• Get application security done the right way! Detect, Protect, Monitor, Accelerate, and more…
  • Wondering what Docker Compose is?

    Docker is the most popular containerization tool in the DevOps world. But, What is Docker Compose?

    Docker Compose is used to run applications which have multiple containers using a YAML file.

    There can be several cases where the docker application must run multiple containers for different technology stack. Now building, running, connecting separate dockerfiles for each container can be a difficult task; this is where docker-compose helps you out.

    Using a single and straightforward docker-compose.yml file, you can build, connect, and launch all the containers by running a single command. This is very useful for enterprise applications in production, where several applications run inside containers. It saves a lot of time by running 100s of application inside docker containers with ease.

    Installing Docker Compose

    Docker should already be installed on your system before installing compose.

    Run the command below to install docker-compose.

    [email protected]:/home/geekflare$ sudo curl -L "https://github.com/docker/compose/releases/download/1.23.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
    
    [sudo] password for geekflare:
    
    % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
    
    Dload  Upload   Total   Spent    Left  Speed
    
    100   617    0   617    0     0   1209      0 --:--:-- --:--:-- --:--:--  1209
    
    100 11.1M  100 11.1M    0     0   348k      0  0:00:32  0:00:32 --:--:--  476k

    Run the command below to set file permissions.

    [email protected]:/home/geekflare$ sudo chmod +x /usr/local/bin/docker-compose

    Check if it got installed correctly, it should return the docker-compose version.

    [email protected]:/home/geekflare$ docker-compose --version
    
    docker-compose version 1.23.1, build b02f1306

    Below is the list of commands you can use with docker-compose.

    [email protected]:/home/geekflare$ docker-compose
    
    Define and run multi-container applications with Docker.
    
    Usage:
    
    docker-compose [-f <arg>…] [options] [COMMAND] [ARGS…]
    
    docker-compose -h|--help
    
    Options:
    
    -f, --file FILE             Specify an alternate compose file
    
    (default: docker-compose.yml)
    
    -p, --project-name NAME     Specify an alternate project name
    
    (default: directory name)
    
    --verbose                   Show more output
    
    --log-level LEVEL           Set log level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
    
    --no-ansi                   Do not print ANSI control characters
    
    -v, --version               Print version and exit
    
    -H, --host HOST             Daemon socket to connect to
    
    
    --tls                       Use TLS; implied by –tlsverify
    
    --tlscacert CA_PATH         Trust certs signed only by this CA
    
    --tlscert CLIENT_CERT_PATH  Path to TLS certificate file
    
    --tlskey TLS_KEY_PATH       Path to TLS key file
    
    --tlsverify                 Use TLS and verify the remote
    
    --skip-hostname-check       Don’t check the daemon’s hostname against the
    
    name specified in the client certificate
    
    --project-directory PATH    Specify an alternate working directory
    
    (default: the path of the Compose file)
    
    --compatibility             If set, Compose will attempt to convert deploy
    
    keys in v3 files to their non-Swarm equivalent
    
    Commands:
    
    build              Build or rebuild services
    
    bundle             Generate a Docker bundle from the Compose file
    
    config             Validate and view the Compose file
    
    create             Create services
    
    down               Stop and remove containers, networks, images, and volumes
    
    events             Receive real time events from containers
    
    exec               Execute a command in a running container
    
    help               Get help on a command
    
    images             List images
    
    kill               Kill containers
    
    logs               View output from containers
    
    pause              Pause services
    
    port               Print the public port for a port binding
    
    ps                 List containers
    
    pull               Pull service images
    
    push               Push service images
    
    restart            Restart services
    
    rm                 Remove stopped containers
    
    run                Run a one-off command
    
    scale              Set number of containers for a service
    
    start              Start services
    
    stop               Stop services
    
    top                Display the running processes
    
    unpause            Unpause services
    
    up                 Create and start containers
    
    version            Show the Docker-Compose version information

    Docker Compose File

    Here is a sample docker-compose file which does all the magic.

    version: '3'
    
    services:
    
    web:
    
    build: .
    
    ports:
    
    - "5000:5000"
    
    redis:
    
    image: "redis:alpine"

    The first line in this file specifies the version being used. This number depends on the Docker engine installed on your system. I have Docker 18.09.6 installed which belongs to version 3 of docker-compose. Check out more details on versions here – https://docs.docker.com/compose/compose-file/compose-versioning/

    This docker file is running two services/applications, web and Redis. The web service is built through a dockerfile and runs at default flask webserver port – 5000. The Redis service runs by pulling the Redis image from docker hub registry.

