Add README for docker compose

docker-compose/README.md

@@ -0,0 +1,59 @@
+# Docker compose for Datomic Database with PostgreSQL backend
+
+## Docker compose file provides
+- Memcached
+- Postgres
+- Init container for Postgres
+  - This container executes migrations needed for Datomic
+- Datomic transactor
+- Init container for Datomic
+  - This container creates a database in Datomic system
+  - This step is needed for the Peer to start
+- Datomic peer
+
+## The configuration variables for docker compose file are in [`.env`](./.env) file
+
+## Usage
+
+### Starting the docker compose 
+1. Start containers
+```bash
+docker compose up --build transactor peer datomic-db-initialization -d
+```
+2. Connect via Datomic peer
+```clojure
+(require '[datomic.api :as d])
+;; nil
+
+(def db-uri (format "datomic:sql://%s?jdbc:postgresql://localhost:5432/datomic?user=datomic&password=datomic" DATOMIC_DB_NAME))
+;; #'user/db-uri
+
+user=> (d/connect db-uri)
+;; #object[datomic.peer.Connection 0x738da6f2 "{:unsent-updates-queue 0, :pending-txes 0, :next-t 1000, :basis-t 66, :index-rev 0, :db-id \"hello-275c1f24-482a-4ae2-86a8-844555f04f46\"}"]
+
+```
+3. Connect via Datomic client
+```clojure
+(require '[datomic.client.api :as dc])
+
+(def client (dd/client {:server-type :peer-server
+                        :access-key "myaccesskey" ;; PEER_ACCESSKEY
+                        :secret "mysecret" ;; PEER_SECRET
+                        :endpoint "localhost:8998"
+                        :validate-hostnames false}))
+;; #'user/client
+
+user=> (dc/connect client {:db-name "test-database"}) ;; DATOMIC_DB_NAME
+{:db-name "hello", :database-id "hello-275c1f24-482a-4ae2-86a8-844555f04f46", :t 66, :next-t 1000, :type :datomic.client/conn}
+
+```
+
+### Stopping the docker compose
+```bash
+docker compose down
+```
+
+### Complete cleanup (persistent volumes would get deleted!!)
+```bash
+docker compose down --remove-orphans -t 1 || true && docker compose down -t 1 || true && docker compose -f docker-compose.yml down --volumes -t 1
+```