I am trying to work with a master + some agents in a single docker cluster orchestrated by docker-compose with Jenkins ver. 2.176.3 under Windows 10 to experiment locally.  

Unfortunately the agents spin up much faster than the master, so they try to connect before the master is ready, which for a docker cluster results in a ConnectException (as the docker daemon handles the connect to the socket, but the instance is not ready yet).   From my reading of the source the initial connect is not try-catch proctected for this, so the retry mechanism does not come into play.

This means that in this case that all the agents fail at startup and has to be started manually afterwards.   For my immediate purposes a "–wait" flag waiting X seconds when starting the agent will be fine (or similar), but perhaps the resilience mechanism needs to incoorporate this usecase too?

```

Sep 17, 2019 9:32:17 AM hudson.remoting.jnlp.Main$CuiListener statuscsr-jenkins-agent-base3_1 | INFO: Locating server among http://docker-images_csr-jenkins_1.local:8080csr-jenkins-agent-base3_1 | Sep 17, 2019 9:32:17 AM hudson.remoting.jnlp.Main$CuiListener errorcsr-jenkins-agent-base3_1 | SEVERE: Failed to connect to http://docker-images_csr-jenkins_1.local:8080/tcpSlaveAgentListener/: Connection refused (Connection refused)
csr-jenkins-agent-base3_1 | java.io.IOException: Failed to connect to http://docker-images_csr-jenkins_1.local:8080/tcpSlaveAgentListener/: Connection refused (Connection refused)
csr-jenkins-agent-base3_1 |
at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.resolve(JnlpAgentEndpointResolver.java:197)
csr-jenkins-agent-base3_1 |
at hudson.remoting.Engine.innerRun(Engine.java:523)
csr-jenkins-agent-base3_1 |
at hudson.remoting.Engine.run(Engine.java:474)
csr-jenkins-agent-base3_1 | Caused by: java.net.ConnectException: Connection refused (Connection refused)
csr-jenkins-agent-base3_1 |
at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
csr-jenkins-agent-base3_1 |
at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
csr-jenkins-agent-base3_1 |
at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
csr-jenkins-agent-base3_1 |
at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
csr-jenkins-agent-base3_1 |
at java.base/java.net.Socket.connect(Socket.java:591)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1242)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1181)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1075)
csr-jenkins-agent-base3_1 |
at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1009)
csr-jenkins-agent-base3_1 |
at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.resolve(JnlpAgentEndpointResolver.java:194)
csr-jenkins-agent-base3_1 | ... 2 more

```