Step 2: Modifying a Docker Image
Table of Contents
Objective: Modify a docker to include updated packages.
One problem with projects on GitHub is that they get stale. A developer built the project for their current need but then didn’t maintain it.
Tip
We should modify Docker projects with up-to-date packages.
4.2.1 Updating old Code
The version of Node in the pandoc-as-a-service Dockerfile has a long list of published security vulnerabilities. We will replace Node 6.10 with the latest version of Node (v 15.2) in DockerHub.
Edit the pandoc-as-a-service
Dockerfileand replace the version of Node.FROM node:latest # Create app directory COPY . /usr/src/pandoc-as-a-service WORKDIR /usr/src/pandoc-as-a-service . . .
Let’s try to rebuild. It will fail because we need to make additional changes, but we’ll do them one at a time.
We will give our updated version a new tag (
latest).docker build -t pandoc:latest .
npm auditfound a problem!17 vulnerabilities (3 low, 2 high, 2 critical) 2 3To address all issues (including breaking changes), run: 4 npm audit fix --force
The fix is simple. We need to append
npm audit fix --forceto theRUNcommand.# Install packages RUN apt-get update --fix-missing \ && apt-get install -y pandoc \ && apt-get clean \ && rm -rf /var/lib/apt/lists/* \ && npm install \ && npm audit fix --force
Save the file and then rerun the same build command to fix the issues.
7 vulnerabilities (3 low, 2 high, 2 critical) To address all issues (including breaking changes), run: npm audit fix --force Run `npm audit` for details. npm notice npm notice New patch version of npm available! 7.0.8 -> 7.0.10 npm notice Changelog: <https://github.com/npm/cli/releases/tag/v7.0.10> npm notice Run `npm install -g npm@7.0.10` to update! npm notice npm WARN using --force Recommended protections disabled. npm WARN audit Updating mocha to 8.2.1,which is a SemVer major change. added 90 packages, removed 9 packages, changed 9 packages, and audited 194 packages in 4s 15 packages are looking for funding run `npm fund` for details found 0 vulnerabilities Removing intermediate container 6c3ea353ed6f
We can also update the HTML by modifying
views/index.ejs. For example, we updated the URLs in the code on our pandoc.bilimedtech.com site.
4.2.2. Cleanup Failed Builds
Docker will tag an image as <none> anytime the build fails.
root@vps298933:~/pandoc-as-a-service# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
pandoc latest 79ad25bc9c62 11 seconds ago 1.03GB
<none> <none> 5847e41654f3 14 minutes ago 1.03GB
<none> <none> deec2993cbc8 22 minutes ago 1.02GB
pandoc default 7eb0798f4080 6 hours ago 720MB
node latest f1974cfde44f 36 hours ago 935MB
mariadb latest 2ab9d091310d 39 hours ago 414MB
nextcloud latest 3ed6ea445002 7 days ago 811MB
wordpress latest 6edecd0f5c75 7 days ago 546MB
redis latest 62f1d3402b78 2 weeks ago 104MB
node 6.10 3f3928767182 3 years ago 661MB
Tip
Remove the unused images using the command: docker rmi IMAGE_ID
For example, we can remove the two images above using:
