chore: add docker example, close #109 (#110)

Author: bahmutov

README.md

@@ -55,6 +55,19 @@ sha: COMMIT_INFO_SHA
 remote: COMMIT_INFO_REMOTE
 ```
 
+### For Docker containers
+
+When running your application inside a Docker container, you should set these environment variables using `-e` syntax.
+
+```shell
+$ docker run \
+  -e COMMIT_INFO_BRANCH=develop \
+  -e COMMIT_INFO_SHA=e5d9eb66474bc0b681da9240aa5a457fe17bc8f3 \
+  <container name>
+```
+
+See [docker-example](docker-example) for a full example.
+
 ## Individual methods
 
 In addition to `commitInfo` this module also exposes individual promise-returning

docker-example/Dockerfile

@@ -0,0 +1,4 @@
+FROM node:alpine
+WORKDIR /app
+COPY index.js /app
+ENTRYPOINT [ "node", "." ]

docker-example/README.md

@@ -0,0 +1,30 @@
+# Docker example
+
+Shows how to pass environment variables with Git commit information when starting a Docker container.
+
+To see the example:
+
+```text
+$ ./build.sh
+...
+
+Successfully built 54bcfe1f016e
+Successfully tagged local/test:latest
+docker-example index.js
+{
+  branch: 'develop',
+  message: 'This is commit message',
+  email: null,
+  author: null,
+  sha: 'e5d9eb66474bc0b681da9240aa5a457fe17bc8f3',
+  remote: null
+}
+```
+
+See [build.sh](build.sh) to see how we are passing the commit values as environment variables.
+
+If you want to see debug messages, run the command with `DEBUG=commit-info` environment variable.
+
+```text
+$ DEBUG=commit-info ./build.sh
+```

docker-example/build.sh

@@ -0,0 +1,19 @@
+set e+x
+
+LOCAL_NAME=local/test
+
+docker build -t $LOCAL_NAME .
+
+# run the example with source code and node_modules
+# mapped from the parent folder
+# pass commit message and branch and sha using environment variable -e
+# you can pass all other COMMIT_INFO_* if needed
+# if the user wants to see debug messages, just pass the environment
+# variable DEBUG as is
+docker run \
+  -v $PWD/../src:/app/src -v $PWD/../node_modules:/app/node_modules \
+  -e COMMIT_INFO_BRANCH=develop \
+  -e COMMIT_INFO_MESSAGE="This is commit message" \
+  -e COMMIT_INFO_SHA=e5d9eb66474bc0b681da9240aa5a457fe17bc8f3 \
+  -e DEBUG \
+  local/test

docker-example/index.js

@@ -0,0 +1,4 @@
+console.log('docker-example index.js')
+
+const { commitInfo } = require('./src')
+commitInfo().then(console.log)