    To execute the docker-compose.yml file, you need to run a very simple command: docker-compose up

    Docker Compose Workflow

    Below are the three steps to use docker-compose.

    1. Create dockerfile of each service
    2. Create a docker-compose.yml file to connect all the dockerfiles
    3. Run docker-compose up command to start the system

    Let me take an example of the sample docker-compose file we saw earlier and show you how the project structure will be created.

    my-app
    
    |-----web
    
    |---------Dockerfile
    
    |-----redis
    
    |docker-compose.yml

    my-app is my main project directory. This directory has web and Redis service directories and the docker-compose YAML file. Dockerfile of Web service is present in a web directory. Since Redis service is being pulled from docker hub directly, no dockerfile is required in Redis directory. This is how docker-compose workflow looks like.

    Containerizing A MEAN Stack Application using Docker Compose

    Now that you have understood fundamental concepts. Let me show a demo on how to containerize a MEAN stack application using docker-compose.

    MEAN stands for MongoDB, Express, Angular and Node.js. Applications using these services together is also called a MEAN/Full-stack application.

    For this demo, we will run three docker containers:

    • Container 1 – Angular
    • Container 2 – NodeJS and ExpressJS
    • Container 3 – MongoDB

    Download the complete application here: http://bit.ly/2St7r3A (not tested for production)

    This is how my docker-compose.yml file will look like to run these three containers:

    version: '3'
    
    services:
    
    angular:
    
    build: angular-client
    
    ports:
    
    - "4200:4200"
    
    volumes:
    
    - ./angular-client/:/var/www/app
    
    express:
    
    build: express-server
    
    ports:
    
    - "3000:3000"
    
    volumes:
    
    - ./express-server/:/var/www/app
    
    links:
    
    - database
    
    database:
    
    image: mongo
    
    ports:
    
    - "27017:27017"
    • The first line specifies the docker-compose version being used
    • We are running three services – angular, express and database
    • Angular service will be built using a dockerfile. It will run on port 4200, and the application volume is /var/www/app
    • Express service will be built using a dockerfile. The express server will run at port 3000, and the volume is /var/www/app
    • Database service will pull MongoDB image from dockerhub and start it at post 27017

    Extract the project in the home directory and go to the angular-client directory.

    [email protected]:~$ cd mean
    
    [email protected]:~/mean$ cd angular-client 

    Run the command below if you don’t have node package manager (npm) installed on your system (ignore if it’s installed).

    [email protected]:~/mean/angular-client$ sudo apt install npm
    
    [sudo] password for geekflare:
    
    Reading package lists... Done
    
    Building dependency tree
    
    Reading state information... Done
    
    The following additional packages will be installed:
    
    gyp javascript-common libc-ares2 libhttp-parser2.8 libjs-async libjs-inherits libjs-is-typedarray
    
    libjs-jquery libjs-node-uuid libjs-underscore libssl1.0-dev libuv1 libuv1-dev node-abbrev node-ajv
    
    node-ansi node-ansi-color-table node-ansi-regex node-ansi-styles node-ansistyles node-aproba node-archy
    
    node-are-we-there-yet node-async node-aws-sign2 node-balanced-match node-block-stream node-bluebird
    
    node-boom node-brace-expansion node-builtin-modules node-camelcase node-caseless node-chalk node-cliui
    
    node-clone node-co node-color-convert node-color-name node-combined-stream node-concat-map
    
    node-config-chain node-console-control-strings node-cookie-jar node-copy-concurrently node-core-util-is
    
    node-yallist node-yargs node-yargs-parser nodejs nodejs-dev nodejs-doc
    
    Suggested packages:
    
    apache2 | lighttpd | httpd node-aws-sign node-oauth-sign node-http-signature debhelper
    
    The following NEW packages will be installed:
    
    gyp javascript-common libc-ares2 libhttp-parser2.8 libjs-async libjs-inherits libjs-is-typedarray
    
    libjs-jquery libjs-node-uuid libjs-underscore libssl1.0-dev libuv1 libuv1-dev node-abbrev node-ajv
    
    node-ansi node-ansi-color-table node-ansi-regex node-ansi-styles node-ansistyles node-aproba node-archy
    
    node-are-we-there-yet node-async node-aws-sign2 node-balanced-match node-block-stream node-bluebird
    
    0 upgraded, 212 newly installed, 0 to remove and 233 not upgraded.
    
    Need to get 10.5 MB of archives.
    
    After this operation, 53.6 MB of additional disk space will be used.
    
    Do you want to continue? [Y/n] Y
    
    Get:1 http://us.archive.ubuntu.com/ubuntu cosmic/universe amd64 gyp all 0.1+20180428git4d467626-1 [237 kB]
    
    Get:2 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 javascript-common all 11 [6,066 B]
    
    Get:3 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 libhttp-parser2.8 amd64 2.8.1-1 [20.8 kB]
    
    Get:4 http://us.archive.ubuntu.com/ubuntu cosmic/universe amd64 libjs-async all 0.8.0-3 [25.4 kB]
    
    Get:5 http://us.archive.ubuntu.com/ubuntu cosmic/universe amd64 libjs-is-typedarray all 1.0.0-2 [2,934 B]
    
    Get:6 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 libjs-jquery all 3.2.1-1 [152 kB]
    
    Get:7 http://us.archive.ubuntu.com/ubuntu cosmic/universe amd64 libjs-node-uuid all 1.4.7-5 [11.5 kB]
    
    Get:8 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 libjs-underscore all 1.8.3~dfsg-1 [59.9 kB]
    
    Get:9 http://us.archive.ubuntu.com/ubuntu cosmic-updates/main amd64 libssl1.0-dev amd64 1.0.2n-1ubuntu6.2 [1,366 kB]
    
    Fetched 10.5 MB in 1min 34s (112 kB/s)
    
    Extracting templates from packages: 100%
    
    Selecting previously unselected package gyp.
    
    (Reading database ... 180130 files and directories currently installed.)
    
    Preparing to unpack .../000-gyp_0.1+20180428git4d467626-1_all.deb ...
    
    Unpacking gyp (0.1+20180428git4d467626-1) ...
    
    Selecting previously unselected package javascript-common.
    
    Preparing to unpack .../001-javascript-common_11_all.deb ...
    
    Unpacking javascript-common (11) ...
    
    Selecting previously unselected package libhttp-parser2.8:amd64.
    
    Preparing to unpack .../002-libhttp-parser2.8_2.8.1-1_amd64.deb ...
    
    Setting up node-fstream-ignore (0.0.6-2) ...
    
    Setting up node-gyp (3.6.2-2) ...
    
    Setting up node-yargs (10.0.3-2) ...
    
    Setting up npm (5.8.0+ds-2) ...
    
    Processing triggers for libc-bin (2.28-0ubuntu1) ...
    

    In angular-client directory and run npm install.

    [email protected]:~/mean/angular-client$ npm install
    
    > [email protected] install /home/geekflare/mean/angular-client/node_modules/uws
    
    > node-gyp rebuild > build_log.txt 2>&1 || exit 0
    
    > [email protected] install /home/geekflare/mean/angular-client/node_modules/node-sass
    
    > node scripts/install.js
    
    Downloading binary from https://github.com/sass/node-sass/releases/download/v4.7.2/linux-x64-57_binding.node
    
    Download complete  ] - :
    
    Binary saved to /home/geekflare/mean/angular-client/node_modules/node-sass/vendor/linux-x64-57/binding.node
    
    Caching binary to /home/geekflare/.npm/node-sass/4.7.2/linux-x64-57_binding.node
    
    > [email protected] postinstall /home/geekflare/mean/angular-client/node_modules/webpack/node_modules/uglifyjs-webpack-plugin
    
    > node lib/post_install.js
    
    > [email protected] postinstall /home/geekflare/mean/angular-client/node_modules/node-sass
    
    > node scripts/build.js
    
    Binary found at /home/geekflare/mean/angular-client/node_modules/node-sass/vendor/linux-x64-57/binding.node
    
    Testing binary
    
    Binary is fine
    
    added 1457 packages from 1250 contributors in 80.009s

    Now go to express directory and run npm install.

