Add support for application_name

.gitignore

@@ -8,3 +8,4 @@ spec/.run_auth_specs
 .cert
 .envrc
 result
+.direnv

spec/pg/connection_spec.cr

@@ -6,6 +6,15 @@ describe PG::Connection, "#initialize" do
       DB.open("postgres://localhost:5433")
     }
   end
+
+  it "set application name" do
+    URI.parse(DB_URL).tap do |uri|
+      uri.query = "application_name=specs"
+      DB.open(uri.to_s) do |db|
+        db.query_one("SHOW application_name", as: String).should eq("specs")
+      end
+    end
+  end
 end
 
 describe PG::Connection, "#on_notice" do

spec/pq/conninfo_spec.cr

@@ -9,6 +9,7 @@ private def assert_default_params(ci)
   ci.password.should eq(nil)
   ci.port.should eq(5432)
   ci.sslmode.should eq(:prefer)
+  ci.application_name.should eq("crystal")
 end
 
 private def assert_custom_params(ci)
@@ -18,6 +19,7 @@ private def assert_custom_params(ci)
   ci.password.should eq("pass")
   ci.port.should eq(5555)
   ci.sslmode.should eq(:require)
+  ci.application_name.should eq("specs")
 end
 
 private def assert_ssl_params(ci)
@@ -36,7 +38,7 @@ describe PQ::ConnInfo, "parts" do
   end
 
   it "can take settings" do
-    ci = PQ::ConnInfo.new("host", "db", "user", "pass", 5555, :require)
+    ci = PQ::ConnInfo.new("host", "db", "user", "pass", 5555, :require, "specs")
     assert_custom_params ci
   end
 end
@@ -51,15 +53,15 @@ describe PQ::ConnInfo, ".from_conninfo_string" do
 
   it "parses postgres urls" do
     ci = PQ::ConnInfo.from_conninfo_string(
-      "postgres://user:pass@host:5555/db?sslmode=require&otherparam=ignore")
+      "postgres://user:pass@host:5555/db?sslmode=require&otherparam=ignore&application_name=specs")
     assert_custom_params ci
 
     ci = PQ::ConnInfo.from_conninfo_string(
       "postgres://user:pass@host:5555/db?sslmode=verify-full&sslcert=postgresql.crt&sslkey=postgresql.key&sslrootcert=root.crt")
     assert_ssl_params ci
 
     ci = PQ::ConnInfo.from_conninfo_string(
-      "postgresql://user:pass@host:5555/db?sslmode=require")
+      "postgresql://user:pass@host:5555/db?sslmode=require&application_name=specs")
     assert_custom_params ci
   end
 
@@ -72,7 +74,7 @@ describe PQ::ConnInfo, ".from_conninfo_string" do
 
   it "parses libpq style strings" do
     ci = PQ::ConnInfo.from_conninfo_string(
-      "host=host dbname=db user=user password=pass port=5555 sslmode=require")
+      "host=host dbname=db user=user password=pass port=5555 sslmode=require application_name=specs")
     assert_custom_params ci
 
     ci = PQ::ConnInfo.from_conninfo_string(
@@ -125,12 +127,14 @@ describe PQ::ConnInfo, ".from_conninfo_string" do
       ENV["PGPASSWORD"] = "C"
       ENV["PGPORT"] = "1"
       ENV["PGUSER"] = "D"
+      ENV["PGAPPNAME"] = "S"
       ci = PQ::ConnInfo.from_conninfo_string("postgres://")
       ci.database.should eq("A")
       ci.host.should eq("B")
       ci.password.should eq("C")
       ci.port.should eq(1)
       ci.user.should eq("D")
+      ci.application_name.should eq("S")
     end
 
     env_var_bubble do

src/pq/connection.cr

@@ -244,7 +244,7 @@ module PQ
       startup_args = [
         "user", @conninfo.user,
         "database", @conninfo.database,
-        "application_name", "crystal",
+        "application_name", @conninfo.application_name,
         "client_encoding", "utf8",
       ]
 

src/pq/conninfo.cr

@@ -35,17 +35,21 @@ module PQ
     # The sslrootcert. Optional.
     getter sslrootcert : String?
 
+    # The application name. Optional (defaults to "crystal").
+    getter application_name : String
+
     getter auth_methods : Array(String) = %w[scram-sha-256-plus scram-sha-256 md5]
 
     # Create a new ConnInfo from all parts
-    def initialize(host : String? = nil, database : String? = nil, user : String? = nil, password : String? = nil, port : Int | String? = nil, sslmode : String | Symbol? = nil)
+    def initialize(host : String? = nil, database : String? = nil, user : String? = nil, password : String? = nil, port : Int | String? = nil, sslmode : String | Symbol? = nil, application_name : String? = nil)
       @host = default_host host
       db = default_database database
       @database = db.lchop('/')
       @user = default_user user
       @port = (port || ENV.fetch("PGPORT", "5432")).to_i
       @sslmode = default_sslmode sslmode
       @password = password || ENV.fetch("PGPASSWORD", PgPass.locate(@host, @port, @database, @user))
+      @application_name = default_application_name application_name
     end
 
     # Initialize with either "postgres://" urls or postgres "key=value" pairs
@@ -71,8 +75,9 @@ module PQ
 
     # Initializes with a `URI`
     def initialize(uri : URI)
-      hostname = uri.hostname.presence || URI::Params.parse(uri.query.to_s).fetch("host", "")
-      initialize(hostname, uri.path, uri.user, uri.password, uri.port, :prefer)
+      params = URI::Params.parse(uri.query.to_s)
+      hostname = uri.hostname.presence || params.fetch("host", "")
+      initialize(hostname, uri.path, uri.user, uri.password, uri.port, :prefer, params.fetch("application_name", nil))
       if q = uri.query
         HTTP::Params.parse(q) do |key, value|
           handle_sslparam(key, value)
@@ -83,10 +88,11 @@ module PQ
     # Initialize with a `Hash`
     #
     # Valid keys match Postgres "conninfo" keys and are `"host"`, `"dbname"`,
-    # `"user"`, `"password"`, `"port"`, `"sslmode"`, `"sslcert"`, `"sslkey"` and `"sslrootcert"`
+    # `"user"`, `"password"`, `"port"`, `"sslmode"`, `"sslcert"`, `"sslkey"`,
+    # `"sslrootcert"` and `"application_name"`.
     def initialize(params : Hash)
       initialize(params["host"]?, params["dbname"]?, params["user"]?,
-        params["password"]?, params["port"]?, params["sslmode"]?)
+        params["password"]?, params["port"]?, params["sslmode"]?, params["application_name"]?)
       params.each do |key, value|
         handle_sslparam(key, value)
       end
@@ -137,6 +143,10 @@ module PQ
       end
     end
 
+    private def default_application_name(application_name, fallback_application_name = "crystal")
+      application_name || ENV.fetch("PGAPPNAME", nil) || fallback_application_name
+    end
+
     private def default_user(u)
       u || ENV.fetch("PGUSER", current_user_name)
     end