Change how services are loaded from the env and add support for legacy

.travis.yml

@@ -1,6 +1,6 @@
 language: go
 
 go:
-  - 1.11
+  - 1.13
 
 script: go build .

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2015-2018 Cash Payment Solutions GmbH
+Copyright (c) 2015-2019 Cash Payment Solutions GmbH
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -1,3 +1,3 @@
 all:
-	docker run --rm -e CGO_ENABLED=0 -v $(CURDIR):/go golang:1.11.2 \
+	docker run --rm -e CGO_ENABLED=0 -v $(CURDIR):/go golang:1.13 \
 		go build -o /go/build/waitforservices

README.md

@@ -2,20 +2,12 @@
 
 A small utility waiting for services linked to a Docker container being ready.
 
-**NOTE**: [Docker link environment variables are deprecated and will be removed](https://docs.docker.com/compose/link-env-deprecated/). We haven't thought about how waitforservices will work then. See [issue 3](https://github.com/Barzahlen/waitforservices/issues/3) for more information. We'd be happy about ideas.
-
-When starting multiple Docker containers at once with containers depending on and [linking to other containers](http://docs.docker.com/userguide/dockerlinks/) (e.g. using [docker compose](https://github.com/docker/compose)), you might want to do some initalization in one container depending on a service in another container already running. E.g. a web application running database migrations on startup (for testing) might need a database service in a separate container to be running, but the database container might need a few seconds until it's started and ready for connections.
-
-In your container startup script, waitforservices allows you to wait for other services to be ready by repeatedly trying to open a TCP connection to all linked services and blocking until it succeeds or times out.
-
-We wrote a [blog post explaining why we built waitforservices how we use it](http://barzahlen.github.io/docker-waitforservices/).
-
 ## Installation
 
 First, install the utility into your image by adding this to your Dockerfile:
 
     RUN curl --location --silent --show-error --fail \
-            https://github.com/Barzahlen/waitforservices/releases/download/v0.5/waitforservices \
+            https://github.com/Barzahlen/waitforservices/releases/download/v0.6/waitforservices \
             > /usr/local/bin/waitforservices && \
         chmod +x /usr/local/bin/waitforservices
 
@@ -25,20 +17,26 @@ Then, during container startup, you can use the `waitforservices` command to wai
 
 ## Usage
 
-Without configuration, it finds all TCP services linked to a Docker container via their [environment variables](http://docs.docker.com/userguide/dockerlinks/#environment-variables) and concurrently and repeatedly tries to open a TCP connection to all of them.
+Without configuration, it finds all TCP services specified by the environement variable declared like _\_HOST and _\_PORT (for exemple POSTGRES_HOST and POSTGRES_PORT) and concurrently and repeatedly tries to open a TCP connection to all of them.
+
+When the _legacy_ option is specified, it finds all TCP services linked to a Docker container via their [environment variables](http://docs.docker.com/userguide/dockerlinks/#environment-variables)
 
 When all connections are successful, it returns. If one or more services aren't ready within a specified timeout (60 seconds by default), it aborts and exits with status 1.
 
 `waitforservices` also supports waiting for an HTTP request to `/` to return a response.
 
     $ ./waitforservice -help
     Usage of ./waitforservices:
-      -httpport=0: wait for an http request if target port is given port
-      -ignoreport=0: don't wait for services on this port to be up
-      -timeout=60: time to wait for all services to be up (seconds)
+      -httpport int  wait for an http request if target port is given port
+      -ignoreport int don't wait for services on this port to be up
+      -legacy use docker link enviroment variables
+      -timeout int time to wait for all services to be up (seconds) (default 60)
+
+    Attempt to connect to all TCP services linked  by the environement variable
+    declared like _HOST and _PORT and wait for them to accept a TCP connection.
 
-    Attempt to connect to all TCP services linked to a Docker container (found
-    via their env vars) and wait for them to accept a TCP connection.
+    When the _legacy_ option is specified, it finds all TCP services linked to
+    a Docker container via their environment variables.
 
