// event-bus/index.js
app.post('/events', (req, res) => {
const event = req.body;
events.push(event);
axios.post('http://localhost:4000/events', event);
axios.post('http://localhost:4001/events', event);
axios.post('http://localhost:4002/events', event);
axios.post('http://localhost:4003/events', event);
axios.post('http://localhost:4006/events', event);
axios.post('http://localhost:4007/events', event);
res.send({ status: 'OK' });
});
// event-bus/index.js
app.post('/events', (req, res) => {
const event = req.body;
events.push(event);
axios.post('http://localhost:4000/events', event);
axios.post('http://localhost:4001/events', event);
axios.post('http://localhost:4002/events', event);
axios.post('http://localhost:4003/events', event);
if(it is not 1 am) {
axios.post('http://181.143.203.151/events', event);
axios.post('http://181.143.203.152/events', event);
}
res.send({ status: 'OK' });
});Issues
- Running our app right now makes big assumptions about our environment
- Running our app requires precise knowledge of how to start it (npm start)
Docker solves both these issues
- Containers wrap up everything that is needed for a program + how to start and run it
Kubernetes is a tool for running a bunch of different containers We give it some configuration to describe how we want our containers to run and interact with each other
Here is the format of the Dockerfile:
| INSTRUCTION | arguments | Comment |
|---|---|---|
| FROM | node:alpine | Specify base image |
| WORKDIR | /app | Set the working directory to '/app' in the container |
| COPY | package.json ./ | Copy over only the package.json file |
| RUN | npm install | Install all dependencies |
| COPY | ./ ./ | Copy over all of our remaining source code |
| CMD | ["npm", "start"] | Set the command to run when the container starts up |
| Docker Commands | Explanation |
|---|---|
| docker build -t chesterheng/posts . | Build an image based on the dockerfile in the current directory. Tag it as 'chesterheng/posts' |
| docker run [image id or image tag] | Create and start a container based on the provided image id or tag |
| docker run -it [image id or image tag] [cmd] | Create and start container, but also override the default command |
| docker ps | Print out information about all of the running containers |
| docker exec -it [container id] [cmd] | Execute the given command in a running container |
| docker logs [container id] | Print out logs from the given container |
cd section-03/blog/posts
docker build -t chesterheng/posts .
docker run chesterheng/posts
docker run -it chesterheng/posts sh
docker ps
docker exec -it a643fdbf134e sh
docker logs a643fdbf134ecd section-03/blog/event-bus
docker build -t chesterheng/event-bus .
docker run chesterheng/event-bus
docker run -it chesterheng/posts sh
docker ps
docker exec -it a643fdbf134e sh
docker logs a643fdbf134e