    [email protected]:~/mean/angular-client$ cd ..
    
    [email protected]:~/mean$ cd express-server/
    
    [email protected]:~/mean/express-server$ npm install

    Now that everything is set, its time to run docker-compose.yml file which is going to launch all the docker containers and run the MEAN stack application.

    [email protected]:~/mean/express-server$ cd ..
    
    [email protected]:~/mean$ docker-compose up
    
    Creating network "mean_default" with the default driver
    
    Building angular
    
    Step 1/8 : FROM node:8
    
    8: Pulling from library/node
    
    a4d8138d0f6b: Pull complete
    
    dbdc36973392: Pull complete
    
    f59d6d019dd5: Pull complete
    
    aaef3e026258: Pull complete
    
    6e454d3b6c28: Pull complete
    
    c717a7c205aa: Pull complete
    
    37add8e5ac11: Pull complete
    
    0314ab675d31: Pull complete
    
    012886364728: Pull complete
    
    Digest: sha256:310db2abcff097ef44af205d81833282a6d5471002a1b59d7b7459a74152c856
    
    Status: Downloaded newer image for node:8
    
    ---> 8e45c884a32e
    
    Step 2/8 : RUN mkdir -p /var/www/app
    
    ---> Running in c70a0cab7994
    
    Removing intermediate container c70a0cab7994
    
    ---> 001c5e840b24
    
    Step 3/8 : WORKDIR /var/www/app
    
    ---> Running in 622ebdc41b2f
    
    Removing intermediate container 622ebdc41b2f
    
    ---> baa2e2347259
    
    Step 4/8 : COPY package.json /var/www/app
    
    ---> 5b97543befab
    
    Step 5/8 : RUN npm install
    
    ---> Running in 73e3d8b7a701
    
    > [email protected] install /var/www/app/node_modules/uws
    
    > node-gyp rebuild > build_log.txt 2>&1 || exit 0
    
    > [email protected] install /var/www/app/node_modules/node-sass
    
    > node scripts/install.js
    
    Downloading binary from https://github.com/sass/node-sass/releases/download/v4.12.0/linux-x64-57_binding.node
    
    Download complete
    
    Binary saved to /var/www/app/node_modules/node-sass/vendor/linux-x64-57/binding.node
    
    Caching binary to /root/.npm/node-sass/4.12.0/linux-x64-57_binding.node
    
    > [email protected] postinstall /var/www/app/node_modules/core-js
    
    > node scripts/postinstall || echo "ignore"
    
    The project needs your help! Please consider supporting of core-js on Open Collective or Patreon:
    
    > https://opencollective.com/core-js
    
    > https://www.patreon.com/zloirock
    
    > [email protected] postinstall /var/www/app/node_modules/webpack/node_modules/uglifyjs-webpack-plugin
    
    > node lib/post_install.js
    
    > [email protected] postinstall /var/www/app/node_modules/node-sass
    
    > node scripts/build.js
    
    Binary found at /var/www/app/node_modules/node-sass/vendor/linux-x64-57/binding.node
    
    Testing binary
    
    Binary is fine
    
    added 1606 packages from 1329 contributors and audited 15092 packages in 112.427s
    
    Removing intermediate container 73e3d8b7a701
    
    ---> 55790d2fae93
    
    Step 6/8 : COPY . /var/www/app
    
    ---> 61537aa487f4
    
    Step 7/8 : EXPOSE 4200
    
    ---> Running in 632eedc35a45
    
    Removing intermediate container 632eedc35a45
    
    ---> 51e75b0e2ebe
    
    Step 8/8 : CMD ["npm", "start"]
    
