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https://github.com/jurajkubelka/docker-exercise
An docker and docker-compose exercise
https://github.com/jurajkubelka/docker-exercise
Last synced: 6 days ago
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An docker and docker-compose exercise
- Host: GitHub
- URL: https://github.com/jurajkubelka/docker-exercise
- Owner: JurajKubelka
- License: mit
- Created: 2021-09-21T15:48:59.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2021-09-22T21:38:00.000Z (over 3 years ago)
- Last Synced: 2024-10-31T13:45:58.357Z (about 2 months ago)
- Language: Shell
- Size: 20.5 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Docker Exercises
An docker and docker-compose exercises.
## nginx with named volume
Create new container listening at 5680:
```shell
docker run -d -v nginx-test-volume:/usr/share/nginx/html -p 5680:80 --name nginx-test nginx:stable
```
If you stop and start again, the same files will be served as they are persisted in the volume called `nginx-test-volume`.
If you remove the `nginx-test` container and creates a new one, files remains persistent in the named volume.
If you remove also the volume, then the served data will be recreated.
### List Volume Files
You can list the data using:
```shell
docker run --rm -v nginx-test-volume:/opt/data:ro ubuntu ls -laR /opt/data
```
### Backup Volume
You can backup the `nginx-test-volume` as follows:
```shell
docker run --rm -v nginx-test-volume:/opt/data:ro -v "$(pwd):/opt/backup" ubuntu tar cvf /opt/backup/backup.tar /opt/data
```
The above snippet works only for local docker contexts due to `$(pwd)` usage that will point to another directory in a remote disk in case of remote contexts. The [docker/backup-volumes.sh](docker/backup-volumes.sh) provides solution that backups locally in any context.
### Restore Volume
You can restore the `nginx-test-volume` as follows:
```shell
docker run --rm -v nginx-test-volume:/opt/data -v "$(pwd):/opt/backup:ro" ubuntu bash -c "cd /opt/data && tar xvf /opt/backup/backup.tar --strip 2"
```
The above snippet works only for local docker contexts due to `$(pwd)` usage that will point to another directory in a remote disk in case of remote contexts. The [docker/restore-volumes.sh](docker/restore-volumes.sh) provides solution that backups locally in any context.
## nginx Dockerfile
The [docker](docker) directory show how to build and run the nginx service with a named volume that contains particular files from [server-files](server-files).
In includes two shell scripts:
- [docker/build-services.sh](docker/build-services.sh): to build a new docker image
- [docker/run-services.sh](docker/run-services.sh): to create and run new docker container, which also includes a backup commands
Notice, that we cannot access [server-files](server-files) from the [docker/web](docker/web) directory. For that reason we copy the directory [server-files](server-files) into the [docker/web](docker/web). When a new image is built, we remove the copied files. I did not find better solution, as the `docker -f docker/web/Dockerfile` from the top directory generates other issues that are reported in several occasions on StackOverflow and yet no satisfactory solution provided. If you have better working solution, please, let me know.
## Updating Named Volume Content
When [server-files](server-files) are updated, the named volume keeps the same old files. To update the existing volume content, we need to create a new container, similar to the backup one, that updates the volume content.
We can update the content using a temporal container. The [docker/update-assets.sh](docker/update-assets.sh) script exemplify such situation, updating `assets` directory.
The fact, that an existing volume content is never updated, suggests that we do not need to copy `cdn/assets` files into the web docker image as we do in [docker/web/Dockerfile](docker/web/Dockerfile).
### Notes
An example of `copy-to-docker-volume` bash function: [copy-to-docker-volume](https://stackoverflow.com/a/68511611/1065654).
Another example creates a `busybox` container to use `docker cp`: [docker cp](https://stackoverflow.com/a/55683656). The problem with `docker cp` command is that it does not remove old files that do not exist anymore in a source file.
## docker-compose
[docker-compose/docker-compose.yml](docker-compose/docker-compose.yml) shows how to define a service that uses the docker image created by [docker/build-services.sh](docker/build-services.sh) and use the existing volume created by [docker/run-services.sh](docker/run-services.sh).
## docker-compose-independent
[docker-compose-independent/docker-compose.yml](docker-compose-independent/docker-compose.yml) shows how to define a service that creates necessary volumes, images, and containers. The `data` service is not necessary and can be replaced by a script execution similar to [docker-compose-independent/update-asserts.sh](docker-compose-independent/update-asserts.sh) that initialize (or update) the volume content.
The `web` service cannot write to the volume. If we allow it, the volume initialization can happen using the `web` service.
## Other Tips
Open shell in docker ubuntu: `docker run -it --rm ubuntu`. With a mounted named volume: `docker run -it --rm -v example-docker-volume:/opt/data ubuntu`.
## Documentation
- [compose file v.3](https://docs.docker.com/compose/compose-file/compose-file-v3/)