

Example 9: Stuff that doesn’t work

I’ve got 2 digital thermometers. Side by side.

One reads 18.4C, the other 17.5.

They’re probably both wrong. So the temperature could be 16C or 19C. Who knows.

Example 10: Web page insertions

You go to click on a Google result. And suddenly Google (and they’re not the only culprits) inserts something else into the page and you click on something else.

Example 11: Cookies

Accept this

Accept this

Accept this

Accept this

Accept this

Accept this

Accept this

 

Every single website you go to. Over and over and over again.

 

Example 12: Inconsistencies

Why can’t all command line tools use the same flags?

Some use double-dash, some don’t.

They can’t even output versions in the same way.

 

AWS: Kinesis Data Streams

KDS (Amazon Kinesis Data Streams) lets you collect streaming data, at scale, for real-time analytics. 

From https://aws.amazon.com/kinesis/data-streams/

  • within 70ms
  • scales from megabytes to terabytes per hour, and from thousands to millions of PUT records per second
  • costs: for $0.015 per hour, you can have a Kinesis data stream with 1MB/second ingest and 2MB/second egress capacity

Welcome to the Gutenberg Editor

Default page when first installing Gutenberg

The default content is the Welcome block above (which you can’t seem to put anything above – oddly) and the blocks below starting with the visual “Of Mountains & Printing” block.

Of Mountains & Printing Presses

The goal of this new editor is to make adding rich content to WordPress simple and enjoyable. This whole post is composed of pieces of content—somewhat similar to LEGO bricks—that you can move around and interact with. Move your cursor around and you’ll notice the different blocks light up with outlines and arrows. Press the arrows to reposition blocks quickly, without fearing about losing things in the process of copying and pasting.

What you are reading now is a text block the most basic block of all. The text block has its own controls to be moved freely around the post…

… like this one, which is right aligned.

Headings are separate blocks as well, which helps with the outline and organization of your content.

A Picture is Worth a Thousand Words

Handling images and media with the utmost care is a primary focus of the new editor. Hopefully, you’ll find aspects of adding captions or going full-width with your pictures much easier and robust than before.

Beautiful landscape
If your theme supports it, you’ll see the “wide” button on the image toolbar. Give it a try.

Try selecting and removing or editing the caption, now you don’t have to be careful about selecting the image or other text by mistake and ruining the presentation.

The Inserter Tool

Imagine everything that WordPress can do is available to you quickly and in the same place on the interface. No need to figure out HTML tags, classes, or remember complicated shortcode syntax. That’s the spirit behind the inserter—the (+) button you’ll see around the editor—which allows you to browse all available content blocks and add them into your post. Plugins and themes are able to register their own, opening up all sort of possibilities for rich editing and publishing.

Go give it a try, you may discover things WordPress can already add into your posts that you didn’t know about. Here’s a short list of what you can currently find there:

  • Text & Headings
  • Images & Videos
  • Galleries
  • Embeds, like YouTube, Tweets, or other WordPress posts.
  • Layout blocks, like Buttons, Hero Images, Separators, etc.
  • And Lists like this one of course 🙂


Visual Editing

A huge benefit of blocks is that you can edit them in place and manipulate your content directly. Instead of having fields for editing things like the source of a quote, or the text of a button, you can directly change the content. Try editing the following quote:

The editor will endeavor to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.

Matt Mullenweg, 2017

The information corresponding to the source of the quote is a separate text field, similar to captions under images, so the structure of the quote is protected even if you select, modify, or remove the source. It’s always easy to add it back.

Blocks can be anything you need. For instance, you may want to add a subdued quote as part of the composition of your text, or you may prefer to display a giant stylized one. All of these options are available in the inserter.

You can change the amount of columns in your galleries by dragging a slider in the block inspector in the sidebar.

Media Rich

If you combine the new wide and full-wide alignments with galleries, you can create a very media rich layout, very quickly:

Accessibility is important — don’t forget image alt attribute

Sure, the full-wide image can be pretty big. But sometimes the image is worth it.

The above is a gallery with just two images. It’s an easier way to create visually appealing layouts, without having to deal with floats. You can also easily convert the gallery back to individual images again, by using the block switcher.

Any block can opt into these alignments. The embed block has them also, and is responsive out of the box:

You can build any block you like, static or dynamic, decorative or plain. Here’s a pullquote block:

Code is Poetry

The WordPress community


If you want to learn more about how to build additional blocks, or if you are interested in helping with the project, head over to the GitHub repository.


Thanks for testing Gutenberg!

👋