    ---> Running in 36bbb12a0d38
    
    Removing intermediate container 36bbb12a0d38
    
    ---> 9f8d61db600c
    
    Successfully built 9f8d61db600c
    
    Successfully tagged mean_angular:latest
    
    Pulling database (mongo:)...
    
    latest: Pulling from library/mongo
    
    35b42117c431: Pull complete
    
    ad9c569a8d98: Pull complete
    
    293b44f45162: Pull complete
    
    0c175077525d: Pull complete
    
    4e73525b52ba: Pull complete
    
    a22695a3f5e9: Pull complete
    
    c5175bcf2977: Pull complete
    
    3e320da07793: Pull complete
    
    01c6db6b2b5a: Pull complete
    
    3bd6e9d03e78: Pull complete
    
    e03dcf51513f: Pull complete
    
    c1956a9e136a: Pull complete
    
    4c35cf22b1d5: Pull complete
    
    Building express
    
    Step 1/9 : FROM node:8
    
    ---> 8e45c884a32e
    
    Step 2/9 : RUN mkdir -p /var/www/app
    
    ---> Using cache
    
    ---> 001c5e840b24
    
    Step 3/9 : WORKDIR /var/www/app
    
    ---> Using cache
    
    ---> baa2e2347259
    
    Step 4/9 : COPY package.json /var/www/app
    
    ---> 0232ad53c679
    
    Step 5/9 : RUN npm install
    
    ---> Running in c309bf6f218e
    
    added 128 packages from 151 contributors and audited 233 packages in 9.055s
    
    Removing intermediate container c309bf6f218e
    
    ---> 49e652884562
    
    Step 6/9 : RUN npm install -g nodemon
    
    ---> Running in 0ed5d7f3642b
    
    /usr/local/bin/nodemon -> /usr/local/lib/node_modules/nodemon/bin/nodemon.js
    
    > [email protected] postinstall /usr/local/lib/node_modules/nodemon
    
    > node bin/postinstall || exit 0
    
    Love nodemon? You can now support the project via the open collective:
    
    > https://opencollective.com/nodemon/donate
    
    + [email protected]
    
    added 221 packages from 128 contributors in 18.856s
    
    Removing intermediate container 0ed5d7f3642b
    
    ---> 32c55606f35e
    
    Step 7/9 : COPY . /var/www/app
    
    ---> a618b38a2812
    
    Step 8/9 : EXPOSE 3000
    
    ---> Running in bea389ab3ef1
    
    Removing intermediate container bea389ab3ef1
    
    ---> 684bbfb31371
    
    Step 9/9 : CMD ["npm", "start"]
    
    ---> Running in 9aa1b72e4a4e
    
    Removing intermediate container 9aa1b72e4a4e
    
    ---> 35dcb3df9806
    
    Successfully built 35dcb3df9806
    
    Successfully tagged mean_express:latest
    
    Creating mean_angular_1_de44b3f5b988  ... done
    
    Creating mean_database_1_708f8f9c3c33 ... done
    
    Creating mean_express_1_b57a483a72ee  ... done
    
    Attaching to mean_angular_1_f257e2233ef1, mean_database_1_ccc5c677e00b, mean_express_1_574f07b045fc
    
    angular_1_f257e2233ef1 |
    
    angular_1_f257e2233ef1 | > [email protected] start /var/www/app
    
    angular_1_f257e2233ef1 | > ng serve -H 0.0.0.0
    
    angular_1_f257e2233ef1 |
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.933+0000 I CONTROL  [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] MongoDB starting : pid=1 port=27017 dbpath=/data/db 64-bit host=f74b56905249
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] db version v4.0.10
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] git version: c389e7f69f637f7a1ac3cc9fae843b635f20b766
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] OpenSSL version: OpenSSL 1.0.2g  1 Mar 2016
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] allocator: tcmalloc
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] modules: none
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] build environment:
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten]     distmod: ubuntu1604
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten]     distarch: x86_64
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten]     target_arch: x86_64
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:25.937+0000 I CONTROL  [initandlisten] options: { net: { bindIpAll: true } }
    
