Update README.md

README.md

@@ -3,12 +3,17 @@ aka. GOOGLE_APPLICATION_CREDENTIALS_to_access_token, GOOGLE_APPLICATION_CREDENTI
 
 ## TLDR usage
 Download either executable `google-auth-library-token(.exe)` from `dist`:
-```bash
+
+Windows:
+```cmd
 curl.exe -L https://github.com/Masterxilo/google-auth-library-token/raw/master/dist/google-auth-library-token.exe -o google-auth-library-token.exe
+```
+Linux:
+```bash
 curl -L https://github.com/Masterxilo/google-auth-library-token/raw/master/dist/google-auth-library-token -o google-auth-library-token ; chmod +x ./google-auth-library-token
 ```
 
-Define the environment variable `GOOGLE_APPLICATION_CREDENTIALS` to point to a service account credentials .json file `export GOOGLE_APPLICATION_CREDENTIALS` or `$env:GOOGLE_APPLICATION_CREDENTIALS`, `%GOOGLE_APPLICATION_CREDENTIALS%`, e.g.
+Define the environment variable [`GOOGLE_APPLICATION_CREDENTIALS`](https://cloud.google.com/docs/authentication/application-default-credentials) to point to a service account credentials .json file `export GOOGLE_APPLICATION_CREDENTIALS` or `$env:GOOGLE_APPLICATION_CREDENTIALS`, `%GOOGLE_APPLICATION_CREDENTIALS%`, e.g.
 
 ```bash
 export GOOGLE_APPLICATION_CREDENTIALS="$(realpath GOOGLE_APPLICATION_CREDENTIALS)"
@@ -39,6 +44,7 @@ then run it
 ```bash
 ./google-auth-library-token
 
+
 # or alternatively, using docker
 sudo docker run --rm --volume /:/host --env "GOOGLE_APPLICATION_CREDENTIALS=/host${GOOGLE_APPLICATION_CREDENTIALS}" masterxilo/google-auth-library-token
 ```
@@ -55,6 +61,58 @@ that can be sent to authenticate/authorize the given client to Google APIs via h
 Authorization: Bearer ${access_token}
 ```
 
+# Performance Comparison
+Given a properly configured `GOOGLE_APPLICATION_CREDENTIALS` env variable:
+
+```bash
+$ time gcloud auth application-default print-access-token
+ya29.c.c0ASRK0GYgbQi9-jPK19_NeEPenRviiM7-G3FetLySV_nRT1kdzexKPzwRj-IQpCyAu_T4h8z5BsjQ3eepXIWk5uV8O5wlij2i7oonYh_4QUCQMpP0jDU6Q2q9OcKcacEAvSgTEOJd2aGtzRUj3cKx_UtqP5iOOsD0Ueix-lilAQdistCh26zahKJaZ3_dfDPslOpJDAlG0IUqxrmD0TjfnxFqLLf84VRt2bTuoGh9mcx_HpXMvSkunxGBqDtMLXVHDxg-SCA3UJ3HNtS92ZBbcXiU0RDrRzJjOxTe8MONZ5ggGY.....9wdygyXz9rlVwvJpz1-tpQcmdp2Jv3V7
+
+real    0m0.543s
+user    0m0.422s
+sys     0m0.053s
+
+$ time ./google-auth-library-token 2>/dev/null
+ya29.c.c0ASRK0GYmRff9DmE-vfSSqi4hEsIGZG7JPUZtLK18X_J7kk2kErH8qQjYN3ugNqxTHIkb0AQ2ffy...5qhSbczqZtdBo43V-hi7kR7m-4Uogvc644eBgI2_izl6FJB-YJ8SQF5MS6phB0VRcMUysdSOjX1F3XmmzcrfSs
+
+real    0m0.172s
+user    0m0.079s
+sys     0m0.023s
+
+```
+
+# Troubleshooting
+```
+{
+  error: Error: error:25066067:DSO support routines:dlfcn_load:could not load the shared library
+      at Sign.sign (internal/crypto/sig.js:105:29)
+      at Object.sign (/snapshot/app/node_modules/jwa/index.js:152:45)
+      at Object.jwsSign [as sign] (/snapshot/app/node_modules/jws/lib/sign-stream.js:32:24)
+      at GoogleToken.requestToken (/snapshot/app/node_modules/gtoken/build/src/index.js:225:31)
+      at GoogleToken.getTokenAsyncInner (/snapshot/app/node_modules/gtoken/build/src/index.js:163:21)
+      at GoogleToken.getTokenAsync (/snapshot/app/node_modules/gtoken/build/src/index.js:142:55)
+      at GoogleToken.getToken (/snapshot/app/node_modules/gtoken/build/src/index.js:94:21)
+      at JWT.refreshTokenNoCache (/snapshot/app/node_modules/google-auth-library/build/src/auth/jwtclient.js:171:36)
+      at JWT.refreshToken (/snapshot/app/node_modules/google-auth-library/build/src/auth/oauth2client.js:152:24)
+      at JWT.refreshAccessTokenAsync (/snapshot/app/node_modules/google-auth-library/build/src/auth/oauth2client.js:198:30) {
+    opensslErrorStack: [
+      'error:0E076071:configuration file routines:module_run:unknown module name',
+      'error:0E07506E:configuration file routines:module_load_dso:error loading dso',
+      'error:25070067:DSO support routines:DSO_load:could not load the shared library'
+    ],
+    library: 'DSO support routines',
+    function: 'dlfcn_load',
+    reason: 'could not load the shared library',
+    code: 'ERR_OSSL_DSO_COULD_NOT_LOAD_THE_SHARED_LIBRARY'
+  }
+}
+```
+
+workaround
+```bash
+export OPENSSL_CONF=/dev/null
+```
+
 # Description
 Reads the file pointed to by the GOOGLE_APPLICATION_CREDENTIALS environment variable and obtains a new oauth 2 token for the service client/service account described by it to access Google APIs.
 
@@ -68,7 +126,7 @@ gcloud auth application-default print-access-token
 
 but does not depend on the entire google-cloud-sdk.
 
-## See
+# See
 * https://cloud.google.com/docs/authentication/getting-started
 * https://cloud.google.com/docs/authentication/production