Merge pull request #139 from outlyer-net/pr/api-token-doc-update

API token handling clarification

README.md

@@ -35,7 +35,7 @@ There are different options for using this script.
 - Click on [![Deploy](https://www.herokucdn.com/deploy/button.svg)][heroku]
 - Login to Heroku if not already happened
 - Provide proper values for the `environment variables`
-- **Important: make sure that yor Nightscout API token is hashed with SHA1**
+- **Important: make sure that yor Nightscout API token is [hashed with SHA1](#hashing-api-token)**
 - Click `Deploy` to deploy the app
 
 ### Variant 2: Local
@@ -69,7 +69,7 @@ docker run -e LINK_UP_USERNAME="[email protected]" \
            -e LINK_UP_TIME_INTERVAL="5" \
            -e LINK_UP_REGION="EU" \
            -e NIGHTSCOUT_URL="nightscout.yourdomain.com" \
-           -e NIGHTSCOUT_API_TOKEN="librelinku-123456789abcde" \
+           -e NIGHTSCOUT_API_TOKEN=$(echo -n "foo-bar-baz" | sha1sum | cut -d ' ' -f 1) \
            -e LOG_LEVEL="info" \
            timoschlueter/nightscout-librelink-up
 ```
@@ -92,10 +92,28 @@ services:
       LINK_UP_TIME_INTERVAL: "5"
       LINK_UP_REGION: "DE"
       NIGHTSCOUT_URL: "nightscout.yourdomain.com"
-      NIGHTSCOUT_API_TOKEN: "librelinku-123456789abcde"
+      NIGHTSCOUT_API_TOKEN: "14c779d01a34ad1337ab59c2168e31b141eb2de6"
       LOG_LEVEL: "info"
 ```
 
+### Hashing API token
+
+`NIGHTSCOUT_API_TOKEN` must be a SHA1 hash of an Access Token from Nightscout (_Add new subject_ first in Nightscout's _Admin Tools_ if required), e.g. your Access Token for a subject named _LibreLinkUp_ might be `librelinku-123456789abcde`.
+
+Obtain your hash with
+
+```shell
+echo -n "librelinku-123456789abcde" | sha1sum | cut -d ' ' -f 1
+```
+(use `shasum` instead of `sha1sum` on Mac)
+
+which will print the hash (40 characters in length):
+```
+14c779d01a34ad1337ab59c2168e31b141eb2de6
+```
+
+You might also use an online tool to generate your hash, e.g. https://codebeautify.org/sha1-hash-generator
+
 ## ToDo
 
 - **Integration into Nightscout**: I have not yet looked into the plugin architecture of Nightscout. Maybe this should