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chat server

Build and tag a chat server image

For a Dockerfile.

docker build -t chat-carbon:1.0.0 -f Dockerfile.carbon .

Check out the sizes of the images:

$ docker image ls
REPOSITORY                                 TAG                 IMAGE ID            CREATED             SIZE
chat-carbon                                1.0.0               15ffeec7f290        25 seconds ago      103MB

Check out the layers that comprise the chat image

$docker image history chat-carbon:1.0.0
IMAGE               CREATED              CREATED BY                                      SIZE                COMMENT
15ffeec7f290        About a minute ago   /bin/sh -c #(nop)  CMD ["npm" "start"]          0B
a5a2dc2602bb        8 minutes ago        /bin/sh -c #(nop)  EXPOSE 3000                  0B
a6307759f027        8 minutes ago        /bin/sh -c npm install --only=production        1.75MB
0f837712eb0b        8 minutes ago        /bin/sh -c #(nop) WORKDIR /app/examples/chat    0B
0de5b82476a5        8 minutes ago        /bin/sh -c npm install --only=production        11.2MB
83054dfe3056        8 minutes ago        /bin/sh -c #(nop) COPY dir:807cf83cd7b73b428…   24.1MB
adb54f08a144        8 minutes ago        /bin/sh -c #(nop) WORKDIR /app                  0B
df48b68da02a        4 weeks ago          /bin/sh -c #(nop)  CMD ["node"]                 0B
<missing>           4 weeks ago          /bin/sh -c apk add --no-cache --virtual .bui…   4.53MB
<missing>           4 weeks ago          /bin/sh -c #(nop)  ENV YARN_VERSION=1.9.4       0B
<missing>           4 weeks ago          /bin/sh -c addgroup -g 1000 node     && addu…   56.7MB
<missing>           4 weeks ago          /bin/sh -c #(nop)  ENV NODE_VERSION=8.12.0      0B
<missing>           4 weeks ago          /bin/sh -c #(nop)  CMD ["/bin/sh"]              0B
<missing>           4 weeks ago          /bin/sh -c #(nop) ADD file:25c10b1d1b41d46a1…   4.41MB


## Run the chat server

docker run -p 3000:30000 chat-carbon:latest

socket.io-chat@0.0.0 start /app/examples/chat node index.js

Server listening at port 3000


Check the docker process 

```shell
$ docker container ls
CONTAINER ID        IMAGE                COMMAND             CREATED             STATUS              PORTS                               NAMES
9c53ce46b96d        chat-carbon:latest   "npm start"         3 seconds ago       Up 2 seconds        3000/tcp, 0.0.0.0:3000->30000/tcp   inspiring_noyce

Check the file size, please note the virtual below shows the image size.

$ docker ps -s
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES                                                                                  SIZE
8b6fffdbf470        05b2c3d28d84        "npm start"         18 hours ago        Up 18 hours                             k8s_chat-carbon_chat-8595bc48c5-k6rpr_default_184b122a-c062-11e8-8ad8-025000000001_0   55B (virtual 103MB)

Let's chat

Go to http://localhost:3000/ in any browser

JSON syntax vs string syntax

Let's check what if the image is built with the following string format in the Dockerfile instead of JSON format.

CMD npm start

Then build an image from it.

$docker build -t chat-carbon-shell:1.0.0 -f Dockerfile.carbon-shell .
$docker image history chat-carbon-shell:1.0.0
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
23694b6e5ff0        16 seconds ago      /bin/sh -c #(nop)  CMD ["/bin/sh" "-c" "npm …   0B
b9db19aa63f6        20 seconds ago      /bin/sh -c #(nop)  EXPOSE 3000                  0B
10783d7541b3        20 seconds ago      /bin/sh -c npm install --only=${env}            1.75MB
1fa71ed207f0        24 seconds ago      /bin/sh -c #(nop) WORKDIR /app/examples/chat    0B
236cc7bec467        25 seconds ago      /bin/sh -c npm install --only=${env}            11.2MB
d8c0df423136        38 seconds ago      /bin/sh -c #(nop)  ENV env=production           0B
83054dfe3056        17 minutes ago      /bin/sh -c #(nop) COPY dir:807cf83cd7b73b428…   24.1MB
adb54f08a144        17 minutes ago      /bin/sh -c #(nop) WORKDIR /app                  0B
df48b68da02a        4 weeks ago         /bin/sh -c #(nop)  CMD ["node"]                 0B
<missing>           4 weeks ago         /bin/sh -c apk add --no-cache --virtual .bui…   4.53MB
<missing>           4 weeks ago         /bin/sh -c #(nop)  ENV YARN_VERSION=1.9.4       0B
<missing>           4 weeks ago         /bin/sh -c addgroup -g 1000 node     && addu…   56.7MB
<missing>           4 weeks ago         /bin/sh -c #(nop)  ENV NODE_VERSION=8.12.0      0B
<missing>           4 weeks ago         /bin/sh -c #(nop)  CMD ["/bin/sh"]              0B
<missing>           4 weeks ago         /bin/sh -c #(nop) ADD file:25c10b1d1b41d46a1…   4.41MB

Please note the CMD npm start (String format) is used instead of CMD [ "npm", "start" ] (JSON format). There is an extra process /bin/sh invoked in string format and we can pass interpolates environment variables as a benefit.

Exercise

Please build, tag and run a new image based on Dockerfile.heavy, comparing the size with the carbon image.

Further readings on Dockerfile