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Rework presentation of DockerCoins

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The last 5(ish) times I presented DockerCoins, I ended up
explaining it slightly differently. While the application
is building, I explain what it does and its architecture
(instead of watching the build and pointing out, 'oh look
there is ruby... and python...') and I found that it
worked better. It may also be better for shorter
workshops, because we can deliver useful information
while the app is building (instead of filling with
a tapdancing show).

@bretfisher and @bridgetkromhout, do you like the new
flow for that section? If not, I can figure something
out so that we each have our own section here, but I
hope you will actually like this one better. :)
This commit is contained in:
Jerome Petazzoni
2018-11-17 12:03:01 -06:00
committed by Jérôme Petazzoni
parent 5fad84a7cf
commit fe93dccbac
1 changed files with 86 additions and 40 deletions
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126
slides/shared/sampleapp.md
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@@ -54,49 +54,84 @@ and displays aggregated logs.
---
## More detail on our sample application
## What's this application?
- Visit the GitHub repository with all the materials of this workshop:
<br/>https://@@GITREPO@@
--
- The application is in the [dockercoins](
https://@@GITREPO@@/tree/master/dockercoins)
subdirectory
- It is a DockerCoin miner! .emoji[💰🐳📦🚢]
- Let's look at the general layout of the source code:
--
there is a Compose file [docker-compose.yml](
https://@@GITREPO@@/blob/master/dockercoins/docker-compose.yml) ...
- No, you can't buy coffee with DockerCoins
... and 4 other services, each in its own directory:
--
- `rng` = web service generating random bytes
- `hasher` = web service computing hash of POSTed data
- `worker` = background process using `rng` and `hasher`
- `webui` = web interface to watch progress
- How DockerCoins works:
- generate a few random bytes
- hash these bytes
- increment a counter (to keep track of speed)
- repeat forever!
--
- DockerCoins is *not* a cryptocurrency
(the only common points are "randomness", "hashing", and "coins" in the name)
---
class: extra-details
## DockerCoins in the microservices era
## Compose file format version
- DockerCoins is made of 5 services:
*Particularly relevant if you have used Compose before...*
- `rng` = web service generating random bytes
- Compose 1.6 introduced support for a new Compose file format (aka "v2")
- `hasher` = web service computing hash of POSTed data
- Services are no longer at the top level, but under a `services` section
- `worker` = background process calling `rng` and `hasher`
- There has to be a `version` key at the top level, with value `"2"` (as a string, not an integer)
- `webui` = web interface to watch progress
- Containers are placed on a dedicated network, making links unnecessary
- `redis` = data store (holds a counter updated by `worker`)
- There are other minor differences, but upgrade is easy and straightforward
- These 5 services are visible in the application's Compose file,
[docker-compose.yml](
https://@@GITREPO@@/blob/master/dockercoins/docker-compose.yml)
---
## How DockerCoins works
- `worker` invokes web service `rng` to generate random bytes
- `worker` invokes web servie `hasher` to hash these bytes
- `worker` does this in an infinite loop
- every second, `worker` updates `redis` to indicate how many loops were done
- `webui` queries `redis`, and computes and exposes "hashing speed" in our browser
*(See diagram on next slide!)*
---
class: pic
![Diagram showing the 5 containers of the applications](images/dockercoins-diagram.svg)
---
## Service discovery in container-land
How does each service find out the address of the other ones?
--
- We do not hard-code IP addresses in the code
- We do not hard-code FQDN in the code, either
@@ -150,35 +185,46 @@ class: extra-details
---
## What's this application?
## Show me the code!
--
- You can check the GitHub repository with all the materials of this workshop:
<br/>https://@@GITREPO@@
- It is a DockerCoin miner! .emoji[💰🐳📦🚢]
- The application is in the [dockercoins](
https://@@GITREPO@@/tree/master/dockercoins)
subdirectory
--
- The Compose file ([docker-compose.yml](
https://@@GITREPO@@/blob/master/dockercoins/docker-compose.yml))
lists all 5 services
- No, you can't buy coffee with DockerCoins
- `redis` is using an official image from the Docker Hub
--
- `hasher`, `rng`, `worker`, `webui` are each built from a Dockerfile
- How DockerCoins works:
- Each service's Dockerfile and source code is in its own directory
- `worker` asks to `rng` to generate a few random bytes
- `worker` feeds these bytes into `hasher`
- and repeat forever!
- every second, `worker` updates `redis` to indicate how many loops were done
- `webui` queries `redis`, and computes and exposes "hashing speed" in your browser
(`hasher` is in the [hasher](https://@@GITREPO@@/blob/master/dockercoins/hasher/) directory,
`rng` is in the [rng](https://@@GITREPO@@/blob/master/dockercoins/rng/)
directory, etc.)
---
class: pic
class: extra-details
![Diagram showing the 5 containers of the applications](images/dockercoins-diagram.svg)
## 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
---