Just an script for dealing with modular Dockerfile creation, in absence of a "INCLUDE" directive.
It's as of now a very untested, yolo-crafted script born in a rainy mood Sunday afternoon. If proven useful, I'll be spent time to refine it.
Any text file containing go template syntax.
A special function include permits to specify as argument a path to a file that will be merged into the template.
When a template file is passed, all include directives will be resolved based on the folder the template is located.
Instead, when reading from Stdin, all include directives will use the current directory for resolving relative paths.
-t/-template: path to the template file. If missing, reads from Stdin.
-o/-output: path for the rendered template. If missing, prints to Stdout.
-var=VARNAME=VARVALUE: variables that will be used when rendering the template. Optional. Default VARVALUE is an empty string.
Dockerfile
FROM python:{{ or .version "3.6-slim" }}
COPY . /app
RUN make /app
{{ include "./Dockerfile.deps" -}}
CMD python /app/app.py
Dockerfile.deps
RUN pip install -r requirements.txt
gotempl -t Dockerfile
is equivalent to
cat Dockerfile | gotempl
outputs
FROM python:3.6-slim
COPY . /app
RUN make /app
RUN pip install -r requirements.txt
CMD python /app/app.py
gotempl -t Dockerfile -var=version=3.7-slim
outputs
FROM python:3.7-slim
COPY . /app
RUN make /app
RUN pip install -r requirements.txt
CMD python /app/app.py
go build -ldflags "-s -w"