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Prep deck

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Jerome Petazzoni
2019-11-15 10:21:54 -06:00
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2
slides/shared/prereqs.md
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@@ -50,7 +50,9 @@ Misattributed to Benjamin Franklin
- Go to @@SLIDES@@ to view these slides
<!--
- Join the chat room: @@CHAT@@
-->
<!-- ```open @@SLIDES@@``` -->

145
slides/shared/sampleapp.md
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@@ -26,9 +26,7 @@ fi
---
## Downloading and running the application
Let's start this before we look around, as downloading will take a little time...
## Having a look at the application
.exercise[
@@ -37,20 +35,22 @@ Let's start this before we look around, as downloading will take a little time..
cd ~/container.training/dockercoins
```
- Use Compose to build and run all containers:
- Check the files and directories:
```bash
docker-compose up
tree
```
<!--
```longwait units of work done```
-->
]
Compose tells Docker to build all container images (pulling
the corresponding base images), then starts all containers,
and displays aggregated logs.
---
## Viewing the application
- Jérôme is going to wear his developer hat ...
- ... start the application on his developer's machine ...
- ... and wait for the app to be up and running.
---
@@ -165,26 +165,6 @@ https://@@GITREPO@@/blob/8279a3bce9398f7c1a53bdd95187c53eda4e6435/dockercoins/wo
---
class: extra-details
## Links, naming, and service discovery
- Containers can have network aliases (resolvable through DNS)
- Compose file version 2+ makes each container reachable through its service name
- Compose file version 1 required "links" sections to accomplish this
- Network aliases are automatically namespaced
- you can have multiple apps declaring and using a service named `database`
- containers in the blue app will resolve `database` to the IP of the blue database
- containers in the green app will resolve `database` to the IP of the green database
---
## Show me the code!
- You can check the GitHub repository with all the materials of this workshop:
@@ -210,24 +190,6 @@ class: extra-details
---
class: extra-details
## Compose file format version
*This is relevant only if you have used Compose before 2016...*
- Compose 1.6 introduced support for a new Compose file format (aka "v2")
- Services are no longer at the top level, but under a `services` section
- There has to be a `version` key at the top level, with value `"2"` (as a string, not an integer)
- Containers are placed on a dedicated network, making links unnecessary
- There are other minor differences, but upgrade is easy and straightforward
---
## Our application at work
- On the left-hand side, the "rainbow strip" shows the container names
@@ -246,18 +208,6 @@ class: extra-details
- The `webui` container exposes a web dashboard; let's view it
.exercise[
- With a web browser, connect to `node1` on port 8000
- Remember: the `nodeX` aliases are valid only on the nodes themselves
- In your browser, you need to enter the IP address of your node
<!-- ```open http://node1:8000``` -->
]
A drawing area should show up, and after a few seconds, a blue
graph will appear.
@@ -283,74 +233,3 @@ work on a local environment, or when using Docker Desktop for Mac or Windows.
How to fix this?
Stop the app with `^C`, edit `dockercoins.yml`, comment out the `volumes` section, and try again.
---
class: extra-details
## Why does the speed seem irregular?
- It *looks like* the speed is approximately 4 hashes/second
- Or more precisely: 4 hashes/second, with regular dips down to zero
- Why?
--
class: extra-details
- The app actually has a constant, steady speed: 3.33 hashes/second
<br/>
(which corresponds to 1 hash every 0.3 seconds, for *reasons*)
- Yes, and?
---
class: extra-details
## The reason why this graph is *not awesome*
- The worker doesn't update the counter after every loop, but up to once per second
- The speed is computed by the browser, checking the counter about once per second
- Between two consecutive updates, the counter will increase either by 4, or by 0
- The perceived speed will therefore be 4 - 4 - 4 - 0 - 4 - 4 - 0 etc.
- What can we conclude from this?
--
class: extra-details
- "I'm clearly incapable of writing good frontend code!" 😀 — Jérôme
---
## Stopping the application
- If we interrupt Compose (with `^C`), it will politely ask the Docker Engine to stop the app
- The Docker Engine will send a `TERM` signal to the containers
- If the containers do not exit in a timely manner, the Engine sends a `KILL` signal
.exercise[
- Stop the application by hitting `^C`
<!--
```keys ^C```
-->
]
--
Some containers exit immediately, others take longer.
The containers that do not handle `SIGTERM` end up being killed after a 10s timeout. If we are very impatient, we can hit `^C` a second time!

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slides/shared/title.md
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@@ -11,11 +11,12 @@ class: title, in-person
@@TITLE@@<br/></br>
.footnote[
<!--
**Be kind to the WiFi!**<br/>
<!-- *Use the 5G network.* -->
*Don't use your hotspot.*<br/>
*Don't stream videos or download big files during the workshop[.](https://www.youtube.com/watch?v=h16zyxiwDLY)*<br/>
*Thank you!*
-->
**Slides: @@SLIDES@@**
]