     When an <httpport> is specified, for services running on <httpport>, after
     a successful TCP connect, do an HTTP request and wait until it's done. This
@@ -48,9 +46,19 @@ When all connections are successful, it returns. If one or more services aren't
     When timeout is over and TCP connect or HTTP request were unsucecssful, exit
     with status 1.
 
+## Legacy support
+
+**NOTE**: [Docker link environment variables are deprecated and will be removed](https://docs.docker.com/compose/link-env-deprecated/). We haven't thought about how waitforservices will work then. See [issue 3](https://github.com/Barzahlen/waitforservices/issues/3) for more information. We'd be happy about ideas.
+
+When starting multiple Docker containers at once with containers depending on and [linking to other containers](http://docs.docker.com/userguide/dockerlinks/) (e.g. using [docker compose](https://github.com/docker/compose)), you might want to do some initalization in one container depending on a service in another container already running. E.g. a web application running database migrations on startup (for testing) might need a database service in a separate container to be running, but the database container might need a few seconds until it's started and ready for connections.
+
+In your container startup script, waitforservices allows you to wait for other services to be ready by repeatedly trying to open a TCP connection to all linked services and blocking until it succeeds or times out.
+
+We wrote a [blog post explaining why we built waitforservices how we use it](http://barzahlen.github.io/docker-waitforservices/).
+
 ## Contributions
 
-waitforservices' options are pretty limited at the moment (e.g. the `-httpport`  and `-ignoreport` parameters could support multiple ports), so we'd be happy if you create pull requests or report issues.
+waitforservices' options are pretty limited at the moment (e.g. the `-httpport` and `-ignoreport` parameters could support multiple ports), so we'd be happy if you create pull requests or report issues.
 
 ## License
 

main.go

@@ -29,6 +29,7 @@ func (s Service) AddressAndPort() string {
 var timeout = flag.Int64("timeout", 60, "time to wait for all services to be up (seconds)")
 var httpPort = flag.Int("httpport", 0, "wait for an http request if target port is given port")
 var ignorePort = flag.Int("ignoreport", 0, "don't wait for services on this port to be up")
+var legacy = flag.Bool("legacy", false, "use docker link enviroment variables")
 
 func main() {
 	setupUsage()
@@ -78,9 +79,12 @@ func setupUsage() {
 	flag.CommandLine.Usage = func() {
 		flag.Usage()
 		fmt.Fprint(os.Stderr, `
-Attempt to connect to all TCP services linked to a Docker container (found
-via their env vars) and wait for them to accept a TCP connection.
+Attempt to connect to all TCP services linked  by the environement variable
+declared like _HOST and _PORT and wait for them to accept a TCP connection.
 
+When the _legacy_ option is specified, it finds all TCP services linked to
+ a Docker container via their environment variables.
+
 When an <httpport> is specified, for services running on <httpport>, after
 a successful TCP connect, do an HTTP request and wait until it's done. This
 is useful for slow-starting services that only start up when they receive
@@ -94,14 +98,24 @@ with status 1.
 
 func loadServicesFromEnv() []Service {
 	services := make([]Service, 0)
+	hostSuffix := "_HOST"
+	portSuffix := "_PORT"
+	offset := 5
+
+	if *legacy {
+		hostSuffix = "_TCP_ADDR"
+		portSuffix = "_TCP_PORT"
+		offset = 9
+	}
+
 	for _, line := range os.Environ() {
 		keyAndValue := strings.SplitN(line, "=", 2)
 		addrKey := keyAndValue[0]
-		if strings.HasSuffix(addrKey, "_TCP_ADDR") {
+		if strings.HasSuffix(addrKey, hostSuffix) {
 			addr := os.Getenv(addrKey)
-			name := addrKey[:len(addrKey)-9] // cut off "_TCP_ADDR"
+			name := addrKey[:len(addrKey)-offset] // cut off "_HOST"
 
-			portKey := name + "_TCP_PORT"
+			portKey := name + portSuffix
 			portStr := os.Getenv(portKey)
 			port, err := strconv.Atoi(portStr)
 			if err != nil {