    express_1_574f07b045fc |
    
    express_1_574f07b045fc | > [email protected] start /var/www/app
    
    express_1_574f07b045fc | > nodemon ./bin/www
    
    express_1_574f07b045fc |
    
    express_1_574f07b045fc | [nodemon] 1.19.1
    
    express_1_574f07b045fc | [nodemon] to restart at any time, enter `rs`
    
    express_1_574f07b045fc | [nodemon] watching: *.*
    
    express_1_574f07b045fc | [nodemon] starting `node ./bin/www`
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:33.543+0000 I NETWORK  [listener] connection accepted from 172.19.0.4:38958 #1 (1 connection now open)
    
    database_1_ccc5c677e00b | 2019-07-20T22:33:33.560+0000 I NETWORK  [conn1] received client metadata from 172.19.0.4:38958 conn1: { driver: { name: "nodejs", version: "3.0.1" }, os: { type: "Linux", name: "linux", architecture: "x64", version: "4.18.0-25-generic" }, platform: "Node.js v8.16.0, LE, mongodb-core: 3.0.1" }
    
    express_1_574f07b045fc | mongodb: connected
    
    angular_1_f257e2233ef1 | ** NG Live Development Server is listening on 0.0.0.0:4200, open your browser on http://localhost:4200/ **
    
    angular_1_f257e2233ef1 | Date: 2019-07-21T11:21:03.868Z - Hash: 639d9a968476ed482b5c - Time: 336ms
    
    angular_1_f257e2233ef1 | 4 unchanged chunks
    
    angular_1_f257e2233ef1 | chunk {main} main.bundle.js (main) 19.8 kB [initial] [rendered]
    
    angular_1_f257e2233ef1 |
    
    angular_1_f257e2233ef1 | webpack: Compiled successfully.
    
    angular_1_f257e2233ef1 | webpack: Compiling...
    
    angular_1_f257e2233ef1 | Date: 2019-07-21T11:25:15.661Z - Hash: e5a2b1c1afe0deb396c3 - Time: 251ms
    
    angular_1_f257e2233ef1 | 4 unchanged chunks
    
    angular_1_f257e2233ef1 | chunk {main} main.bundle.js (main) 19.8 kB [initial] [rendered]
    
    angular_1_f257e2233ef1 |
    
    angular_1_f257e2233ef1 | webpack: Compiled successfully.

    Go to your browser and check https://localhost:4200, your application will be up and running.

    angular - docker compose

    Go to https://localhost:3000 to check if an express server is running.

    express - docker compose

    Also, you can run docker images command to see which all images are present in docker.

    [email protected]:~/mean$ docker images
    
    REPOSITORY                 TAG                 IMAGE ID            CREATED             SIZE
    
    mean_express               latest              35dcb3df9806        14 hours ago        923MB
    
    mean_angular               latest              9f8d61db600c        14 hours ago        1.29GB
    
    node                       8                   8e45c884a32e        9 days ago          895MB
    
    mongo                      latest              785c65f61380        2 weeks ago         412MB

    Run the command below to see the containers running inside docker.

    [email protected]:~/mean$ docker ps
    
    CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                      NAMES
    
    681c9c34bee2        mean_express        "docker-entrypoint.s…"   14 hours ago        Up 14 hours         0.0.0.0:3000->3000/tcp     mean_express_1_574f07b045fc
    
    f74b56905249        mongo               "docker-entrypoint.s…"   14 hours ago        Up 14 hours         0.0.0.0:27017->27017/tcp   mean_database_1_ccc5c677e00b
    
    260ef1e52dab        mean_angular        "docker-entrypoint.s…"   14 hours ago        Up 14 hours         0.0.0.0:4200->4200/tcp     mean_angular_1_f257e2233ef1

    So now, all three docker containers are up and running.

    Docker-compose took care of running all the containers with ease. This was a simple example for running three containers; you can imagine how useful it will be if the applications have to be launched on 100s of containers. Go ahead and try out to see how it works.