Create branch tag action

.github/workflows/main.yml

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+name: Main
+
+on: [push]
+
+jobs:
+  print_branch_tag:
+    runs-on: ubuntu-latest
+    name: A job to print branch tag
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: ./
+        name: Extract branch tag
+        id: extract
+
+      # Use the output/env from the `extract` step
+      - name: Print the values
+        run: |
+          echo "The branch tag is ${{ steps.extract.outputs.branch_tag }}"
+          echo "or ${{ env.BRANCH_TAG }}"

Dockerfile

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+FROM alpine:3
+
+COPY entrypoint.sh /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]

README.md

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+# Branch tag action
+
+This action returns the valid docker image tag name by extracting the branch from branch name or tag ref and replacing `/` by `-` using [Shell Parameter Expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html)
+
+```
+#refs/heads/feature/add-new-action -> feature-add-new-action
+```
+
+## Inputs
+
+### `ref`
+
+**Required** The name of the branch or tag ref.
+Default is the current branch that runs this action.
+
+## Outputs
+
+### `branch_tag`
+
+The valid branch tag
+
+## Environment variables
+
+### `BRANCH_TAG`
+
+The valid branch tag
+
+## Example usage
+
+```
+uses: nimblehq/branch-tag-action@v1
+# or
+uses: nimblehq/branch-tag-action@v1
+with:
+  ref: 'feature/add-new-action'
+```
+
+### Full workflow
+
+```
+on: [push]
+
+jobs:
+  print_branch_tag:
+    runs-on: ubuntu-latest
+    name: A job to print branch tag
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: nimblehq/branch-tag-action@v1
+        id: extract
+
+      # Use the output/env from the `extract` step
+      - name: Print the values
+        run: |
+          echo "The branch tag is ${{ steps.extract.outputs.branch_tag }}"
+          echo "or ${{ env.BRANCH_TAG }}"
+```

action.yml

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+name: Branch Tag Action
+description: Get branch tag and set to ENV
+inputs:
+  ref:
+    description: 'The branch or tag ref'
+    required: true
+    default: ${{ github.ref }}
+runs:
+  using: docker
+  image: Dockerfile
+  args:
+    - ${{ inputs.ref }}

entrypoint.sh

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+#!/bin/sh -l
+
+BRANCH_NAME="${1#refs/heads/}"
+
+# shellcheck disable=SC2039
+BRANCH_TAG="${BRANCH_NAME/\//-}"
+
+echo "::set-env name=BRANCH_TAG::$BRANCH_TAG"
+echo "::set-output name=branch_tag::$BRANCH_TAG"