Initial Commit

Global Variables/fhirInterface.js

@@ -0,0 +1,88 @@
+return {
+  getToken() {
+    return new Promise(async (resolve, reject) => {
+      try {
+        getRedisKey = function () {
+          return `fhir-${fhirSettings.jwt.clientId}`;
+        };
+
+        const tokenEntry = await redis.hGetAll(getRedisKey());
+        const currentTimeInSeconds = Math.floor(new Date().getTime() / 1000);
+
+        if (tokenEntry.exp >= currentTimeInSeconds) {
+          resolve(JSON.parse(tokenEntry.token));
+          return;
+        }
+
+        // start the expiry base before we create a new token
+        let expiryInSeconds = Math.floor(new Date().getTime() / 1000);
+
+        // Define headers
+        const headers = {
+          alg: "RS256",
+          typ: "JWT",
+        };
+
+        // Define your payload
+        const payload = {
+          iss: fhirSettings.jwt.client_id,
+          sub: fhirSettings.jwt.client_id,
+          aud: fhirSettings.token_url,
+        };
+
+        // Define token options (optional)
+        const options = {
+          expiresIn: "4m", // Token expires in 1 hour
+          notBefore: "0",
+          algorithm: "RS384",
+          keyid: "iva_id_1234",
+          jwtid: uuidv5("jwtid", fhirSettings.jwt.uuid_namespace),
+        };
+
+        let data = qs.stringify({
+          grant_type: "client_credentials",
+          client_assertion_type:
+            "urn:ietf:params:oauth:client-assertion-type:jwt-bearer",
+          client_assertion: jwt.sign(
+            payload,
+            fhirSettings.jwt.privateKey,
+            options
+          ),
+        });
+
+        let config = {
+          method: "post",
+          maxBodyLength: Infinity,
+          url: fhirSettings.token_url,
+          headers: {
+            "Content-Type": "application/x-www-form-urlencoded",
+          },
+          data: data,
+        };
+
+        const result = await axios(config);
+
+        if (result.status == 200) {
+          expiryInSeconds += result.data.expires_in;
+          console.log(
+            `fhirInterface.getToken: Adding ${getRedisKey()} to redis with expiry=${new Date(
+              expiryInSeconds * 1000
+            )}`
+          );
+          await redis.hSet(getRedisKey(), "exp", expiryInSeconds);
+          await redis.hSet(getRedisKey(), "token", JSON.stringify(result.data));
+          resolve(result.data);
+        } else {
+          reject(result.status);
+        }
+      } catch (err) {
+        console.log("fhirInterface.getToken: Error getting Token");
+        console.log(err);
+        if (err.response) {
+          console.log(err.response.data); // => the response payload
+        }
+        reject(err);
+      }
+    });
+  },
+};

Global Variables/fhirSettings.json

@@ -0,0 +1,10 @@
+{
+  "base_url": "https://fhir.epic.com/interconnect-fhir-oauth/api/FHIR",
+  "token_url": "https://fhir.epic.com/interconnect-fhir-oauth/oauth2/token",
+  "jwt": {
+    "uuid_namespace": "30e3078d-59fe-4151-8571-304c87580209",
+    "client_id": "66eaeb38-c5f7-41cb-8cd3-791efacf25e5",
+    "privateKey": "*****"
+  },
+  "patient_id": "T81lum-5p6QvDR7l6hv7lfE52bAbA2ylWBnv9CZEzNb0B"
+}