docker rmi 5847e41654f3 docker rmi deec2993cbc8Outputroot@vps298933:~/pandoc-as-a-service# docker rmi 5847e41654f3 Deleted: sha256:5847e41654f3cf0a46c27e945e405b3489d1d18a9c879b8a5efbfac5d9ec9067 Deleted: sha256:d0fb7d96057e7a465b59ed72d085f0eead2b8a4dda69700098a1ad26c78b50da Deleted: sha256:f9c88be69a1f5c321eac2630990f13bfc3a86aa06f7a8e4d16c276e73ba397f7 Deleted: sha256:1d64eef5852b108a449afbac6c6c052f1d18737ee4d682beb3cd2e3dcb0347d5 Deleted: sha256:ef049b742654a3f283b81b6316c3bff4e64c9ab8393fed77cda150f31679b1ae Deleted: sha256:3ad253af23d8e51634b39eea4f7616e7b035ba3e3f04c1dbc5e1bd0b8897adf3 Deleted: sha256:bdc818d89e59373738c425951cb5d392a34284530539b9584ab358a9df239748 root@vps298933:~/pandoc-as-a-service# root@vps298933:~/pandoc-as-a-service# docker rmi deec2993cbc8 Deleted: sha256:deec2993cbc88b7002e3bd9ece516b0694e93961cb0cfe7668a1bd1f8738ece0 Deleted: sha256:922ce00047ef1ab341768c4ad1a2a1991d4c7b0d4825b0014126a363a53d88a2 Deleted: sha256:674e57717b3b0ff7d0bc05ec8ffa81d7354266139e7272ff12343ce211ba84eb Deleted: sha256:3afad23927db55d4cf44f576df7682f19c85d93959d4c939cd2bf81003a08f8b Deleted: sha256:9ff091f132f82f82843fa1f75954077ad9276f10845df88843ed464a29a0fe11 Deleted: sha256:4c464b8d162e93c6391a11b7d48e0531c3a489571817522202715d871a486a49 Deleted: sha256:b6831928fccd0c0c6b961024846544dec21fcf540dea22a41006903fae01f0c4 Deleted: sha256:dc62fb20fb9ead1ab565487b3c44ec6fb970a124272070c8726643d292373b6c Deleted: sha256:5bbec8dd291ea1213ac73bd5079000a2c89deaa10aedd070ea12fb090160b589 Deleted: sha256:4242bfc2cb701c295cf7fdcc72011e5fde65530610f0d5cd2b3549cffb1da2f8 root@vps298933:~/pandoc-as-a-service# root@vps298933:~/pandoc-as-a-service# docker images REPOSITORY TAG IMAGE ID CREATED SIZE pandoc latest 79ad25bc9c62 6 minutes ago 1.03GB pandoc default 7eb0798f4080 6 hours ago 720MB node latest f1974cfde44f 36 hours ago 935MB mariadb latest 2ab9d091310d 40 hours ago 414MB nextcloud latest 3ed6ea445002 7 days ago 811MB wordpress latest 6edecd0f5c75 7 days ago 546MB redis latest 62f1d3402b78 2 weeks ago 104MB node 6.10 3f3928767182 3 years ago 661MB root@vps298933:~/pandoc-as-a-service#
4.2.3 Relaunch with the updated Images
The final step is to update the docker-compose.yml file with
the new tag. Also, let’s add a volume for the source code so that
we can change it without rebuilding the image.
Change to the project directory, update the image name, and then restart
cd ~/pandoc-docker nano docker-compose.yml docker-compose down && docker-compose up -d
docker-compose.ymlversion: "3.3" services: pandoc: image: pandoc:latest ports: - 20852:8080 restart: always
Verify that the new image is in use.
root@vps298933:~/pandoc-docker# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9aaf93a4aa5b pandoc:latest "docker-entrypoint.s…" 38 seconds ago Up 35 seconds 0.0.0.0:20852->8080/tcp pandocdocker_pandoc_1 1a13f235f757 nextcloud "/entrypoint.sh apac…" 10 hours ago Up 10 hours 0.0.0.0:20850->80/tcp nextclouddocker_app_1 74b008e6fc1a redis:latest "docker-entrypoint.s…" 10 hours ago Up 10 hours 6379/tcp nextclouddocker_redis_1 de86f8cd7ca1 mariadb:latest "docker-entrypoint.s…" 10 hours ago Up 10 hours 3306/tcp nextclouddocker_db_1 cd832a14a92c wordpress:latest "docker-entrypoint.s…" 23 hours ago Up 23 hours 0.0.0.0:20851->80/tcp wordpressdocker_wordpress_1 b61ce1aedf86 redis "docker-entrypoint.s…" 23 hours ago Up 23 hours 6379/tcp wordpressdocker_redis_1 651734395eb0 mariadb:latest "docker-entrypoint.s…" 23 hours ago Up 23 hours 3306/tcp wordpressdocker_db_1 root@vps298933:~/pandoc-docker#
Open the URL in the browser that it works.