Add WORKDIR to Dockerfile to allow mounting charts, expand docs

Currently helm-docs is scanning current directory and walks down the
path, but because binary is in /usr/bin/ then it is a bit inconvenient.
Adding WORKDIR allows to mount there helm charts from the host
and then process them much easier.

Updated docs with example commands.
Add section how to build helm-docs binary on your own.

Signed-off-by: Michał Sochoń <[email protected]>

Author: nvtkaszpir

Dockerfile

@@ -1,5 +1,7 @@
-FROM alpine
+FROM alpine:3.11.5
 
 COPY helm-docs /usr/bin/
 
+WORKDIR /helm-docs
+
 ENTRYPOINT ["helm-docs"]

README.md

@@ -14,7 +14,7 @@ If no template file is provided, the tool has a default internal template that w
 ## Installation
 helm-docs can be installed using [homebrew](https://brew.sh/):
 
-```
+```bash
 brew install norwoodj/tap/helm-docs
 ```
 
@@ -23,13 +23,16 @@ of the tool.
 
 To build from source in this repository:
 
-```
+```bash
 cd cmd/helm-docs
 go build
 ```
 
 
 ## Usage
+
+## Using binary directly
+
 To run and generate documentation into READMEs for all helm charts within or recursively contained by a directory:
 
 ```bash
@@ -41,6 +44,37 @@ helm-docs --dry-run # prints generated documentation to stdout rather than modif
 The tool searches recursively through subdirectories of the current directory for `Chart.yaml` files and generates documentation
 for every chart that it finds.
 
+## Using docker
+
+You can mount directory with charts under `/helm-docs` within container.
+
+Print generated documentation to stdout rather than modifying READMEs:
+
+```bash
+docker run -v "$(pwd):/helm-docs" jnorwood/helm-docs:latest --dry-run
+```
+
+Overwrite READMEs within mounted directory:
+
+```bash
+docker run -v "$(pwd):/helm-docs" jnorwood/helm-docs:latest
+```
+
+Notice: You may need to fix permissions to the created files.
+
+
+# Building from source
+
+Notice that you need to have build chain toolkit for given platform and golang installed.
+Next you may need to export some vars to build standalone, non-linked binary for given platform and architecture:
+
+```bash
+export CGO_ENABLED=0 GOOS=linux GOARCH=amd64
+make clean
+make fmt
+make test
+make
+```
 
 ## Available Templates
 The templates generated by the tool are shown below, and can be included in your `README.md.gotmpl` file like so: