Basic utilities within Docker images/containers

Known utilities to use/build docker containers/images

Common Functions

A collection of bash functions to make easier common tasks

env_vars_in_file

Write your environment variables into a file.

For instance, suppose you have these vars and want to write them into a file "/conf.properties":

SERVER_TIMEOUT=60
SERVER_URL=https://mysite.com
SERVER_BIND_IP=192.168.10.10

The Dockerfile would be like this:

...
ENV SERVER_TIMEOUT=60 \
    SERVER_URL=https://mysite.com \
    SERVER_BIND_IP=192.168.10.10
...
RUN ["wget", "https://raw.githubusercontent.com/engapa/utils-docker/master/common-functions.sh"]
RUN . common-functions.sh \
    && PREFIX=SERVER_ DEST_FILE='/conf.properties' DEBUG=true env_vars_in_file
...

When we're building the Docker image we find out these lines in the output :

$ docker build -t engapa/common_functions --rm .
...
Step 5/6 : RUN . common-functions.sh && PREFIX=SERVER_ DEST_FILE='/conf.properties' DEBUG=true env_vars_in_file
 ---> Running in 4420331fd948
Writing environment variables to file :

PREFIX           : SERVER_
DEST_FILE        : /conf.properties
EXCLUSIONS       :
CREATE_FILE      : true
OVERRIDE         : true
FROM_SEPARATOR   : _
TO_SEPARATOR     : .
LOWER            : true
.......................................

[  ADD   ] : SERVER_BIND_IP --> bind.ip=192.168.10.10
[  ADD   ] : SERVER_TIMEOUT --> timeout=60
[  ADD   ] : SERVER_URL --> url=https://mysite.com
...
Successfully built c3cee6c14084

So, the contents of file /conf.properties, in a new container created from this image, are the expected:

$ docker run c3cee6c14084 cat /conf.properties
bind.ip=192.168.10.10
timeout=60
url=https://mysite.com

And finally, if you want to change or add any more parameter then launch the container (or extended Dockerfile with 'ENV' entries) like this:

$ docker run -e "SERVER_BIND_IP=0.0.0.0" -e "SERVER_VERIFY_SKIP=True" c3cee6c14084 \
  /bin/bash -c ". common-functions.sh && PREFIX=SERVER_ DEST_FILE='/conf.properties' DEBUG=true env_vars_in_file && cat /conf.properties"

Writing environment variables to file :

PREFIX           : SERVER_
DEST_FILE        : /conf.properties
EXCLUSIONS       :
CREATE_FILE      : true
OVERRIDE         : true
FROM_SEPARATOR   : _
TO_SEPARATOR     : .
LOWER            : true
.......................................

[OVERRIDE] : SERVER_BIND_IP --> bind.ip=0.0.0.0
[  ADD   ] : SERVER_VERIFY_SKIP --> verify.skip=True
[OVERRIDE] : SERVER_TIMEOUT --> timeout=60
[OVERRIDE] : SERVER_URL --> url=https://mysite.com

bind.ip=0.0.0.0
timeout=60
url=https://mysite.com
verify.skip=True

NOTE: Do not forget to remove test containers and image to avoid resource consumption on your host by typing : $ docker rm -f $(docker ps -q -f ancestor=c3cee6c14084) $ docker rmi c3cee6c14084

GitHub Release

If you wonder how to publish a release on github this utility is for you.

Publish a release on GitHub

The gh-release function aims you to publish a release in GitHub.

All-in-One container

If you prefer to use directly a docker container, for instance in your workflow pipelines we may have a step like this one:

$ docker run -it engapa/utils-docker:latest
... Outputs all available functions ...
$ docker run -it engapa/utils-docker:latest log Hello Enk
[INFO] [2019-01-03_08:29:46] -  Hello Enk