docs: updated readme; added changelog for 1.3

CHANGELOG.md

@@ -0,0 +1,27 @@
+# Invalidate Cloudfront Action Changelog
+
+## v1.3
+
+### Additions
+
+* added PATHS_FROM option for reading invalidation paths from the given file
+
+## v1.2
+
+### Fixes
+
+* Fix invalidation of multiple paths
+
+## v1.1
+
+### Fixes
+
+* invalidation of multiple space-separated paths
+
+### Additions
+
+* added DEBUG="1" flag for extra troubleshooting.
+
+## v1.0
+
+First cut! Works as advertised.

README.md

@@ -73,19 +73,68 @@ jobs:
 
 ```
 
-### Configuration
+## Configuration
 
 Param | Required? | Description
 ----- | --------- | -----------
+PATHS | yes* | A list of one or more space-separated paths to invalidate
+PATHS_FROM | yes* | Filename to read list of paths from
 DISTRIBUTION | yes |  Cloudfront distribution ID to operate on, e.g., 'EDFDVBD6EXAMPLE'
-PATHS | yes | A list of one or more space-separated paths to invalidate
 AWS_REGION | yes | AWS Region to operate in
 AWS_ACCESS_KEY_ID | yes | Access key with necessary permissions to invalidate objects in the target distribution (see below)
 AWS_SECRET_ACCESS_KEY | yes | Secret key
 DEBUG | no | When set to "1", prints the final awscli invalidation command for troubleshooting purposes
 
+__Note__: *either* `PATHS` or `PATHS_FROM` is required. `PATHS_FROM` will
+overwrite `PATHS` if both are set.
+
 See also: [AWS CLI reference](https://docs.aws.amazon.com/cli/latest/reference/cloudfront/create-invalidation.html)
 
+### Paths
+
+Paths are passed directly to the aws cli `create-invalidation` command and so
+must be a proper space-separated list of paths. Examples:
+
+```sh
+PATHS=/index.html
+PATHS=/ /index.html /foo/bar/baz
+```
+
+Alternatively, you can write the list of files to invalidate to a file which
+will then be slurped into the PATHS variable. This lets you use some other
+method to dynamically generate the list of files based on the commit, etc.
+Example workflow steps:
+
+```yaml
+- name: checkout dist
+  uses: actions/checkout@master
+  with:
+    ref: dist
+    # need at least 2 here so we can get a proper log in next step
+    fetch-depth: 2
+
+- name: get updated files
+  run: |
+    # no pipefail so we can allow grep to fail quietly
+    set -e
+    FILES=$(git log --stat="1000" -1 | grep '|' | awk '{print "/"$1}' | grep -e '\.html$')
+    [ -z "$FILES" ] && touch .updated_files && exit 0
+    for file in $FILES; do
+      echo $file
+      # add bare directory to list of updated paths when we see index.html
+      [[ "$file" == *"/index.html" ]] && echo $file | sed -e 's/\/index.html$/\//'
+    done | sort | uniq | tr '\n' ' ' > .updated_filess
+
+- name: invalidate
+  uses: chetan/invalidate-cloudfront-action@master
+  env:
+    PATHS_FROM: .updated_files
+    AWS_REGION: 'us-east-1'
+    DISTRIBUTION: ${{ secrets.DISTRIBUTION }}
+    AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+    AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+```
+
 ### AWS IAM Policy
 
 In order to use this action, you will need to supply an access key pair which has, at minimum, the following permission: