support FILE BASED VCAP_SERVICES

[Soontao]

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used patch-package to patch @cap-js-community/mtx-tool@0.10.2 for the project I'm working on.

Here is the diff that solved my problem:

diff --git a/node_modules/@cap-js-community/mtx-tool/src/context.js b/node_modules/@cap-js-community/mtx-tool/src/context.js
index 3e29916..286f385 100644
--- a/node_modules/@cap-js-community/mtx-tool/src/context.js
+++ b/node_modules/@cap-js-community/mtx-tool/src/context.js
@@ -237,7 +237,21 @@ const newContext = async ({ usePersistedCache = true, isReadonlyCommand = false
     const cfBuildpack = cfApp.lifecycle?.data?.buildpacks?.[0];
     const cfEnv = await _cfRequest(cfInfo, `/v3/apps/${cfApp.guid}/env`);
     const [cfProcess] = await _cfRequestPaged(cfInfo, `/v3/apps/${cfApp.guid}/processes`);
-    const cfEnvServices = cfEnv.system_env_json?.VCAP_SERVICES;
+    let cfEnvServices = cfEnv.system_env_json?.VCAP_SERVICES;
+    if (cfEnv.system_env_json.VCAP_SERVICES_FILE_PATH) {
+      // cf ssh <app_name> -c 'cat $VCAP_SERVICES_FILE_PATH'
+      const [stdout, stderr] = await _cfSsh(cfApp.name, { command: `cat $VCAP_SERVICES_FILE_PATH` });
+      assert(!stderr, "got stderr output from cf ssh while reading VCAP_SERVICES_FILE_PATH\n%s", stderr);
+      try {
+        cfEnvServices = JSON.parse(stdout);
+      } catch (err) {
+        return fail(
+          "caught error parsing VCAP_SERVICES_FILE_PATH content from cf ssh:\n%s\ncontent:\n%s",
+          err.message,
+          stdout
+        );
+      }
+    }
     const cfEnvApp = cfEnv.application_env_json?.VCAP_APPLICATION;
     const cfEnvVariables = cfEnv.environment_variables;
 

This issue body was partially generated by patch-package.

[Soontao]

or via cf service credentials binding api

[rlindner81]

I think the right approach here is to avoid the VCAP SERVICES of the app environment entirely.

mtx-tool could access the necessary service credentials through the relevant app service binding directly.
https://v3-apidocs.cloudfoundry.org/version/3.207.0/index.html#service-credential-binding

This will take some more calls, but it's stable and the results will be cached anyways.